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Diffstat (limited to 'Modules/_decimal/libmpdec/mpdecimal.c')
| -rw-r--r-- | Modules/_decimal/libmpdec/mpdecimal.c | 8410 |
1 files changed, 8410 insertions, 0 deletions
diff --git a/Modules/_decimal/libmpdec/mpdecimal.c b/Modules/_decimal/libmpdec/mpdecimal.c new file mode 100644 index 0000000000..21d222277c --- /dev/null +++ b/Modules/_decimal/libmpdec/mpdecimal.c @@ -0,0 +1,8410 @@ +/* + * Copyright (c) 2008-2016 Stefan Krah. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS "AS IS" AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + + +#include "mpdecimal.h" +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <limits.h> +#include <math.h> +#include "basearith.h" +#include "bits.h" +#include "convolute.h" +#include "crt.h" +#include "memory.h" +#include "typearith.h" +#include "umodarith.h" + +#ifdef PPRO + #if defined(_MSC_VER) + #include <float.h> + #pragma fenv_access(on) + #elif !defined(__OpenBSD__) && !defined(__NetBSD__) + /* C99 */ + #include <fenv.h> + #pragma STDC FENV_ACCESS ON + #endif +#endif + + +#if defined(_MSC_VER) + #define ALWAYS_INLINE __forceinline +#elif defined(LEGACY_COMPILER) + #define ALWAYS_INLINE + #undef inline + #define inline +#else + #ifdef TEST_COVERAGE + #define ALWAYS_INLINE + #else + #define ALWAYS_INLINE inline __attribute__ ((always_inline)) + #endif +#endif + + +#define MPD_NEWTONDIV_CUTOFF 1024L + +#define MPD_NEW_STATIC(name, flags, exp, digits, len) \ + mpd_uint_t name##_data[MPD_MINALLOC_MAX]; \ + mpd_t name = {flags|MPD_STATIC|MPD_STATIC_DATA, exp, digits, \ + len, MPD_MINALLOC_MAX, name##_data} + +#define MPD_NEW_CONST(name, flags, exp, digits, len, alloc, initval) \ + mpd_uint_t name##_data[alloc] = {initval}; \ + mpd_t name = {flags|MPD_STATIC|MPD_CONST_DATA, exp, digits, \ + len, alloc, name##_data} + +#define MPD_NEW_SHARED(name, a) \ + mpd_t name = {(a->flags&~MPD_DATAFLAGS)|MPD_STATIC|MPD_SHARED_DATA, \ + a->exp, a->digits, a->len, a->alloc, a->data} + + +static mpd_uint_t data_one[1] = {1}; +static mpd_uint_t data_zero[1] = {0}; +static const mpd_t one = {MPD_STATIC|MPD_CONST_DATA, 0, 1, 1, 1, data_one}; +static const mpd_t minus_one = {MPD_NEG|MPD_STATIC|MPD_CONST_DATA, 0, 1, 1, 1, + data_one}; +static const mpd_t zero = {MPD_STATIC|MPD_CONST_DATA, 0, 1, 1, 1, data_zero}; + +static inline void _mpd_check_exp(mpd_t *dec, const mpd_context_t *ctx, + uint32_t *status); +static void _settriple(mpd_t *result, uint8_t sign, mpd_uint_t a, + mpd_ssize_t exp); +static inline mpd_ssize_t _mpd_real_size(mpd_uint_t *data, mpd_ssize_t size); + +static int _mpd_cmp_abs(const mpd_t *a, const mpd_t *b); + +static void _mpd_qadd(mpd_t *result, const mpd_t *a, const mpd_t *b, + const mpd_context_t *ctx, uint32_t *status); +static inline void _mpd_qmul(mpd_t *result, const mpd_t *a, const mpd_t *b, + const mpd_context_t *ctx, uint32_t *status); +static void _mpd_base_ndivmod(mpd_t *q, mpd_t *r, const mpd_t *a, + const mpd_t *b, uint32_t *status); +static inline void _mpd_qpow_uint(mpd_t *result, const mpd_t *base, + mpd_uint_t exp, uint8_t resultsign, + const mpd_context_t *ctx, uint32_t *status); + +static mpd_uint_t mpd_qsshiftr(mpd_t *result, const mpd_t *a, mpd_ssize_t n); + + +/******************************************************************************/ +/* Version */ +/******************************************************************************/ + +const char * +mpd_version(void) +{ + return MPD_VERSION; +} + + +/******************************************************************************/ +/* Performance critical inline functions */ +/******************************************************************************/ + +#ifdef CONFIG_64 +/* Digits in a word, primarily useful for the most significant word. */ +ALWAYS_INLINE int +mpd_word_digits(mpd_uint_t word) +{ + if (word < mpd_pow10[9]) { + if (word < mpd_pow10[4]) { + if (word < mpd_pow10[2]) { + return (word < mpd_pow10[1]) ? 1 : 2; + } + return (word < mpd_pow10[3]) ? 3 : 4; + } + if (word < mpd_pow10[6]) { + return (word < mpd_pow10[5]) ? 5 : 6; + } + if (word < mpd_pow10[8]) { + return (word < mpd_pow10[7]) ? 7 : 8; + } + return 9; + } + if (word < mpd_pow10[14]) { + if (word < mpd_pow10[11]) { + return (word < mpd_pow10[10]) ? 10 : 11; + } + if (word < mpd_pow10[13]) { + return (word < mpd_pow10[12]) ? 12 : 13; + } + return 14; + } + if (word < mpd_pow10[18]) { + if (word < mpd_pow10[16]) { + return (word < mpd_pow10[15]) ? 15 : 16; + } + return (word < mpd_pow10[17]) ? 17 : 18; + } + + return (word < mpd_pow10[19]) ? 19 : 20; +} +#else +ALWAYS_INLINE int +mpd_word_digits(mpd_uint_t word) +{ + if (word < mpd_pow10[4]) { + if (word < mpd_pow10[2]) { + return (word < mpd_pow10[1]) ? 1 : 2; + } + return (word < mpd_pow10[3]) ? 3 : 4; + } + if (word < mpd_pow10[6]) { + return (word < mpd_pow10[5]) ? 5 : 6; + } + if (word < mpd_pow10[8]) { + return (word < mpd_pow10[7]) ? 7 : 8; + } + + return (word < mpd_pow10[9]) ? 9 : 10; +} +#endif + + +/* Adjusted exponent */ +ALWAYS_INLINE mpd_ssize_t +mpd_adjexp(const mpd_t *dec) +{ + return (dec->exp + dec->digits) - 1; +} + +/* Etiny */ +ALWAYS_INLINE mpd_ssize_t +mpd_etiny(const mpd_context_t *ctx) +{ + return ctx->emin - (ctx->prec - 1); +} + +/* Etop: used for folding down in IEEE clamping */ +ALWAYS_INLINE mpd_ssize_t +mpd_etop(const mpd_context_t *ctx) +{ + return ctx->emax - (ctx->prec - 1); +} + +/* Most significant word */ +ALWAYS_INLINE mpd_uint_t +mpd_msword(const mpd_t *dec) +{ + assert(dec->len > 0); + return dec->data[dec->len-1]; +} + +/* Most significant digit of a word */ +inline mpd_uint_t +mpd_msd(mpd_uint_t word) +{ + int n; + + n = mpd_word_digits(word); + return word / mpd_pow10[n-1]; +} + +/* Least significant digit of a word */ +ALWAYS_INLINE mpd_uint_t +mpd_lsd(mpd_uint_t word) +{ + return word % 10; +} + +/* Coefficient size needed to store 'digits' */ +ALWAYS_INLINE mpd_ssize_t +mpd_digits_to_size(mpd_ssize_t digits) +{ + mpd_ssize_t q, r; + + _mpd_idiv_word(&q, &r, digits, MPD_RDIGITS); + return (r == 0) ? q : q+1; +} + +/* Number of digits in the exponent. Not defined for MPD_SSIZE_MIN. */ +inline int +mpd_exp_digits(mpd_ssize_t exp) +{ + exp = (exp < 0) ? -exp : exp; + return mpd_word_digits(exp); +} + +/* Canonical */ +ALWAYS_INLINE int +mpd_iscanonical(const mpd_t *dec UNUSED) +{ + return 1; +} + +/* Finite */ +ALWAYS_INLINE int +mpd_isfinite(const mpd_t *dec) +{ + return !(dec->flags & MPD_SPECIAL); +} + +/* Infinite */ +ALWAYS_INLINE int +mpd_isinfinite(const mpd_t *dec) +{ + return dec->flags & MPD_INF; +} + +/* NaN */ +ALWAYS_INLINE int +mpd_isnan(const mpd_t *dec) +{ + return dec->flags & (MPD_NAN|MPD_SNAN); +} + +/* Negative */ +ALWAYS_INLINE int +mpd_isnegative(const mpd_t *dec) +{ + return dec->flags & MPD_NEG; +} + +/* Positive */ +ALWAYS_INLINE int +mpd_ispositive(const mpd_t *dec) +{ + return !(dec->flags & MPD_NEG); +} + +/* qNaN */ +ALWAYS_INLINE int +mpd_isqnan(const mpd_t *dec) +{ + return dec->flags & MPD_NAN; +} + +/* Signed */ +ALWAYS_INLINE int +mpd_issigned(const mpd_t *dec) +{ + return dec->flags & MPD_NEG; +} + +/* sNaN */ +ALWAYS_INLINE int +mpd_issnan(const mpd_t *dec) +{ + return dec->flags & MPD_SNAN; +} + +/* Special */ +ALWAYS_INLINE int +mpd_isspecial(const mpd_t *dec) +{ + return dec->flags & MPD_SPECIAL; +} + +/* Zero */ +ALWAYS_INLINE int +mpd_iszero(const mpd_t *dec) +{ + return !mpd_isspecial(dec) && mpd_msword(dec) == 0; +} + +/* Test for zero when specials have been ruled out already */ +ALWAYS_INLINE int +mpd_iszerocoeff(const mpd_t *dec) +{ + return mpd_msword(dec) == 0; +} + +/* Normal */ +inline int +mpd_isnormal(const mpd_t *dec, const mpd_context_t *ctx) +{ + if (mpd_isspecial(dec)) return 0; + if (mpd_iszerocoeff(dec)) return 0; + + return mpd_adjexp(dec) >= ctx->emin; +} + +/* Subnormal */ +inline int +mpd_issubnormal(const mpd_t *dec, const mpd_context_t *ctx) +{ + if (mpd_isspecial(dec)) return 0; + if (mpd_iszerocoeff(dec)) return 0; + + return mpd_adjexp(dec) < ctx->emin; +} + +/* Odd word */ +ALWAYS_INLINE int +mpd_isoddword(mpd_uint_t word) +{ + return word & 1; +} + +/* Odd coefficient */ +ALWAYS_INLINE int +mpd_isoddcoeff(const mpd_t *dec) +{ + return mpd_isoddword(dec->data[0]); +} + +/* 0 if dec is positive, 1 if dec is negative */ +ALWAYS_INLINE uint8_t +mpd_sign(const mpd_t *dec) +{ + return dec->flags & MPD_NEG; +} + +/* 1 if dec is positive, -1 if dec is negative */ +ALWAYS_INLINE int +mpd_arith_sign(const mpd_t *dec) +{ + return 1 - 2 * mpd_isnegative(dec); +} + +/* Radix */ +ALWAYS_INLINE long +mpd_radix(void) +{ + return 10; +} + +/* Dynamic decimal */ +ALWAYS_INLINE int +mpd_isdynamic(const mpd_t *dec) +{ + return !(dec->flags & MPD_STATIC); +} + +/* Static decimal */ +ALWAYS_INLINE int +mpd_isstatic(const mpd_t *dec) +{ + return dec->flags & MPD_STATIC; +} + +/* Data of decimal is dynamic */ +ALWAYS_INLINE int +mpd_isdynamic_data(const mpd_t *dec) +{ + return !(dec->flags & MPD_DATAFLAGS); +} + +/* Data of decimal is static */ +ALWAYS_INLINE int +mpd_isstatic_data(const mpd_t *dec) +{ + return dec->flags & MPD_STATIC_DATA; +} + +/* Data of decimal is shared */ +ALWAYS_INLINE int +mpd_isshared_data(const mpd_t *dec) +{ + return dec->flags & MPD_SHARED_DATA; +} + +/* Data of decimal is const */ +ALWAYS_INLINE int +mpd_isconst_data(const mpd_t *dec) +{ + return dec->flags & MPD_CONST_DATA; +} + + +/******************************************************************************/ +/* Inline memory handling */ +/******************************************************************************/ + +/* Fill destination with zeros */ +ALWAYS_INLINE void +mpd_uint_zero(mpd_uint_t *dest, mpd_size_t len) +{ + mpd_size_t i; + + for (i = 0; i < len; i++) { + dest[i] = 0; + } +} + +/* Free a decimal */ +ALWAYS_INLINE void +mpd_del(mpd_t *dec) +{ + if (mpd_isdynamic_data(dec)) { + mpd_free(dec->data); + } + if (mpd_isdynamic(dec)) { + mpd_free(dec); + } +} + +/* + * Resize the coefficient. Existing data up to 'nwords' is left untouched. + * Return 1 on success, 0 otherwise. + * + * Input invariant: MPD_MINALLOC <= result->alloc. + * + * Case nwords == result->alloc: + * 'result' is unchanged. Return 1. + * + * Case nwords > result->alloc: + * Case realloc success: + * The value of 'result' does not change. Return 1. + * Case realloc failure: + * 'result' is NaN, status is updated with MPD_Malloc_error. Return 0. + * + * Case nwords < result->alloc: + * Case is_static_data or realloc failure [1]: + * 'result' is unchanged. Return 1. + * Case realloc success: + * The value of result is undefined (expected). Return 1. + * + * + * [1] In that case the old (now oversized) area is still valid. + */ +ALWAYS_INLINE int +mpd_qresize(mpd_t *result, mpd_ssize_t nwords, uint32_t *status) +{ + assert(!mpd_isconst_data(result)); /* illegal operation for a const */ + assert(!mpd_isshared_data(result)); /* illegal operation for a shared */ + assert(MPD_MINALLOC <= result->alloc); + + nwords = (nwords <= MPD_MINALLOC) ? MPD_MINALLOC : nwords; + if (nwords == result->alloc) { + return 1; + } + if (mpd_isstatic_data(result)) { + if (nwords > result->alloc) { + return mpd_switch_to_dyn(result, nwords, status); + } + return 1; + } + + return mpd_realloc_dyn(result, nwords, status); +} + +/* Same as mpd_qresize, but the complete coefficient (including the old + * memory area!) is initialized to zero. */ +ALWAYS_INLINE int +mpd_qresize_zero(mpd_t *result, mpd_ssize_t nwords, uint32_t *status) +{ + assert(!mpd_isconst_data(result)); /* illegal operation for a const */ + assert(!mpd_isshared_data(result)); /* illegal operation for a shared */ + assert(MPD_MINALLOC <= result->alloc); + + nwords = (nwords <= MPD_MINALLOC) ? MPD_MINALLOC : nwords; + if (nwords != result->alloc) { + if (mpd_isstatic_data(result)) { + if (nwords > result->alloc) { + return mpd_switch_to_dyn_zero(result, nwords, status); + } + } + else if (!mpd_realloc_dyn(result, nwords, status)) { + return 0; + } + } + + mpd_uint_zero(result->data, nwords); + return 1; +} + +/* + * Reduce memory size for the coefficient to MPD_MINALLOC. In theory, + * realloc may fail even when reducing the memory size. But in that case + * the old memory area is always big enough, so checking for MPD_Malloc_error + * is not imperative. + */ +ALWAYS_INLINE void +mpd_minalloc(mpd_t *result) +{ + assert(!mpd_isconst_data(result)); /* illegal operation for a const */ + assert(!mpd_isshared_data(result)); /* illegal operation for a shared */ + + if (!mpd_isstatic_data(result) && result->alloc > MPD_MINALLOC) { + uint8_t err = 0; + result->data = mpd_realloc(result->data, MPD_MINALLOC, + sizeof *result->data, &err); + if (!err) { + result->alloc = MPD_MINALLOC; + } + } +} + +int +mpd_resize(mpd_t *result, mpd_ssize_t nwords, mpd_context_t *ctx) +{ + uint32_t status = 0; + if (!mpd_qresize(result, nwords, &status)) { + mpd_addstatus_raise(ctx, status); + return 0; + } + return 1; +} + +int +mpd_resize_zero(mpd_t *result, mpd_ssize_t nwords, mpd_context_t *ctx) +{ + uint32_t status = 0; + if (!mpd_qresize_zero(result, nwords, &status)) { + mpd_addstatus_raise(ctx, status); + return 0; + } + return 1; +} + + +/******************************************************************************/ +/* Set attributes of a decimal */ +/******************************************************************************/ + +/* Set digits. Assumption: result->len is initialized and > 0. */ +inline void +mpd_setdigits(mpd_t *result) +{ + mpd_ssize_t wdigits = mpd_word_digits(mpd_msword(result)); + result->digits = wdigits + (result->len-1) * MPD_RDIGITS; +} + +/* Set sign */ +ALWAYS_INLINE void +mpd_set_sign(mpd_t *result, uint8_t sign) +{ + result->flags &= ~MPD_NEG; + result->flags |= sign; +} + +/* Copy sign from another decimal */ +ALWAYS_INLINE void +mpd_signcpy(mpd_t *result, const mpd_t *a) +{ + uint8_t sign = a->flags&MPD_NEG; + + result->flags &= ~MPD_NEG; + result->flags |= sign; +} + +/* Set infinity */ +ALWAYS_INLINE void +mpd_set_infinity(mpd_t *result) +{ + result->flags &= ~MPD_SPECIAL; + result->flags |= MPD_INF; +} + +/* Set qNaN */ +ALWAYS_INLINE void +mpd_set_qnan(mpd_t *result) +{ + result->flags &= ~MPD_SPECIAL; + result->flags |= MPD_NAN; +} + +/* Set sNaN */ +ALWAYS_INLINE void +mpd_set_snan(mpd_t *result) +{ + result->flags &= ~MPD_SPECIAL; + result->flags |= MPD_SNAN; +} + +/* Set to negative */ +ALWAYS_INLINE void +mpd_set_negative(mpd_t *result) +{ + result->flags |= MPD_NEG; +} + +/* Set to positive */ +ALWAYS_INLINE void +mpd_set_positive(mpd_t *result) +{ + result->flags &= ~MPD_NEG; +} + +/* Set to dynamic */ +ALWAYS_INLINE void +mpd_set_dynamic(mpd_t *result) +{ + result->flags &= ~MPD_STATIC; +} + +/* Set to static */ +ALWAYS_INLINE void +mpd_set_static(mpd_t *result) +{ + result->flags |= MPD_STATIC; +} + +/* Set data to dynamic */ +ALWAYS_INLINE void +mpd_set_dynamic_data(mpd_t *result) +{ + result->flags &= ~MPD_DATAFLAGS; +} + +/* Set data to static */ +ALWAYS_INLINE void +mpd_set_static_data(mpd_t *result) +{ + result->flags &= ~MPD_DATAFLAGS; + result->flags |= MPD_STATIC_DATA; +} + +/* Set data to shared */ +ALWAYS_INLINE void +mpd_set_shared_data(mpd_t *result) +{ + result->flags &= ~MPD_DATAFLAGS; + result->flags |= MPD_SHARED_DATA; +} + +/* Set data to const */ +ALWAYS_INLINE void +mpd_set_const_data(mpd_t *result) +{ + result->flags &= ~MPD_DATAFLAGS; + result->flags |= MPD_CONST_DATA; +} + +/* Clear flags, preserving memory attributes. */ +ALWAYS_INLINE void +mpd_clear_flags(mpd_t *result) +{ + result->flags &= (MPD_STATIC|MPD_DATAFLAGS); +} + +/* Set flags, preserving memory attributes. */ +ALWAYS_INLINE void +mpd_set_flags(mpd_t *result, uint8_t flags) +{ + result->flags &= (MPD_STATIC|MPD_DATAFLAGS); + result->flags |= flags; +} + +/* Copy flags, preserving memory attributes of result. */ +ALWAYS_INLINE void +mpd_copy_flags(mpd_t *result, const mpd_t *a) +{ + uint8_t aflags = a->flags; + result->flags &= (MPD_STATIC|MPD_DATAFLAGS); + result->flags |= (aflags & ~(MPD_STATIC|MPD_DATAFLAGS)); +} + +/* Initialize a workcontext from ctx. Set traps, flags and newtrap to 0. */ +static inline void +mpd_workcontext(mpd_context_t *workctx, const mpd_context_t *ctx) +{ + workctx->prec = ctx->prec; + workctx->emax = ctx->emax; + workctx->emin = ctx->emin; + workctx->round = ctx->round; + workctx->traps = 0; + workctx->status = 0; + workctx->newtrap = 0; + workctx->clamp = ctx->clamp; + workctx->allcr = ctx->allcr; +} + + +/******************************************************************************/ +/* Getting and setting parts of decimals */ +/******************************************************************************/ + +/* Flip the sign of a decimal */ +static inline void +_mpd_negate(mpd_t *dec) +{ + dec->flags ^= MPD_NEG; +} + +/* Set coefficient to zero */ +void +mpd_zerocoeff(mpd_t *result) +{ + mpd_minalloc(result); + result->digits = 1; + result->len = 1; + result->data[0] = 0; +} + +/* Set the coefficient to all nines. */ +void +mpd_qmaxcoeff(mpd_t *result, const mpd_context_t *ctx, uint32_t *status) +{ + mpd_ssize_t len, r; + + _mpd_idiv_word(&len, &r, ctx->prec, MPD_RDIGITS); + len = (r == 0) ? len : len+1; + + if (!mpd_qresize(result, len, status)) { + return; + } + + result->len = len; + result->digits = ctx->prec; + + --len; + if (r > 0) { + result->data[len--] = mpd_pow10[r]-1; + } + for (; len >= 0; --len) { + result->data[len] = MPD_RADIX-1; + } +} + +/* + * Cut off the most significant digits so that the rest fits in ctx->prec. + * Cannot fail. + */ +static void +_mpd_cap(mpd_t *result, const mpd_context_t *ctx) +{ + uint32_t dummy; + mpd_ssize_t len, r; + + if (result->len > 0 && result->digits > ctx->prec) { + _mpd_idiv_word(&len, &r, ctx->prec, MPD_RDIGITS); + len = (r == 0) ? len : len+1; + + if (r != 0) { + result->data[len-1] %= mpd_pow10[r]; + } + + len = _mpd_real_size(result->data, len); + /* resize to fewer words cannot fail */ + mpd_qresize(result, len, &dummy); + result->len = len; + mpd_setdigits(result); + } + if (mpd_iszero(result)) { + _settriple(result, mpd_sign(result), 0, result->exp); + } +} + +/* + * Cut off the most significant digits of a NaN payload so that the rest + * fits in ctx->prec - ctx->clamp. Cannot fail. + */ +static void +_mpd_fix_nan(mpd_t *result, const mpd_context_t *ctx) +{ + uint32_t dummy; + mpd_ssize_t prec; + mpd_ssize_t len, r; + + prec = ctx->prec - ctx->clamp; + if (result->len > 0 && result->digits > prec) { + if (prec == 0) { + mpd_minalloc(result); + result->len = result->digits = 0; + } + else { + _mpd_idiv_word(&len, &r, prec, MPD_RDIGITS); + len = (r == 0) ? len : len+1; + + if (r != 0) { + result->data[len-1] %= mpd_pow10[r]; + } + + len = _mpd_real_size(result->data, len); + /* resize to fewer words cannot fail */ + mpd_qresize(result, len, &dummy); + result->len = len; + mpd_setdigits(result); + if (mpd_iszerocoeff(result)) { + /* NaN0 is not a valid representation */ + result->len = result->digits = 0; + } + } + } +} + +/* + * Get n most significant digits from a decimal, where 0 < n <= MPD_UINT_DIGITS. + * Assumes MPD_UINT_DIGITS == MPD_RDIGITS+1, which is true for 32 and 64 bit + * machines. + * + * The result of the operation will be in lo. If the operation is impossible, + * hi will be nonzero. This is used to indicate an error. + */ +static inline void +_mpd_get_msdigits(mpd_uint_t *hi, mpd_uint_t *lo, const mpd_t *dec, + unsigned int n) +{ + mpd_uint_t r, tmp; + + assert(0 < n && n <= MPD_RDIGITS+1); + + _mpd_div_word(&tmp, &r, dec->digits, MPD_RDIGITS); + r = (r == 0) ? MPD_RDIGITS : r; /* digits in the most significant word */ + + *hi = 0; + *lo = dec->data[dec->len-1]; + if (n <= r) { + *lo /= mpd_pow10[r-n]; + } + else if (dec->len > 1) { + /* at this point 1 <= r < n <= MPD_RDIGITS+1 */ + _mpd_mul_words(hi, lo, *lo, mpd_pow10[n-r]); + tmp = dec->data[dec->len-2] / mpd_pow10[MPD_RDIGITS-(n-r)]; + *lo = *lo + tmp; + if (*lo < tmp) (*hi)++; + } +} + + +/******************************************************************************/ +/* Gathering information about a decimal */ +/******************************************************************************/ + +/* The real size of the coefficient without leading zero words. */ +static inline mpd_ssize_t +_mpd_real_size(mpd_uint_t *data, mpd_ssize_t size) +{ + while (size > 1 && data[size-1] == 0) { + size--; + } + + return size; +} + +/* Return number of trailing zeros. No errors are possible. */ +mpd_ssize_t +mpd_trail_zeros(const mpd_t *dec) +{ + mpd_uint_t word; + mpd_ssize_t i, tz = 0; + + for (i=0; i < dec->len; ++i) { + if (dec->data[i] != 0) { + word = dec->data[i]; + tz = i * MPD_RDIGITS; + while (word % 10 == 0) { + word /= 10; + tz++; + } + break; + } + } + + return tz; +} + +/* Integer: Undefined for specials */ +static int +_mpd_isint(const mpd_t *dec) +{ + mpd_ssize_t tz; + + if (mpd_iszerocoeff(dec)) { + return 1; + } + + tz = mpd_trail_zeros(dec); + return (dec->exp + tz >= 0); +} + +/* Integer */ +int +mpd_isinteger(const mpd_t *dec) +{ + if (mpd_isspecial(dec)) { + return 0; + } + return _mpd_isint(dec); +} + +/* Word is a power of 10 */ +static int +mpd_word_ispow10(mpd_uint_t word) +{ + int n; + + n = mpd_word_digits(word); + if (word == mpd_pow10[n-1]) { + return 1; + } + + return 0; +} + +/* Coefficient is a power of 10 */ +static int +mpd_coeff_ispow10(const mpd_t *dec) +{ + if (mpd_word_ispow10(mpd_msword(dec))) { + if (_mpd_isallzero(dec->data, dec->len-1)) { + return 1; + } + } + + return 0; +} + +/* All digits of a word are nines */ +static int +mpd_word_isallnine(mpd_uint_t word) +{ + int n; + + n = mpd_word_digits(word); + if (word == mpd_pow10[n]-1) { + return 1; + } + + return 0; +} + +/* All digits of the coefficient are nines */ +static int +mpd_coeff_isallnine(const mpd_t *dec) +{ + if (mpd_word_isallnine(mpd_msword(dec))) { + if (_mpd_isallnine(dec->data, dec->len-1)) { + return 1; + } + } + + return 0; +} + +/* Odd decimal: Undefined for non-integers! */ +int +mpd_isodd(const mpd_t *dec) +{ + mpd_uint_t q, r; + assert(mpd_isinteger(dec)); + if (mpd_iszerocoeff(dec)) return 0; + if (dec->exp < 0) { + _mpd_div_word(&q, &r, -dec->exp, MPD_RDIGITS); + q = dec->data[q] / mpd_pow10[r]; + return mpd_isoddword(q); + } + return dec->exp == 0 && mpd_isoddword(dec->data[0]); +} + +/* Even: Undefined for non-integers! */ +int +mpd_iseven(const mpd_t *dec) +{ + return !mpd_isodd(dec); +} + +/******************************************************************************/ +/* Getting and setting decimals */ +/******************************************************************************/ + +/* Internal function: Set a static decimal from a triple, no error checking. */ +static void +_ssettriple(mpd_t *result, uint8_t sign, mpd_uint_t a, mpd_ssize_t exp) +{ + mpd_set_flags(result, sign); + result->exp = exp; + _mpd_div_word(&result->data[1], &result->data[0], a, MPD_RADIX); + result->len = (result->data[1] == 0) ? 1 : 2; + mpd_setdigits(result); +} + +/* Internal function: Set a decimal from a triple, no error checking. */ +static void +_settriple(mpd_t *result, uint8_t sign, mpd_uint_t a, mpd_ssize_t exp) +{ + mpd_minalloc(result); + mpd_set_flags(result, sign); + result->exp = exp; + _mpd_div_word(&result->data[1], &result->data[0], a, MPD_RADIX); + result->len = (result->data[1] == 0) ? 1 : 2; + mpd_setdigits(result); +} + +/* Set a special number from a triple */ +void +mpd_setspecial(mpd_t *result, uint8_t sign, uint8_t type) +{ + mpd_minalloc(result); + result->flags &= ~(MPD_NEG|MPD_SPECIAL); + result->flags |= (sign|type); + result->exp = result->digits = result->len = 0; +} + +/* Set result of NaN with an error status */ +void +mpd_seterror(mpd_t *result, uint32_t flags, uint32_t *status) +{ + mpd_minalloc(result); + mpd_set_qnan(result); + mpd_set_positive(result); + result->exp = result->digits = result->len = 0; + *status |= flags; +} + +/* quietly set a static decimal from an mpd_ssize_t */ +void +mpd_qsset_ssize(mpd_t *result, mpd_ssize_t a, const mpd_context_t *ctx, + uint32_t *status) +{ + mpd_uint_t u; + uint8_t sign = MPD_POS; + + if (a < 0) { + if (a == MPD_SSIZE_MIN) { + u = (mpd_uint_t)MPD_SSIZE_MAX + + (-(MPD_SSIZE_MIN+MPD_SSIZE_MAX)); + } + else { + u = -a; + } + sign = MPD_NEG; + } + else { + u = a; + } + _ssettriple(result, sign, u, 0); + mpd_qfinalize(result, ctx, status); +} + +/* quietly set a static decimal from an mpd_uint_t */ +void +mpd_qsset_uint(mpd_t *result, mpd_uint_t a, const mpd_context_t *ctx, + uint32_t *status) +{ + _ssettriple(result, MPD_POS, a, 0); + mpd_qfinalize(result, ctx, status); +} + +/* quietly set a static decimal from an int32_t */ +void +mpd_qsset_i32(mpd_t *result, int32_t a, const mpd_context_t *ctx, + uint32_t *status) +{ + mpd_qsset_ssize(result, a, ctx, status); +} + +/* quietly set a static decimal from a uint32_t */ +void +mpd_qsset_u32(mpd_t *result, uint32_t a, const mpd_context_t *ctx, + uint32_t *status) +{ + mpd_qsset_uint(result, a, ctx, status); +} + +#ifdef CONFIG_64 +/* quietly set a static decimal from an int64_t */ +void +mpd_qsset_i64(mpd_t *result, int64_t a, const mpd_context_t *ctx, + uint32_t *status) +{ + mpd_qsset_ssize(result, a, ctx, status); +} + +/* quietly set a static decimal from a uint64_t */ +void +mpd_qsset_u64(mpd_t *result, uint64_t a, const mpd_context_t *ctx, + uint32_t *status) +{ + mpd_qsset_uint(result, a, ctx, status); +} +#endif + +/* quietly set a decimal from an mpd_ssize_t */ +void +mpd_qset_ssize(mpd_t *result, mpd_ssize_t a, const mpd_context_t *ctx, + uint32_t *status) +{ + mpd_minalloc(result); + mpd_qsset_ssize(result, a, ctx, status); +} + +/* quietly set a decimal from an mpd_uint_t */ +void +mpd_qset_uint(mpd_t *result, mpd_uint_t a, const mpd_context_t *ctx, + uint32_t *status) +{ + _settriple(result, MPD_POS, a, 0); + mpd_qfinalize(result, ctx, status); +} + +/* quietly set a decimal from an int32_t */ +void +mpd_qset_i32(mpd_t *result, int32_t a, const mpd_context_t *ctx, + uint32_t *status) +{ + mpd_qset_ssize(result, a, ctx, status); +} + +/* quietly set a decimal from a uint32_t */ +void +mpd_qset_u32(mpd_t *result, uint32_t a, const mpd_context_t *ctx, + uint32_t *status) +{ + mpd_qset_uint(result, a, ctx, status); +} + +#if defined(CONFIG_32) && !defined(LEGACY_COMPILER) +/* set a decimal from a uint64_t */ +static void +_c32setu64(mpd_t *result, uint64_t u, uint8_t sign, uint32_t *status) +{ + mpd_uint_t w[3]; + uint64_t q; + int i, len; + + len = 0; + do { + q = u / MPD_RADIX; + w[len] = (mpd_uint_t)(u - q * MPD_RADIX); + u = q; len++; + } while (u != 0); + + if (!mpd_qresize(result, len, status)) { + return; + } + for (i = 0; i < len; i++) { + result->data[i] = w[i]; + } + + mpd_set_sign(result, sign); + result->exp = 0; + result->len = len; + mpd_setdigits(result); +} + +static void +_c32_qset_u64(mpd_t *result, uint64_t a, const mpd_context_t *ctx, + uint32_t *status) +{ + _c32setu64(result, a, MPD_POS, status); + mpd_qfinalize(result, ctx, status); +} + +/* set a decimal from an int64_t */ +static void +_c32_qset_i64(mpd_t *result, int64_t a, const mpd_context_t *ctx, + uint32_t *status) +{ + uint64_t u; + uint8_t sign = MPD_POS; + + if (a < 0) { + if (a == INT64_MIN) { + u = (uint64_t)INT64_MAX + (-(INT64_MIN+INT64_MAX)); + } + else { + u = -a; + } + sign = MPD_NEG; + } + else { + u = a; + } + _c32setu64(result, u, sign, status); + mpd_qfinalize(result, ctx, status); +} +#endif /* CONFIG_32 && !LEGACY_COMPILER */ + +#ifndef LEGACY_COMPILER +/* quietly set a decimal from an int64_t */ +void +mpd_qset_i64(mpd_t *result, int64_t a, const mpd_context_t *ctx, + uint32_t *status) +{ +#ifdef CONFIG_64 + mpd_qset_ssize(result, a, ctx, status); +#else + _c32_qset_i64(result, a, ctx, status); +#endif +} + +/* quietly set a decimal from a uint64_t */ +void +mpd_qset_u64(mpd_t *result, uint64_t a, const mpd_context_t *ctx, + uint32_t *status) +{ +#ifdef CONFIG_64 + mpd_qset_uint(result, a, ctx, status); +#else + _c32_qset_u64(result, a, ctx, status); +#endif +} +#endif /* !LEGACY_COMPILER */ + + +/* + * Quietly get an mpd_uint_t from a decimal. Assumes + * MPD_UINT_DIGITS == MPD_RDIGITS+1, which is true for + * 32 and 64 bit machines. + * + * If the operation is impossible, MPD_Invalid_operation is set. + */ +static mpd_uint_t +_mpd_qget_uint(int use_sign, const mpd_t *a, uint32_t *status) +{ + mpd_t tmp; + mpd_uint_t tmp_data[2]; + mpd_uint_t lo, hi; + + if (mpd_isspecial(a)) { + *status |= MPD_Invalid_operation; + return MPD_UINT_MAX; + } + if (mpd_iszero(a)) { + return 0; + } + if (use_sign && mpd_isnegative(a)) { + *status |= MPD_Invalid_operation; + return MPD_UINT_MAX; + } + + if (a->digits+a->exp > MPD_RDIGITS+1) { + *status |= MPD_Invalid_operation; + return MPD_UINT_MAX; + } + + if (a->exp < 0) { + if (!_mpd_isint(a)) { + *status |= MPD_Invalid_operation; + return MPD_UINT_MAX; + } + /* At this point a->digits+a->exp <= MPD_RDIGITS+1, + * so the shift fits. */ + tmp.data = tmp_data; + tmp.flags = MPD_STATIC|MPD_STATIC_DATA; + tmp.alloc = 2; + mpd_qsshiftr(&tmp, a, -a->exp); + tmp.exp = 0; + a = &tmp; + } + + _mpd_get_msdigits(&hi, &lo, a, MPD_RDIGITS+1); + if (hi) { + *status |= MPD_Invalid_operation; + return MPD_UINT_MAX; + } + + if (a->exp > 0) { + _mpd_mul_words(&hi, &lo, lo, mpd_pow10[a->exp]); + if (hi) { + *status |= MPD_Invalid_operation; + return MPD_UINT_MAX; + } + } + + return lo; +} + +/* + * Sets Invalid_operation for: + * - specials + * - negative numbers (except negative zero) + * - non-integers + * - overflow + */ +mpd_uint_t +mpd_qget_uint(const mpd_t *a, uint32_t *status) +{ + return _mpd_qget_uint(1, a, status); +} + +/* Same as above, but gets the absolute value, i.e. the sign is ignored. */ +mpd_uint_t +mpd_qabs_uint(const mpd_t *a, uint32_t *status) +{ + return _mpd_qget_uint(0, a, status); +} + +/* quietly get an mpd_ssize_t from a decimal */ +mpd_ssize_t +mpd_qget_ssize(const mpd_t *a, uint32_t *status) +{ + mpd_uint_t u; + int isneg; + + u = mpd_qabs_uint(a, status); + if (*status&MPD_Invalid_operation) { + return MPD_SSIZE_MAX; + } + + isneg = mpd_isnegative(a); + if (u <= MPD_SSIZE_MAX) { + return isneg ? -((mpd_ssize_t)u) : (mpd_ssize_t)u; + } + else if (isneg && u+(MPD_SSIZE_MIN+MPD_SSIZE_MAX) == MPD_SSIZE_MAX) { + return MPD_SSIZE_MIN; + } + + *status |= MPD_Invalid_operation; + return MPD_SSIZE_MAX; +} + +#if defined(CONFIG_32) && !defined(LEGACY_COMPILER) +/* + * Quietly get a uint64_t from a decimal. If the operation is impossible, + * MPD_Invalid_operation is set. + */ +static uint64_t +_c32_qget_u64(int use_sign, const mpd_t *a, uint32_t *status) +{ + MPD_NEW_STATIC(tmp,0,0,20,3); + mpd_context_t maxcontext; + uint64_t ret; + + tmp_data[0] = 709551615; + tmp_data[1] = 446744073; + tmp_data[2] = 18; + + if (mpd_isspecial(a)) { + *status |= MPD_Invalid_operation; + return UINT64_MAX; + } + if (mpd_iszero(a)) { + return 0; + } + if (use_sign && mpd_isnegative(a)) { + *status |= MPD_Invalid_operation; + return UINT64_MAX; + } + if (!_mpd_isint(a)) { + *status |= MPD_Invalid_operation; + return UINT64_MAX; + } + + if (_mpd_cmp_abs(a, &tmp) > 0) { + *status |= MPD_Invalid_operation; + return UINT64_MAX; + } + + mpd_maxcontext(&maxcontext); + mpd_qrescale(&tmp, a, 0, &maxcontext, &maxcontext.status); + maxcontext.status &= ~MPD_Rounded; + if (maxcontext.status != 0) { + *status |= (maxcontext.status|MPD_Invalid_operation); /* GCOV_NOT_REACHED */ + return UINT64_MAX; /* GCOV_NOT_REACHED */ + } + + ret = 0; + switch (tmp.len) { + case 3: + ret += (uint64_t)tmp_data[2] * 1000000000000000000ULL; + case 2: + ret += (uint64_t)tmp_data[1] * 1000000000ULL; + case 1: + ret += tmp_data[0]; + break; + default: + abort(); /* GCOV_NOT_REACHED */ + } + + return ret; +} + +static int64_t +_c32_qget_i64(const mpd_t *a, uint32_t *status) +{ + uint64_t u; + int isneg; + + u = _c32_qget_u64(0, a, status); + if (*status&MPD_Invalid_operation) { + return INT64_MAX; + } + + isneg = mpd_isnegative(a); + if (u <= INT64_MAX) { + return isneg ? -((int64_t)u) : (int64_t)u; + } + else if (isneg && u+(INT64_MIN+INT64_MAX) == INT64_MAX) { + return INT64_MIN; + } + + *status |= MPD_Invalid_operation; + return INT64_MAX; +} +#endif /* CONFIG_32 && !LEGACY_COMPILER */ + +#ifdef CONFIG_64 +/* quietly get a uint64_t from a decimal */ +uint64_t +mpd_qget_u64(const mpd_t *a, uint32_t *status) +{ + return mpd_qget_uint(a, status); +} + +/* quietly get an int64_t from a decimal */ +int64_t +mpd_qget_i64(const mpd_t *a, uint32_t *status) +{ + return mpd_qget_ssize(a, status); +} + +/* quietly get a uint32_t from a decimal */ +uint32_t +mpd_qget_u32(const mpd_t *a, uint32_t *status) +{ + uint64_t x = mpd_qget_uint(a, status); + + if (*status&MPD_Invalid_operation) { + return UINT32_MAX; + } + if (x > UINT32_MAX) { + *status |= MPD_Invalid_operation; + return UINT32_MAX; + } + + return (uint32_t)x; +} + +/* quietly get an int32_t from a decimal */ +int32_t +mpd_qget_i32(const mpd_t *a, uint32_t *status) +{ + int64_t x = mpd_qget_ssize(a, status); + + if (*status&MPD_Invalid_operation) { + return INT32_MAX; + } + if (x < INT32_MIN || x > INT32_MAX) { + *status |= MPD_Invalid_operation; + return INT32_MAX; + } + + return (int32_t)x; +} +#else +#ifndef LEGACY_COMPILER +/* quietly get a uint64_t from a decimal */ +uint64_t +mpd_qget_u64(const mpd_t *a, uint32_t *status) +{ + return _c32_qget_u64(1, a, status); +} + +/* quietly get an int64_t from a decimal */ +int64_t +mpd_qget_i64(const mpd_t *a, uint32_t *status) +{ + return _c32_qget_i64(a, status); +} +#endif + +/* quietly get a uint32_t from a decimal */ +uint32_t +mpd_qget_u32(const mpd_t *a, uint32_t *status) +{ + return mpd_qget_uint(a, status); +} + +/* quietly get an int32_t from a decimal */ +int32_t +mpd_qget_i32(const mpd_t *a, uint32_t *status) +{ + return mpd_qget_ssize(a, status); +} +#endif + + +/******************************************************************************/ +/* Filtering input of functions, finalizing output of functions */ +/******************************************************************************/ + +/* + * Check if the operand is NaN, copy to result and return 1 if this is + * the case. Copying can fail since NaNs are allowed to have a payload that + * does not fit in MPD_MINALLOC. + */ +int +mpd_qcheck_nan(mpd_t *result, const mpd_t *a, const mpd_context_t *ctx, + uint32_t *status) +{ + if (mpd_isnan(a)) { + *status |= mpd_issnan(a) ? MPD_Invalid_operation : 0; + mpd_qcopy(result, a, status); + mpd_set_qnan(result); + _mpd_fix_nan(result, ctx); + return 1; + } + return 0; +} + +/* + * Check if either operand is NaN, copy to result and return 1 if this + * is the case. Copying can fail since NaNs are allowed to have a payload + * that does not fit in MPD_MINALLOC. + */ +int +mpd_qcheck_nans(mpd_t *result, const mpd_t *a, const mpd_t *b, + const mpd_context_t *ctx, uint32_t *status) +{ + if ((a->flags|b->flags)&(MPD_NAN|MPD_SNAN)) { + const mpd_t *choice = b; + if (mpd_issnan(a)) { + choice = a; + *status |= MPD_Invalid_operation; + } + else if (mpd_issnan(b)) { + *status |= MPD_Invalid_operation; + } + else if (mpd_isqnan(a)) { + choice = a; + } + mpd_qcopy(result, choice, status); + mpd_set_qnan(result); + _mpd_fix_nan(result, ctx); + return 1; + } + return 0; +} + +/* + * Check if one of the operands is NaN, copy to result and return 1 if this + * is the case. Copying can fail since NaNs are allowed to have a payload + * that does not fit in MPD_MINALLOC. + */ +static int +mpd_qcheck_3nans(mpd_t *result, const mpd_t *a, const mpd_t *b, const mpd_t *c, + const mpd_context_t *ctx, uint32_t *status) +{ + if ((a->flags|b->flags|c->flags)&(MPD_NAN|MPD_SNAN)) { + const mpd_t *choice = c; + if (mpd_issnan(a)) { + choice = a; + *status |= MPD_Invalid_operation; + } + else if (mpd_issnan(b)) { + choice = b; + *status |= MPD_Invalid_operation; + } + else if (mpd_issnan(c)) { + *status |= MPD_Invalid_operation; + } + else if (mpd_isqnan(a)) { + choice = a; + } + else if (mpd_isqnan(b)) { + choice = b; + } + mpd_qcopy(result, choice, status); + mpd_set_qnan(result); + _mpd_fix_nan(result, ctx); + return 1; + } + return 0; +} + +/* Check if rounding digit 'rnd' leads to an increment. */ +static inline int +_mpd_rnd_incr(const mpd_t *dec, mpd_uint_t rnd, const mpd_context_t *ctx) +{ + int ld; + + switch (ctx->round) { + case MPD_ROUND_DOWN: case MPD_ROUND_TRUNC: + return 0; + case MPD_ROUND_HALF_UP: + return (rnd >= 5); + case MPD_ROUND_HALF_EVEN: + return (rnd > 5) || ((rnd == 5) && mpd_isoddcoeff(dec)); + case MPD_ROUND_CEILING: + return !(rnd == 0 || mpd_isnegative(dec)); + case MPD_ROUND_FLOOR: + return !(rnd == 0 || mpd_ispositive(dec)); + case MPD_ROUND_HALF_DOWN: + return (rnd > 5); + case MPD_ROUND_UP: + return !(rnd == 0); + case MPD_ROUND_05UP: + ld = (int)mpd_lsd(dec->data[0]); + return (!(rnd == 0) && (ld == 0 || ld == 5)); + default: + /* Without a valid context, further results will be undefined. */ + return 0; /* GCOV_NOT_REACHED */ + } +} + +/* + * Apply rounding to a decimal that has been right-shifted into a full + * precision decimal. If an increment leads to an overflow of the precision, + * adjust the coefficient and the exponent and check the new exponent for + * overflow. + */ +static inline void +_mpd_apply_round(mpd_t *dec, mpd_uint_t rnd, const mpd_context_t *ctx, + uint32_t *status) +{ + if (_mpd_rnd_incr(dec, rnd, ctx)) { + /* We have a number with exactly ctx->prec digits. The increment + * can only lead to an overflow if the decimal is all nines. In + * that case, the result is a power of ten with prec+1 digits. + * + * If the precision is a multiple of MPD_RDIGITS, this situation is + * detected by _mpd_baseincr returning a carry. + * If the precision is not a multiple of MPD_RDIGITS, we have to + * check if the result has one digit too many. + */ + mpd_uint_t carry = _mpd_baseincr(dec->data, dec->len); + if (carry) { + dec->data[dec->len-1] = mpd_pow10[MPD_RDIGITS-1]; + dec->exp += 1; + _mpd_check_exp(dec, ctx, status); + return; + } + mpd_setdigits(dec); + if (dec->digits > ctx->prec) { + mpd_qshiftr_inplace(dec, 1); + dec->exp += 1; + dec->digits = ctx->prec; + _mpd_check_exp(dec, ctx, status); + } + } +} + +/* + * Apply rounding to a decimal. Allow overflow of the precision. + */ +static inline void +_mpd_apply_round_excess(mpd_t *dec, mpd_uint_t rnd, const mpd_context_t *ctx, + uint32_t *status) +{ + if (_mpd_rnd_incr(dec, rnd, ctx)) { + mpd_uint_t carry = _mpd_baseincr(dec->data, dec->len); + if (carry) { + if (!mpd_qresize(dec, dec->len+1, status)) { + return; + } + dec->data[dec->len] = 1; + dec->len += 1; + } + mpd_setdigits(dec); + } +} + +/* + * Apply rounding to a decimal that has been right-shifted into a decimal + * with full precision or less. Return failure if an increment would + * overflow the precision. + */ +static inline int +_mpd_apply_round_fit(mpd_t *dec, mpd_uint_t rnd, const mpd_context_t *ctx, + uint32_t *status) +{ + if (_mpd_rnd_incr(dec, rnd, ctx)) { + mpd_uint_t carry = _mpd_baseincr(dec->data, dec->len); + if (carry) { + if (!mpd_qresize(dec, dec->len+1, status)) { + return 0; + } + dec->data[dec->len] = 1; + dec->len += 1; + } + mpd_setdigits(dec); + if (dec->digits > ctx->prec) { + mpd_seterror(dec, MPD_Invalid_operation, status); + return 0; + } + } + return 1; +} + +/* Check a normal number for overflow, underflow, clamping. If the operand + is modified, it will be zero, special or (sub)normal with a coefficient + that fits into the current context precision. */ +static inline void +_mpd_check_exp(mpd_t *dec, const mpd_context_t *ctx, uint32_t *status) +{ + mpd_ssize_t adjexp, etiny, shift; + int rnd; + + adjexp = mpd_adjexp(dec); + if (adjexp > ctx->emax) { + + if (mpd_iszerocoeff(dec)) { + dec->exp = ctx->emax; + if (ctx->clamp) { + dec->exp -= (ctx->prec-1); + } + mpd_zerocoeff(dec); + *status |= MPD_Clamped; + return; + } + + switch (ctx->round) { + case MPD_ROUND_HALF_UP: case MPD_ROUND_HALF_EVEN: + case MPD_ROUND_HALF_DOWN: case MPD_ROUND_UP: + case MPD_ROUND_TRUNC: + mpd_setspecial(dec, mpd_sign(dec), MPD_INF); + break; + case MPD_ROUND_DOWN: case MPD_ROUND_05UP: + mpd_qmaxcoeff(dec, ctx, status); + dec->exp = ctx->emax - ctx->prec + 1; + break; + case MPD_ROUND_CEILING: + if (mpd_isnegative(dec)) { + mpd_qmaxcoeff(dec, ctx, status); + dec->exp = ctx->emax - ctx->prec + 1; + } + else { + mpd_setspecial(dec, MPD_POS, MPD_INF); + } + break; + case MPD_ROUND_FLOOR: + if (mpd_ispositive(dec)) { + mpd_qmaxcoeff(dec, ctx, status); + dec->exp = ctx->emax - ctx->prec + 1; + } + else { + mpd_setspecial(dec, MPD_NEG, MPD_INF); + } + break; + default: /* debug */ + abort(); /* GCOV_NOT_REACHED */ + } + + *status |= MPD_Overflow|MPD_Inexact|MPD_Rounded; + + } /* fold down */ + else if (ctx->clamp && dec->exp > mpd_etop(ctx)) { + /* At this point adjexp=exp+digits-1 <= emax and exp > etop=emax-prec+1: + * (1) shift = exp -emax+prec-1 > 0 + * (2) digits+shift = exp+digits-1 - emax + prec <= prec */ + shift = dec->exp - mpd_etop(ctx); + if (!mpd_qshiftl(dec, dec, shift, status)) { + return; + } + dec->exp -= shift; + *status |= MPD_Clamped; + if (!mpd_iszerocoeff(dec) && adjexp < ctx->emin) { + /* Underflow is impossible, since exp < etiny=emin-prec+1 + * and exp > etop=emax-prec+1 would imply emax < emin. */ + *status |= MPD_Subnormal; + } + } + else if (adjexp < ctx->emin) { + + etiny = mpd_etiny(ctx); + + if (mpd_iszerocoeff(dec)) { + if (dec->exp < etiny) { + dec->exp = etiny; + mpd_zerocoeff(dec); + *status |= MPD_Clamped; + } + return; + } + + *status |= MPD_Subnormal; + if (dec->exp < etiny) { + /* At this point adjexp=exp+digits-1 < emin and exp < etiny=emin-prec+1: + * (1) shift = emin-prec+1 - exp > 0 + * (2) digits-shift = exp+digits-1 - emin + prec < prec */ + shift = etiny - dec->exp; + rnd = (int)mpd_qshiftr_inplace(dec, shift); + dec->exp = etiny; + /* We always have a spare digit in case of an increment. */ + _mpd_apply_round_excess(dec, rnd, ctx, status); + *status |= MPD_Rounded; + if (rnd) { + *status |= (MPD_Inexact|MPD_Underflow); + if (mpd_iszerocoeff(dec)) { + mpd_zerocoeff(dec); + *status |= MPD_Clamped; + } + } + } + /* Case exp >= etiny=emin-prec+1: + * (1) adjexp=exp+digits-1 < emin + * (2) digits < emin-exp+1 <= prec */ + } +} + +/* Transcendental functions do not always set Underflow reliably, + * since they only use as much precision as is necessary for correct + * rounding. If a result like 1.0000000000e-101 is finalized, there + * is no rounding digit that would trigger Underflow. But we can + * assume Inexact, so a short check suffices. */ +static inline void +mpd_check_underflow(mpd_t *dec, const mpd_context_t *ctx, uint32_t *status) +{ + if (mpd_adjexp(dec) < ctx->emin && !mpd_iszero(dec) && + dec->exp < mpd_etiny(ctx)) { + *status |= MPD_Underflow; + } +} + +/* Check if a normal number must be rounded after the exponent has been checked. */ +static inline void +_mpd_check_round(mpd_t *dec, const mpd_context_t *ctx, uint32_t *status) +{ + mpd_uint_t rnd; + mpd_ssize_t shift; + + /* must handle specials: _mpd_check_exp() can produce infinities or NaNs */ + if (mpd_isspecial(dec)) { + return; + } + + if (dec->digits > ctx->prec) { + shift = dec->digits - ctx->prec; + rnd = mpd_qshiftr_inplace(dec, shift); + dec->exp += shift; + _mpd_apply_round(dec, rnd, ctx, status); + *status |= MPD_Rounded; + if (rnd) { + *status |= MPD_Inexact; + } + } +} + +/* Finalize all operations. */ +void +mpd_qfinalize(mpd_t *result, const mpd_context_t *ctx, uint32_t *status) +{ + if (mpd_isspecial(result)) { + if (mpd_isnan(result)) { + _mpd_fix_nan(result, ctx); + } + return; + } + + _mpd_check_exp(result, ctx, status); + _mpd_check_round(result, ctx, status); +} + + +/******************************************************************************/ +/* Copying */ +/******************************************************************************/ + +/* Internal function: Copy a decimal, share data with src: USE WITH CARE! */ +static inline void +_mpd_copy_shared(mpd_t *dest, const mpd_t *src) +{ + dest->flags = src->flags; + dest->exp = src->exp; + dest->digits = src->digits; + dest->len = src->len; + dest->alloc = src->alloc; + dest->data = src->data; + + mpd_set_shared_data(dest); +} + +/* + * Copy a decimal. In case of an error, status is set to MPD_Malloc_error. + */ +int +mpd_qcopy(mpd_t *result, const mpd_t *a, uint32_t *status) +{ + if (result == a) return 1; + + if (!mpd_qresize(result, a->len, status)) { + return 0; + } + + mpd_copy_flags(result, a); + result->exp = a->exp; + result->digits = a->digits; + result->len = a->len; + memcpy(result->data, a->data, a->len * (sizeof *result->data)); + + return 1; +} + +/* + * Copy to a decimal with a static buffer. The caller has to make sure that + * the buffer is big enough. Cannot fail. + */ +static void +mpd_qcopy_static(mpd_t *result, const mpd_t *a) +{ + if (result == a) return; + + memcpy(result->data, a->data, a->len * (sizeof *result->data)); + + mpd_copy_flags(result, a); + result->exp = a->exp; + result->digits = a->digits; + result->len = a->len; +} + +/* + * Return a newly allocated copy of the operand. In case of an error, + * status is set to MPD_Malloc_error and the return value is NULL. + */ +mpd_t * +mpd_qncopy(const mpd_t *a) +{ + mpd_t *result; + + if ((result = mpd_qnew_size(a->len)) == NULL) { + return NULL; + } + memcpy(result->data, a->data, a->len * (sizeof *result->data)); + mpd_copy_flags(result, a); + result->exp = a->exp; + result->digits = a->digits; + result->len = a->len; + + return result; +} + +/* + * Copy a decimal and set the sign to positive. In case of an error, the + * status is set to MPD_Malloc_error. + */ +int +mpd_qcopy_abs(mpd_t *result, const mpd_t *a, uint32_t *status) +{ + if (!mpd_qcopy(result, a, status)) { + return 0; + } + mpd_set_positive(result); + return 1; +} + +/* + * Copy a decimal and negate the sign. In case of an error, the + * status is set to MPD_Malloc_error. + */ +int +mpd_qcopy_negate(mpd_t *result, const mpd_t *a, uint32_t *status) +{ + if (!mpd_qcopy(result, a, status)) { + return 0; + } + _mpd_negate(result); + return 1; +} + +/* + * Copy a decimal, setting the sign of the first operand to the sign of the + * second operand. In case of an error, the status is set to MPD_Malloc_error. + */ +int +mpd_qcopy_sign(mpd_t *result, const mpd_t *a, const mpd_t *b, uint32_t *status) +{ + uint8_t sign_b = mpd_sign(b); /* result may equal b! */ + + if (!mpd_qcopy(result, a, status)) { + return 0; + } + mpd_set_sign(result, sign_b); + return 1; +} + + +/******************************************************************************/ +/* Comparisons */ +/******************************************************************************/ + +/* + * For all functions that compare two operands and return an int the usual + * convention applies to the return value: + * + * -1 if op1 < op2 + * 0 if op1 == op2 + * 1 if op1 > op2 + * + * INT_MAX for error + */ + + +/* Convenience macro. If a and b are not equal, return from the calling + * function with the correct comparison value. */ +#define CMP_EQUAL_OR_RETURN(a, b) \ + if (a != b) { \ + if (a < b) { \ + return -1; \ + } \ + return 1; \ + } + +/* + * Compare the data of big and small. This function does the equivalent + * of first shifting small to the left and then comparing the data of + * big and small, except that no allocation for the left shift is needed. + */ +static int +_mpd_basecmp(mpd_uint_t *big, mpd_uint_t *small, mpd_size_t n, mpd_size_t m, + mpd_size_t shift) +{ +#if defined(__GNUC__) && !defined(__INTEL_COMPILER) && !defined(__clang__) + /* spurious uninitialized warnings */ + mpd_uint_t l=l, lprev=lprev, h=h; +#else + mpd_uint_t l, lprev, h; +#endif + mpd_uint_t q, r; + mpd_uint_t ph, x; + + assert(m > 0 && n >= m && shift > 0); + + _mpd_div_word(&q, &r, (mpd_uint_t)shift, MPD_RDIGITS); + + if (r != 0) { + + ph = mpd_pow10[r]; + + --m; --n; + _mpd_divmod_pow10(&h, &lprev, small[m--], MPD_RDIGITS-r); + if (h != 0) { + CMP_EQUAL_OR_RETURN(big[n], h) + --n; + } + for (; m != MPD_SIZE_MAX; m--,n--) { + _mpd_divmod_pow10(&h, &l, small[m], MPD_RDIGITS-r); + x = ph * lprev + h; + CMP_EQUAL_OR_RETURN(big[n], x) + lprev = l; + } + x = ph * lprev; + CMP_EQUAL_OR_RETURN(big[q], x) + } + else { + while (--m != MPD_SIZE_MAX) { + CMP_EQUAL_OR_RETURN(big[m+q], small[m]) + } + } + + return !_mpd_isallzero(big, q); +} + +/* Compare two decimals with the same adjusted exponent. */ +static int +_mpd_cmp_same_adjexp(const mpd_t *a, const mpd_t *b) +{ + mpd_ssize_t shift, i; + + if (a->exp != b->exp) { + /* Cannot wrap: a->exp + a->digits = b->exp + b->digits, so + * a->exp - b->exp = b->digits - a->digits. */ + shift = a->exp - b->exp; + if (shift > 0) { + return -1 * _mpd_basecmp(b->data, a->data, b->len, a->len, shift); + } + else { + return _mpd_basecmp(a->data, b->data, a->len, b->len, -shift); + } + } + + /* + * At this point adjexp(a) == adjexp(b) and a->exp == b->exp, + * so a->digits == b->digits, therefore a->len == b->len. + */ + for (i = a->len-1; i >= 0; --i) { + CMP_EQUAL_OR_RETURN(a->data[i], b->data[i]) + } + + return 0; +} + +/* Compare two numerical values. */ +static int +_mpd_cmp(const mpd_t *a, const mpd_t *b) +{ + mpd_ssize_t adjexp_a, adjexp_b; + + /* equal pointers */ + if (a == b) { + return 0; + } + + /* infinities */ + if (mpd_isinfinite(a)) { + if (mpd_isinfinite(b)) { + return mpd_isnegative(b) - mpd_isnegative(a); + } + return mpd_arith_sign(a); + } + if (mpd_isinfinite(b)) { + return -mpd_arith_sign(b); + } + + /* zeros */ + if (mpd_iszerocoeff(a)) { + if (mpd_iszerocoeff(b)) { + return 0; + } + return -mpd_arith_sign(b); + } + if (mpd_iszerocoeff(b)) { + return mpd_arith_sign(a); + } + + /* different signs */ + if (mpd_sign(a) != mpd_sign(b)) { + return mpd_sign(b) - mpd_sign(a); + } + + /* different adjusted exponents */ + adjexp_a = mpd_adjexp(a); + adjexp_b = mpd_adjexp(b); + if (adjexp_a != adjexp_b) { + if (adjexp_a < adjexp_b) { + return -1 * mpd_arith_sign(a); + } + return mpd_arith_sign(a); + } + + /* same adjusted exponents */ + return _mpd_cmp_same_adjexp(a, b) * mpd_arith_sign(a); +} + +/* Compare the absolutes of two numerical values. */ +static int +_mpd_cmp_abs(const mpd_t *a, const mpd_t *b) +{ + mpd_ssize_t adjexp_a, adjexp_b; + + /* equal pointers */ + if (a == b) { + return 0; + } + + /* infinities */ + if (mpd_isinfinite(a)) { + if (mpd_isinfinite(b)) { + return 0; + } + return 1; + } + if (mpd_isinfinite(b)) { + return -1; + } + + /* zeros */ + if (mpd_iszerocoeff(a)) { + if (mpd_iszerocoeff(b)) { + return 0; + } + return -1; + } + if (mpd_iszerocoeff(b)) { + return 1; + } + + /* different adjusted exponents */ + adjexp_a = mpd_adjexp(a); + adjexp_b = mpd_adjexp(b); + if (adjexp_a != adjexp_b) { + if (adjexp_a < adjexp_b) { + return -1; + } + return 1; + } + + /* same adjusted exponents */ + return _mpd_cmp_same_adjexp(a, b); +} + +/* Compare two values and return an integer result. */ +int +mpd_qcmp(const mpd_t *a, const mpd_t *b, uint32_t *status) +{ + if (mpd_isspecial(a) || mpd_isspecial(b)) { + if (mpd_isnan(a) || mpd_isnan(b)) { + *status |= MPD_Invalid_operation; + return INT_MAX; + } + } + + return _mpd_cmp(a, b); +} + +/* + * Compare a and b, convert the usual integer result to a decimal and + * store it in 'result'. For convenience, the integer result of the comparison + * is returned. Comparisons involving NaNs return NaN/INT_MAX. + */ +int +mpd_qcompare(mpd_t *result, const mpd_t *a, const mpd_t *b, + const mpd_context_t *ctx, uint32_t *status) +{ + int c; + + if (mpd_isspecial(a) || mpd_isspecial(b)) { + if (mpd_qcheck_nans(result, a, b, ctx, status)) { + return INT_MAX; + } + } + + c = _mpd_cmp(a, b); + _settriple(result, (c < 0), (c != 0), 0); + return c; +} + +/* Same as mpd_compare(), but signal for all NaNs, i.e. also for quiet NaNs. */ +int +mpd_qcompare_signal(mpd_t *result, const mpd_t *a, const mpd_t *b, + const mpd_context_t *ctx, uint32_t *status) +{ + int c; + + if (mpd_isspecial(a) || mpd_isspecial(b)) { + if (mpd_qcheck_nans(result, a, b, ctx, status)) { + *status |= MPD_Invalid_operation; + return INT_MAX; + } + } + + c = _mpd_cmp(a, b); + _settriple(result, (c < 0), (c != 0), 0); + return c; +} + +/* Compare the operands using a total order. */ +int +mpd_cmp_total(const mpd_t *a, const mpd_t *b) +{ + mpd_t aa, bb; + int nan_a, nan_b; + int c; + + if (mpd_sign(a) != mpd_sign(b)) { + return mpd_sign(b) - mpd_sign(a); + } + + + if (mpd_isnan(a)) { + c = 1; + if (mpd_isnan(b)) { + nan_a = (mpd_isqnan(a)) ? 1 : 0; + nan_b = (mpd_isqnan(b)) ? 1 : 0; + if (nan_b == nan_a) { + if (a->len > 0 && b->len > 0) { + _mpd_copy_shared(&aa, a); + _mpd_copy_shared(&bb, b); + aa.exp = bb.exp = 0; + /* compare payload */ + c = _mpd_cmp_abs(&aa, &bb); + } + else { + c = (a->len > 0) - (b->len > 0); + } + } + else { + c = nan_a - nan_b; + } + } + } + else if (mpd_isnan(b)) { + c = -1; + } + else { + c = _mpd_cmp_abs(a, b); + if (c == 0 && a->exp != b->exp) { + c = (a->exp < b->exp) ? -1 : 1; + } + } + + return c * mpd_arith_sign(a); +} + +/* + * Compare a and b according to a total order, convert the usual integer result + * to a decimal and store it in 'result'. For convenience, the integer result + * of the comparison is returned. + */ +int +mpd_compare_total(mpd_t *result, const mpd_t *a, const mpd_t *b) +{ + int c; + + c = mpd_cmp_total(a, b); + _settriple(result, (c < 0), (c != 0), 0); + return c; +} + +/* Compare the magnitude of the operands using a total order. */ +int +mpd_cmp_total_mag(const mpd_t *a, const mpd_t *b) +{ + mpd_t aa, bb; + + _mpd_copy_shared(&aa, a); + _mpd_copy_shared(&bb, b); + + mpd_set_positive(&aa); + mpd_set_positive(&bb); + + return mpd_cmp_total(&aa, &bb); +} + +/* + * Compare the magnitude of a and b according to a total order, convert the + * the usual integer result to a decimal and store it in 'result'. + * For convenience, the integer result of the comparison is returned. + */ +int +mpd_compare_total_mag(mpd_t *result, const mpd_t *a, const mpd_t *b) +{ + int c; + + c = mpd_cmp_total_mag(a, b); + _settriple(result, (c < 0), (c != 0), 0); + return c; +} + +/* Determine an ordering for operands that are numerically equal. */ +static inline int +_mpd_cmp_numequal(const mpd_t *a, const mpd_t *b) +{ + int sign_a, sign_b; + int c; + + sign_a = mpd_sign(a); + sign_b = mpd_sign(b); + if (sign_a != sign_b) { + c = sign_b - sign_a; + } + else { + c = (a->exp < b->exp) ? -1 : 1; + c *= mpd_arith_sign(a); + } + + return c; +} + + +/******************************************************************************/ +/* Shifting the coefficient */ +/******************************************************************************/ + +/* + * Shift the coefficient of the operand to the left, no check for specials. + * Both operands may be the same pointer. If the result length has to be + * increased, mpd_qresize() might fail with MPD_Malloc_error. + */ +int +mpd_qshiftl(mpd_t *result, const mpd_t *a, mpd_ssize_t n, uint32_t *status) +{ + mpd_ssize_t size; + + assert(!mpd_isspecial(a)); + assert(n >= 0); + + if (mpd_iszerocoeff(a) || n == 0) { + return mpd_qcopy(result, a, status); + } + + size = mpd_digits_to_size(a->digits+n); + if (!mpd_qresize(result, size, status)) { + return 0; /* result is NaN */ + } + + _mpd_baseshiftl(result->data, a->data, size, a->len, n); + + mpd_copy_flags(result, a); + result->exp = a->exp; + result->digits = a->digits+n; + result->len = size; + + return 1; +} + +/* Determine the rounding indicator if all digits of the coefficient are shifted + * out of the picture. */ +static mpd_uint_t +_mpd_get_rnd(const mpd_uint_t *data, mpd_ssize_t len, int use_msd) +{ + mpd_uint_t rnd = 0, rest = 0, word; + + word = data[len-1]; + /* special treatment for the most significant digit if shift == digits */ + if (use_msd) { + _mpd_divmod_pow10(&rnd, &rest, word, mpd_word_digits(word)-1); + if (len > 1 && rest == 0) { + rest = !_mpd_isallzero(data, len-1); + } + } + else { + rest = !_mpd_isallzero(data, len); + } + + return (rnd == 0 || rnd == 5) ? rnd + !!rest : rnd; +} + +/* + * Same as mpd_qshiftr(), but 'result' is an mpd_t with a static coefficient. + * It is the caller's responsibility to ensure that the coefficient is big + * enough. The function cannot fail. + */ +static mpd_uint_t +mpd_qsshiftr(mpd_t *result, const mpd_t *a, mpd_ssize_t n) +{ + mpd_uint_t rnd; + mpd_ssize_t size; + + assert(!mpd_isspecial(a)); + assert(n >= 0); + + if (mpd_iszerocoeff(a) || n == 0) { + mpd_qcopy_static(result, a); + return 0; + } + + if (n >= a->digits) { + rnd = _mpd_get_rnd(a->data, a->len, (n==a->digits)); + mpd_zerocoeff(result); + } + else { + result->digits = a->digits-n; + size = mpd_digits_to_size(result->digits); + rnd = _mpd_baseshiftr(result->data, a->data, a->len, n); + result->len = size; + } + + mpd_copy_flags(result, a); + result->exp = a->exp; + + return rnd; +} + +/* + * Inplace shift of the coefficient to the right, no check for specials. + * Returns the rounding indicator for mpd_rnd_incr(). + * The function cannot fail. + */ +mpd_uint_t +mpd_qshiftr_inplace(mpd_t *result, mpd_ssize_t n) +{ + uint32_t dummy; + mpd_uint_t rnd; + mpd_ssize_t size; + + assert(!mpd_isspecial(result)); + assert(n >= 0); + + if (mpd_iszerocoeff(result) || n == 0) { + return 0; + } + + if (n >= result->digits) { + rnd = _mpd_get_rnd(result->data, result->len, (n==result->digits)); + mpd_zerocoeff(result); + } + else { + rnd = _mpd_baseshiftr(result->data, result->data, result->len, n); + result->digits -= n; + size = mpd_digits_to_size(result->digits); + /* reducing the size cannot fail */ + mpd_qresize(result, size, &dummy); + result->len = size; + } + + return rnd; +} + +/* + * Shift the coefficient of the operand to the right, no check for specials. + * Both operands may be the same pointer. Returns the rounding indicator to + * be used by mpd_rnd_incr(). If the result length has to be increased, + * mpd_qcopy() or mpd_qresize() might fail with MPD_Malloc_error. In those + * cases, MPD_UINT_MAX is returned. + */ +mpd_uint_t +mpd_qshiftr(mpd_t *result, const mpd_t *a, mpd_ssize_t n, uint32_t *status) +{ + mpd_uint_t rnd; + mpd_ssize_t size; + + assert(!mpd_isspecial(a)); + assert(n >= 0); + + if (mpd_iszerocoeff(a) || n == 0) { + if (!mpd_qcopy(result, a, status)) { + return MPD_UINT_MAX; + } + return 0; + } + + if (n >= a->digits) { + rnd = _mpd_get_rnd(a->data, a->len, (n==a->digits)); + mpd_zerocoeff(result); + } + else { + result->digits = a->digits-n; + size = mpd_digits_to_size(result->digits); + if (result == a) { + rnd = _mpd_baseshiftr(result->data, a->data, a->len, n); + /* reducing the size cannot fail */ + mpd_qresize(result, size, status); + } + else { + if (!mpd_qresize(result, size, status)) { + return MPD_UINT_MAX; + } + rnd = _mpd_baseshiftr(result->data, a->data, a->len, n); + } + result->len = size; + } + + mpd_copy_flags(result, a); + result->exp = a->exp; + + return rnd; +} + + +/******************************************************************************/ +/* Miscellaneous operations */ +/******************************************************************************/ + +/* Logical And */ +void +mpd_qand(mpd_t *result, const mpd_t *a, const mpd_t *b, + const mpd_context_t *ctx, uint32_t *status) +{ + const mpd_t *big = a, *small = b; + mpd_uint_t x, y, z, xbit, ybit; + int k, mswdigits; + mpd_ssize_t i; + + if (mpd_isspecial(a) || mpd_isspecial(b) || + mpd_isnegative(a) || mpd_isnegative(b) || + a->exp != 0 || b->exp != 0) { + mpd_seterror(result, MPD_Invalid_operation, status); + return; + } + if (b->digits > a->digits) { + big = b; + small = a; + } + if (!mpd_qresize(result, big->len, status)) { + return; + } + + + /* full words */ + for (i = 0; i < small->len-1; i++) { + x = small->data[i]; + y = big->data[i]; + z = 0; + for (k = 0; k < MPD_RDIGITS; k++) { + xbit = x % 10; + x /= 10; + ybit = y % 10; + y /= 10; + if (xbit > 1 || ybit > 1) { + goto invalid_operation; + } + z += (xbit&ybit) ? mpd_pow10[k] : 0; + } + result->data[i] = z; + } + /* most significant word of small */ + x = small->data[i]; + y = big->data[i]; + z = 0; + mswdigits = mpd_word_digits(x); + for (k = 0; k < mswdigits; k++) { + xbit = x % 10; + x /= 10; + ybit = y % 10; + y /= 10; + if (xbit > 1 || ybit > 1) { + goto invalid_operation; + } + z += (xbit&ybit) ? mpd_pow10[k] : 0; + } + result->data[i++] = z; + + /* scan the rest of y for digits > 1 */ + for (; k < MPD_RDIGITS; k++) { + ybit = y % 10; + y /= 10; + if (ybit > 1) { + goto invalid_operation; + } + } + /* scan the rest of big for digits > 1 */ + for (; i < big->len; i++) { + y = big->data[i]; + for (k = 0; k < MPD_RDIGITS; k++) { + ybit = y % 10; + y /= 10; + if (ybit > 1) { + goto invalid_operation; + } + } + } + + mpd_clear_flags(result); + result->exp = 0; + result->len = _mpd_real_size(result->data, small->len); + mpd_qresize(result, result->len, status); + mpd_setdigits(result); + _mpd_cap(result, ctx); + return; + +invalid_operation: + mpd_seterror(result, MPD_Invalid_operation, status); +} + +/* Class of an operand. Returns a pointer to the constant name. */ +const char * +mpd_class(const mpd_t *a, const mpd_context_t *ctx) +{ + if (mpd_isnan(a)) { + if (mpd_isqnan(a)) + return "NaN"; + else + return "sNaN"; + } + else if (mpd_ispositive(a)) { + if (mpd_isinfinite(a)) + return "+Infinity"; + else if (mpd_iszero(a)) + return "+Zero"; + else if (mpd_isnormal(a, ctx)) + return "+Normal"; + else + return "+Subnormal"; + } + else { + if (mpd_isinfinite(a)) + return "-Infinity"; + else if (mpd_iszero(a)) + return "-Zero"; + else if (mpd_isnormal(a, ctx)) + return "-Normal"; + else + return "-Subnormal"; + } +} + +/* Logical Xor */ +void +mpd_qinvert(mpd_t *result, const mpd_t *a, const mpd_context_t *ctx, + uint32_t *status) +{ + mpd_uint_t x, z, xbit; + mpd_ssize_t i, digits, len; + mpd_ssize_t q, r; + int k; + + if (mpd_isspecial(a) || mpd_isnegative(a) || a->exp != 0) { + mpd_seterror(result, MPD_Invalid_operation, status); + return; + } + + digits = (a->digits < ctx->prec) ? ctx->prec : a->digits; + _mpd_idiv_word(&q, &r, digits, MPD_RDIGITS); + len = (r == 0) ? q : q+1; + if (!mpd_qresize(result, len, status)) { + return; + } + + for (i = 0; i < len; i++) { + x = (i < a->len) ? a->data[i] : 0; + z = 0; + for (k = 0; k < MPD_RDIGITS; k++) { + xbit = x % 10; + x /= 10; + if (xbit > 1) { + goto invalid_operation; + } + z += !xbit ? mpd_pow10[k] : 0; + } + result->data[i] = z; + } + + mpd_clear_flags(result); + result->exp = 0; + result->len = _mpd_real_size(result->data, len); + mpd_qresize(result, result->len, status); + mpd_setdigits(result); + _mpd_cap(result, ctx); + return; + +invalid_operation: + mpd_seterror(result, MPD_Invalid_operation, status); +} + +/* Exponent of the magnitude of the most significant digit of the operand. */ +void +mpd_qlogb(mpd_t *result, const mpd_t *a, const mpd_context_t *ctx, + uint32_t *status) +{ + if (mpd_isspecial(a)) { + if (mpd_qcheck_nan(result, a, ctx, status)) { + return; + } + mpd_setspecial(result, MPD_POS, MPD_INF); + } + else if (mpd_iszerocoeff(a)) { + mpd_setspecial(result, MPD_NEG, MPD_INF); + *status |= MPD_Division_by_zero; + } + else { + mpd_qset_ssize(result, mpd_adjexp(a), ctx, status); + } +} + +/* Logical Or */ +void +mpd_qor(mpd_t *result, const mpd_t *a, const mpd_t *b, + const mpd_context_t *ctx, uint32_t *status) +{ + const mpd_t *big = a, *small = b; + mpd_uint_t x, y, z, xbit, ybit; + int k, mswdigits; + mpd_ssize_t i; + + if (mpd_isspecial(a) || mpd_isspecial(b) || + mpd_isnegative(a) || mpd_isnegative(b) || + a->exp != 0 || b->exp != 0) { + mpd_seterror(result, MPD_Invalid_operation, status); + return; + } + if (b->digits > a->digits) { + big = b; + small = a; + } + if (!mpd_qresize(result, big->len, status)) { + return; + } + + + /* full words */ + for (i = 0; i < small->len-1; i++) { + x = small->data[i]; + y = big->data[i]; + z = 0; + for (k = 0; k < MPD_RDIGITS; k++) { + xbit = x % 10; + x /= 10; + ybit = y % 10; + y /= 10; + if (xbit > 1 || ybit > 1) { + goto invalid_operation; + } + z += (xbit|ybit) ? mpd_pow10[k] : 0; + } + result->data[i] = z; + } + /* most significant word of small */ + x = small->data[i]; + y = big->data[i]; + z = 0; + mswdigits = mpd_word_digits(x); + for (k = 0; k < mswdigits; k++) { + xbit = x % 10; + x /= 10; + ybit = y % 10; + y /= 10; + if (xbit > 1 || ybit > 1) { + goto invalid_operation; + } + z += (xbit|ybit) ? mpd_pow10[k] : 0; + } + + /* scan for digits > 1 and copy the rest of y */ + for (; k < MPD_RDIGITS; k++) { + ybit = y % 10; + y /= 10; + if (ybit > 1) { + goto invalid_operation; + } + z += ybit*mpd_pow10[k]; + } + result->data[i++] = z; + /* scan for digits > 1 and copy the rest of big */ + for (; i < big->len; i++) { + y = big->data[i]; + for (k = 0; k < MPD_RDIGITS; k++) { + ybit = y % 10; + y /= 10; + if (ybit > 1) { + goto invalid_operation; + } + } + result->data[i] = big->data[i]; + } + + mpd_clear_flags(result); + result->exp = 0; + result->len = _mpd_real_size(result->data, big->len); + mpd_qresize(result, result->len, status); + mpd_setdigits(result); + _mpd_cap(result, ctx); + return; + +invalid_operation: + mpd_seterror(result, MPD_Invalid_operation, status); +} + +/* + * Rotate the coefficient of 'a' by 'b' digits. 'b' must be an integer with + * exponent 0. + */ +void +mpd_qrotate(mpd_t *result, const mpd_t *a, const mpd_t *b, + const mpd_context_t *ctx, uint32_t *status) +{ + uint32_t workstatus = 0; + MPD_NEW_STATIC(tmp,0,0,0,0); + MPD_NEW_STATIC(big,0,0,0,0); + MPD_NEW_STATIC(small,0,0,0,0); + mpd_ssize_t n, lshift, rshift; + + if (mpd_isspecial(a) || mpd_isspecial(b)) { + if (mpd_qcheck_nans(result, a, b, ctx, status)) { + return; + } + } + if (b->exp != 0 || mpd_isinfinite(b)) { + mpd_seterror(result, MPD_Invalid_operation, status); + return; + } + + n = mpd_qget_ssize(b, &workstatus); + if (workstatus&MPD_Invalid_operation) { + mpd_seterror(result, MPD_Invalid_operation, status); + return; + } + if (n > ctx->prec || n < -ctx->prec) { + mpd_seterror(result, MPD_Invalid_operation, status); + return; + } + if (mpd_isinfinite(a)) { + mpd_qcopy(result, a, status); + return; + } + + if (n >= 0) { + lshift = n; + rshift = ctx->prec-n; + } + else { + lshift = ctx->prec+n; + rshift = -n; + } + + if (a->digits > ctx->prec) { + if (!mpd_qcopy(&tmp, a, status)) { + mpd_seterror(result, MPD_Malloc_error, status); + goto finish; + } + _mpd_cap(&tmp, ctx); + a = &tmp; + } + + if (!mpd_qshiftl(&big, a, lshift, status)) { + mpd_seterror(result, MPD_Malloc_error, status); + goto finish; + } + _mpd_cap(&big, ctx); + + if (mpd_qshiftr(&small, a, rshift, status) == MPD_UINT_MAX) { + mpd_seterror(result, MPD_Malloc_error, status); + goto finish; + } + _mpd_qadd(result, &big, &small, ctx, status); + + +finish: + mpd_del(&tmp); + mpd_del(&big); + mpd_del(&small); +} + +/* + * b must be an integer with exponent 0 and in the range +-2*(emax + prec). + * XXX: In my opinion +-(2*emax + prec) would be more sensible. + * The result is a with the value of b added to its exponent. + */ +void +mpd_qscaleb(mpd_t *result, const mpd_t *a, const mpd_t *b, + const mpd_context_t *ctx, uint32_t *status) +{ + uint32_t workstatus = 0; + mpd_uint_t n, maxjump; +#ifndef LEGACY_COMPILER + int64_t exp; +#else + mpd_uint_t x; + int x_sign, n_sign; + mpd_ssize_t exp; +#endif + + if (mpd_isspecial(a) || mpd_isspecial(b)) { + if (mpd_qcheck_nans(result, a, b, ctx, status)) { + return; + } + } + if (b->exp != 0 || mpd_isinfinite(b)) { + mpd_seterror(result, MPD_Invalid_operation, status); + return; + } + + n = mpd_qabs_uint(b, &workstatus); + /* the spec demands this */ + maxjump = 2 * (mpd_uint_t)(ctx->emax + ctx->prec); + + if (n > maxjump || workstatus&MPD_Invalid_operation) { + mpd_seterror(result, MPD_Invalid_operation, status); + return; + } + if (mpd_isinfinite(a)) { + mpd_qcopy(result, a, status); + return; + } + +#ifndef LEGACY_COMPILER + exp = a->exp + (int64_t)n * mpd_arith_sign(b); + exp = (exp > MPD_EXP_INF) ? MPD_EXP_INF : exp; + exp = (exp < MPD_EXP_CLAMP) ? MPD_EXP_CLAMP : exp; +#else + x = (a->exp < 0) ? -a->exp : a->exp; + x_sign = (a->exp < 0) ? 1 : 0; + n_sign = mpd_isnegative(b) ? 1 : 0; + + if (x_sign == n_sign) { + x = x + n; + if (x < n) x = MPD_UINT_MAX; + } + else { + x_sign = (x >= n) ? x_sign : n_sign; + x = (x >= n) ? x - n : n - x; + } + if (!x_sign && x > MPD_EXP_INF) x = MPD_EXP_INF; + if (x_sign && x > -MPD_EXP_CLAMP) x = -MPD_EXP_CLAMP; + exp = x_sign ? -((mpd_ssize_t)x) : (mpd_ssize_t)x; +#endif + + mpd_qcopy(result, a, status); + result->exp = (mpd_ssize_t)exp; + + mpd_qfinalize(result, ctx, status); +} + +/* + * Shift the coefficient by n digits, positive n is a left shift. In the case + * of a left shift, the result is decapitated to fit the context precision. If + * you don't want that, use mpd_shiftl(). + */ +void +mpd_qshiftn(mpd_t *result, const mpd_t *a, mpd_ssize_t n, const mpd_context_t *ctx, + uint32_t *status) +{ + if (mpd_isspecial(a)) { + if (mpd_qcheck_nan(result, a, ctx, status)) { + return; + } + mpd_qcopy(result, a, status); + return; + } + + if (n >= 0 && n <= ctx->prec) { + mpd_qshiftl(result, a, n, status); + _mpd_cap(result, ctx); + } + else if (n < 0 && n >= -ctx->prec) { + if (!mpd_qcopy(result, a, status)) { + return; + } + _mpd_cap(result, ctx); + mpd_qshiftr_inplace(result, -n); + } + else { + mpd_seterror(result, MPD_Invalid_operation, status); + } +} + +/* + * Same as mpd_shiftn(), but the shift is specified by the decimal b, which + * must be an integer with a zero exponent. Infinities remain infinities. + */ +void +mpd_qshift(mpd_t *result, const mpd_t *a, const mpd_t *b, const mpd_context_t *ctx, + uint32_t *status) +{ + uint32_t workstatus = 0; + mpd_ssize_t n; + + if (mpd_isspecial(a) || mpd_isspecial(b)) { + if (mpd_qcheck_nans(result, a, b, ctx, status)) { + return; + } + } + if (b->exp != 0 || mpd_isinfinite(b)) { + mpd_seterror(result, MPD_Invalid_operation, status); + return; + } + + n = mpd_qget_ssize(b, &workstatus); + if (workstatus&MPD_Invalid_operation) { + mpd_seterror(result, MPD_Invalid_operation, status); + return; + } + if (n > ctx->prec || n < -ctx->prec) { + mpd_seterror(result, MPD_Invalid_operation, status); + return; + } + if (mpd_isinfinite(a)) { + mpd_qcopy(result, a, status); + return; + } + + if (n >= 0) { + mpd_qshiftl(result, a, n, status); + _mpd_cap(result, ctx); + } + else { + if (!mpd_qcopy(result, a, status)) { + return; + } + _mpd_cap(result, ctx); + mpd_qshiftr_inplace(result, -n); + } +} + +/* Logical Xor */ +void +mpd_qxor(mpd_t *result, const mpd_t *a, const mpd_t *b, + const mpd_context_t *ctx, uint32_t *status) +{ + const mpd_t *big = a, *small = b; + mpd_uint_t x, y, z, xbit, ybit; + int k, mswdigits; + mpd_ssize_t i; + + if (mpd_isspecial(a) || mpd_isspecial(b) || + mpd_isnegative(a) || mpd_isnegative(b) || + a->exp != 0 || b->exp != 0) { + mpd_seterror(result, MPD_Invalid_operation, status); + return; + } + if (b->digits > a->digits) { + big = b; + small = a; + } + if (!mpd_qresize(result, big->len, status)) { + return; + } + + + /* full words */ + for (i = 0; i < small->len-1; i++) { + x = small->data[i]; + y = big->data[i]; + z = 0; + for (k = 0; k < MPD_RDIGITS; k++) { + xbit = x % 10; + x /= 10; + ybit = y % 10; + y /= 10; + if (xbit > 1 || ybit > 1) { + goto invalid_operation; + } + z += (xbit^ybit) ? mpd_pow10[k] : 0; + } + result->data[i] = z; + } + /* most significant word of small */ + x = small->data[i]; + y = big->data[i]; + z = 0; + mswdigits = mpd_word_digits(x); + for (k = 0; k < mswdigits; k++) { + xbit = x % 10; + x /= 10; + ybit = y % 10; + y /= 10; + if (xbit > 1 || ybit > 1) { + goto invalid_operation; + } + z += (xbit^ybit) ? mpd_pow10[k] : 0; + } + + /* scan for digits > 1 and copy the rest of y */ + for (; k < MPD_RDIGITS; k++) { + ybit = y % 10; + y /= 10; + if (ybit > 1) { + goto invalid_operation; + } + z += ybit*mpd_pow10[k]; + } + result->data[i++] = z; + /* scan for digits > 1 and copy the rest of big */ + for (; i < big->len; i++) { + y = big->data[i]; + for (k = 0; k < MPD_RDIGITS; k++) { + ybit = y % 10; + y /= 10; + if (ybit > 1) { + goto invalid_operation; + } + } + result->data[i] = big->data[i]; + } + + mpd_clear_flags(result); + result->exp = 0; + result->len = _mpd_real_size(result->data, big->len); + mpd_qresize(result, result->len, status); + mpd_setdigits(result); + _mpd_cap(result, ctx); + return; + +invalid_operation: + mpd_seterror(result, MPD_Invalid_operation, status); +} + + +/******************************************************************************/ +/* Arithmetic operations */ +/******************************************************************************/ + +/* + * The absolute value of a. If a is negative, the result is the same + * as the result of the minus operation. Otherwise, the result is the + * result of the plus operation. + */ +void +mpd_qabs(mpd_t *result, const mpd_t *a, const mpd_context_t *ctx, + uint32_t *status) +{ + if (mpd_isspecial(a)) { + if (mpd_qcheck_nan(result, a, ctx, status)) { + return; + } + } + + if (mpd_isnegative(a)) { + mpd_qminus(result, a, ctx, status); + } + else { + mpd_qplus(result, a, ctx, status); + } +} + +static inline void +_mpd_ptrswap(const mpd_t **a, const mpd_t **b) +{ + const mpd_t *t = *a; + *a = *b; + *b = t; +} + +/* Add or subtract infinities. */ +static void +_mpd_qaddsub_inf(mpd_t *result, const mpd_t *a, const mpd_t *b, uint8_t sign_b, + uint32_t *status) +{ + if (mpd_isinfinite(a)) { + if (mpd_sign(a) != sign_b && mpd_isinfinite(b)) { + mpd_seterror(result, MPD_Invalid_operation, status); + } + else { + mpd_setspecial(result, mpd_sign(a), MPD_INF); + } + return; + } + assert(mpd_isinfinite(b)); + mpd_setspecial(result, sign_b, MPD_INF); +} + +/* Add or subtract non-special numbers. */ +static void +_mpd_qaddsub(mpd_t *result, const mpd_t *a, const mpd_t *b, uint8_t sign_b, + const mpd_context_t *ctx, uint32_t *status) +{ + const mpd_t *big, *small; + MPD_NEW_STATIC(big_aligned,0,0,0,0); + MPD_NEW_CONST(tiny,0,0,1,1,1,1); + mpd_uint_t carry; + mpd_ssize_t newsize, shift; + mpd_ssize_t exp, i; + int swap = 0; + + + /* compare exponents */ + big = a; small = b; + if (big->exp != small->exp) { + if (small->exp > big->exp) { + _mpd_ptrswap(&big, &small); + swap++; + } + /* align the coefficients */ + if (!mpd_iszerocoeff(big)) { + exp = big->exp - 1; + exp += (big->digits > ctx->prec) ? 0 : big->digits-ctx->prec-1; + if (mpd_adjexp(small) < exp) { + /* + * Avoid huge shifts by substituting a value for small that is + * guaranteed to produce the same results. + * + * adjexp(small) < exp if and only if: + * + * bdigits <= prec AND + * bdigits+shift >= prec+2+sdigits AND + * exp = bexp+bdigits-prec-2 + * + * 1234567000000000 -> bdigits + shift + * ----------XX1234 -> sdigits + * ----------X1 -> tiny-digits + * |- prec -| + * + * OR + * + * bdigits > prec AND + * shift > sdigits AND + * exp = bexp-1 + * + * 1234567892100000 -> bdigits + shift + * ----------XX1234 -> sdigits + * ----------X1 -> tiny-digits + * |- prec -| + * + * If tiny is zero, adding or subtracting is a no-op. + * Otherwise, adding tiny generates a non-zero digit either + * below the rounding digit or the least significant digit + * of big. When subtracting, tiny is in the same position as + * the carry that would be generated by subtracting sdigits. + */ + mpd_copy_flags(&tiny, small); + tiny.exp = exp; + tiny.digits = 1; + tiny.len = 1; + tiny.data[0] = mpd_iszerocoeff(small) ? 0 : 1; + small = &tiny; + } + /* This cannot wrap: the difference is positive and <= maxprec */ + shift = big->exp - small->exp; + if (!mpd_qshiftl(&big_aligned, big, shift, status)) { + mpd_seterror(result, MPD_Malloc_error, status); + goto finish; + } + big = &big_aligned; + } + } + result->exp = small->exp; + + + /* compare length of coefficients */ + if (big->len < small->len) { + _mpd_ptrswap(&big, &small); + swap++; + } + + newsize = big->len; + if (!mpd_qresize(result, newsize, status)) { + goto finish; + } + + if (mpd_sign(a) == sign_b) { + + carry = _mpd_baseadd(result->data, big->data, small->data, + big->len, small->len); + + if (carry) { + newsize = big->len + 1; + if (!mpd_qresize(result, newsize, status)) { + goto finish; + } + result->data[newsize-1] = carry; + } + + result->len = newsize; + mpd_set_flags(result, sign_b); + } + else { + if (big->len == small->len) { + for (i=big->len-1; i >= 0; --i) { + if (big->data[i] != small->data[i]) { + if (big->data[i] < small->data[i]) { + _mpd_ptrswap(&big, &small); + swap++; + } + break; + } + } + } + + _mpd_basesub(result->data, big->data, small->data, + big->len, small->len); + newsize = _mpd_real_size(result->data, big->len); + /* resize to smaller cannot fail */ + (void)mpd_qresize(result, newsize, status); + + result->len = newsize; + sign_b = (swap & 1) ? sign_b : mpd_sign(a); + mpd_set_flags(result, sign_b); + + if (mpd_iszerocoeff(result)) { + mpd_set_positive(result); + if (ctx->round == MPD_ROUND_FLOOR) { + mpd_set_negative(result); + } + } + } + + mpd_setdigits(result); + +finish: + mpd_del(&big_aligned); +} + +/* Add a and b. No specials, no finalizing. */ +static void +_mpd_qadd(mpd_t *result, const mpd_t *a, const mpd_t *b, + const mpd_context_t *ctx, uint32_t *status) +{ + _mpd_qaddsub(result, a, b, mpd_sign(b), ctx, status); +} + +/* Subtract b from a. No specials, no finalizing. */ +static void +_mpd_qsub(mpd_t *result, const mpd_t *a, const mpd_t *b, + const mpd_context_t *ctx, uint32_t *status) +{ + _mpd_qaddsub(result, a, b, !mpd_sign(b), ctx, status); +} + +/* Add a and b. */ +void +mpd_qadd(mpd_t *result, const mpd_t *a, const mpd_t *b, + const mpd_context_t *ctx, uint32_t *status) +{ + if (mpd_isspecial(a) || mpd_isspecial(b)) { + if (mpd_qcheck_nans(result, a, b, ctx, status)) { + return; + } + _mpd_qaddsub_inf(result, a, b, mpd_sign(b), status); + return; + } + + _mpd_qaddsub(result, a, b, mpd_sign(b), ctx, status); + mpd_qfinalize(result, ctx, status); +} + +/* Add a and b. Set NaN/Invalid_operation if the result is inexact. */ +static void +_mpd_qadd_exact(mpd_t *result, const mpd_t *a, const mpd_t *b, + const mpd_context_t *ctx, uint32_t *status) +{ + uint32_t workstatus = 0; + + mpd_qadd(result, a, b, ctx, &workstatus); + *status |= workstatus; + if (workstatus & (MPD_Inexact|MPD_Rounded|MPD_Clamped)) { + mpd_seterror(result, MPD_Invalid_operation, status); + } +} + +/* Subtract b from a. */ +void +mpd_qsub(mpd_t *result, const mpd_t *a, const mpd_t *b, + const mpd_context_t *ctx, uint32_t *status) +{ + if (mpd_isspecial(a) || mpd_isspecial(b)) { + if (mpd_qcheck_nans(result, a, b, ctx, status)) { + return; + } + _mpd_qaddsub_inf(result, a, b, !mpd_sign(b), status); + return; + } + + _mpd_qaddsub(result, a, b, !mpd_sign(b), ctx, status); + mpd_qfinalize(result, ctx, status); +} + +/* Subtract b from a. Set NaN/Invalid_operation if the result is inexact. */ +static void +_mpd_qsub_exact(mpd_t *result, const mpd_t *a, const mpd_t *b, + const mpd_context_t *ctx, uint32_t *status) +{ + uint32_t workstatus = 0; + + mpd_qsub(result, a, b, ctx, &workstatus); + *status |= workstatus; + if (workstatus & (MPD_Inexact|MPD_Rounded|MPD_Clamped)) { + mpd_seterror(result, MPD_Invalid_operation, status); + } +} + +/* Add decimal and mpd_ssize_t. */ +void +mpd_qadd_ssize(mpd_t *result, const mpd_t *a, mpd_ssize_t b, + const mpd_context_t *ctx, uint32_t *status) +{ + mpd_context_t maxcontext; + MPD_NEW_STATIC(bb,0,0,0,0); + + mpd_maxcontext(&maxcontext); + mpd_qsset_ssize(&bb, b, &maxcontext, status); + mpd_qadd(result, a, &bb, ctx, status); + mpd_del(&bb); +} + +/* Add decimal and mpd_uint_t. */ +void +mpd_qadd_uint(mpd_t *result, const mpd_t *a, mpd_uint_t b, + const mpd_context_t *ctx, uint32_t *status) +{ + mpd_context_t maxcontext; + MPD_NEW_STATIC(bb,0,0,0,0); + + mpd_maxcontext(&maxcontext); + mpd_qsset_uint(&bb, b, &maxcontext, status); + mpd_qadd(result, a, &bb, ctx, status); + mpd_del(&bb); +} + +/* Subtract mpd_ssize_t from decimal. */ +void +mpd_qsub_ssize(mpd_t *result, const mpd_t *a, mpd_ssize_t b, + const mpd_context_t *ctx, uint32_t *status) +{ + mpd_context_t maxcontext; + MPD_NEW_STATIC(bb,0,0,0,0); + + mpd_maxcontext(&maxcontext); + mpd_qsset_ssize(&bb, b, &maxcontext, status); + mpd_qsub(result, a, &bb, ctx, status); + mpd_del(&bb); +} + +/* Subtract mpd_uint_t from decimal. */ +void +mpd_qsub_uint(mpd_t *result, const mpd_t *a, mpd_uint_t b, + const mpd_context_t *ctx, uint32_t *status) +{ + mpd_context_t maxcontext; + MPD_NEW_STATIC(bb,0,0,0,0); + + mpd_maxcontext(&maxcontext); + mpd_qsset_uint(&bb, b, &maxcontext, status); + mpd_qsub(result, a, &bb, ctx, status); + mpd_del(&bb); +} + +/* Add decimal and int32_t. */ +void +mpd_qadd_i32(mpd_t *result, const mpd_t *a, int32_t b, + const mpd_context_t *ctx, uint32_t *status) +{ + mpd_qadd_ssize(result, a, b, ctx, status); +} + +/* Add decimal and uint32_t. */ +void +mpd_qadd_u32(mpd_t *result, const mpd_t *a, uint32_t b, + const mpd_context_t *ctx, uint32_t *status) +{ + mpd_qadd_uint(result, a, b, ctx, status); +} + +#ifdef CONFIG_64 +/* Add decimal and int64_t. */ +void +mpd_qadd_i64(mpd_t *result, const mpd_t *a, int64_t b, + const mpd_context_t *ctx, uint32_t *status) +{ + mpd_qadd_ssize(result, a, b, ctx, status); +} + +/* Add decimal and uint64_t. */ +void +mpd_qadd_u64(mpd_t *result, const mpd_t *a, uint64_t b, + const mpd_context_t *ctx, uint32_t *status) +{ + mpd_qadd_uint(result, a, b, ctx, status); +} +#elif !defined(LEGACY_COMPILER) +/* Add decimal and int64_t. */ +void +mpd_qadd_i64(mpd_t *result, const mpd_t *a, int64_t b, + const mpd_context_t *ctx, uint32_t *status) +{ + mpd_context_t maxcontext; + MPD_NEW_STATIC(bb,0,0,0,0); + + mpd_maxcontext(&maxcontext); + mpd_qset_i64(&bb, b, &maxcontext, status); + mpd_qadd(result, a, &bb, ctx, status); + mpd_del(&bb); +} + +/* Add decimal and uint64_t. */ +void +mpd_qadd_u64(mpd_t *result, const mpd_t *a, uint64_t b, + const mpd_context_t *ctx, uint32_t *status) +{ + mpd_context_t maxcontext; + MPD_NEW_STATIC(bb,0,0,0,0); + + mpd_maxcontext(&maxcontext); + mpd_qset_u64(&bb, b, &maxcontext, status); + mpd_qadd(result, a, &bb, ctx, status); + mpd_del(&bb); +} +#endif + +/* Subtract int32_t from decimal. */ +void +mpd_qsub_i32(mpd_t *result, const mpd_t *a, int32_t b, + const mpd_context_t *ctx, uint32_t *status) +{ + mpd_qsub_ssize(result, a, b, ctx, status); +} + +/* Subtract uint32_t from decimal. */ +void +mpd_qsub_u32(mpd_t *result, const mpd_t *a, uint32_t b, + const mpd_context_t *ctx, uint32_t *status) +{ + mpd_qsub_uint(result, a, b, ctx, status); +} + +#ifdef CONFIG_64 +/* Subtract int64_t from decimal. */ +void +mpd_qsub_i64(mpd_t *result, const mpd_t *a, int64_t b, + const mpd_context_t *ctx, uint32_t *status) +{ + mpd_qsub_ssize(result, a, b, ctx, status); +} + +/* Subtract uint64_t from decimal. */ +void +mpd_qsub_u64(mpd_t *result, const mpd_t *a, uint64_t b, + const mpd_context_t *ctx, uint32_t *status) +{ + mpd_qsub_uint(result, a, b, ctx, status); +} +#elif !defined(LEGACY_COMPILER) +/* Subtract int64_t from decimal. */ +void +mpd_qsub_i64(mpd_t *result, const mpd_t *a, int64_t b, + const mpd_context_t *ctx, uint32_t *status) +{ + mpd_context_t maxcontext; + MPD_NEW_STATIC(bb,0,0,0,0); + + mpd_maxcontext(&maxcontext); + mpd_qset_i64(&bb, b, &maxcontext, status); + mpd_qsub(result, a, &bb, ctx, status); + mpd_del(&bb); +} + +/* Subtract uint64_t from decimal. */ +void +mpd_qsub_u64(mpd_t *result, const mpd_t *a, uint64_t b, + const mpd_context_t *ctx, uint32_t *status) +{ + mpd_context_t maxcontext; + MPD_NEW_STATIC(bb,0,0,0,0); + + mpd_maxcontext(&maxcontext); + mpd_qset_u64(&bb, b, &maxcontext, status); + mpd_qsub(result, a, &bb, ctx, status); + mpd_del(&bb); +} +#endif + + +/* Divide infinities. */ +static void +_mpd_qdiv_inf(mpd_t *result, const mpd_t *a, const mpd_t *b, + const mpd_context_t *ctx, uint32_t *status) +{ + if (mpd_isinfinite(a)) { + if (mpd_isinfinite(b)) { + mpd_seterror(result, MPD_Invalid_operation, status); + return; + } + mpd_setspecial(result, mpd_sign(a)^mpd_sign(b), MPD_INF); + return; + } + assert(mpd_isinfinite(b)); + _settriple(result, mpd_sign(a)^mpd_sign(b), 0, mpd_etiny(ctx)); + *status |= MPD_Clamped; +} + +enum {NO_IDEAL_EXP, SET_IDEAL_EXP}; +/* Divide a by b. */ +static void +_mpd_qdiv(int action, mpd_t *q, const mpd_t *a, const mpd_t *b, + const mpd_context_t *ctx, uint32_t *status) +{ + MPD_NEW_STATIC(aligned,0,0,0,0); + mpd_uint_t ld; + mpd_ssize_t shift, exp, tz; + mpd_ssize_t newsize; + mpd_ssize_t ideal_exp; + mpd_uint_t rem; + uint8_t sign_a = mpd_sign(a); + uint8_t sign_b = mpd_sign(b); + + + if (mpd_isspecial(a) || mpd_isspecial(b)) { + if (mpd_qcheck_nans(q, a, b, ctx, status)) { + return; + } + _mpd_qdiv_inf(q, a, b, ctx, status); + return; + } + if (mpd_iszerocoeff(b)) { + if (mpd_iszerocoeff(a)) { + mpd_seterror(q, MPD_Division_undefined, status); + } + else { + mpd_setspecial(q, sign_a^sign_b, MPD_INF); + *status |= MPD_Division_by_zero; + } + return; + } + if (mpd_iszerocoeff(a)) { + exp = a->exp - b->exp; + _settriple(q, sign_a^sign_b, 0, exp); + mpd_qfinalize(q, ctx, status); + return; + } + + shift = (b->digits - a->digits) + ctx->prec + 1; + ideal_exp = a->exp - b->exp; + exp = ideal_exp - shift; + if (shift > 0) { + if (!mpd_qshiftl(&aligned, a, shift, status)) { + mpd_seterror(q, MPD_Malloc_error, status); + goto finish; + } + a = &aligned; + } + else if (shift < 0) { + shift = -shift; + if (!mpd_qshiftl(&aligned, b, shift, status)) { + mpd_seterror(q, MPD_Malloc_error, status); + goto finish; + } + b = &aligned; + } + + + newsize = a->len - b->len + 1; + if ((q != b && q != a) || (q == b && newsize > b->len)) { + if (!mpd_qresize(q, newsize, status)) { + mpd_seterror(q, MPD_Malloc_error, status); + goto finish; + } + } + + + if (b->len == 1) { + rem = _mpd_shortdiv(q->data, a->data, a->len, b->data[0]); + } + else if (b->len <= MPD_NEWTONDIV_CUTOFF) { + int ret = _mpd_basedivmod(q->data, NULL, a->data, b->data, + a->len, b->len); + if (ret < 0) { + mpd_seterror(q, MPD_Malloc_error, status); + goto finish; + } + rem = ret; + } + else { + MPD_NEW_STATIC(r,0,0,0,0); + _mpd_base_ndivmod(q, &r, a, b, status); + if (mpd_isspecial(q) || mpd_isspecial(&r)) { + mpd_setspecial(q, MPD_POS, MPD_NAN); + mpd_del(&r); + goto finish; + } + rem = !mpd_iszerocoeff(&r); + mpd_del(&r); + newsize = q->len; + } + + newsize = _mpd_real_size(q->data, newsize); + /* resize to smaller cannot fail */ + mpd_qresize(q, newsize, status); + mpd_set_flags(q, sign_a^sign_b); + q->len = newsize; + mpd_setdigits(q); + + shift = ideal_exp - exp; + if (rem) { + ld = mpd_lsd(q->data[0]); + if (ld == 0 || ld == 5) { + q->data[0] += 1; + } + } + else if (action == SET_IDEAL_EXP && shift > 0) { + tz = mpd_trail_zeros(q); + shift = (tz > shift) ? shift : tz; + mpd_qshiftr_inplace(q, shift); + exp += shift; + } + + q->exp = exp; + + +finish: + mpd_del(&aligned); + mpd_qfinalize(q, ctx, status); +} + +/* Divide a by b. */ +void +mpd_qdiv(mpd_t *q, const mpd_t *a, const mpd_t *b, + const mpd_context_t *ctx, uint32_t *status) +{ + _mpd_qdiv(SET_IDEAL_EXP, q, a, b, ctx, status); +} + +/* Internal function. */ +static void +_mpd_qdivmod(mpd_t *q, mpd_t *r, const mpd_t *a, const mpd_t *b, + const mpd_context_t *ctx, uint32_t *status) +{ + MPD_NEW_STATIC(aligned,0,0,0,0); + mpd_ssize_t qsize, rsize; + mpd_ssize_t ideal_exp, expdiff, shift; + uint8_t sign_a = mpd_sign(a); + uint8_t sign_ab = mpd_sign(a)^mpd_sign(b); + + + ideal_exp = (a->exp > b->exp) ? b->exp : a->exp; + if (mpd_iszerocoeff(a)) { + if (!mpd_qcopy(r, a, status)) { + goto nanresult; /* GCOV_NOT_REACHED */ + } + r->exp = ideal_exp; + _settriple(q, sign_ab, 0, 0); + return; + } + + expdiff = mpd_adjexp(a) - mpd_adjexp(b); + if (expdiff < 0) { + if (a->exp > b->exp) { + /* positive and less than b->digits - a->digits */ + shift = a->exp - b->exp; + if (!mpd_qshiftl(r, a, shift, status)) { + goto nanresult; + } + r->exp = ideal_exp; + } + else { + if (!mpd_qcopy(r, a, status)) { + goto nanresult; + } + } + _settriple(q, sign_ab, 0, 0); + return; + } + if (expdiff > ctx->prec) { + *status |= MPD_Division_impossible; + goto nanresult; + } + + + /* + * At this point we have: + * (1) 0 <= a->exp + a->digits - b->exp - b->digits <= prec + * (2) a->exp - b->exp >= b->digits - a->digits + * (3) a->exp - b->exp <= prec + b->digits - a->digits + */ + if (a->exp != b->exp) { + shift = a->exp - b->exp; + if (shift > 0) { + /* by (3), after the shift a->digits <= prec + b->digits */ + if (!mpd_qshiftl(&aligned, a, shift, status)) { + goto nanresult; + } + a = &aligned; + } + else { + shift = -shift; + /* by (2), after the shift b->digits <= a->digits */ + if (!mpd_qshiftl(&aligned, b, shift, status)) { + goto nanresult; + } + b = &aligned; + } + } + + + qsize = a->len - b->len + 1; + if (!(q == a && qsize < a->len) && !(q == b && qsize < b->len)) { + if (!mpd_qresize(q, qsize, status)) { + goto nanresult; + } + } + + rsize = b->len; + if (!(r == a && rsize < a->len)) { + if (!mpd_qresize(r, rsize, status)) { + goto nanresult; + } + } + + if (b->len == 1) { + if (a->len == 1) { + _mpd_div_word(&q->data[0], &r->data[0], a->data[0], b->data[0]); + } + else { + r->data[0] = _mpd_shortdiv(q->data, a->data, a->len, b->data[0]); + } + } + else if (b->len <= MPD_NEWTONDIV_CUTOFF) { + int ret; + ret = _mpd_basedivmod(q->data, r->data, a->data, b->data, + a->len, b->len); + if (ret == -1) { + *status |= MPD_Malloc_error; + goto nanresult; + } + } + else { + _mpd_base_ndivmod(q, r, a, b, status); + if (mpd_isspecial(q) || mpd_isspecial(r)) { + goto nanresult; + } + qsize = q->len; + rsize = r->len; + } + + qsize = _mpd_real_size(q->data, qsize); + /* resize to smaller cannot fail */ + mpd_qresize(q, qsize, status); + q->len = qsize; + mpd_setdigits(q); + mpd_set_flags(q, sign_ab); + q->exp = 0; + if (q->digits > ctx->prec) { + *status |= MPD_Division_impossible; + goto nanresult; + } + + rsize = _mpd_real_size(r->data, rsize); + /* resize to smaller cannot fail */ + mpd_qresize(r, rsize, status); + r->len = rsize; + mpd_setdigits(r); + mpd_set_flags(r, sign_a); + r->exp = ideal_exp; + +out: + mpd_del(&aligned); + return; + +nanresult: + mpd_setspecial(q, MPD_POS, MPD_NAN); + mpd_setspecial(r, MPD_POS, MPD_NAN); + goto out; +} + +/* Integer division with remainder. */ +void +mpd_qdivmod(mpd_t *q, mpd_t *r, const mpd_t *a, const mpd_t *b, + const mpd_context_t *ctx, uint32_t *status) +{ + uint8_t sign = mpd_sign(a)^mpd_sign(b); + + if (mpd_isspecial(a) || mpd_isspecial(b)) { + if (mpd_qcheck_nans(q, a, b, ctx, status)) { + mpd_qcopy(r, q, status); + return; + } + if (mpd_isinfinite(a)) { + if (mpd_isinfinite(b)) { + mpd_setspecial(q, MPD_POS, MPD_NAN); + } + else { + mpd_setspecial(q, sign, MPD_INF); + } + mpd_setspecial(r, MPD_POS, MPD_NAN); + *status |= MPD_Invalid_operation; + return; + } + if (mpd_isinfinite(b)) { + if (!mpd_qcopy(r, a, status)) { + mpd_seterror(q, MPD_Malloc_error, status); + return; + } + mpd_qfinalize(r, ctx, status); + _settriple(q, sign, 0, 0); + return; + } + /* debug */ + abort(); /* GCOV_NOT_REACHED */ + } + if (mpd_iszerocoeff(b)) { + if (mpd_iszerocoeff(a)) { + mpd_setspecial(q, MPD_POS, MPD_NAN); + mpd_setspecial(r, MPD_POS, MPD_NAN); + *status |= MPD_Division_undefined; + } + else { + mpd_setspecial(q, sign, MPD_INF); + mpd_setspecial(r, MPD_POS, MPD_NAN); + *status |= (MPD_Division_by_zero|MPD_Invalid_operation); + } + return; + } + + _mpd_qdivmod(q, r, a, b, ctx, status); + mpd_qfinalize(q, ctx, status); + mpd_qfinalize(r, ctx, status); +} + +void +mpd_qdivint(mpd_t *q, const mpd_t *a, const mpd_t *b, + const mpd_context_t *ctx, uint32_t *status) +{ + MPD_NEW_STATIC(r,0,0,0,0); + uint8_t sign = mpd_sign(a)^mpd_sign(b); + + if (mpd_isspecial(a) || mpd_isspecial(b)) { + if (mpd_qcheck_nans(q, a, b, ctx, status)) { + return; + } + if (mpd_isinfinite(a) && mpd_isinfinite(b)) { + mpd_seterror(q, MPD_Invalid_operation, status); + return; + } + if (mpd_isinfinite(a)) { + mpd_setspecial(q, sign, MPD_INF); + return; + } + if (mpd_isinfinite(b)) { + _settriple(q, sign, 0, 0); + return; + } + /* debug */ + abort(); /* GCOV_NOT_REACHED */ + } + if (mpd_iszerocoeff(b)) { + if (mpd_iszerocoeff(a)) { + mpd_seterror(q, MPD_Division_undefined, status); + } + else { + mpd_setspecial(q, sign, MPD_INF); + *status |= MPD_Division_by_zero; + } + return; + } + + + _mpd_qdivmod(q, &r, a, b, ctx, status); + mpd_del(&r); + mpd_qfinalize(q, ctx, status); +} + +/* Divide decimal by mpd_ssize_t. */ +void +mpd_qdiv_ssize(mpd_t *result, const mpd_t *a, mpd_ssize_t b, + const mpd_context_t *ctx, uint32_t *status) +{ + mpd_context_t maxcontext; + MPD_NEW_STATIC(bb,0,0,0,0); + + mpd_maxcontext(&maxcontext); + mpd_qsset_ssize(&bb, b, &maxcontext, status); + mpd_qdiv(result, a, &bb, ctx, status); + mpd_del(&bb); +} + +/* Divide decimal by mpd_uint_t. */ +void +mpd_qdiv_uint(mpd_t *result, const mpd_t *a, mpd_uint_t b, + const mpd_context_t *ctx, uint32_t *status) +{ + mpd_context_t maxcontext; + MPD_NEW_STATIC(bb,0,0,0,0); + + mpd_maxcontext(&maxcontext); + mpd_qsset_uint(&bb, b, &maxcontext, status); + mpd_qdiv(result, a, &bb, ctx, status); + mpd_del(&bb); +} + +/* Divide decimal by int32_t. */ +void +mpd_qdiv_i32(mpd_t *result, const mpd_t *a, int32_t b, + const mpd_context_t *ctx, uint32_t *status) +{ + mpd_qdiv_ssize(result, a, b, ctx, status); +} + +/* Divide decimal by uint32_t. */ +void +mpd_qdiv_u32(mpd_t *result, const mpd_t *a, uint32_t b, + const mpd_context_t *ctx, uint32_t *status) +{ + mpd_qdiv_uint(result, a, b, ctx, status); +} + +#ifdef CONFIG_64 +/* Divide decimal by int64_t. */ +void +mpd_qdiv_i64(mpd_t *result, const mpd_t *a, int64_t b, + const mpd_context_t *ctx, uint32_t *status) +{ + mpd_qdiv_ssize(result, a, b, ctx, status); +} + +/* Divide decimal by uint64_t. */ +void +mpd_qdiv_u64(mpd_t *result, const mpd_t *a, uint64_t b, + const mpd_context_t *ctx, uint32_t *status) +{ + mpd_qdiv_uint(result, a, b, ctx, status); +} +#elif !defined(LEGACY_COMPILER) +/* Divide decimal by int64_t. */ +void +mpd_qdiv_i64(mpd_t *result, const mpd_t *a, int64_t b, + const mpd_context_t *ctx, uint32_t *status) +{ + mpd_context_t maxcontext; + MPD_NEW_STATIC(bb,0,0,0,0); + + mpd_maxcontext(&maxcontext); + mpd_qset_i64(&bb, b, &maxcontext, status); + mpd_qdiv(result, a, &bb, ctx, status); + mpd_del(&bb); +} + +/* Divide decimal by uint64_t. */ +void +mpd_qdiv_u64(mpd_t *result, const mpd_t *a, uint64_t b, + const mpd_context_t *ctx, uint32_t *status) +{ + mpd_context_t maxcontext; + MPD_NEW_STATIC(bb,0,0,0,0); + + mpd_maxcontext(&maxcontext); + mpd_qset_u64(&bb, b, &maxcontext, status); + mpd_qdiv(result, a, &bb, ctx, status); + mpd_del(&bb); +} +#endif + +/* Pad the result with trailing zeros if it has fewer digits than prec. */ +static void +_mpd_zeropad(mpd_t *result, const mpd_context_t *ctx, uint32_t *status) +{ + if (!mpd_isspecial(result) && !mpd_iszero(result) && + result->digits < ctx->prec) { + mpd_ssize_t shift = ctx->prec - result->digits; + mpd_qshiftl(result, result, shift, status); + result->exp -= shift; + } +} + +/* Check if the result is guaranteed to be one. */ +static int +_mpd_qexp_check_one(mpd_t *result, const mpd_t *a, const mpd_context_t *ctx, + uint32_t *status) +{ + MPD_NEW_CONST(lim,0,-(ctx->prec+1),1,1,1,9); + MPD_NEW_SHARED(aa, a); + + mpd_set_positive(&aa); + + /* abs(a) <= 9 * 10**(-prec-1) */ + if (_mpd_cmp(&aa, &lim) <= 0) { + _settriple(result, 0, 1, 0); + *status |= MPD_Rounded|MPD_Inexact; + return 1; + } + + return 0; +} + +/* + * Get the number of iterations for the Horner scheme in _mpd_qexp(). + */ +static inline mpd_ssize_t +_mpd_get_exp_iterations(const mpd_t *r, mpd_ssize_t p) +{ + mpd_ssize_t log10pbyr; /* lower bound for log10(p / abs(r)) */ + mpd_ssize_t n; + + assert(p >= 10); + assert(!mpd_iszero(r)); + assert(-p < mpd_adjexp(r) && mpd_adjexp(r) <= -1); + +#ifdef CONFIG_64 + if (p > (mpd_ssize_t)(1ULL<<52)) { + return MPD_SSIZE_MAX; + } +#endif + + /* + * Lower bound for log10(p / abs(r)): adjexp(p) - (adjexp(r) + 1) + * At this point (for CONFIG_64, CONFIG_32 is not problematic): + * 1) 10 <= p <= 2**52 + * 2) -p < adjexp(r) <= -1 + * 3) 1 <= log10pbyr <= 2**52 + 14 + */ + log10pbyr = (mpd_word_digits(p)-1) - (mpd_adjexp(r)+1); + + /* + * The numerator in the paper is 1.435 * p - 1.182, calculated + * exactly. We compensate for rounding errors by using 1.43503. + * ACL2 proofs: + * 1) exp-iter-approx-lower-bound: The term below evaluated + * in 53-bit floating point arithmetic is greater than or + * equal to the exact term used in the paper. + * 2) exp-iter-approx-upper-bound: The term below is less than + * or equal to 3/2 * p <= 3/2 * 2**52. + */ + n = (mpd_ssize_t)ceil((1.43503*(double)p - 1.182) / (double)log10pbyr); + return n >= 3 ? n : 3; +} + +/* + * Internal function, specials have been dealt with. Apart from Overflow + * and Underflow, two cases must be considered for the error of the result: + * + * 1) abs(a) <= 9 * 10**(-prec-1) ==> result == 1 + * + * Absolute error: abs(1 - e**x) < 10**(-prec) + * ------------------------------------------- + * + * 2) abs(a) > 9 * 10**(-prec-1) + * + * Relative error: abs(result - e**x) < 0.5 * 10**(-prec) * e**x + * ------------------------------------------------------------- + * + * The algorithm is from Hull&Abrham, Variable Precision Exponential Function, + * ACM Transactions on Mathematical Software, Vol. 12, No. 2, June 1986. + * + * Main differences: + * + * - The number of iterations for the Horner scheme is calculated using + * 53-bit floating point arithmetic. + * + * - In the error analysis for ER (relative error accumulated in the + * evaluation of the truncated series) the reduced operand r may + * have any number of digits. + * ACL2 proof: exponent-relative-error + * + * - The analysis for early abortion has been adapted for the mpd_t + * ranges. + */ +static void +_mpd_qexp(mpd_t *result, const mpd_t *a, const mpd_context_t *ctx, + uint32_t *status) +{ + mpd_context_t workctx; + MPD_NEW_STATIC(tmp,0,0,0,0); + MPD_NEW_STATIC(sum,0,0,0,0); + MPD_NEW_CONST(word,0,0,1,1,1,1); + mpd_ssize_t j, n, t; + + assert(!mpd_isspecial(a)); + + if (mpd_iszerocoeff(a)) { + _settriple(result, MPD_POS, 1, 0); + return; + } + + /* + * We are calculating e^x = e^(r*10^t) = (e^r)^(10^t), where abs(r) < 1 and t >= 0. + * + * If t > 0, we have: + * + * (1) 0.1 <= r < 1, so e^0.1 <= e^r. If t > MAX_T, overflow occurs: + * + * MAX-EMAX+1 < log10(e^(0.1*10*t)) <= log10(e^(r*10^t)) < adjexp(e^(r*10^t))+1 + * + * (2) -1 < r <= -0.1, so e^r <= e^-0.1. If t > MAX_T, underflow occurs: + * + * adjexp(e^(r*10^t)) <= log10(e^(r*10^t)) <= log10(e^(-0.1*10^t)) < MIN-ETINY + */ +#if defined(CONFIG_64) + #define MPD_EXP_MAX_T 19 +#elif defined(CONFIG_32) + #define MPD_EXP_MAX_T 10 +#endif + t = a->digits + a->exp; + t = (t > 0) ? t : 0; + if (t > MPD_EXP_MAX_T) { + if (mpd_ispositive(a)) { + mpd_setspecial(result, MPD_POS, MPD_INF); + *status |= MPD_Overflow|MPD_Inexact|MPD_Rounded; + } + else { + _settriple(result, MPD_POS, 0, mpd_etiny(ctx)); + *status |= (MPD_Inexact|MPD_Rounded|MPD_Subnormal| + MPD_Underflow|MPD_Clamped); + } + return; + } + + /* abs(a) <= 9 * 10**(-prec-1) */ + if (_mpd_qexp_check_one(result, a, ctx, status)) { + return; + } + + mpd_maxcontext(&workctx); + workctx.prec = ctx->prec + t + 2; + workctx.prec = (workctx.prec < 10) ? 10 : workctx.prec; + workctx.round = MPD_ROUND_HALF_EVEN; + + if (!mpd_qcopy(result, a, status)) { + return; + } + result->exp -= t; + + /* + * At this point: + * 1) 9 * 10**(-prec-1) < abs(a) + * 2) 9 * 10**(-prec-t-1) < abs(r) + * 3) log10(9) - prec - t - 1 < log10(abs(r)) < adjexp(abs(r)) + 1 + * 4) - prec - t - 2 < adjexp(abs(r)) <= -1 + */ + n = _mpd_get_exp_iterations(result, workctx.prec); + if (n == MPD_SSIZE_MAX) { + mpd_seterror(result, MPD_Invalid_operation, status); /* GCOV_UNLIKELY */ + return; /* GCOV_UNLIKELY */ + } + + _settriple(&sum, MPD_POS, 1, 0); + + for (j = n-1; j >= 1; j--) { + word.data[0] = j; + mpd_setdigits(&word); + mpd_qdiv(&tmp, result, &word, &workctx, &workctx.status); + mpd_qfma(&sum, &sum, &tmp, &one, &workctx, &workctx.status); + } + +#ifdef CONFIG_64 + _mpd_qpow_uint(result, &sum, mpd_pow10[t], MPD_POS, &workctx, status); +#else + if (t <= MPD_MAX_POW10) { + _mpd_qpow_uint(result, &sum, mpd_pow10[t], MPD_POS, &workctx, status); + } + else { + t -= MPD_MAX_POW10; + _mpd_qpow_uint(&tmp, &sum, mpd_pow10[MPD_MAX_POW10], MPD_POS, + &workctx, status); + _mpd_qpow_uint(result, &tmp, mpd_pow10[t], MPD_POS, &workctx, status); + } +#endif + + mpd_del(&tmp); + mpd_del(&sum); + *status |= (workctx.status&MPD_Errors); + *status |= (MPD_Inexact|MPD_Rounded); +} + +/* exp(a) */ +void +mpd_qexp(mpd_t *result, const mpd_t *a, const mpd_context_t *ctx, + uint32_t *status) +{ + mpd_context_t workctx; + + if (mpd_isspecial(a)) { + if (mpd_qcheck_nan(result, a, ctx, status)) { + return; + } + if (mpd_isnegative(a)) { + _settriple(result, MPD_POS, 0, 0); + } + else { + mpd_setspecial(result, MPD_POS, MPD_INF); + } + return; + } + if (mpd_iszerocoeff(a)) { + _settriple(result, MPD_POS, 1, 0); + return; + } + + workctx = *ctx; + workctx.round = MPD_ROUND_HALF_EVEN; + + if (ctx->allcr) { + MPD_NEW_STATIC(t1, 0,0,0,0); + MPD_NEW_STATIC(t2, 0,0,0,0); + MPD_NEW_STATIC(ulp, 0,0,0,0); + MPD_NEW_STATIC(aa, 0,0,0,0); + mpd_ssize_t prec; + mpd_ssize_t ulpexp; + uint32_t workstatus; + + if (result == a) { + if (!mpd_qcopy(&aa, a, status)) { + mpd_seterror(result, MPD_Malloc_error, status); + return; + } + a = &aa; + } + + workctx.clamp = 0; + prec = ctx->prec + 3; + while (1) { + workctx.prec = prec; + workstatus = 0; + + _mpd_qexp(result, a, &workctx, &workstatus); + *status |= workstatus; + + ulpexp = result->exp + result->digits - workctx.prec; + if (workstatus & MPD_Underflow) { + /* The effective work precision is result->digits. */ + ulpexp = result->exp; + } + _ssettriple(&ulp, MPD_POS, 1, ulpexp); + + /* + * At this point [1]: + * 1) abs(result - e**x) < 0.5 * 10**(-prec) * e**x + * 2) result - ulp < e**x < result + ulp + * 3) result - ulp < result < result + ulp + * + * If round(result-ulp)==round(result+ulp), then + * round(result)==round(e**x). Therefore the result + * is correctly rounded. + * + * [1] If abs(a) <= 9 * 10**(-prec-1), use the absolute + * error for a similar argument. + */ + workctx.prec = ctx->prec; + mpd_qadd(&t1, result, &ulp, &workctx, &workctx.status); + mpd_qsub(&t2, result, &ulp, &workctx, &workctx.status); + if (mpd_isspecial(result) || mpd_iszerocoeff(result) || + mpd_qcmp(&t1, &t2, status) == 0) { + workctx.clamp = ctx->clamp; + _mpd_zeropad(result, &workctx, status); + mpd_check_underflow(result, &workctx, status); + mpd_qfinalize(result, &workctx, status); + break; + } + prec += MPD_RDIGITS; + } + mpd_del(&t1); + mpd_del(&t2); + mpd_del(&ulp); + mpd_del(&aa); + } + else { + _mpd_qexp(result, a, &workctx, status); + _mpd_zeropad(result, &workctx, status); + mpd_check_underflow(result, &workctx, status); + mpd_qfinalize(result, &workctx, status); + } +} + +/* Fused multiply-add: (a * b) + c, with a single final rounding. */ +void +mpd_qfma(mpd_t *result, const mpd_t *a, const mpd_t *b, const mpd_t *c, + const mpd_context_t *ctx, uint32_t *status) +{ + uint32_t workstatus = 0; + mpd_t *cc = NULL; + + if (result == c) { + if ((cc = mpd_qncopy(c)) == NULL) { + mpd_seterror(result, MPD_Malloc_error, status); + return; + } + c = cc; + } + + _mpd_qmul(result, a, b, ctx, &workstatus); + if (!(workstatus&MPD_Invalid_operation)) { + mpd_qadd(result, result, c, ctx, &workstatus); + } + + if (cc) mpd_del(cc); + *status |= workstatus; +} + +/* + * Schedule the optimal precision increase for the Newton iteration. + * v := input operand + * z_0 := initial approximation + * initprec := natural number such that abs(log(v) - z_0) < 10**-initprec + * maxprec := target precision + * + * For convenience the output klist contains the elements in reverse order: + * klist := [k_n-1, ..., k_0], where + * 1) k_0 <= initprec and + * 2) abs(log(v) - result) < 10**(-2*k_n-1 + 1) <= 10**-maxprec. + */ +static inline int +ln_schedule_prec(mpd_ssize_t klist[MPD_MAX_PREC_LOG2], mpd_ssize_t maxprec, + mpd_ssize_t initprec) +{ + mpd_ssize_t k; + int i; + + assert(maxprec >= 2 && initprec >= 2); + if (maxprec <= initprec) return -1; + + i = 0; k = maxprec; + do { + k = (k+2) / 2; + klist[i++] = k; + } while (k > initprec); + + return i-1; +} + +/* The constants have been verified with both decimal.py and mpfr. */ +#ifdef CONFIG_64 +#if MPD_RDIGITS != 19 + #error "mpdecimal.c: MPD_RDIGITS must be 19." +#endif +static const mpd_uint_t mpd_ln10_data[MPD_MINALLOC_MAX] = { + 6983716328982174407ULL, 9089704281976336583ULL, 1515961135648465461ULL, + 4416816335727555703ULL, 2900988039194170265ULL, 2307925037472986509ULL, + 107598438319191292ULL, 3466624107184669231ULL, 4450099781311469159ULL, + 9807828059751193854ULL, 7713456862091670584ULL, 1492198849978748873ULL, + 6528728696511086257ULL, 2385392051446341972ULL, 8692180205189339507ULL, + 6518769751037497088ULL, 2375253577097505395ULL, 9095610299291824318ULL, + 982748238504564801ULL, 5438635917781170543ULL, 7547331541421808427ULL, + 752371033310119785ULL, 3171643095059950878ULL, 9785265383207606726ULL, + 2932258279850258550ULL, 5497347726624257094ULL, 2976979522110718264ULL, + 9221477656763693866ULL, 1979650047149510504ULL, 6674183485704422507ULL, + 9702766860595249671ULL, 9278096762712757753ULL, 9314848524948644871ULL, + 6826928280848118428ULL, 754403708474699401ULL, 230105703089634572ULL, + 1929203337658714166ULL, 7589402567763113569ULL, 4208241314695689016ULL, + 2922455440575892572ULL, 9356734206705811364ULL, 2684916746550586856ULL, + 644507064800027750ULL, 9476834636167921018ULL, 5659121373450747856ULL, + 2835522011480466371ULL, 6470806855677432162ULL, 7141748003688084012ULL, + 9619404400222105101ULL, 5504893431493939147ULL, 6674744042432743651ULL, + 2287698219886746543ULL, 7773262884616336622ULL, 1985283935053089653ULL, + 4680843799894826233ULL, 8168948290720832555ULL, 8067566662873690987ULL, + 6248633409525465082ULL, 9829834196778404228ULL, 3524802359972050895ULL, + 3327900967572609677ULL, 110148862877297603ULL, 179914546843642076ULL, + 2302585092994045684ULL +}; +#else +#if MPD_RDIGITS != 9 + #error "mpdecimal.c: MPD_RDIGITS must be 9." +#endif +static const mpd_uint_t mpd_ln10_data[MPD_MINALLOC_MAX] = { + 401682692UL, 708474699UL, 720754403UL, 30896345UL, 602301057UL, 765871416UL, + 192920333UL, 763113569UL, 589402567UL, 956890167UL, 82413146UL, 589257242UL, + 245544057UL, 811364292UL, 734206705UL, 868569356UL, 167465505UL, 775026849UL, + 706480002UL, 18064450UL, 636167921UL, 569476834UL, 734507478UL, 156591213UL, + 148046637UL, 283552201UL, 677432162UL, 470806855UL, 880840126UL, 417480036UL, + 210510171UL, 940440022UL, 939147961UL, 893431493UL, 436515504UL, 440424327UL, + 654366747UL, 821988674UL, 622228769UL, 884616336UL, 537773262UL, 350530896UL, + 319852839UL, 989482623UL, 468084379UL, 720832555UL, 168948290UL, 736909878UL, + 675666628UL, 546508280UL, 863340952UL, 404228624UL, 834196778UL, 508959829UL, + 23599720UL, 967735248UL, 96757260UL, 603332790UL, 862877297UL, 760110148UL, + 468436420UL, 401799145UL, 299404568UL, 230258509UL +}; +#endif +/* _mpd_ln10 is used directly for precisions smaller than MINALLOC_MAX*RDIGITS. + Otherwise, it serves as the initial approximation for calculating ln(10). */ +static const mpd_t _mpd_ln10 = { + MPD_STATIC|MPD_CONST_DATA, -(MPD_MINALLOC_MAX*MPD_RDIGITS-1), + MPD_MINALLOC_MAX*MPD_RDIGITS, MPD_MINALLOC_MAX, MPD_MINALLOC_MAX, + (mpd_uint_t *)mpd_ln10_data +}; + +/* + * Set 'result' to log(10). + * Ulp error: abs(result - log(10)) < ulp(log(10)) + * Relative error: abs(result - log(10)) < 5 * 10**-prec * log(10) + * + * NOTE: The relative error is not derived from the ulp error, but + * calculated separately using the fact that 23/10 < log(10) < 24/10. + */ +void +mpd_qln10(mpd_t *result, mpd_ssize_t prec, uint32_t *status) +{ + mpd_context_t varcontext, maxcontext; + MPD_NEW_STATIC(tmp, 0,0,0,0); + MPD_NEW_CONST(static10, 0,0,2,1,1,10); + mpd_ssize_t klist[MPD_MAX_PREC_LOG2]; + mpd_uint_t rnd; + mpd_ssize_t shift; + int i; + + assert(prec >= 1); + + shift = MPD_MINALLOC_MAX*MPD_RDIGITS-prec; + shift = shift < 0 ? 0 : shift; + + rnd = mpd_qshiftr(result, &_mpd_ln10, shift, status); + if (rnd == MPD_UINT_MAX) { + mpd_seterror(result, MPD_Malloc_error, status); + return; + } + result->exp = -(result->digits-1); + + mpd_maxcontext(&maxcontext); + if (prec < MPD_MINALLOC_MAX*MPD_RDIGITS) { + maxcontext.prec = prec; + _mpd_apply_round_excess(result, rnd, &maxcontext, status); + *status |= (MPD_Inexact|MPD_Rounded); + return; + } + + mpd_maxcontext(&varcontext); + varcontext.round = MPD_ROUND_TRUNC; + + i = ln_schedule_prec(klist, prec+2, -result->exp); + for (; i >= 0; i--) { + varcontext.prec = 2*klist[i]+3; + result->flags ^= MPD_NEG; + _mpd_qexp(&tmp, result, &varcontext, status); + result->flags ^= MPD_NEG; + mpd_qmul(&tmp, &static10, &tmp, &varcontext, status); + mpd_qsub(&tmp, &tmp, &one, &maxcontext, status); + mpd_qadd(result, result, &tmp, &maxcontext, status); + if (mpd_isspecial(result)) { + break; + } + } + + mpd_del(&tmp); + maxcontext.prec = prec; + mpd_qfinalize(result, &maxcontext, status); +} + +/* + * Initial approximations for the ln() iteration. The values have the + * following properties (established with both decimal.py and mpfr): + * + * Index 0 - 400, logarithms of x in [1.00, 5.00]: + * abs(lnapprox[i] * 10**-3 - log((i+100)/100)) < 10**-2 + * abs(lnapprox[i] * 10**-3 - log((i+1+100)/100)) < 10**-2 + * + * Index 401 - 899, logarithms of x in (0.500, 0.999]: + * abs(-lnapprox[i] * 10**-3 - log((i+100)/1000)) < 10**-2 + * abs(-lnapprox[i] * 10**-3 - log((i+1+100)/1000)) < 10**-2 + */ +static const uint16_t lnapprox[900] = { + /* index 0 - 400: log((i+100)/100) * 1000 */ + 0, 10, 20, 30, 39, 49, 58, 68, 77, 86, 95, 104, 113, 122, 131, 140, 148, 157, + 166, 174, 182, 191, 199, 207, 215, 223, 231, 239, 247, 255, 262, 270, 278, + 285, 293, 300, 308, 315, 322, 329, 336, 344, 351, 358, 365, 372, 378, 385, + 392, 399, 406, 412, 419, 425, 432, 438, 445, 451, 457, 464, 470, 476, 482, + 489, 495, 501, 507, 513, 519, 525, 531, 536, 542, 548, 554, 560, 565, 571, + 577, 582, 588, 593, 599, 604, 610, 615, 621, 626, 631, 637, 642, 647, 652, + 658, 663, 668, 673, 678, 683, 688, 693, 698, 703, 708, 713, 718, 723, 728, + 732, 737, 742, 747, 751, 756, 761, 766, 770, 775, 779, 784, 788, 793, 798, + 802, 806, 811, 815, 820, 824, 829, 833, 837, 842, 846, 850, 854, 859, 863, + 867, 871, 876, 880, 884, 888, 892, 896, 900, 904, 908, 912, 916, 920, 924, + 928, 932, 936, 940, 944, 948, 952, 956, 959, 963, 967, 971, 975, 978, 982, + 986, 990, 993, 997, 1001, 1004, 1008, 1012, 1015, 1019, 1022, 1026, 1030, + 1033, 1037, 1040, 1044, 1047, 1051, 1054, 1058, 1061, 1065, 1068, 1072, 1075, + 1078, 1082, 1085, 1089, 1092, 1095, 1099, 1102, 1105, 1109, 1112, 1115, 1118, + 1122, 1125, 1128, 1131, 1135, 1138, 1141, 1144, 1147, 1151, 1154, 1157, 1160, + 1163, 1166, 1169, 1172, 1176, 1179, 1182, 1185, 1188, 1191, 1194, 1197, 1200, + 1203, 1206, 1209, 1212, 1215, 1218, 1221, 1224, 1227, 1230, 1233, 1235, 1238, + 1241, 1244, 1247, 1250, 1253, 1256, 1258, 1261, 1264, 1267, 1270, 1273, 1275, + 1278, 1281, 1284, 1286, 1289, 1292, 1295, 1297, 1300, 1303, 1306, 1308, 1311, + 1314, 1316, 1319, 1322, 1324, 1327, 1330, 1332, 1335, 1338, 1340, 1343, 1345, + 1348, 1351, 1353, 1356, 1358, 1361, 1364, 1366, 1369, 1371, 1374, 1376, 1379, + 1381, 1384, 1386, 1389, 1391, 1394, 1396, 1399, 1401, 1404, 1406, 1409, 1411, + 1413, 1416, 1418, 1421, 1423, 1426, 1428, 1430, 1433, 1435, 1437, 1440, 1442, + 1445, 1447, 1449, 1452, 1454, 1456, 1459, 1461, 1463, 1466, 1468, 1470, 1472, + 1475, 1477, 1479, 1482, 1484, 1486, 1488, 1491, 1493, 1495, 1497, 1500, 1502, + 1504, 1506, 1509, 1511, 1513, 1515, 1517, 1520, 1522, 1524, 1526, 1528, 1530, + 1533, 1535, 1537, 1539, 1541, 1543, 1545, 1548, 1550, 1552, 1554, 1556, 1558, + 1560, 1562, 1564, 1567, 1569, 1571, 1573, 1575, 1577, 1579, 1581, 1583, 1585, + 1587, 1589, 1591, 1593, 1595, 1597, 1599, 1601, 1603, 1605, 1607, 1609, + /* index 401 - 899: -log((i+100)/1000) * 1000 */ + 691, 689, 687, 685, 683, 681, 679, 677, 675, 673, 671, 669, 668, 666, 664, + 662, 660, 658, 656, 654, 652, 650, 648, 646, 644, 642, 641, 639, 637, 635, + 633, 631, 629, 627, 626, 624, 622, 620, 618, 616, 614, 612, 611, 609, 607, + 605, 603, 602, 600, 598, 596, 594, 592, 591, 589, 587, 585, 583, 582, 580, + 578, 576, 574, 573, 571, 569, 567, 566, 564, 562, 560, 559, 557, 555, 553, + 552, 550, 548, 546, 545, 543, 541, 540, 538, 536, 534, 533, 531, 529, 528, + 526, 524, 523, 521, 519, 518, 516, 514, 512, 511, 509, 508, 506, 504, 502, + 501, 499, 498, 496, 494, 493, 491, 489, 488, 486, 484, 483, 481, 480, 478, + 476, 475, 473, 472, 470, 468, 467, 465, 464, 462, 460, 459, 457, 456, 454, + 453, 451, 449, 448, 446, 445, 443, 442, 440, 438, 437, 435, 434, 432, 431, + 429, 428, 426, 425, 423, 422, 420, 419, 417, 416, 414, 412, 411, 410, 408, + 406, 405, 404, 402, 400, 399, 398, 396, 394, 393, 392, 390, 389, 387, 386, + 384, 383, 381, 380, 378, 377, 375, 374, 372, 371, 370, 368, 367, 365, 364, + 362, 361, 360, 358, 357, 355, 354, 352, 351, 350, 348, 347, 345, 344, 342, + 341, 340, 338, 337, 336, 334, 333, 331, 330, 328, 327, 326, 324, 323, 322, + 320, 319, 318, 316, 315, 313, 312, 311, 309, 308, 306, 305, 304, 302, 301, + 300, 298, 297, 296, 294, 293, 292, 290, 289, 288, 286, 285, 284, 282, 281, + 280, 278, 277, 276, 274, 273, 272, 270, 269, 268, 267, 265, 264, 263, 261, + 260, 259, 258, 256, 255, 254, 252, 251, 250, 248, 247, 246, 245, 243, 242, + 241, 240, 238, 237, 236, 234, 233, 232, 231, 229, 228, 227, 226, 224, 223, + 222, 221, 219, 218, 217, 216, 214, 213, 212, 211, 210, 208, 207, 206, 205, + 203, 202, 201, 200, 198, 197, 196, 195, 194, 192, 191, 190, 189, 188, 186, + 185, 184, 183, 182, 180, 179, 178, 177, 176, 174, 173, 172, 171, 170, 168, + 167, 166, 165, 164, 162, 161, 160, 159, 158, 157, 156, 154, 153, 152, 151, + 150, 148, 147, 146, 145, 144, 143, 142, 140, 139, 138, 137, 136, 135, 134, + 132, 131, 130, 129, 128, 127, 126, 124, 123, 122, 121, 120, 119, 118, 116, + 115, 114, 113, 112, 111, 110, 109, 108, 106, 105, 104, 103, 102, 101, 100, + 99, 98, 97, 95, 94, 93, 92, 91, 90, 89, 88, 87, 86, 84, 83, 82, 81, 80, 79, + 78, 77, 76, 75, 74, 73, 72, 70, 69, 68, 67, 66, 65, 64, 63, 62, 61, 60, 59, + 58, 57, 56, 54, 53, 52, 51, 50, 49, 48, 47, 46, 45, 44, 43, 42, 41, 40, 39, + 38, 37, 36, 35, 34, 33, 31, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, + 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1 +}; + +/* + * Internal ln() function that does not check for specials, zero or one. + * Relative error: abs(result - log(a)) < 0.1 * 10**-prec * abs(log(a)) + */ +static void +_mpd_qln(mpd_t *result, const mpd_t *a, const mpd_context_t *ctx, + uint32_t *status) +{ + mpd_context_t varcontext, maxcontext; + mpd_t *z = (mpd_t *) result; + MPD_NEW_STATIC(v,0,0,0,0); + MPD_NEW_STATIC(vtmp,0,0,0,0); + MPD_NEW_STATIC(tmp,0,0,0,0); + mpd_ssize_t klist[MPD_MAX_PREC_LOG2]; + mpd_ssize_t maxprec, shift, t; + mpd_ssize_t a_digits, a_exp; + mpd_uint_t dummy, x; + int i; + + assert(!mpd_isspecial(a) && !mpd_iszerocoeff(a)); + + /* + * We are calculating ln(a) = ln(v * 10^t) = ln(v) + t*ln(10), + * where 0.5 < v <= 5. + */ + if (!mpd_qcopy(&v, a, status)) { + mpd_seterror(result, MPD_Malloc_error, status); + goto finish; + } + + /* Initial approximation: we have at least one non-zero digit */ + _mpd_get_msdigits(&dummy, &x, &v, 3); + if (x < 10) x *= 10; + if (x < 100) x *= 10; + x -= 100; + + /* a may equal z */ + a_digits = a->digits; + a_exp = a->exp; + + mpd_minalloc(z); + mpd_clear_flags(z); + z->data[0] = lnapprox[x]; + z->len = 1; + z->exp = -3; + mpd_setdigits(z); + + if (x <= 400) { + /* Reduce the input operand to 1.00 <= v <= 5.00. Let y = x + 100, + * so 100 <= y <= 500. Since y contains the most significant digits + * of v, y/100 <= v < (y+1)/100 and abs(z - log(v)) < 10**-2. */ + v.exp = -(a_digits - 1); + t = a_exp + a_digits - 1; + } + else { + /* Reduce the input operand to 0.500 < v <= 0.999. Let y = x + 100, + * so 500 < y <= 999. Since y contains the most significant digits + * of v, y/1000 <= v < (y+1)/1000 and abs(z - log(v)) < 10**-2. */ + v.exp = -a_digits; + t = a_exp + a_digits; + mpd_set_negative(z); + } + + mpd_maxcontext(&maxcontext); + mpd_maxcontext(&varcontext); + varcontext.round = MPD_ROUND_TRUNC; + + maxprec = ctx->prec + 2; + if (t == 0 && (x <= 15 || x >= 800)) { + /* 0.900 <= v <= 1.15: Estimate the magnitude of the logarithm. + * If ln(v) will underflow, skip the loop. Otherwise, adjust the + * precision upwards in order to obtain a sufficient number of + * significant digits. + * + * Case v > 1: + * abs((v-1)/10) < abs((v-1)/v) < abs(ln(v)) < abs(v-1) + * Case v < 1: + * abs(v-1) < abs(ln(v)) < abs((v-1)/v) < abs((v-1)*10) + */ + int cmp = _mpd_cmp(&v, &one); + + /* Upper bound (assume v > 1): abs(v-1), unrounded */ + _mpd_qsub(&tmp, &v, &one, &maxcontext, &maxcontext.status); + if (maxcontext.status & MPD_Errors) { + mpd_seterror(result, MPD_Malloc_error, status); + goto finish; + } + + if (cmp < 0) { + /* v < 1: abs((v-1)*10) */ + tmp.exp += 1; + } + if (mpd_adjexp(&tmp) < mpd_etiny(ctx)) { + /* The upper bound is less than etiny: Underflow to zero */ + _settriple(result, (cmp<0), 1, mpd_etiny(ctx)-1); + goto finish; + } + /* Lower bound: abs((v-1)/10) or abs(v-1) */ + tmp.exp -= 1; + if (mpd_adjexp(&tmp) < 0) { + /* Absolute error of the loop: abs(z - log(v)) < 10**-p. If + * p = ctx->prec+2-adjexp(lower), then the relative error of + * the result is (using 10**adjexp(x) <= abs(x)): + * + * abs(z - log(v)) / abs(log(v)) < 10**-p / abs(log(v)) + * <= 10**(-ctx->prec-2) + */ + maxprec = maxprec - mpd_adjexp(&tmp); + } + } + + i = ln_schedule_prec(klist, maxprec, 2); + for (; i >= 0; i--) { + varcontext.prec = 2*klist[i]+3; + z->flags ^= MPD_NEG; + _mpd_qexp(&tmp, z, &varcontext, status); + z->flags ^= MPD_NEG; + + if (v.digits > varcontext.prec) { + shift = v.digits - varcontext.prec; + mpd_qshiftr(&vtmp, &v, shift, status); + vtmp.exp += shift; + mpd_qmul(&tmp, &vtmp, &tmp, &varcontext, status); + } + else { + mpd_qmul(&tmp, &v, &tmp, &varcontext, status); + } + + mpd_qsub(&tmp, &tmp, &one, &maxcontext, status); + mpd_qadd(z, z, &tmp, &maxcontext, status); + if (mpd_isspecial(z)) { + break; + } + } + + /* + * Case t == 0: + * t * log(10) == 0, the result does not change and the analysis + * above applies. If v < 0.900 or v > 1.15, the relative error is + * less than 10**(-ctx.prec-1). + * Case t != 0: + * z := approx(log(v)) + * y := approx(log(10)) + * p := maxprec = ctx->prec + 2 + * Absolute errors: + * 1) abs(z - log(v)) < 10**-p + * 2) abs(y - log(10)) < 10**-p + * The multiplication is exact, so: + * 3) abs(t*y - t*log(10)) < t*10**-p + * The sum is exact, so: + * 4) abs((z + t*y) - (log(v) + t*log(10))) < (abs(t) + 1) * 10**-p + * Bounds for log(v) and log(10): + * 5) -7/10 < log(v) < 17/10 + * 6) 23/10 < log(10) < 24/10 + * Using 4), 5), 6) and t != 0, the relative error is: + * + * 7) relerr < ((abs(t) + 1)*10**-p) / abs(log(v) + t*log(10)) + * < 0.5 * 10**(-p + 1) = 0.5 * 10**(-ctx->prec-1) + */ + mpd_qln10(&v, maxprec+1, status); + mpd_qmul_ssize(&tmp, &v, t, &maxcontext, status); + mpd_qadd(result, &tmp, z, &maxcontext, status); + + +finish: + *status |= (MPD_Inexact|MPD_Rounded); + mpd_del(&v); + mpd_del(&vtmp); + mpd_del(&tmp); +} + +/* ln(a) */ +void +mpd_qln(mpd_t *result, const mpd_t *a, const mpd_context_t *ctx, + uint32_t *status) +{ + mpd_context_t workctx; + mpd_ssize_t adjexp, t; + + if (mpd_isspecial(a)) { + if (mpd_qcheck_nan(result, a, ctx, status)) { + return; + } + if (mpd_isnegative(a)) { + mpd_seterror(result, MPD_Invalid_operation, status); + return; + } + mpd_setspecial(result, MPD_POS, MPD_INF); + return; + } + if (mpd_iszerocoeff(a)) { + mpd_setspecial(result, MPD_NEG, MPD_INF); + return; + } + if (mpd_isnegative(a)) { + mpd_seterror(result, MPD_Invalid_operation, status); + return; + } + if (_mpd_cmp(a, &one) == 0) { + _settriple(result, MPD_POS, 0, 0); + return; + } + /* + * Check if the result will overflow (0 < x, x != 1): + * 1) log10(x) < 0 iff adjexp(x) < 0 + * 2) 0 < x /\ x <= y ==> adjexp(x) <= adjexp(y) + * 3) 0 < x /\ x != 1 ==> 2 * abs(log10(x)) < abs(log(x)) + * 4) adjexp(x) <= log10(x) < adjexp(x) + 1 + * + * Case adjexp(x) >= 0: + * 5) 2 * adjexp(x) < abs(log(x)) + * Case adjexp(x) > 0: + * 6) adjexp(2 * adjexp(x)) <= adjexp(abs(log(x))) + * Case adjexp(x) == 0: + * mpd_exp_digits(t)-1 == 0 <= emax (the shortcut is not triggered) + * + * Case adjexp(x) < 0: + * 7) 2 * (-adjexp(x) - 1) < abs(log(x)) + * Case adjexp(x) < -1: + * 8) adjexp(2 * (-adjexp(x) - 1)) <= adjexp(abs(log(x))) + * Case adjexp(x) == -1: + * mpd_exp_digits(t)-1 == 0 <= emax (the shortcut is not triggered) + */ + adjexp = mpd_adjexp(a); + t = (adjexp < 0) ? -adjexp-1 : adjexp; + t *= 2; + if (mpd_exp_digits(t)-1 > ctx->emax) { + *status |= MPD_Overflow|MPD_Inexact|MPD_Rounded; + mpd_setspecial(result, (adjexp<0), MPD_INF); + return; + } + + workctx = *ctx; + workctx.round = MPD_ROUND_HALF_EVEN; + + if (ctx->allcr) { + MPD_NEW_STATIC(t1, 0,0,0,0); + MPD_NEW_STATIC(t2, 0,0,0,0); + MPD_NEW_STATIC(ulp, 0,0,0,0); + MPD_NEW_STATIC(aa, 0,0,0,0); + mpd_ssize_t prec; + + if (result == a) { + if (!mpd_qcopy(&aa, a, status)) { + mpd_seterror(result, MPD_Malloc_error, status); + return; + } + a = &aa; + } + + workctx.clamp = 0; + prec = ctx->prec + 3; + while (1) { + workctx.prec = prec; + _mpd_qln(result, a, &workctx, status); + _ssettriple(&ulp, MPD_POS, 1, + result->exp + result->digits-workctx.prec); + + workctx.prec = ctx->prec; + mpd_qadd(&t1, result, &ulp, &workctx, &workctx.status); + mpd_qsub(&t2, result, &ulp, &workctx, &workctx.status); + if (mpd_isspecial(result) || mpd_iszerocoeff(result) || + mpd_qcmp(&t1, &t2, status) == 0) { + workctx.clamp = ctx->clamp; + mpd_check_underflow(result, &workctx, status); + mpd_qfinalize(result, &workctx, status); + break; + } + prec += MPD_RDIGITS; + } + mpd_del(&t1); + mpd_del(&t2); + mpd_del(&ulp); + mpd_del(&aa); + } + else { + _mpd_qln(result, a, &workctx, status); + mpd_check_underflow(result, &workctx, status); + mpd_qfinalize(result, &workctx, status); + } +} + +/* + * Internal log10() function that does not check for specials, zero or one. + * Case SKIP_FINALIZE: + * Relative error: abs(result - log10(a)) < 0.1 * 10**-prec * abs(log10(a)) + * Case DO_FINALIZE: + * Ulp error: abs(result - log10(a)) < ulp(log10(a)) + */ +enum {SKIP_FINALIZE, DO_FINALIZE}; +static void +_mpd_qlog10(int action, mpd_t *result, const mpd_t *a, + const mpd_context_t *ctx, uint32_t *status) +{ + mpd_context_t workctx; + MPD_NEW_STATIC(ln10,0,0,0,0); + + mpd_maxcontext(&workctx); + workctx.prec = ctx->prec + 3; + /* relative error: 0.1 * 10**(-p-3). The specific underflow shortcut + * in _mpd_qln() does not change the final result. */ + _mpd_qln(result, a, &workctx, status); + /* relative error: 5 * 10**(-p-3) */ + mpd_qln10(&ln10, workctx.prec, status); + + if (action == DO_FINALIZE) { + workctx = *ctx; + workctx.round = MPD_ROUND_HALF_EVEN; + } + /* SKIP_FINALIZE: relative error: 5 * 10**(-p-3) */ + _mpd_qdiv(NO_IDEAL_EXP, result, result, &ln10, &workctx, status); + + mpd_del(&ln10); +} + +/* log10(a) */ +void +mpd_qlog10(mpd_t *result, const mpd_t *a, const mpd_context_t *ctx, + uint32_t *status) +{ + mpd_context_t workctx; + mpd_ssize_t adjexp, t; + + workctx = *ctx; + workctx.round = MPD_ROUND_HALF_EVEN; + + if (mpd_isspecial(a)) { + if (mpd_qcheck_nan(result, a, ctx, status)) { + return; + } + if (mpd_isnegative(a)) { + mpd_seterror(result, MPD_Invalid_operation, status); + return; + } + mpd_setspecial(result, MPD_POS, MPD_INF); + return; + } + if (mpd_iszerocoeff(a)) { + mpd_setspecial(result, MPD_NEG, MPD_INF); + return; + } + if (mpd_isnegative(a)) { + mpd_seterror(result, MPD_Invalid_operation, status); + return; + } + if (mpd_coeff_ispow10(a)) { + uint8_t sign = 0; + adjexp = mpd_adjexp(a); + if (adjexp < 0) { + sign = 1; + adjexp = -adjexp; + } + _settriple(result, sign, adjexp, 0); + mpd_qfinalize(result, &workctx, status); + return; + } + /* + * Check if the result will overflow (0 < x, x != 1): + * 1) log10(x) < 0 iff adjexp(x) < 0 + * 2) 0 < x /\ x <= y ==> adjexp(x) <= adjexp(y) + * 3) adjexp(x) <= log10(x) < adjexp(x) + 1 + * + * Case adjexp(x) >= 0: + * 4) adjexp(x) <= abs(log10(x)) + * Case adjexp(x) > 0: + * 5) adjexp(adjexp(x)) <= adjexp(abs(log10(x))) + * Case adjexp(x) == 0: + * mpd_exp_digits(t)-1 == 0 <= emax (the shortcut is not triggered) + * + * Case adjexp(x) < 0: + * 6) -adjexp(x) - 1 < abs(log10(x)) + * Case adjexp(x) < -1: + * 7) adjexp(-adjexp(x) - 1) <= adjexp(abs(log(x))) + * Case adjexp(x) == -1: + * mpd_exp_digits(t)-1 == 0 <= emax (the shortcut is not triggered) + */ + adjexp = mpd_adjexp(a); + t = (adjexp < 0) ? -adjexp-1 : adjexp; + if (mpd_exp_digits(t)-1 > ctx->emax) { + *status |= MPD_Overflow|MPD_Inexact|MPD_Rounded; + mpd_setspecial(result, (adjexp<0), MPD_INF); + return; + } + + if (ctx->allcr) { + MPD_NEW_STATIC(t1, 0,0,0,0); + MPD_NEW_STATIC(t2, 0,0,0,0); + MPD_NEW_STATIC(ulp, 0,0,0,0); + MPD_NEW_STATIC(aa, 0,0,0,0); + mpd_ssize_t prec; + + if (result == a) { + if (!mpd_qcopy(&aa, a, status)) { + mpd_seterror(result, MPD_Malloc_error, status); + return; + } + a = &aa; + } + + workctx.clamp = 0; + prec = ctx->prec + 3; + while (1) { + workctx.prec = prec; + _mpd_qlog10(SKIP_FINALIZE, result, a, &workctx, status); + _ssettriple(&ulp, MPD_POS, 1, + result->exp + result->digits-workctx.prec); + + workctx.prec = ctx->prec; + mpd_qadd(&t1, result, &ulp, &workctx, &workctx.status); + mpd_qsub(&t2, result, &ulp, &workctx, &workctx.status); + if (mpd_isspecial(result) || mpd_iszerocoeff(result) || + mpd_qcmp(&t1, &t2, status) == 0) { + workctx.clamp = ctx->clamp; + mpd_check_underflow(result, &workctx, status); + mpd_qfinalize(result, &workctx, status); + break; + } + prec += MPD_RDIGITS; + } + mpd_del(&t1); + mpd_del(&t2); + mpd_del(&ulp); + mpd_del(&aa); + } + else { + _mpd_qlog10(DO_FINALIZE, result, a, &workctx, status); + mpd_check_underflow(result, &workctx, status); + } +} + +/* + * Maximum of the two operands. Attention: If one operand is a quiet NaN and the + * other is numeric, the numeric operand is returned. This may not be what one + * expects. + */ +void +mpd_qmax(mpd_t *result, const mpd_t *a, const mpd_t *b, + const mpd_context_t *ctx, uint32_t *status) +{ + int c; + + if (mpd_isqnan(a) && !mpd_isnan(b)) { + mpd_qcopy(result, b, status); + } + else if (mpd_isqnan(b) && !mpd_isnan(a)) { + mpd_qcopy(result, a, status); + } + else if (mpd_qcheck_nans(result, a, b, ctx, status)) { + return; + } + else { + c = _mpd_cmp(a, b); + if (c == 0) { + c = _mpd_cmp_numequal(a, b); + } + + if (c < 0) { + mpd_qcopy(result, b, status); + } + else { + mpd_qcopy(result, a, status); + } + } + + mpd_qfinalize(result, ctx, status); +} + +/* + * Maximum magnitude: Same as mpd_max(), but compares the operands with their + * sign ignored. + */ +void +mpd_qmax_mag(mpd_t *result, const mpd_t *a, const mpd_t *b, + const mpd_context_t *ctx, uint32_t *status) +{ + int c; + + if (mpd_isqnan(a) && !mpd_isnan(b)) { + mpd_qcopy(result, b, status); + } + else if (mpd_isqnan(b) && !mpd_isnan(a)) { + mpd_qcopy(result, a, status); + } + else if (mpd_qcheck_nans(result, a, b, ctx, status)) { + return; + } + else { + c = _mpd_cmp_abs(a, b); + if (c == 0) { + c = _mpd_cmp_numequal(a, b); + } + + if (c < 0) { + mpd_qcopy(result, b, status); + } + else { + mpd_qcopy(result, a, status); + } + } + + mpd_qfinalize(result, ctx, status); +} + +/* + * Minimum of the two operands. Attention: If one operand is a quiet NaN and the + * other is numeric, the numeric operand is returned. This may not be what one + * expects. + */ +void +mpd_qmin(mpd_t *result, const mpd_t *a, const mpd_t *b, + const mpd_context_t *ctx, uint32_t *status) +{ + int c; + + if (mpd_isqnan(a) && !mpd_isnan(b)) { + mpd_qcopy(result, b, status); + } + else if (mpd_isqnan(b) && !mpd_isnan(a)) { + mpd_qcopy(result, a, status); + } + else if (mpd_qcheck_nans(result, a, b, ctx, status)) { + return; + } + else { + c = _mpd_cmp(a, b); + if (c == 0) { + c = _mpd_cmp_numequal(a, b); + } + + if (c < 0) { + mpd_qcopy(result, a, status); + } + else { + mpd_qcopy(result, b, status); + } + } + + mpd_qfinalize(result, ctx, status); +} + +/* + * Minimum magnitude: Same as mpd_min(), but compares the operands with their + * sign ignored. + */ +void +mpd_qmin_mag(mpd_t *result, const mpd_t *a, const mpd_t *b, + const mpd_context_t *ctx, uint32_t *status) +{ + int c; + + if (mpd_isqnan(a) && !mpd_isnan(b)) { + mpd_qcopy(result, b, status); + } + else if (mpd_isqnan(b) && !mpd_isnan(a)) { + mpd_qcopy(result, a, status); + } + else if (mpd_qcheck_nans(result, a, b, ctx, status)) { + return; + } + else { + c = _mpd_cmp_abs(a, b); + if (c == 0) { + c = _mpd_cmp_numequal(a, b); + } + + if (c < 0) { + mpd_qcopy(result, a, status); + } + else { + mpd_qcopy(result, b, status); + } + } + + mpd_qfinalize(result, ctx, status); +} + +/* Minimum space needed for the result array in _karatsuba_rec(). */ +static inline mpd_size_t +_kmul_resultsize(mpd_size_t la, mpd_size_t lb) +{ + mpd_size_t n, m; + + n = add_size_t(la, lb); + n = add_size_t(n, 1); + + m = (la+1)/2 + 1; + m = mul_size_t(m, 3); + + return (m > n) ? m : n; +} + +/* Work space needed in _karatsuba_rec(). lim >= 4 */ +static inline mpd_size_t +_kmul_worksize(mpd_size_t n, mpd_size_t lim) +{ + mpd_size_t m; + + if (n <= lim) { + return 0; + } + + m = (n+1)/2 + 1; + + return add_size_t(mul_size_t(m, 2), _kmul_worksize(m, lim)); +} + + +#define MPD_KARATSUBA_BASECASE 16 /* must be >= 4 */ + +/* + * Add the product of a and b to c. + * c must be _kmul_resultsize(la, lb) in size. + * w is used as a work array and must be _kmul_worksize(a, lim) in size. + * Roman E. Maeder, Storage Allocation for the Karatsuba Integer Multiplication + * Algorithm. In "Design and implementation of symbolic computation systems", + * Springer, 1993, ISBN 354057235X, 9783540572350. + */ +static void +_karatsuba_rec(mpd_uint_t *c, const mpd_uint_t *a, const mpd_uint_t *b, + mpd_uint_t *w, mpd_size_t la, mpd_size_t lb) +{ + mpd_size_t m, lt; + + assert(la >= lb && lb > 0); + assert(la <= MPD_KARATSUBA_BASECASE || w != NULL); + + if (la <= MPD_KARATSUBA_BASECASE) { + _mpd_basemul(c, a, b, la, lb); + return; + } + + m = (la+1)/2; /* ceil(la/2) */ + + /* lb <= m < la */ + if (lb <= m) { + + /* lb can now be larger than la-m */ + if (lb > la-m) { + lt = lb + lb + 1; /* space needed for result array */ + mpd_uint_zero(w, lt); /* clear result array */ + _karatsuba_rec(w, b, a+m, w+lt, lb, la-m); /* b*ah */ + } + else { + lt = (la-m) + (la-m) + 1; /* space needed for result array */ + mpd_uint_zero(w, lt); /* clear result array */ + _karatsuba_rec(w, a+m, b, w+lt, la-m, lb); /* ah*b */ + } + _mpd_baseaddto(c+m, w, (la-m)+lb); /* add ah*b*B**m */ + + lt = m + m + 1; /* space needed for the result array */ + mpd_uint_zero(w, lt); /* clear result array */ + _karatsuba_rec(w, a, b, w+lt, m, lb); /* al*b */ + _mpd_baseaddto(c, w, m+lb); /* add al*b */ + + return; + } + + /* la >= lb > m */ + memcpy(w, a, m * sizeof *w); + w[m] = 0; + _mpd_baseaddto(w, a+m, la-m); + + memcpy(w+(m+1), b, m * sizeof *w); + w[m+1+m] = 0; + _mpd_baseaddto(w+(m+1), b+m, lb-m); + + _karatsuba_rec(c+m, w, w+(m+1), w+2*(m+1), m+1, m+1); + + lt = (la-m) + (la-m) + 1; + mpd_uint_zero(w, lt); + + _karatsuba_rec(w, a+m, b+m, w+lt, la-m, lb-m); + + _mpd_baseaddto(c+2*m, w, (la-m) + (lb-m)); + _mpd_basesubfrom(c+m, w, (la-m) + (lb-m)); + + lt = m + m + 1; + mpd_uint_zero(w, lt); + + _karatsuba_rec(w, a, b, w+lt, m, m); + _mpd_baseaddto(c, w, m+m); + _mpd_basesubfrom(c+m, w, m+m); + + return; +} + +/* + * Multiply u and v, using Karatsuba multiplication. Returns a pointer + * to the result or NULL in case of failure (malloc error). + * Conditions: ulen >= vlen, ulen >= 4 + */ +static mpd_uint_t * +_mpd_kmul(const mpd_uint_t *u, const mpd_uint_t *v, + mpd_size_t ulen, mpd_size_t vlen, + mpd_size_t *rsize) +{ + mpd_uint_t *result = NULL, *w = NULL; + mpd_size_t m; + + assert(ulen >= 4); + assert(ulen >= vlen); + + *rsize = _kmul_resultsize(ulen, vlen); + if ((result = mpd_calloc(*rsize, sizeof *result)) == NULL) { + return NULL; + } + + m = _kmul_worksize(ulen, MPD_KARATSUBA_BASECASE); + if (m && ((w = mpd_calloc(m, sizeof *w)) == NULL)) { + mpd_free(result); + return NULL; + } + + _karatsuba_rec(result, u, v, w, ulen, vlen); + + + if (w) mpd_free(w); + return result; +} + + +/* + * Determine the minimum length for the number theoretic transform. Valid + * transform lengths are 2**n or 3*2**n, where 2**n <= MPD_MAXTRANSFORM_2N. + * The function finds the shortest length m such that rsize <= m. + */ +static inline mpd_size_t +_mpd_get_transform_len(mpd_size_t rsize) +{ + mpd_size_t log2rsize; + mpd_size_t x, step; + + assert(rsize >= 4); + log2rsize = mpd_bsr(rsize); + + if (rsize <= 1024) { + /* 2**n is faster in this range. */ + x = ((mpd_size_t)1)<<log2rsize; + return (rsize == x) ? x : x<<1; + } + else if (rsize <= MPD_MAXTRANSFORM_2N) { + x = ((mpd_size_t)1)<<log2rsize; + if (rsize == x) return x; + step = x>>1; + x += step; + return (rsize <= x) ? x : x + step; + } + else if (rsize <= MPD_MAXTRANSFORM_2N+MPD_MAXTRANSFORM_2N/2) { + return MPD_MAXTRANSFORM_2N+MPD_MAXTRANSFORM_2N/2; + } + else if (rsize <= 3*MPD_MAXTRANSFORM_2N) { + return 3*MPD_MAXTRANSFORM_2N; + } + else { + return MPD_SIZE_MAX; + } +} + +#ifdef PPRO +#ifndef _MSC_VER +static inline unsigned short +_mpd_get_control87(void) +{ + unsigned short cw; + + __asm__ __volatile__ ("fnstcw %0" : "=m" (cw)); + return cw; +} + +static inline void +_mpd_set_control87(unsigned short cw) +{ + __asm__ __volatile__ ("fldcw %0" : : "m" (cw)); +} +#endif + +static unsigned int +mpd_set_fenv(void) +{ + unsigned int cw; +#ifdef _MSC_VER + unsigned int flags = + _EM_INVALID|_EM_DENORMAL|_EM_ZERODIVIDE|_EM_OVERFLOW| + _EM_UNDERFLOW|_EM_INEXACT|_RC_CHOP|_PC_64; + unsigned int mask = _MCW_EM|_MCW_RC|_MCW_PC; + unsigned int dummy; + + __control87_2(0, 0, &cw, NULL); + __control87_2(flags, mask, &dummy, NULL); +#else + cw = _mpd_get_control87(); + _mpd_set_control87(cw|0xF3F); +#endif + return cw; +} + +static void +mpd_restore_fenv(unsigned int cw) +{ +#ifdef _MSC_VER + unsigned int mask = _MCW_EM|_MCW_RC|_MCW_PC; + unsigned int dummy; + + __control87_2(cw, mask, &dummy, NULL); +#else + _mpd_set_control87((unsigned short)cw); +#endif +} +#endif /* PPRO */ + +/* + * Multiply u and v, using the fast number theoretic transform. Returns + * a pointer to the result or NULL in case of failure (malloc error). + */ +static mpd_uint_t * +_mpd_fntmul(const mpd_uint_t *u, const mpd_uint_t *v, + mpd_size_t ulen, mpd_size_t vlen, + mpd_size_t *rsize) +{ + mpd_uint_t *c1 = NULL, *c2 = NULL, *c3 = NULL, *vtmp = NULL; + mpd_size_t n; + +#ifdef PPRO + unsigned int cw; + cw = mpd_set_fenv(); +#endif + + *rsize = add_size_t(ulen, vlen); + if ((n = _mpd_get_transform_len(*rsize)) == MPD_SIZE_MAX) { + goto malloc_error; + } + + if ((c1 = mpd_calloc(n, sizeof *c1)) == NULL) { + goto malloc_error; + } + if ((c2 = mpd_calloc(n, sizeof *c2)) == NULL) { + goto malloc_error; + } + if ((c3 = mpd_calloc(n, sizeof *c3)) == NULL) { + goto malloc_error; + } + + memcpy(c1, u, ulen * (sizeof *c1)); + memcpy(c2, u, ulen * (sizeof *c2)); + memcpy(c3, u, ulen * (sizeof *c3)); + + if (u == v) { + if (!fnt_autoconvolute(c1, n, P1) || + !fnt_autoconvolute(c2, n, P2) || + !fnt_autoconvolute(c3, n, P3)) { + goto malloc_error; + } + } + else { + if ((vtmp = mpd_calloc(n, sizeof *vtmp)) == NULL) { + goto malloc_error; + } + + memcpy(vtmp, v, vlen * (sizeof *vtmp)); + if (!fnt_convolute(c1, vtmp, n, P1)) { + mpd_free(vtmp); + goto malloc_error; + } + + memcpy(vtmp, v, vlen * (sizeof *vtmp)); + mpd_uint_zero(vtmp+vlen, n-vlen); + if (!fnt_convolute(c2, vtmp, n, P2)) { + mpd_free(vtmp); + goto malloc_error; + } + + memcpy(vtmp, v, vlen * (sizeof *vtmp)); + mpd_uint_zero(vtmp+vlen, n-vlen); + if (!fnt_convolute(c3, vtmp, n, P3)) { + mpd_free(vtmp); + goto malloc_error; + } + + mpd_free(vtmp); + } + + crt3(c1, c2, c3, *rsize); + +out: +#ifdef PPRO + mpd_restore_fenv(cw); +#endif + if (c2) mpd_free(c2); + if (c3) mpd_free(c3); + return c1; + +malloc_error: + if (c1) mpd_free(c1); + c1 = NULL; + goto out; +} + + +/* + * Karatsuba multiplication with FNT/basemul as the base case. + */ +static int +_karatsuba_rec_fnt(mpd_uint_t *c, const mpd_uint_t *a, const mpd_uint_t *b, + mpd_uint_t *w, mpd_size_t la, mpd_size_t lb) +{ + mpd_size_t m, lt; + + assert(la >= lb && lb > 0); + assert(la <= 3*(MPD_MAXTRANSFORM_2N/2) || w != NULL); + + if (la <= 3*(MPD_MAXTRANSFORM_2N/2)) { + + if (lb <= 192) { + _mpd_basemul(c, b, a, lb, la); + } + else { + mpd_uint_t *result; + mpd_size_t dummy; + + if ((result = _mpd_fntmul(a, b, la, lb, &dummy)) == NULL) { + return 0; + } + memcpy(c, result, (la+lb) * (sizeof *result)); + mpd_free(result); + } + return 1; + } + + m = (la+1)/2; /* ceil(la/2) */ + + /* lb <= m < la */ + if (lb <= m) { + + /* lb can now be larger than la-m */ + if (lb > la-m) { + lt = lb + lb + 1; /* space needed for result array */ + mpd_uint_zero(w, lt); /* clear result array */ + if (!_karatsuba_rec_fnt(w, b, a+m, w+lt, lb, la-m)) { /* b*ah */ + return 0; /* GCOV_UNLIKELY */ + } + } + else { + lt = (la-m) + (la-m) + 1; /* space needed for result array */ + mpd_uint_zero(w, lt); /* clear result array */ + if (!_karatsuba_rec_fnt(w, a+m, b, w+lt, la-m, lb)) { /* ah*b */ + return 0; /* GCOV_UNLIKELY */ + } + } + _mpd_baseaddto(c+m, w, (la-m)+lb); /* add ah*b*B**m */ + + lt = m + m + 1; /* space needed for the result array */ + mpd_uint_zero(w, lt); /* clear result array */ + if (!_karatsuba_rec_fnt(w, a, b, w+lt, m, lb)) { /* al*b */ + return 0; /* GCOV_UNLIKELY */ + } + _mpd_baseaddto(c, w, m+lb); /* add al*b */ + + return 1; + } + + /* la >= lb > m */ + memcpy(w, a, m * sizeof *w); + w[m] = 0; + _mpd_baseaddto(w, a+m, la-m); + + memcpy(w+(m+1), b, m * sizeof *w); + w[m+1+m] = 0; + _mpd_baseaddto(w+(m+1), b+m, lb-m); + + if (!_karatsuba_rec_fnt(c+m, w, w+(m+1), w+2*(m+1), m+1, m+1)) { + return 0; /* GCOV_UNLIKELY */ + } + + lt = (la-m) + (la-m) + 1; + mpd_uint_zero(w, lt); + + if (!_karatsuba_rec_fnt(w, a+m, b+m, w+lt, la-m, lb-m)) { + return 0; /* GCOV_UNLIKELY */ + } + + _mpd_baseaddto(c+2*m, w, (la-m) + (lb-m)); + _mpd_basesubfrom(c+m, w, (la-m) + (lb-m)); + + lt = m + m + 1; + mpd_uint_zero(w, lt); + + if (!_karatsuba_rec_fnt(w, a, b, w+lt, m, m)) { + return 0; /* GCOV_UNLIKELY */ + } + _mpd_baseaddto(c, w, m+m); + _mpd_basesubfrom(c+m, w, m+m); + + return 1; +} + +/* + * Multiply u and v, using Karatsuba multiplication with the FNT as the + * base case. Returns a pointer to the result or NULL in case of failure + * (malloc error). Conditions: ulen >= vlen, ulen >= 4. + */ +static mpd_uint_t * +_mpd_kmul_fnt(const mpd_uint_t *u, const mpd_uint_t *v, + mpd_size_t ulen, mpd_size_t vlen, + mpd_size_t *rsize) +{ + mpd_uint_t *result = NULL, *w = NULL; + mpd_size_t m; + + assert(ulen >= 4); + assert(ulen >= vlen); + + *rsize = _kmul_resultsize(ulen, vlen); + if ((result = mpd_calloc(*rsize, sizeof *result)) == NULL) { + return NULL; + } + + m = _kmul_worksize(ulen, 3*(MPD_MAXTRANSFORM_2N/2)); + if (m && ((w = mpd_calloc(m, sizeof *w)) == NULL)) { + mpd_free(result); /* GCOV_UNLIKELY */ + return NULL; /* GCOV_UNLIKELY */ + } + + if (!_karatsuba_rec_fnt(result, u, v, w, ulen, vlen)) { + mpd_free(result); + result = NULL; + } + + + if (w) mpd_free(w); + return result; +} + + +/* Deal with the special cases of multiplying infinities. */ +static void +_mpd_qmul_inf(mpd_t *result, const mpd_t *a, const mpd_t *b, uint32_t *status) +{ + if (mpd_isinfinite(a)) { + if (mpd_iszero(b)) { + mpd_seterror(result, MPD_Invalid_operation, status); + } + else { + mpd_setspecial(result, mpd_sign(a)^mpd_sign(b), MPD_INF); + } + return; + } + assert(mpd_isinfinite(b)); + if (mpd_iszero(a)) { + mpd_seterror(result, MPD_Invalid_operation, status); + } + else { + mpd_setspecial(result, mpd_sign(a)^mpd_sign(b), MPD_INF); + } +} + +/* + * Internal function: Multiply a and b. _mpd_qmul deals with specials but + * does NOT finalize the result. This is for use in mpd_fma(). + */ +static inline void +_mpd_qmul(mpd_t *result, const mpd_t *a, const mpd_t *b, + const mpd_context_t *ctx, uint32_t *status) +{ + const mpd_t *big = a, *small = b; + mpd_uint_t *rdata = NULL; + mpd_uint_t rbuf[MPD_MINALLOC_MAX]; + mpd_size_t rsize, i; + + + if (mpd_isspecial(a) || mpd_isspecial(b)) { + if (mpd_qcheck_nans(result, a, b, ctx, status)) { + return; + } + _mpd_qmul_inf(result, a, b, status); + return; + } + + if (small->len > big->len) { + _mpd_ptrswap(&big, &small); + } + + rsize = big->len + small->len; + + if (big->len == 1) { + _mpd_singlemul(result->data, big->data[0], small->data[0]); + goto finish; + } + if (rsize <= (mpd_size_t)MPD_MINALLOC_MAX) { + if (big->len == 2) { + _mpd_mul_2_le2(rbuf, big->data, small->data, small->len); + } + else { + mpd_uint_zero(rbuf, rsize); + if (small->len == 1) { + _mpd_shortmul(rbuf, big->data, big->len, small->data[0]); + } + else { + _mpd_basemul(rbuf, small->data, big->data, small->len, big->len); + } + } + if (!mpd_qresize(result, rsize, status)) { + return; + } + for(i = 0; i < rsize; i++) { + result->data[i] = rbuf[i]; + } + goto finish; + } + + + if (small->len <= 256) { + rdata = mpd_calloc(rsize, sizeof *rdata); + if (rdata != NULL) { + if (small->len == 1) { + _mpd_shortmul(rdata, big->data, big->len, small->data[0]); + } + else { + _mpd_basemul(rdata, small->data, big->data, small->len, big->len); + } + } + } + else if (rsize <= 1024) { + rdata = _mpd_kmul(big->data, small->data, big->len, small->len, &rsize); + } + else if (rsize <= 3*MPD_MAXTRANSFORM_2N) { + rdata = _mpd_fntmul(big->data, small->data, big->len, small->len, &rsize); + } + else { + rdata = _mpd_kmul_fnt(big->data, small->data, big->len, small->len, &rsize); + } + + if (rdata == NULL) { + mpd_seterror(result, MPD_Malloc_error, status); + return; + } + + if (mpd_isdynamic_data(result)) { + mpd_free(result->data); + } + result->data = rdata; + result->alloc = rsize; + mpd_set_dynamic_data(result); + + +finish: + mpd_set_flags(result, mpd_sign(a)^mpd_sign(b)); + result->exp = big->exp + small->exp; + result->len = _mpd_real_size(result->data, rsize); + /* resize to smaller cannot fail */ + mpd_qresize(result, result->len, status); + mpd_setdigits(result); +} + +/* Multiply a and b. */ +void +mpd_qmul(mpd_t *result, const mpd_t *a, const mpd_t *b, + const mpd_context_t *ctx, uint32_t *status) +{ + _mpd_qmul(result, a, b, ctx, status); + mpd_qfinalize(result, ctx, status); +} + +/* Multiply a and b. Set NaN/Invalid_operation if the result is inexact. */ +static void +_mpd_qmul_exact(mpd_t *result, const mpd_t *a, const mpd_t *b, + const mpd_context_t *ctx, uint32_t *status) +{ + uint32_t workstatus = 0; + + mpd_qmul(result, a, b, ctx, &workstatus); + *status |= workstatus; + if (workstatus & (MPD_Inexact|MPD_Rounded|MPD_Clamped)) { + mpd_seterror(result, MPD_Invalid_operation, status); + } +} + +/* Multiply decimal and mpd_ssize_t. */ +void +mpd_qmul_ssize(mpd_t *result, const mpd_t *a, mpd_ssize_t b, + const mpd_context_t *ctx, uint32_t *status) +{ + mpd_context_t maxcontext; + MPD_NEW_STATIC(bb,0,0,0,0); + + mpd_maxcontext(&maxcontext); + mpd_qsset_ssize(&bb, b, &maxcontext, status); + mpd_qmul(result, a, &bb, ctx, status); + mpd_del(&bb); +} + +/* Multiply decimal and mpd_uint_t. */ +void +mpd_qmul_uint(mpd_t *result, const mpd_t *a, mpd_uint_t b, + const mpd_context_t *ctx, uint32_t *status) +{ + mpd_context_t maxcontext; + MPD_NEW_STATIC(bb,0,0,0,0); + + mpd_maxcontext(&maxcontext); + mpd_qsset_uint(&bb, b, &maxcontext, status); + mpd_qmul(result, a, &bb, ctx, status); + mpd_del(&bb); +} + +void +mpd_qmul_i32(mpd_t *result, const mpd_t *a, int32_t b, + const mpd_context_t *ctx, uint32_t *status) +{ + mpd_qmul_ssize(result, a, b, ctx, status); +} + +void +mpd_qmul_u32(mpd_t *result, const mpd_t *a, uint32_t b, + const mpd_context_t *ctx, uint32_t *status) +{ + mpd_qmul_uint(result, a, b, ctx, status); +} + +#ifdef CONFIG_64 +void +mpd_qmul_i64(mpd_t *result, const mpd_t *a, int64_t b, + const mpd_context_t *ctx, uint32_t *status) +{ + mpd_qmul_ssize(result, a, b, ctx, status); +} + +void +mpd_qmul_u64(mpd_t *result, const mpd_t *a, uint64_t b, + const mpd_context_t *ctx, uint32_t *status) +{ + mpd_qmul_uint(result, a, b, ctx, status); +} +#elif !defined(LEGACY_COMPILER) +/* Multiply decimal and int64_t. */ +void +mpd_qmul_i64(mpd_t *result, const mpd_t *a, int64_t b, + const mpd_context_t *ctx, uint32_t *status) +{ + mpd_context_t maxcontext; + MPD_NEW_STATIC(bb,0,0,0,0); + + mpd_maxcontext(&maxcontext); + mpd_qset_i64(&bb, b, &maxcontext, status); + mpd_qmul(result, a, &bb, ctx, status); + mpd_del(&bb); +} + +/* Multiply decimal and uint64_t. */ +void +mpd_qmul_u64(mpd_t *result, const mpd_t *a, uint64_t b, + const mpd_context_t *ctx, uint32_t *status) +{ + mpd_context_t maxcontext; + MPD_NEW_STATIC(bb,0,0,0,0); + + mpd_maxcontext(&maxcontext); + mpd_qset_u64(&bb, b, &maxcontext, status); + mpd_qmul(result, a, &bb, ctx, status); + mpd_del(&bb); +} +#endif + +/* Like the minus operator. */ +void +mpd_qminus(mpd_t *result, const mpd_t *a, const mpd_context_t *ctx, + uint32_t *status) +{ + if (mpd_isspecial(a)) { + if (mpd_qcheck_nan(result, a, ctx, status)) { + return; + } + } + + if (mpd_iszero(a) && ctx->round != MPD_ROUND_FLOOR) { + mpd_qcopy_abs(result, a, status); + } + else { + mpd_qcopy_negate(result, a, status); + } + + mpd_qfinalize(result, ctx, status); +} + +/* Like the plus operator. */ +void +mpd_qplus(mpd_t *result, const mpd_t *a, const mpd_context_t *ctx, + uint32_t *status) +{ + if (mpd_isspecial(a)) { + if (mpd_qcheck_nan(result, a, ctx, status)) { + return; + } + } + + if (mpd_iszero(a) && ctx->round != MPD_ROUND_FLOOR) { + mpd_qcopy_abs(result, a, status); + } + else { + mpd_qcopy(result, a, status); + } + + mpd_qfinalize(result, ctx, status); +} + +/* The largest representable number that is smaller than the operand. */ +void +mpd_qnext_minus(mpd_t *result, const mpd_t *a, const mpd_context_t *ctx, + uint32_t *status) +{ + mpd_context_t workctx; + MPD_NEW_CONST(tiny,MPD_POS,mpd_etiny(ctx)-1,1,1,1,1); + + if (mpd_isspecial(a)) { + if (mpd_qcheck_nan(result, a, ctx, status)) { + return; + } + + assert(mpd_isinfinite(a)); + if (mpd_isnegative(a)) { + mpd_qcopy(result, a, status); + return; + } + else { + mpd_clear_flags(result); + mpd_qmaxcoeff(result, ctx, status); + if (mpd_isnan(result)) { + return; + } + result->exp = mpd_etop(ctx); + return; + } + } + + mpd_workcontext(&workctx, ctx); + workctx.round = MPD_ROUND_FLOOR; + + if (!mpd_qcopy(result, a, status)) { + return; + } + + mpd_qfinalize(result, &workctx, &workctx.status); + if (workctx.status&(MPD_Inexact|MPD_Errors)) { + *status |= (workctx.status&MPD_Errors); + return; + } + + workctx.status = 0; + mpd_qsub(result, a, &tiny, &workctx, &workctx.status); + *status |= (workctx.status&MPD_Errors); +} + +/* The smallest representable number that is larger than the operand. */ +void +mpd_qnext_plus(mpd_t *result, const mpd_t *a, const mpd_context_t *ctx, + uint32_t *status) +{ + mpd_context_t workctx; + MPD_NEW_CONST(tiny,MPD_POS,mpd_etiny(ctx)-1,1,1,1,1); + + if (mpd_isspecial(a)) { + if (mpd_qcheck_nan(result, a, ctx, status)) { + return; + } + + assert(mpd_isinfinite(a)); + if (mpd_ispositive(a)) { + mpd_qcopy(result, a, status); + } + else { + mpd_clear_flags(result); + mpd_qmaxcoeff(result, ctx, status); + if (mpd_isnan(result)) { + return; + } + mpd_set_flags(result, MPD_NEG); + result->exp = mpd_etop(ctx); + } + return; + } + + mpd_workcontext(&workctx, ctx); + workctx.round = MPD_ROUND_CEILING; + + if (!mpd_qcopy(result, a, status)) { + return; + } + + mpd_qfinalize(result, &workctx, &workctx.status); + if (workctx.status & (MPD_Inexact|MPD_Errors)) { + *status |= (workctx.status&MPD_Errors); + return; + } + + workctx.status = 0; + mpd_qadd(result, a, &tiny, &workctx, &workctx.status); + *status |= (workctx.status&MPD_Errors); +} + +/* + * The number closest to the first operand that is in the direction towards + * the second operand. + */ +void +mpd_qnext_toward(mpd_t *result, const mpd_t *a, const mpd_t *b, + const mpd_context_t *ctx, uint32_t *status) +{ + int c; + + if (mpd_qcheck_nans(result, a, b, ctx, status)) { + return; + } + + c = _mpd_cmp(a, b); + if (c == 0) { + mpd_qcopy_sign(result, a, b, status); + return; + } + + if (c < 0) { + mpd_qnext_plus(result, a, ctx, status); + } + else { + mpd_qnext_minus(result, a, ctx, status); + } + + if (mpd_isinfinite(result)) { + *status |= (MPD_Overflow|MPD_Rounded|MPD_Inexact); + } + else if (mpd_adjexp(result) < ctx->emin) { + *status |= (MPD_Underflow|MPD_Subnormal|MPD_Rounded|MPD_Inexact); + if (mpd_iszero(result)) { + *status |= MPD_Clamped; + } + } +} + +/* + * Internal function: Integer power with mpd_uint_t exponent. The function + * can fail with MPD_Malloc_error. + * + * The error is equal to the error incurred in k-1 multiplications. Assuming + * the upper bound for the relative error in each operation: + * + * abs(err) = 5 * 10**-prec + * result = x**k * (1 + err)**(k-1) + */ +static inline void +_mpd_qpow_uint(mpd_t *result, const mpd_t *base, mpd_uint_t exp, + uint8_t resultsign, const mpd_context_t *ctx, uint32_t *status) +{ + uint32_t workstatus = 0; + mpd_uint_t n; + + if (exp == 0) { + _settriple(result, resultsign, 1, 0); /* GCOV_NOT_REACHED */ + return; /* GCOV_NOT_REACHED */ + } + + if (!mpd_qcopy(result, base, status)) { + return; + } + + n = mpd_bits[mpd_bsr(exp)]; + while (n >>= 1) { + mpd_qmul(result, result, result, ctx, &workstatus); + if (exp & n) { + mpd_qmul(result, result, base, ctx, &workstatus); + } + if (mpd_isspecial(result) || + (mpd_iszerocoeff(result) && (workstatus & MPD_Clamped))) { + break; + } + } + + *status |= workstatus; + mpd_set_sign(result, resultsign); +} + +/* + * Internal function: Integer power with mpd_t exponent, tbase and texp + * are modified!! Function can fail with MPD_Malloc_error. + * + * The error is equal to the error incurred in k multiplications. Assuming + * the upper bound for the relative error in each operation: + * + * abs(err) = 5 * 10**-prec + * result = x**k * (1 + err)**k + */ +static inline void +_mpd_qpow_mpd(mpd_t *result, mpd_t *tbase, mpd_t *texp, uint8_t resultsign, + const mpd_context_t *ctx, uint32_t *status) +{ + uint32_t workstatus = 0; + mpd_context_t maxctx; + MPD_NEW_CONST(two,0,0,1,1,1,2); + + + mpd_maxcontext(&maxctx); + + /* resize to smaller cannot fail */ + mpd_qcopy(result, &one, status); + + while (!mpd_iszero(texp)) { + if (mpd_isodd(texp)) { + mpd_qmul(result, result, tbase, ctx, &workstatus); + *status |= workstatus; + if (mpd_isspecial(result) || + (mpd_iszerocoeff(result) && (workstatus & MPD_Clamped))) { + break; + } + } + mpd_qmul(tbase, tbase, tbase, ctx, &workstatus); + mpd_qdivint(texp, texp, &two, &maxctx, &workstatus); + if (mpd_isnan(tbase) || mpd_isnan(texp)) { + mpd_seterror(result, workstatus&MPD_Errors, status); + return; + } + } + mpd_set_sign(result, resultsign); +} + +/* + * The power function for integer exponents. Relative error _before_ the + * final rounding to prec: + * abs(result - base**exp) < 0.1 * 10**-prec * abs(base**exp) + */ +static void +_mpd_qpow_int(mpd_t *result, const mpd_t *base, const mpd_t *exp, + uint8_t resultsign, + const mpd_context_t *ctx, uint32_t *status) +{ + mpd_context_t workctx; + MPD_NEW_STATIC(tbase,0,0,0,0); + MPD_NEW_STATIC(texp,0,0,0,0); + mpd_ssize_t n; + + + mpd_workcontext(&workctx, ctx); + workctx.prec += (exp->digits + exp->exp + 2); + workctx.round = MPD_ROUND_HALF_EVEN; + workctx.clamp = 0; + if (mpd_isnegative(exp)) { + workctx.prec += 1; + mpd_qdiv(&tbase, &one, base, &workctx, status); + if (*status&MPD_Errors) { + mpd_setspecial(result, MPD_POS, MPD_NAN); + goto finish; + } + } + else { + if (!mpd_qcopy(&tbase, base, status)) { + mpd_setspecial(result, MPD_POS, MPD_NAN); + goto finish; + } + } + + n = mpd_qabs_uint(exp, &workctx.status); + if (workctx.status&MPD_Invalid_operation) { + if (!mpd_qcopy(&texp, exp, status)) { + mpd_setspecial(result, MPD_POS, MPD_NAN); /* GCOV_UNLIKELY */ + goto finish; /* GCOV_UNLIKELY */ + } + _mpd_qpow_mpd(result, &tbase, &texp, resultsign, &workctx, status); + } + else { + _mpd_qpow_uint(result, &tbase, n, resultsign, &workctx, status); + } + + if (mpd_isinfinite(result)) { + /* for ROUND_DOWN, ROUND_FLOOR, etc. */ + _settriple(result, resultsign, 1, MPD_EXP_INF); + } + +finish: + mpd_del(&tbase); + mpd_del(&texp); + mpd_qfinalize(result, ctx, status); +} + +/* + * If the exponent is infinite and base equals one, the result is one + * with a coefficient of length prec. Otherwise, result is undefined. + * Return the value of the comparison against one. + */ +static int +_qcheck_pow_one_inf(mpd_t *result, const mpd_t *base, uint8_t resultsign, + const mpd_context_t *ctx, uint32_t *status) +{ + mpd_ssize_t shift; + int cmp; + + if ((cmp = _mpd_cmp(base, &one)) == 0) { + shift = ctx->prec-1; + mpd_qshiftl(result, &one, shift, status); + result->exp = -shift; + mpd_set_flags(result, resultsign); + *status |= (MPD_Inexact|MPD_Rounded); + } + + return cmp; +} + +/* + * If abs(base) equals one, calculate the correct power of one result. + * Otherwise, result is undefined. Return the value of the comparison + * against 1. + * + * This is an internal function that does not check for specials. + */ +static int +_qcheck_pow_one(mpd_t *result, const mpd_t *base, const mpd_t *exp, + uint8_t resultsign, + const mpd_context_t *ctx, uint32_t *status) +{ + uint32_t workstatus = 0; + mpd_ssize_t shift; + int cmp; + + if ((cmp = _mpd_cmp_abs(base, &one)) == 0) { + if (_mpd_isint(exp)) { + if (mpd_isnegative(exp)) { + _settriple(result, resultsign, 1, 0); + return 0; + } + /* 1.000**3 = 1.000000000 */ + mpd_qmul_ssize(result, exp, -base->exp, ctx, &workstatus); + if (workstatus&MPD_Errors) { + *status |= (workstatus&MPD_Errors); + return 0; + } + /* digits-1 after exponentiation */ + shift = mpd_qget_ssize(result, &workstatus); + /* shift is MPD_SSIZE_MAX if result is too large */ + if (shift > ctx->prec-1) { + shift = ctx->prec-1; + *status |= MPD_Rounded; + } + } + else if (mpd_ispositive(base)) { + shift = ctx->prec-1; + *status |= (MPD_Inexact|MPD_Rounded); + } + else { + return -2; /* GCOV_NOT_REACHED */ + } + if (!mpd_qshiftl(result, &one, shift, status)) { + return 0; + } + result->exp = -shift; + mpd_set_flags(result, resultsign); + } + + return cmp; +} + +/* + * Detect certain over/underflow of x**y. + * ACL2 proof: pow-bounds.lisp. + * + * Symbols: + * + * e: EXP_INF or EXP_CLAMP + * x: base + * y: exponent + * + * omega(e) = log10(abs(e)) + * zeta(x) = log10(abs(log10(x))) + * theta(y) = log10(abs(y)) + * + * Upper and lower bounds: + * + * ub_omega(e) = ceil(log10(abs(e))) + * lb_theta(y) = floor(log10(abs(y))) + * + * | floor(log10(floor(abs(log10(x))))) if x < 1/10 or x >= 10 + * lb_zeta(x) = | floor(log10(abs(x-1)/10)) if 1/10 <= x < 1 + * | floor(log10(abs((x-1)/100))) if 1 < x < 10 + * + * ub_omega(e) and lb_theta(y) are obviously upper and lower bounds + * for omega(e) and theta(y). + * + * lb_zeta is a lower bound for zeta(x): + * + * x < 1/10 or x >= 10: + * + * abs(log10(x)) >= 1, so the outer log10 is well defined. Since log10 + * is strictly increasing, the end result is a lower bound. + * + * 1/10 <= x < 1: + * + * We use: log10(x) <= (x-1)/log(10) + * abs(log10(x)) >= abs(x-1)/log(10) + * abs(log10(x)) >= abs(x-1)/10 + * + * 1 < x < 10: + * + * We use: (x-1)/(x*log(10)) < log10(x) + * abs((x-1)/100) < abs(log10(x)) + * + * XXX: abs((x-1)/10) would work, need ACL2 proof. + * + * + * Let (0 < x < 1 and y < 0) or (x > 1 and y > 0). (H1) + * Let ub_omega(exp_inf) < lb_zeta(x) + lb_theta(y) (H2) + * + * Then: + * log10(abs(exp_inf)) < log10(abs(log10(x))) + log10(abs(y)). (1) + * exp_inf < log10(x) * y (2) + * 10**exp_inf < x**y (3) + * + * Let (0 < x < 1 and y > 0) or (x > 1 and y < 0). (H3) + * Let ub_omega(exp_clamp) < lb_zeta(x) + lb_theta(y) (H4) + * + * Then: + * log10(abs(exp_clamp)) < log10(abs(log10(x))) + log10(abs(y)). (4) + * log10(x) * y < exp_clamp (5) + * x**y < 10**exp_clamp (6) + * + */ +static mpd_ssize_t +_lower_bound_zeta(const mpd_t *x, uint32_t *status) +{ + mpd_context_t maxctx; + MPD_NEW_STATIC(scratch,0,0,0,0); + mpd_ssize_t t, u; + + t = mpd_adjexp(x); + if (t > 0) { + /* x >= 10 -> floor(log10(floor(abs(log10(x))))) */ + return mpd_exp_digits(t) - 1; + } + else if (t < -1) { + /* x < 1/10 -> floor(log10(floor(abs(log10(x))))) */ + return mpd_exp_digits(t+1) - 1; + } + else { + mpd_maxcontext(&maxctx); + mpd_qsub(&scratch, x, &one, &maxctx, status); + if (mpd_isspecial(&scratch)) { + mpd_del(&scratch); + return MPD_SSIZE_MAX; + } + u = mpd_adjexp(&scratch); + mpd_del(&scratch); + + /* t == -1, 1/10 <= x < 1 -> floor(log10(abs(x-1)/10)) + * t == 0, 1 < x < 10 -> floor(log10(abs(x-1)/100)) */ + return (t == 0) ? u-2 : u-1; + } +} + +/* + * Detect cases of certain overflow/underflow in the power function. + * Assumptions: x != 1, y != 0. The proof above is for positive x. + * If x is negative and y is an odd integer, x**y == -(abs(x)**y), + * so the analysis does not change. + */ +static int +_qcheck_pow_bounds(mpd_t *result, const mpd_t *x, const mpd_t *y, + uint8_t resultsign, + const mpd_context_t *ctx, uint32_t *status) +{ + MPD_NEW_SHARED(abs_x, x); + mpd_ssize_t ub_omega, lb_zeta, lb_theta; + uint8_t sign; + + mpd_set_positive(&abs_x); + + lb_theta = mpd_adjexp(y); + lb_zeta = _lower_bound_zeta(&abs_x, status); + if (lb_zeta == MPD_SSIZE_MAX) { + mpd_seterror(result, MPD_Malloc_error, status); + return 1; + } + + sign = (mpd_adjexp(&abs_x) < 0) ^ mpd_sign(y); + if (sign == 0) { + /* (0 < |x| < 1 and y < 0) or (|x| > 1 and y > 0) */ + ub_omega = mpd_exp_digits(ctx->emax); + if (ub_omega < lb_zeta + lb_theta) { + _settriple(result, resultsign, 1, MPD_EXP_INF); + mpd_qfinalize(result, ctx, status); + return 1; + } + } + else { + /* (0 < |x| < 1 and y > 0) or (|x| > 1 and y < 0). */ + ub_omega = mpd_exp_digits(mpd_etiny(ctx)); + if (ub_omega < lb_zeta + lb_theta) { + _settriple(result, resultsign, 1, mpd_etiny(ctx)-1); + mpd_qfinalize(result, ctx, status); + return 1; + } + } + + return 0; +} + +/* + * TODO: Implement algorithm for computing exact powers from decimal.py. + * In order to prevent infinite loops, this has to be called before + * using Ziv's strategy for correct rounding. + */ +/* +static int +_mpd_qpow_exact(mpd_t *result, const mpd_t *base, const mpd_t *exp, + const mpd_context_t *ctx, uint32_t *status) +{ + return 0; +} +*/ + +/* + * The power function for real exponents. + * Relative error: abs(result - e**y) < e**y * 1/5 * 10**(-prec - 1) + */ +static void +_mpd_qpow_real(mpd_t *result, const mpd_t *base, const mpd_t *exp, + const mpd_context_t *ctx, uint32_t *status) +{ + mpd_context_t workctx; + MPD_NEW_STATIC(texp,0,0,0,0); + + if (!mpd_qcopy(&texp, exp, status)) { + mpd_seterror(result, MPD_Malloc_error, status); + return; + } + + mpd_maxcontext(&workctx); + workctx.prec = (base->digits > ctx->prec) ? base->digits : ctx->prec; + workctx.prec += (4 + MPD_EXPDIGITS); + workctx.round = MPD_ROUND_HALF_EVEN; + workctx.allcr = ctx->allcr; + + /* + * extra := MPD_EXPDIGITS = MPD_EXP_MAX_T + * wp := prec + 4 + extra + * abs(err) < 5 * 10**-wp + * y := log(base) * exp + * Calculate: + * 1) e**(y * (1 + err)**2) * (1 + err) + * = e**y * e**(y * (2*err + err**2)) * (1 + err) + * ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + * Relative error of the underlined term: + * 2) abs(e**(y * (2*err + err**2)) - 1) + * Case abs(y) >= 10**extra: + * 3) adjexp(y)+1 > log10(abs(y)) >= extra + * This triggers the Overflow/Underflow shortcut in _mpd_qexp(), + * so no further analysis is necessary. + * Case abs(y) < 10**extra: + * 4) abs(y * (2*err + err**2)) < 1/5 * 10**(-prec - 2) + * Use (see _mpd_qexp): + * 5) abs(x) <= 9/10 * 10**-p ==> abs(e**x - 1) < 10**-p + * With 2), 4) and 5): + * 6) abs(e**(y * (2*err + err**2)) - 1) < 10**(-prec - 2) + * The complete relative error of 1) is: + * 7) abs(result - e**y) < e**y * 1/5 * 10**(-prec - 1) + */ + mpd_qln(result, base, &workctx, &workctx.status); + mpd_qmul(result, result, &texp, &workctx, &workctx.status); + mpd_qexp(result, result, &workctx, status); + + mpd_del(&texp); + *status |= (workctx.status&MPD_Errors); + *status |= (MPD_Inexact|MPD_Rounded); +} + +/* The power function: base**exp */ +void +mpd_qpow(mpd_t *result, const mpd_t *base, const mpd_t *exp, + const mpd_context_t *ctx, uint32_t *status) +{ + uint8_t resultsign = 0; + int intexp = 0; + int cmp; + + if (mpd_isspecial(base) || mpd_isspecial(exp)) { + if (mpd_qcheck_nans(result, base, exp, ctx, status)) { + return; + } + } + if (mpd_isinteger(exp)) { + intexp = 1; + resultsign = mpd_isnegative(base) && mpd_isodd(exp); + } + + if (mpd_iszero(base)) { + if (mpd_iszero(exp)) { + mpd_seterror(result, MPD_Invalid_operation, status); + } + else if (mpd_isnegative(exp)) { + mpd_setspecial(result, resultsign, MPD_INF); + } + else { + _settriple(result, resultsign, 0, 0); + } + return; + } + if (mpd_isnegative(base)) { + if (!intexp || mpd_isinfinite(exp)) { + mpd_seterror(result, MPD_Invalid_operation, status); + return; + } + } + if (mpd_isinfinite(exp)) { + /* power of one */ + cmp = _qcheck_pow_one_inf(result, base, resultsign, ctx, status); + if (cmp == 0) { + return; + } + else { + cmp *= mpd_arith_sign(exp); + if (cmp < 0) { + _settriple(result, resultsign, 0, 0); + } + else { + mpd_setspecial(result, resultsign, MPD_INF); + } + } + return; + } + if (mpd_isinfinite(base)) { + if (mpd_iszero(exp)) { + _settriple(result, resultsign, 1, 0); + } + else if (mpd_isnegative(exp)) { + _settriple(result, resultsign, 0, 0); + } + else { + mpd_setspecial(result, resultsign, MPD_INF); + } + return; + } + if (mpd_iszero(exp)) { + _settriple(result, resultsign, 1, 0); + return; + } + if (_qcheck_pow_one(result, base, exp, resultsign, ctx, status) == 0) { + return; + } + if (_qcheck_pow_bounds(result, base, exp, resultsign, ctx, status)) { + return; + } + + if (intexp) { + _mpd_qpow_int(result, base, exp, resultsign, ctx, status); + } + else { + _mpd_qpow_real(result, base, exp, ctx, status); + if (!mpd_isspecial(result) && _mpd_cmp(result, &one) == 0) { + mpd_ssize_t shift = ctx->prec-1; + mpd_qshiftl(result, &one, shift, status); + result->exp = -shift; + } + if (mpd_isinfinite(result)) { + /* for ROUND_DOWN, ROUND_FLOOR, etc. */ + _settriple(result, MPD_POS, 1, MPD_EXP_INF); + } + mpd_qfinalize(result, ctx, status); + } +} + +/* + * Internal function: Integer powmod with mpd_uint_t exponent, base is modified! + * Function can fail with MPD_Malloc_error. + */ +static inline void +_mpd_qpowmod_uint(mpd_t *result, mpd_t *base, mpd_uint_t exp, + const mpd_t *mod, uint32_t *status) +{ + mpd_context_t maxcontext; + + mpd_maxcontext(&maxcontext); + + /* resize to smaller cannot fail */ + mpd_qcopy(result, &one, status); + + while (exp > 0) { + if (exp & 1) { + _mpd_qmul_exact(result, result, base, &maxcontext, status); + mpd_qrem(result, result, mod, &maxcontext, status); + } + _mpd_qmul_exact(base, base, base, &maxcontext, status); + mpd_qrem(base, base, mod, &maxcontext, status); + exp >>= 1; + } +} + +/* The powmod function: (base**exp) % mod */ +void +mpd_qpowmod(mpd_t *result, const mpd_t *base, const mpd_t *exp, + const mpd_t *mod, + const mpd_context_t *ctx, uint32_t *status) +{ + mpd_context_t maxcontext; + MPD_NEW_STATIC(tbase,0,0,0,0); + MPD_NEW_STATIC(texp,0,0,0,0); + MPD_NEW_STATIC(tmod,0,0,0,0); + MPD_NEW_STATIC(tmp,0,0,0,0); + MPD_NEW_CONST(two,0,0,1,1,1,2); + mpd_ssize_t tbase_exp, texp_exp; + mpd_ssize_t i; + mpd_t t; + mpd_uint_t r; + uint8_t sign; + + + if (mpd_isspecial(base) || mpd_isspecial(exp) || mpd_isspecial(mod)) { + if (mpd_qcheck_3nans(result, base, exp, mod, ctx, status)) { + return; + } + mpd_seterror(result, MPD_Invalid_operation, status); + return; + } + + + if (!_mpd_isint(base) || !_mpd_isint(exp) || !_mpd_isint(mod)) { + mpd_seterror(result, MPD_Invalid_operation, status); + return; + } + if (mpd_iszerocoeff(mod)) { + mpd_seterror(result, MPD_Invalid_operation, status); + return; + } + if (mod->digits+mod->exp > ctx->prec) { + mpd_seterror(result, MPD_Invalid_operation, status); + return; + } + + sign = (mpd_isnegative(base)) && (mpd_isodd(exp)); + if (mpd_iszerocoeff(exp)) { + if (mpd_iszerocoeff(base)) { + mpd_seterror(result, MPD_Invalid_operation, status); + return; + } + r = (_mpd_cmp_abs(mod, &one)==0) ? 0 : 1; + _settriple(result, sign, r, 0); + return; + } + if (mpd_isnegative(exp)) { + mpd_seterror(result, MPD_Invalid_operation, status); + return; + } + if (mpd_iszerocoeff(base)) { + _settriple(result, sign, 0, 0); + return; + } + + mpd_maxcontext(&maxcontext); + + mpd_qrescale(&tmod, mod, 0, &maxcontext, &maxcontext.status); + if (maxcontext.status&MPD_Errors) { + mpd_seterror(result, maxcontext.status&MPD_Errors, status); + goto out; + } + maxcontext.status = 0; + mpd_set_positive(&tmod); + + mpd_qround_to_int(&tbase, base, &maxcontext, status); + mpd_set_positive(&tbase); + tbase_exp = tbase.exp; + tbase.exp = 0; + + mpd_qround_to_int(&texp, exp, &maxcontext, status); + texp_exp = texp.exp; + texp.exp = 0; + + /* base = (base.int % modulo * pow(10, base.exp, modulo)) % modulo */ + mpd_qrem(&tbase, &tbase, &tmod, &maxcontext, status); + mpd_qshiftl(result, &one, tbase_exp, status); + mpd_qrem(result, result, &tmod, &maxcontext, status); + _mpd_qmul_exact(&tbase, &tbase, result, &maxcontext, status); + mpd_qrem(&tbase, &tbase, &tmod, &maxcontext, status); + if (mpd_isspecial(&tbase) || + mpd_isspecial(&texp) || + mpd_isspecial(&tmod)) { + goto mpd_errors; + } + + for (i = 0; i < texp_exp; i++) { + _mpd_qpowmod_uint(&tmp, &tbase, 10, &tmod, status); + t = tmp; + tmp = tbase; + tbase = t; + } + if (mpd_isspecial(&tbase)) { + goto mpd_errors; /* GCOV_UNLIKELY */ + } + + /* resize to smaller cannot fail */ + mpd_qcopy(result, &one, status); + while (mpd_isfinite(&texp) && !mpd_iszero(&texp)) { + if (mpd_isodd(&texp)) { + _mpd_qmul_exact(result, result, &tbase, &maxcontext, status); + mpd_qrem(result, result, &tmod, &maxcontext, status); + } + _mpd_qmul_exact(&tbase, &tbase, &tbase, &maxcontext, status); + mpd_qrem(&tbase, &tbase, &tmod, &maxcontext, status); + mpd_qdivint(&texp, &texp, &two, &maxcontext, status); + } + if (mpd_isspecial(&texp) || mpd_isspecial(&tbase) || + mpd_isspecial(&tmod) || mpd_isspecial(result)) { + /* MPD_Malloc_error */ + goto mpd_errors; + } + else { + mpd_set_sign(result, sign); + } + +out: + mpd_del(&tbase); + mpd_del(&texp); + mpd_del(&tmod); + mpd_del(&tmp); + return; + +mpd_errors: + mpd_setspecial(result, MPD_POS, MPD_NAN); + goto out; +} + +void +mpd_qquantize(mpd_t *result, const mpd_t *a, const mpd_t *b, + const mpd_context_t *ctx, uint32_t *status) +{ + uint32_t workstatus = 0; + mpd_ssize_t b_exp = b->exp; + mpd_ssize_t expdiff, shift; + mpd_uint_t rnd; + + if (mpd_isspecial(a) || mpd_isspecial(b)) { + if (mpd_qcheck_nans(result, a, b, ctx, status)) { + return; + } + if (mpd_isinfinite(a) && mpd_isinfinite(b)) { + mpd_qcopy(result, a, status); + return; + } + mpd_seterror(result, MPD_Invalid_operation, status); + return; + } + + if (b->exp > ctx->emax || b->exp < mpd_etiny(ctx)) { + mpd_seterror(result, MPD_Invalid_operation, status); + return; + } + + if (mpd_iszero(a)) { + _settriple(result, mpd_sign(a), 0, b->exp); + mpd_qfinalize(result, ctx, status); + return; + } + + + expdiff = a->exp - b->exp; + if (a->digits + expdiff > ctx->prec) { + mpd_seterror(result, MPD_Invalid_operation, status); + return; + } + + if (expdiff >= 0) { + shift = expdiff; + if (!mpd_qshiftl(result, a, shift, status)) { + return; + } + result->exp = b_exp; + } + else { + /* At this point expdiff < 0 and a->digits+expdiff <= prec, + * so the shift before an increment will fit in prec. */ + shift = -expdiff; + rnd = mpd_qshiftr(result, a, shift, status); + if (rnd == MPD_UINT_MAX) { + return; + } + result->exp = b_exp; + if (!_mpd_apply_round_fit(result, rnd, ctx, status)) { + return; + } + workstatus |= MPD_Rounded; + if (rnd) { + workstatus |= MPD_Inexact; + } + } + + if (mpd_adjexp(result) > ctx->emax || + mpd_adjexp(result) < mpd_etiny(ctx)) { + mpd_seterror(result, MPD_Invalid_operation, status); + return; + } + + *status |= workstatus; + mpd_qfinalize(result, ctx, status); +} + +void +mpd_qreduce(mpd_t *result, const mpd_t *a, const mpd_context_t *ctx, + uint32_t *status) +{ + mpd_ssize_t shift, maxexp, maxshift; + uint8_t sign_a = mpd_sign(a); + + if (mpd_isspecial(a)) { + if (mpd_qcheck_nan(result, a, ctx, status)) { + return; + } + mpd_qcopy(result, a, status); + return; + } + + if (!mpd_qcopy(result, a, status)) { + return; + } + mpd_qfinalize(result, ctx, status); + if (mpd_isspecial(result)) { + return; + } + if (mpd_iszero(result)) { + _settriple(result, sign_a, 0, 0); + return; + } + + shift = mpd_trail_zeros(result); + maxexp = (ctx->clamp) ? mpd_etop(ctx) : ctx->emax; + /* After the finalizing above result->exp <= maxexp. */ + maxshift = maxexp - result->exp; + shift = (shift > maxshift) ? maxshift : shift; + + mpd_qshiftr_inplace(result, shift); + result->exp += shift; +} + +void +mpd_qrem(mpd_t *r, const mpd_t *a, const mpd_t *b, const mpd_context_t *ctx, + uint32_t *status) +{ + MPD_NEW_STATIC(q,0,0,0,0); + + if (mpd_isspecial(a) || mpd_isspecial(b)) { + if (mpd_qcheck_nans(r, a, b, ctx, status)) { + return; + } + if (mpd_isinfinite(a)) { + mpd_seterror(r, MPD_Invalid_operation, status); + return; + } + if (mpd_isinfinite(b)) { + mpd_qcopy(r, a, status); + mpd_qfinalize(r, ctx, status); + return; + } + /* debug */ + abort(); /* GCOV_NOT_REACHED */ + } + if (mpd_iszerocoeff(b)) { + if (mpd_iszerocoeff(a)) { + mpd_seterror(r, MPD_Division_undefined, status); + } + else { + mpd_seterror(r, MPD_Invalid_operation, status); + } + return; + } + + _mpd_qdivmod(&q, r, a, b, ctx, status); + mpd_del(&q); + mpd_qfinalize(r, ctx, status); +} + +void +mpd_qrem_near(mpd_t *r, const mpd_t *a, const mpd_t *b, + const mpd_context_t *ctx, uint32_t *status) +{ + mpd_context_t workctx; + MPD_NEW_STATIC(btmp,0,0,0,0); + MPD_NEW_STATIC(q,0,0,0,0); + mpd_ssize_t expdiff, qdigits; + int cmp, isodd, allnine; + + if (mpd_isspecial(a) || mpd_isspecial(b)) { + if (mpd_qcheck_nans(r, a, b, ctx, status)) { + return; + } + if (mpd_isinfinite(a)) { + mpd_seterror(r, MPD_Invalid_operation, status); + return; + } + if (mpd_isinfinite(b)) { + mpd_qcopy(r, a, status); + mpd_qfinalize(r, ctx, status); + return; + } + /* debug */ + abort(); /* GCOV_NOT_REACHED */ + } + if (mpd_iszerocoeff(b)) { + if (mpd_iszerocoeff(a)) { + mpd_seterror(r, MPD_Division_undefined, status); + } + else { + mpd_seterror(r, MPD_Invalid_operation, status); + } + return; + } + + if (r == b) { + if (!mpd_qcopy(&btmp, b, status)) { + mpd_seterror(r, MPD_Malloc_error, status); + return; + } + b = &btmp; + } + + _mpd_qdivmod(&q, r, a, b, ctx, status); + if (mpd_isnan(&q) || mpd_isnan(r)) { + goto finish; + } + if (mpd_iszerocoeff(r)) { + goto finish; + } + + expdiff = mpd_adjexp(b) - mpd_adjexp(r); + if (-1 <= expdiff && expdiff <= 1) { + + allnine = mpd_coeff_isallnine(&q); + qdigits = q.digits; + isodd = mpd_isodd(&q); + + mpd_maxcontext(&workctx); + if (mpd_sign(a) == mpd_sign(b)) { + /* sign(r) == sign(b) */ + _mpd_qsub(&q, r, b, &workctx, &workctx.status); + } + else { + /* sign(r) != sign(b) */ + _mpd_qadd(&q, r, b, &workctx, &workctx.status); + } + + if (workctx.status&MPD_Errors) { + mpd_seterror(r, workctx.status&MPD_Errors, status); + goto finish; + } + + cmp = _mpd_cmp_abs(&q, r); + if (cmp < 0 || (cmp == 0 && isodd)) { + /* abs(r) > abs(b)/2 or abs(r) == abs(b)/2 and isodd(quotient) */ + if (allnine && qdigits == ctx->prec) { + /* abs(quotient) + 1 == 10**prec */ + mpd_seterror(r, MPD_Division_impossible, status); + goto finish; + } + mpd_qcopy(r, &q, status); + } + } + + +finish: + mpd_del(&btmp); + mpd_del(&q); + mpd_qfinalize(r, ctx, status); +} + +static void +_mpd_qrescale(mpd_t *result, const mpd_t *a, mpd_ssize_t exp, + const mpd_context_t *ctx, uint32_t *status) +{ + mpd_ssize_t expdiff, shift; + mpd_uint_t rnd; + + if (mpd_isspecial(a)) { + mpd_qcopy(result, a, status); + return; + } + + if (mpd_iszero(a)) { + _settriple(result, mpd_sign(a), 0, exp); + return; + } + + expdiff = a->exp - exp; + if (expdiff >= 0) { + shift = expdiff; + if (a->digits + shift > MPD_MAX_PREC+1) { + mpd_seterror(result, MPD_Invalid_operation, status); + return; + } + if (!mpd_qshiftl(result, a, shift, status)) { + return; + } + result->exp = exp; + } + else { + shift = -expdiff; + rnd = mpd_qshiftr(result, a, shift, status); + if (rnd == MPD_UINT_MAX) { + return; + } + result->exp = exp; + _mpd_apply_round_excess(result, rnd, ctx, status); + *status |= MPD_Rounded; + if (rnd) { + *status |= MPD_Inexact; + } + } + + if (mpd_issubnormal(result, ctx)) { + *status |= MPD_Subnormal; + } +} + +/* + * Rescale a number so that it has exponent 'exp'. Does not regard context + * precision, emax, emin, but uses the rounding mode. Special numbers are + * quietly copied. Restrictions: + * + * MPD_MIN_ETINY <= exp <= MPD_MAX_EMAX+1 + * result->digits <= MPD_MAX_PREC+1 + */ +void +mpd_qrescale(mpd_t *result, const mpd_t *a, mpd_ssize_t exp, + const mpd_context_t *ctx, uint32_t *status) +{ + if (exp > MPD_MAX_EMAX+1 || exp < MPD_MIN_ETINY) { + mpd_seterror(result, MPD_Invalid_operation, status); + return; + } + + _mpd_qrescale(result, a, exp, ctx, status); +} + +/* + * Same as mpd_qrescale, but with relaxed restrictions. The result of this + * function should only be used for formatting a number and never as input + * for other operations. + * + * MPD_MIN_ETINY-MPD_MAX_PREC <= exp <= MPD_MAX_EMAX+1 + * result->digits <= MPD_MAX_PREC+1 + */ +void +mpd_qrescale_fmt(mpd_t *result, const mpd_t *a, mpd_ssize_t exp, + const mpd_context_t *ctx, uint32_t *status) +{ + if (exp > MPD_MAX_EMAX+1 || exp < MPD_MIN_ETINY-MPD_MAX_PREC) { + mpd_seterror(result, MPD_Invalid_operation, status); + return; + } + + _mpd_qrescale(result, a, exp, ctx, status); +} + +/* Round to an integer according to 'action' and ctx->round. */ +enum {TO_INT_EXACT, TO_INT_SILENT, TO_INT_TRUNC}; +static void +_mpd_qround_to_integral(int action, mpd_t *result, const mpd_t *a, + const mpd_context_t *ctx, uint32_t *status) +{ + mpd_uint_t rnd; + + if (mpd_isspecial(a)) { + if (mpd_qcheck_nan(result, a, ctx, status)) { + return; + } + mpd_qcopy(result, a, status); + return; + } + if (a->exp >= 0) { + mpd_qcopy(result, a, status); + return; + } + if (mpd_iszerocoeff(a)) { + _settriple(result, mpd_sign(a), 0, 0); + return; + } + + rnd = mpd_qshiftr(result, a, -a->exp, status); + if (rnd == MPD_UINT_MAX) { + return; + } + result->exp = 0; + + if (action == TO_INT_EXACT || action == TO_INT_SILENT) { + _mpd_apply_round_excess(result, rnd, ctx, status); + if (action == TO_INT_EXACT) { + *status |= MPD_Rounded; + if (rnd) { + *status |= MPD_Inexact; + } + } + } +} + +void +mpd_qround_to_intx(mpd_t *result, const mpd_t *a, const mpd_context_t *ctx, + uint32_t *status) +{ + (void)_mpd_qround_to_integral(TO_INT_EXACT, result, a, ctx, status); +} + +void +mpd_qround_to_int(mpd_t *result, const mpd_t *a, const mpd_context_t *ctx, + uint32_t *status) +{ + (void)_mpd_qround_to_integral(TO_INT_SILENT, result, a, ctx, status); +} + +void +mpd_qtrunc(mpd_t *result, const mpd_t *a, const mpd_context_t *ctx, + uint32_t *status) +{ + (void)_mpd_qround_to_integral(TO_INT_TRUNC, result, a, ctx, status); +} + +void +mpd_qfloor(mpd_t *result, const mpd_t *a, const mpd_context_t *ctx, + uint32_t *status) +{ + mpd_context_t workctx = *ctx; + workctx.round = MPD_ROUND_FLOOR; + (void)_mpd_qround_to_integral(TO_INT_SILENT, result, a, + &workctx, status); +} + +void +mpd_qceil(mpd_t *result, const mpd_t *a, const mpd_context_t *ctx, + uint32_t *status) +{ + mpd_context_t workctx = *ctx; + workctx.round = MPD_ROUND_CEILING; + (void)_mpd_qround_to_integral(TO_INT_SILENT, result, a, + &workctx, status); +} + +int +mpd_same_quantum(const mpd_t *a, const mpd_t *b) +{ + if (mpd_isspecial(a) || mpd_isspecial(b)) { + return ((mpd_isnan(a) && mpd_isnan(b)) || + (mpd_isinfinite(a) && mpd_isinfinite(b))); + } + + return a->exp == b->exp; +} + +/* Schedule the increase in precision for the Newton iteration. */ +static inline int +recpr_schedule_prec(mpd_ssize_t klist[MPD_MAX_PREC_LOG2], + mpd_ssize_t maxprec, mpd_ssize_t initprec) +{ + mpd_ssize_t k; + int i; + + assert(maxprec > 0 && initprec > 0); + if (maxprec <= initprec) return -1; + + i = 0; k = maxprec; + do { + k = (k+1) / 2; + klist[i++] = k; + } while (k > initprec); + + return i-1; +} + +/* + * Initial approximation for the reciprocal: + * k_0 := MPD_RDIGITS-2 + * z_0 := 10**(-k_0) * floor(10**(2*k_0 + 2) / floor(v * 10**(k_0 + 2))) + * Absolute error: + * |1/v - z_0| < 10**(-k_0) + * ACL2 proof: maxerror-inverse-approx + */ +static void +_mpd_qreciprocal_approx(mpd_t *z, const mpd_t *v, uint32_t *status) +{ + mpd_uint_t p10data[2] = {0, mpd_pow10[MPD_RDIGITS-2]}; + mpd_uint_t dummy, word; + int n; + + assert(v->exp == -v->digits); + + _mpd_get_msdigits(&dummy, &word, v, MPD_RDIGITS); + n = mpd_word_digits(word); + word *= mpd_pow10[MPD_RDIGITS-n]; + + mpd_qresize(z, 2, status); + (void)_mpd_shortdiv(z->data, p10data, 2, word); + + mpd_clear_flags(z); + z->exp = -(MPD_RDIGITS-2); + z->len = (z->data[1] == 0) ? 1 : 2; + mpd_setdigits(z); +} + +/* + * Reciprocal, calculated with Newton's Method. Assumption: result != a. + * NOTE: The comments in the function show that certain operations are + * exact. The proof for the maximum error is too long to fit in here. + * ACL2 proof: maxerror-inverse-complete + */ +static void +_mpd_qreciprocal(mpd_t *result, const mpd_t *a, const mpd_context_t *ctx, + uint32_t *status) +{ + mpd_context_t varcontext, maxcontext; + mpd_t *z = result; /* current approximation */ + mpd_t *v; /* a, normalized to a number between 0.1 and 1 */ + MPD_NEW_SHARED(vtmp, a); /* v shares data with a */ + MPD_NEW_STATIC(s,0,0,0,0); /* temporary variable */ + MPD_NEW_STATIC(t,0,0,0,0); /* temporary variable */ + MPD_NEW_CONST(two,0,0,1,1,1,2); /* const 2 */ + mpd_ssize_t klist[MPD_MAX_PREC_LOG2]; + mpd_ssize_t adj, maxprec, initprec; + uint8_t sign = mpd_sign(a); + int i; + + assert(result != a); + + v = &vtmp; + mpd_clear_flags(v); + adj = v->digits + v->exp; + v->exp = -v->digits; + + /* Initial approximation */ + _mpd_qreciprocal_approx(z, v, status); + + mpd_maxcontext(&varcontext); + mpd_maxcontext(&maxcontext); + varcontext.round = maxcontext.round = MPD_ROUND_TRUNC; + varcontext.emax = maxcontext.emax = MPD_MAX_EMAX + 100; + varcontext.emin = maxcontext.emin = MPD_MIN_EMIN - 100; + maxcontext.prec = MPD_MAX_PREC + 100; + + maxprec = ctx->prec; + maxprec += 2; + initprec = MPD_RDIGITS-3; + + i = recpr_schedule_prec(klist, maxprec, initprec); + for (; i >= 0; i--) { + /* Loop invariant: z->digits <= klist[i]+7 */ + /* Let s := z**2, exact result */ + _mpd_qmul_exact(&s, z, z, &maxcontext, status); + varcontext.prec = 2*klist[i] + 5; + if (v->digits > varcontext.prec) { + /* Let t := v, truncated to n >= 2*k+5 fraction digits */ + mpd_qshiftr(&t, v, v->digits-varcontext.prec, status); + t.exp = -varcontext.prec; + /* Let t := trunc(v)*s, truncated to n >= 2*k+1 fraction digits */ + mpd_qmul(&t, &t, &s, &varcontext, status); + } + else { /* v->digits <= 2*k+5 */ + /* Let t := v*s, truncated to n >= 2*k+1 fraction digits */ + mpd_qmul(&t, v, &s, &varcontext, status); + } + /* Let s := 2*z, exact result */ + _mpd_qmul_exact(&s, z, &two, &maxcontext, status); + /* s.digits < t.digits <= 2*k+5, |adjexp(s)-adjexp(t)| <= 1, + * so the subtraction generates at most 2*k+6 <= klist[i+1]+7 + * digits. The loop invariant is preserved. */ + _mpd_qsub_exact(z, &s, &t, &maxcontext, status); + } + + if (!mpd_isspecial(z)) { + z->exp -= adj; + mpd_set_flags(z, sign); + } + + mpd_del(&s); + mpd_del(&t); + mpd_qfinalize(z, ctx, status); +} + +/* + * Internal function for large numbers: + * + * q, r = divmod(coeff(a), coeff(b)) + * + * Strategy: Multiply the dividend by the reciprocal of the divisor. The + * inexact result is fixed by a small loop, using at most one iteration. + * + * ACL2 proofs: + * ------------ + * 1) q is a natural number. (ndivmod-quotient-natp) + * 2) r is a natural number. (ndivmod-remainder-natp) + * 3) a = q * b + r (ndivmod-q*b+r==a) + * 4) r < b (ndivmod-remainder-<-b) + */ +static void +_mpd_base_ndivmod(mpd_t *q, mpd_t *r, const mpd_t *a, const mpd_t *b, + uint32_t *status) +{ + mpd_context_t workctx; + mpd_t *qq = q, *rr = r; + mpd_t aa, bb; + int k; + + _mpd_copy_shared(&aa, a); + _mpd_copy_shared(&bb, b); + + mpd_set_positive(&aa); + mpd_set_positive(&bb); + aa.exp = 0; + bb.exp = 0; + + if (q == a || q == b) { + if ((qq = mpd_qnew()) == NULL) { + *status |= MPD_Malloc_error; + goto nanresult; + } + } + if (r == a || r == b) { + if ((rr = mpd_qnew()) == NULL) { + *status |= MPD_Malloc_error; + goto nanresult; + } + } + + mpd_maxcontext(&workctx); + + /* Let prec := adigits - bdigits + 4 */ + workctx.prec = a->digits - b->digits + 1 + 3; + if (a->digits > MPD_MAX_PREC || workctx.prec > MPD_MAX_PREC) { + *status |= MPD_Division_impossible; + goto nanresult; + } + + /* Let x := _mpd_qreciprocal(b, prec) + * Then x is bounded by: + * 1) 1/b - 10**(-prec - bdigits) < x < 1/b + 10**(-prec - bdigits) + * 2) 1/b - 10**(-adigits - 4) < x < 1/b + 10**(-adigits - 4) + */ + _mpd_qreciprocal(rr, &bb, &workctx, &workctx.status); + + /* Get an estimate for the quotient. Let q := a * x + * Then q is bounded by: + * 3) a/b - 10**-4 < q < a/b + 10**-4 + */ + _mpd_qmul(qq, &aa, rr, &workctx, &workctx.status); + /* Truncate q to an integer: + * 4) a/b - 2 < trunc(q) < a/b + 1 + */ + mpd_qtrunc(qq, qq, &workctx, &workctx.status); + + workctx.prec = aa.digits + 3; + workctx.emax = MPD_MAX_EMAX + 3; + workctx.emin = MPD_MIN_EMIN - 3; + /* Multiply the estimate for q by b: + * 5) a - 2 * b < trunc(q) * b < a + b + */ + _mpd_qmul(rr, &bb, qq, &workctx, &workctx.status); + /* Get the estimate for r such that a = q * b + r. */ + _mpd_qsub_exact(rr, &aa, rr, &workctx, &workctx.status); + + /* Fix the result. At this point -b < r < 2*b, so the correction loop + takes at most one iteration. */ + for (k = 0;; k++) { + if (mpd_isspecial(qq) || mpd_isspecial(rr)) { + *status |= (workctx.status&MPD_Errors); + goto nanresult; + } + if (k > 2) { /* Allow two iterations despite the proof. */ + mpd_err_warn("libmpdec: internal error in " /* GCOV_NOT_REACHED */ + "_mpd_base_ndivmod: please report"); /* GCOV_NOT_REACHED */ + *status |= MPD_Invalid_operation; /* GCOV_NOT_REACHED */ + goto nanresult; /* GCOV_NOT_REACHED */ + } + /* r < 0 */ + else if (_mpd_cmp(&zero, rr) == 1) { + _mpd_qadd_exact(rr, rr, &bb, &workctx, &workctx.status); + _mpd_qadd_exact(qq, qq, &minus_one, &workctx, &workctx.status); + } + /* 0 <= r < b */ + else if (_mpd_cmp(rr, &bb) == -1) { + break; + } + /* r >= b */ + else { + _mpd_qsub_exact(rr, rr, &bb, &workctx, &workctx.status); + _mpd_qadd_exact(qq, qq, &one, &workctx, &workctx.status); + } + } + + if (qq != q) { + if (!mpd_qcopy(q, qq, status)) { + goto nanresult; /* GCOV_UNLIKELY */ + } + mpd_del(qq); + } + if (rr != r) { + if (!mpd_qcopy(r, rr, status)) { + goto nanresult; /* GCOV_UNLIKELY */ + } + mpd_del(rr); + } + + *status |= (workctx.status&MPD_Errors); + return; + + +nanresult: + if (qq && qq != q) mpd_del(qq); + if (rr && rr != r) mpd_del(rr); + mpd_setspecial(q, MPD_POS, MPD_NAN); + mpd_setspecial(r, MPD_POS, MPD_NAN); +} + +/* LIBMPDEC_ONLY */ +/* + * Schedule the optimal precision increase for the Newton iteration. + * v := input operand + * z_0 := initial approximation + * initprec := natural number such that abs(sqrt(v) - z_0) < 10**-initprec + * maxprec := target precision + * + * For convenience the output klist contains the elements in reverse order: + * klist := [k_n-1, ..., k_0], where + * 1) k_0 <= initprec and + * 2) abs(sqrt(v) - result) < 10**(-2*k_n-1 + 2) <= 10**-maxprec. + */ +static inline int +invroot_schedule_prec(mpd_ssize_t klist[MPD_MAX_PREC_LOG2], + mpd_ssize_t maxprec, mpd_ssize_t initprec) +{ + mpd_ssize_t k; + int i; + + assert(maxprec >= 3 && initprec >= 3); + if (maxprec <= initprec) return -1; + + i = 0; k = maxprec; + do { + k = (k+3) / 2; + klist[i++] = k; + } while (k > initprec); + + return i-1; +} + +/* + * Initial approximation for the inverse square root function. + * Input: + * v := rational number, with 1 <= v < 100 + * vhat := floor(v * 10**6) + * Output: + * z := approximation to 1/sqrt(v), such that abs(z - 1/sqrt(v)) < 10**-3. + */ +static inline void +_invroot_init_approx(mpd_t *z, mpd_uint_t vhat) +{ + mpd_uint_t lo = 1000; + mpd_uint_t hi = 10000; + mpd_uint_t a, sq; + + assert(lo*lo <= vhat && vhat < (hi+1)*(hi+1)); + + for(;;) { + a = (lo + hi) / 2; + sq = a * a; + if (vhat >= sq) { + if (vhat < sq + 2*a + 1) { + break; + } + lo = a + 1; + } + else { + hi = a - 1; + } + } + + /* + * After the binary search we have: + * 1) a**2 <= floor(v * 10**6) < (a + 1)**2 + * This implies: + * 2) a**2 <= v * 10**6 < (a + 1)**2 + * 3) a <= sqrt(v) * 10**3 < a + 1 + * Since 10**3 <= a: + * 4) 0 <= 10**prec/a - 1/sqrt(v) < 10**-prec + * We have: + * 5) 10**3/a - 10**-3 < floor(10**9/a) * 10**-6 <= 10**3/a + * Merging 4) and 5): + * 6) abs(floor(10**9/a) * 10**-6 - 1/sqrt(v)) < 10**-3 + */ + mpd_minalloc(z); + mpd_clear_flags(z); + z->data[0] = 1000000000UL / a; + z->len = 1; + z->exp = -6; + mpd_setdigits(z); +} + +/* + * Set 'result' to 1/sqrt(a). + * Relative error: abs(result - 1/sqrt(a)) < 10**-prec * 1/sqrt(a) + */ +static void +_mpd_qinvroot(mpd_t *result, const mpd_t *a, const mpd_context_t *ctx, + uint32_t *status) +{ + uint32_t workstatus = 0; + mpd_context_t varcontext, maxcontext; + mpd_t *z = result; /* current approximation */ + mpd_t *v; /* a, normalized to a number between 1 and 100 */ + MPD_NEW_SHARED(vtmp, a); /* by default v will share data with a */ + MPD_NEW_STATIC(s,0,0,0,0); /* temporary variable */ + MPD_NEW_STATIC(t,0,0,0,0); /* temporary variable */ + MPD_NEW_CONST(one_half,0,-1,1,1,1,5); + MPD_NEW_CONST(three,0,0,1,1,1,3); + mpd_ssize_t klist[MPD_MAX_PREC_LOG2]; + mpd_ssize_t ideal_exp, shift; + mpd_ssize_t adj, tz; + mpd_ssize_t maxprec, fracdigits; + mpd_uint_t vhat, dummy; + int i, n; + + + ideal_exp = -(a->exp - (a->exp & 1)) / 2; + + v = &vtmp; + if (result == a) { + if ((v = mpd_qncopy(a)) == NULL) { + mpd_seterror(result, MPD_Malloc_error, status); + return; + } + } + + /* normalize a to 1 <= v < 100 */ + if ((v->digits+v->exp) & 1) { + fracdigits = v->digits - 1; + v->exp = -fracdigits; + n = (v->digits > 7) ? 7 : (int)v->digits; + /* Let vhat := floor(v * 10**(2*initprec)) */ + _mpd_get_msdigits(&dummy, &vhat, v, n); + if (n < 7) { + vhat *= mpd_pow10[7-n]; + } + } + else { + fracdigits = v->digits - 2; + v->exp = -fracdigits; + n = (v->digits > 8) ? 8 : (int)v->digits; + /* Let vhat := floor(v * 10**(2*initprec)) */ + _mpd_get_msdigits(&dummy, &vhat, v, n); + if (n < 8) { + vhat *= mpd_pow10[8-n]; + } + } + adj = (a->exp-v->exp) / 2; + + /* initial approximation */ + _invroot_init_approx(z, vhat); + + mpd_maxcontext(&maxcontext); + mpd_maxcontext(&varcontext); + varcontext.round = MPD_ROUND_TRUNC; + maxprec = ctx->prec + 1; + + /* initprec == 3 */ + i = invroot_schedule_prec(klist, maxprec, 3); + for (; i >= 0; i--) { + varcontext.prec = 2*klist[i]+2; + mpd_qmul(&s, z, z, &maxcontext, &workstatus); + if (v->digits > varcontext.prec) { + shift = v->digits - varcontext.prec; + mpd_qshiftr(&t, v, shift, &workstatus); + t.exp += shift; + mpd_qmul(&t, &t, &s, &varcontext, &workstatus); + } + else { + mpd_qmul(&t, v, &s, &varcontext, &workstatus); + } + mpd_qsub(&t, &three, &t, &maxcontext, &workstatus); + mpd_qmul(z, z, &t, &varcontext, &workstatus); + mpd_qmul(z, z, &one_half, &maxcontext, &workstatus); + } + + z->exp -= adj; + + tz = mpd_trail_zeros(result); + shift = ideal_exp - result->exp; + shift = (tz > shift) ? shift : tz; + if (shift > 0) { + mpd_qshiftr_inplace(result, shift); + result->exp += shift; + } + + + mpd_del(&s); + mpd_del(&t); + if (v != &vtmp) mpd_del(v); + *status |= (workstatus&MPD_Errors); + *status |= (MPD_Rounded|MPD_Inexact); +} + +void +mpd_qinvroot(mpd_t *result, const mpd_t *a, const mpd_context_t *ctx, + uint32_t *status) +{ + mpd_context_t workctx; + + if (mpd_isspecial(a)) { + if (mpd_qcheck_nan(result, a, ctx, status)) { + return; + } + if (mpd_isnegative(a)) { + mpd_seterror(result, MPD_Invalid_operation, status); + return; + } + /* positive infinity */ + _settriple(result, MPD_POS, 0, mpd_etiny(ctx)); + *status |= MPD_Clamped; + return; + } + if (mpd_iszero(a)) { + mpd_setspecial(result, mpd_sign(a), MPD_INF); + *status |= MPD_Division_by_zero; + return; + } + if (mpd_isnegative(a)) { + mpd_seterror(result, MPD_Invalid_operation, status); + return; + } + + workctx = *ctx; + workctx.prec += 2; + workctx.round = MPD_ROUND_HALF_EVEN; + _mpd_qinvroot(result, a, &workctx, status); + mpd_qfinalize(result, ctx, status); +} +/* END LIBMPDEC_ONLY */ + +/* Algorithm from decimal.py */ +void +mpd_qsqrt(mpd_t *result, const mpd_t *a, const mpd_context_t *ctx, + uint32_t *status) +{ + mpd_context_t maxcontext; + MPD_NEW_STATIC(c,0,0,0,0); + MPD_NEW_STATIC(q,0,0,0,0); + MPD_NEW_STATIC(r,0,0,0,0); + MPD_NEW_CONST(two,0,0,1,1,1,2); + mpd_ssize_t prec, ideal_exp; + mpd_ssize_t l, shift; + int exact = 0; + + + ideal_exp = (a->exp - (a->exp & 1)) / 2; + + if (mpd_isspecial(a)) { + if (mpd_qcheck_nan(result, a, ctx, status)) { + return; + } + if (mpd_isnegative(a)) { + mpd_seterror(result, MPD_Invalid_operation, status); + return; + } + mpd_setspecial(result, MPD_POS, MPD_INF); + return; + } + if (mpd_iszero(a)) { + _settriple(result, mpd_sign(a), 0, ideal_exp); + mpd_qfinalize(result, ctx, status); + return; + } + if (mpd_isnegative(a)) { + mpd_seterror(result, MPD_Invalid_operation, status); + return; + } + + mpd_maxcontext(&maxcontext); + prec = ctx->prec + 1; + + if (!mpd_qcopy(&c, a, status)) { + goto malloc_error; + } + c.exp = 0; + + if (a->exp & 1) { + if (!mpd_qshiftl(&c, &c, 1, status)) { + goto malloc_error; + } + l = (a->digits >> 1) + 1; + } + else { + l = (a->digits + 1) >> 1; + } + + shift = prec - l; + if (shift >= 0) { + if (!mpd_qshiftl(&c, &c, 2*shift, status)) { + goto malloc_error; + } + exact = 1; + } + else { + exact = !mpd_qshiftr_inplace(&c, -2*shift); + } + + ideal_exp -= shift; + + /* find result = floor(sqrt(c)) using Newton's method */ + if (!mpd_qshiftl(result, &one, prec, status)) { + goto malloc_error; + } + + while (1) { + _mpd_qdivmod(&q, &r, &c, result, &maxcontext, &maxcontext.status); + if (mpd_isspecial(result) || mpd_isspecial(&q)) { + mpd_seterror(result, maxcontext.status&MPD_Errors, status); + goto out; + } + if (_mpd_cmp(result, &q) <= 0) { + break; + } + _mpd_qadd_exact(result, result, &q, &maxcontext, &maxcontext.status); + if (mpd_isspecial(result)) { + mpd_seterror(result, maxcontext.status&MPD_Errors, status); + goto out; + } + _mpd_qdivmod(result, &r, result, &two, &maxcontext, &maxcontext.status); + } + + if (exact) { + _mpd_qmul_exact(&r, result, result, &maxcontext, &maxcontext.status); + if (mpd_isspecial(&r)) { + mpd_seterror(result, maxcontext.status&MPD_Errors, status); + goto out; + } + exact = (_mpd_cmp(&r, &c) == 0); + } + + if (exact) { + if (shift >= 0) { + mpd_qshiftr_inplace(result, shift); + } + else { + if (!mpd_qshiftl(result, result, -shift, status)) { + goto malloc_error; + } + } + ideal_exp += shift; + } + else { + int lsd = (int)mpd_lsd(result->data[0]); + if (lsd == 0 || lsd == 5) { + result->data[0] += 1; + } + } + + result->exp = ideal_exp; + + +out: + mpd_del(&c); + mpd_del(&q); + mpd_del(&r); + maxcontext = *ctx; + maxcontext.round = MPD_ROUND_HALF_EVEN; + mpd_qfinalize(result, &maxcontext, status); + return; + +malloc_error: + mpd_seterror(result, MPD_Malloc_error, status); + goto out; +} + + +/******************************************************************************/ +/* Base conversions */ +/******************************************************************************/ + +/* Space needed to represent an integer mpd_t in base 'base'. */ +size_t +mpd_sizeinbase(const mpd_t *a, uint32_t base) +{ + double x; + size_t digits; + + assert(mpd_isinteger(a)); + assert(base >= 2); + + if (mpd_iszero(a)) { + return 1; + } + + digits = a->digits+a->exp; + assert(digits > 0); + +#ifdef CONFIG_64 + /* ceil(2711437152599294 / log10(2)) + 4 == 2**53 */ + if (digits > 2711437152599294ULL) { + return SIZE_MAX; + } +#endif + + x = (double)digits / log10(base); + return (x > SIZE_MAX-1) ? SIZE_MAX : (size_t)x + 1; +} + +/* Space needed to import a base 'base' integer of length 'srclen'. */ +static mpd_ssize_t +_mpd_importsize(size_t srclen, uint32_t base) +{ + double x; + + assert(srclen > 0); + assert(base >= 2); + +#if SIZE_MAX == UINT64_MAX + if (srclen > (1ULL<<53)) { + return MPD_SSIZE_MAX; + } +#endif + + x = (double)srclen * (log10(base)/MPD_RDIGITS); + return (x >= MPD_MAXIMPORT) ? MPD_SSIZE_MAX : (mpd_ssize_t)x + 1; +} + +static uint8_t +mpd_resize_u16(uint16_t **w, size_t nmemb) +{ + uint8_t err = 0; + *w = mpd_realloc(*w, nmemb, sizeof **w, &err); + return !err; +} + +static uint8_t +mpd_resize_u32(uint32_t **w, size_t nmemb) +{ + uint8_t err = 0; + *w = mpd_realloc(*w, nmemb, sizeof **w, &err); + return !err; +} + +static size_t +_baseconv_to_u16(uint16_t **w, size_t wlen, mpd_uint_t wbase, + mpd_uint_t *u, mpd_ssize_t ulen) +{ + size_t n = 0; + + assert(wlen > 0 && ulen > 0); + assert(wbase <= (1U<<16)); + + do { + if (n >= wlen) { + if (!mpd_resize_u16(w, n+1)) { + return SIZE_MAX; + } + wlen = n+1; + } + (*w)[n++] = (uint16_t)_mpd_shortdiv(u, u, ulen, wbase); + /* ulen is at least 1. u[ulen-1] can only be zero if ulen == 1. */ + ulen = _mpd_real_size(u, ulen); + + } while (u[ulen-1] != 0); + + return n; +} + +static size_t +_coeff_from_u16(mpd_t *w, mpd_ssize_t wlen, + const mpd_uint_t *u, size_t ulen, uint32_t ubase, + uint32_t *status) +{ + mpd_ssize_t n = 0; + mpd_uint_t carry; + + assert(wlen > 0 && ulen > 0); + assert(ubase <= (1U<<16)); + + w->data[n++] = u[--ulen]; + while (--ulen != SIZE_MAX) { + carry = _mpd_shortmul_c(w->data, w->data, n, ubase); + if (carry) { + if (n >= wlen) { + if (!mpd_qresize(w, n+1, status)) { + return SIZE_MAX; + } + wlen = n+1; + } + w->data[n++] = carry; + } + carry = _mpd_shortadd(w->data, n, u[ulen]); + if (carry) { + if (n >= wlen) { + if (!mpd_qresize(w, n+1, status)) { + return SIZE_MAX; + } + wlen = n+1; + } + w->data[n++] = carry; + } + } + + return n; +} + +/* target base wbase < source base ubase */ +static size_t +_baseconv_to_smaller(uint32_t **w, size_t wlen, uint32_t wbase, + mpd_uint_t *u, mpd_ssize_t ulen, mpd_uint_t ubase) +{ + size_t n = 0; + + assert(wlen > 0 && ulen > 0); + assert(wbase < ubase); + + do { + if (n >= wlen) { + if (!mpd_resize_u32(w, n+1)) { + return SIZE_MAX; + } + wlen = n+1; + } + (*w)[n++] = (uint32_t)_mpd_shortdiv_b(u, u, ulen, wbase, ubase); + /* ulen is at least 1. u[ulen-1] can only be zero if ulen == 1. */ + ulen = _mpd_real_size(u, ulen); + + } while (u[ulen-1] != 0); + + return n; +} + +#ifdef CONFIG_32 +/* target base 'wbase' == source base 'ubase' */ +static size_t +_copy_equal_base(uint32_t **w, size_t wlen, + const uint32_t *u, size_t ulen) +{ + if (wlen < ulen) { + if (!mpd_resize_u32(w, ulen)) { + return SIZE_MAX; + } + } + + memcpy(*w, u, ulen * (sizeof **w)); + return ulen; +} + +/* target base 'wbase' > source base 'ubase' */ +static size_t +_baseconv_to_larger(uint32_t **w, size_t wlen, mpd_uint_t wbase, + const mpd_uint_t *u, size_t ulen, mpd_uint_t ubase) +{ + size_t n = 0; + mpd_uint_t carry; + + assert(wlen > 0 && ulen > 0); + assert(ubase < wbase); + + (*w)[n++] = u[--ulen]; + while (--ulen != SIZE_MAX) { + carry = _mpd_shortmul_b(*w, *w, n, ubase, wbase); + if (carry) { + if (n >= wlen) { + if (!mpd_resize_u32(w, n+1)) { + return SIZE_MAX; + } + wlen = n+1; + } + (*w)[n++] = carry; + } + carry = _mpd_shortadd_b(*w, n, u[ulen], wbase); + if (carry) { + if (n >= wlen) { + if (!mpd_resize_u32(w, n+1)) { + return SIZE_MAX; + } + wlen = n+1; + } + (*w)[n++] = carry; + } + } + + return n; +} + +/* target base wbase < source base ubase */ +static size_t +_coeff_from_larger_base(mpd_t *w, size_t wlen, mpd_uint_t wbase, + mpd_uint_t *u, mpd_ssize_t ulen, mpd_uint_t ubase, + uint32_t *status) +{ + size_t n = 0; + + assert(wlen > 0 && ulen > 0); + assert(wbase < ubase); + + do { + if (n >= wlen) { + if (!mpd_qresize(w, n+1, status)) { + return SIZE_MAX; + } + wlen = n+1; + } + w->data[n++] = (uint32_t)_mpd_shortdiv_b(u, u, ulen, wbase, ubase); + /* ulen is at least 1. u[ulen-1] can only be zero if ulen == 1. */ + ulen = _mpd_real_size(u, ulen); + + } while (u[ulen-1] != 0); + + return n; +} +#endif + +/* target base 'wbase' > source base 'ubase' */ +static size_t +_coeff_from_smaller_base(mpd_t *w, mpd_ssize_t wlen, mpd_uint_t wbase, + const uint32_t *u, size_t ulen, mpd_uint_t ubase, + uint32_t *status) +{ + mpd_ssize_t n = 0; + mpd_uint_t carry; + + assert(wlen > 0 && ulen > 0); + assert(wbase > ubase); + + w->data[n++] = u[--ulen]; + while (--ulen != SIZE_MAX) { + carry = _mpd_shortmul_b(w->data, w->data, n, ubase, wbase); + if (carry) { + if (n >= wlen) { + if (!mpd_qresize(w, n+1, status)) { + return SIZE_MAX; + } + wlen = n+1; + } + w->data[n++] = carry; + } + carry = _mpd_shortadd_b(w->data, n, u[ulen], wbase); + if (carry) { + if (n >= wlen) { + if (!mpd_qresize(w, n+1, status)) { + return SIZE_MAX; + } + wlen = n+1; + } + w->data[n++] = carry; + } + } + + return n; +} + +/* + * Convert an integer mpd_t to a multiprecision integer with base <= 2**16. + * The least significant word of the result is (*rdata)[0]. + * + * If rdata is NULL, space is allocated by the function and rlen is irrelevant. + * In case of an error any allocated storage is freed and rdata is set back to + * NULL. + * + * If rdata is non-NULL, it MUST be allocated by one of libmpdec's allocation + * functions and rlen MUST be correct. If necessary, the function will resize + * rdata. In case of an error the caller must free rdata. + * + * Return value: In case of success, the exact length of rdata, SIZE_MAX + * otherwise. + */ +size_t +mpd_qexport_u16(uint16_t **rdata, size_t rlen, uint32_t rbase, + const mpd_t *src, uint32_t *status) +{ + MPD_NEW_STATIC(tsrc,0,0,0,0); + int alloc = 0; /* rdata == NULL */ + size_t n; + + assert(rbase <= (1U<<16)); + + if (mpd_isspecial(src) || !_mpd_isint(src)) { + *status |= MPD_Invalid_operation; + return SIZE_MAX; + } + + if (*rdata == NULL) { + rlen = mpd_sizeinbase(src, rbase); + if (rlen == SIZE_MAX) { + *status |= MPD_Invalid_operation; + return SIZE_MAX; + } + *rdata = mpd_alloc(rlen, sizeof **rdata); + if (*rdata == NULL) { + goto malloc_error; + } + alloc = 1; + } + + if (mpd_iszero(src)) { + **rdata = 0; + return 1; + } + + if (src->exp >= 0) { + if (!mpd_qshiftl(&tsrc, src, src->exp, status)) { + goto malloc_error; + } + } + else { + if (mpd_qshiftr(&tsrc, src, -src->exp, status) == MPD_UINT_MAX) { + goto malloc_error; + } + } + + n = _baseconv_to_u16(rdata, rlen, rbase, tsrc.data, tsrc.len); + if (n == SIZE_MAX) { + goto malloc_error; + } + + +out: + mpd_del(&tsrc); + return n; + +malloc_error: + if (alloc) { + mpd_free(*rdata); + *rdata = NULL; + } + n = SIZE_MAX; + *status |= MPD_Malloc_error; + goto out; +} + +/* + * Convert an integer mpd_t to a multiprecision integer with base<=UINT32_MAX. + * The least significant word of the result is (*rdata)[0]. + * + * If rdata is NULL, space is allocated by the function and rlen is irrelevant. + * In case of an error any allocated storage is freed and rdata is set back to + * NULL. + * + * If rdata is non-NULL, it MUST be allocated by one of libmpdec's allocation + * functions and rlen MUST be correct. If necessary, the function will resize + * rdata. In case of an error the caller must free rdata. + * + * Return value: In case of success, the exact length of rdata, SIZE_MAX + * otherwise. + */ +size_t +mpd_qexport_u32(uint32_t **rdata, size_t rlen, uint32_t rbase, + const mpd_t *src, uint32_t *status) +{ + MPD_NEW_STATIC(tsrc,0,0,0,0); + int alloc = 0; /* rdata == NULL */ + size_t n; + + if (mpd_isspecial(src) || !_mpd_isint(src)) { + *status |= MPD_Invalid_operation; + return SIZE_MAX; + } + + if (*rdata == NULL) { + rlen = mpd_sizeinbase(src, rbase); + if (rlen == SIZE_MAX) { + *status |= MPD_Invalid_operation; + return SIZE_MAX; + } + *rdata = mpd_alloc(rlen, sizeof **rdata); + if (*rdata == NULL) { + goto malloc_error; + } + alloc = 1; + } + + if (mpd_iszero(src)) { + **rdata = 0; + return 1; + } + + if (src->exp >= 0) { + if (!mpd_qshiftl(&tsrc, src, src->exp, status)) { + goto malloc_error; + } + } + else { + if (mpd_qshiftr(&tsrc, src, -src->exp, status) == MPD_UINT_MAX) { + goto malloc_error; + } + } + +#ifdef CONFIG_64 + n = _baseconv_to_smaller(rdata, rlen, rbase, + tsrc.data, tsrc.len, MPD_RADIX); +#else + if (rbase == MPD_RADIX) { + n = _copy_equal_base(rdata, rlen, tsrc.data, tsrc.len); + } + else if (rbase < MPD_RADIX) { + n = _baseconv_to_smaller(rdata, rlen, rbase, + tsrc.data, tsrc.len, MPD_RADIX); + } + else { + n = _baseconv_to_larger(rdata, rlen, rbase, + tsrc.data, tsrc.len, MPD_RADIX); + } +#endif + + if (n == SIZE_MAX) { + goto malloc_error; + } + + +out: + mpd_del(&tsrc); + return n; + +malloc_error: + if (alloc) { + mpd_free(*rdata); + *rdata = NULL; + } + n = SIZE_MAX; + *status |= MPD_Malloc_error; + goto out; +} + + +/* + * Converts a multiprecision integer with base <= UINT16_MAX+1 to an mpd_t. + * The least significant word of the source is srcdata[0]. + */ +void +mpd_qimport_u16(mpd_t *result, + const uint16_t *srcdata, size_t srclen, + uint8_t srcsign, uint32_t srcbase, + const mpd_context_t *ctx, uint32_t *status) +{ + mpd_uint_t *usrc; /* uint16_t src copied to an mpd_uint_t array */ + mpd_ssize_t rlen; /* length of the result */ + size_t n; + + assert(srclen > 0); + assert(srcbase <= (1U<<16)); + + rlen = _mpd_importsize(srclen, srcbase); + if (rlen == MPD_SSIZE_MAX) { + mpd_seterror(result, MPD_Invalid_operation, status); + return; + } + + usrc = mpd_alloc((mpd_size_t)srclen, sizeof *usrc); + if (usrc == NULL) { + mpd_seterror(result, MPD_Malloc_error, status); + return; + } + for (n = 0; n < srclen; n++) { + usrc[n] = srcdata[n]; + } + + if (!mpd_qresize(result, rlen, status)) { + goto finish; + } + + n = _coeff_from_u16(result, rlen, usrc, srclen, srcbase, status); + if (n == SIZE_MAX) { + goto finish; + } + + mpd_set_flags(result, srcsign); + result->exp = 0; + result->len = n; + mpd_setdigits(result); + + mpd_qresize(result, result->len, status); + mpd_qfinalize(result, ctx, status); + + +finish: + mpd_free(usrc); +} + +/* + * Converts a multiprecision integer with base <= UINT32_MAX to an mpd_t. + * The least significant word of the source is srcdata[0]. + */ +void +mpd_qimport_u32(mpd_t *result, + const uint32_t *srcdata, size_t srclen, + uint8_t srcsign, uint32_t srcbase, + const mpd_context_t *ctx, uint32_t *status) +{ + mpd_ssize_t rlen; /* length of the result */ + size_t n; + + assert(srclen > 0); + + rlen = _mpd_importsize(srclen, srcbase); + if (rlen == MPD_SSIZE_MAX) { + mpd_seterror(result, MPD_Invalid_operation, status); + return; + } + + if (!mpd_qresize(result, rlen, status)) { + return; + } + +#ifdef CONFIG_64 + n = _coeff_from_smaller_base(result, rlen, MPD_RADIX, + srcdata, srclen, srcbase, + status); +#else + if (srcbase == MPD_RADIX) { + if (!mpd_qresize(result, srclen, status)) { + return; + } + memcpy(result->data, srcdata, srclen * (sizeof *srcdata)); + n = srclen; + } + else if (srcbase < MPD_RADIX) { + n = _coeff_from_smaller_base(result, rlen, MPD_RADIX, + srcdata, srclen, srcbase, + status); + } + else { + mpd_uint_t *usrc = mpd_alloc((mpd_size_t)srclen, sizeof *usrc); + if (usrc == NULL) { + mpd_seterror(result, MPD_Malloc_error, status); + return; + } + for (n = 0; n < srclen; n++) { + usrc[n] = srcdata[n]; + } + + n = _coeff_from_larger_base(result, rlen, MPD_RADIX, + usrc, (mpd_ssize_t)srclen, srcbase, + status); + mpd_free(usrc); + } +#endif + + if (n == SIZE_MAX) { + return; + } + + mpd_set_flags(result, srcsign); + result->exp = 0; + result->len = n; + mpd_setdigits(result); + + mpd_qresize(result, result->len, status); + mpd_qfinalize(result, ctx, status); +} + + + |