diff options
Diffstat (limited to 'libtommath/bn_s_mp_mul_high_digs.c')
| -rw-r--r-- | libtommath/bn_s_mp_mul_high_digs.c | 111 |
1 files changed, 47 insertions, 64 deletions
diff --git a/libtommath/bn_s_mp_mul_high_digs.c b/libtommath/bn_s_mp_mul_high_digs.c index 031f17b..2bb2a50 100644 --- a/libtommath/bn_s_mp_mul_high_digs.c +++ b/libtommath/bn_s_mp_mul_high_digs.c @@ -1,81 +1,64 @@ -#include <tommath_private.h> +#include "tommath_private.h" #ifdef BN_S_MP_MUL_HIGH_DIGS_C -/* LibTomMath, multiple-precision integer library -- Tom St Denis - * - * LibTomMath is a library that provides multiple-precision - * integer arithmetic as well as number theoretic functionality. - * - * The library was designed directly after the MPI library by - * Michael Fromberger but has been written from scratch with - * additional optimizations in place. - * - * The library is free for all purposes without any express - * guarantee it works. - * - * Tom St Denis, tstdenis82@gmail.com, http://libtom.org - */ +/* LibTomMath, multiple-precision integer library -- Tom St Denis */ +/* SPDX-License-Identifier: Unlicense */ /* multiplies |a| * |b| and does not compute the lower digs digits * [meant to get the higher part of the product] */ -int -s_mp_mul_high_digs (mp_int * a, mp_int * b, mp_int * c, int digs) +mp_err s_mp_mul_high_digs(const mp_int *a, const mp_int *b, mp_int *c, int digs) { - mp_int t; - int res, pa, pb, ix, iy; - mp_digit u; - mp_word r; - mp_digit tmpx, *tmpt, *tmpy; + mp_int t; + int pa, pb, ix, iy; + mp_err err; + mp_digit u; + mp_word r; + mp_digit tmpx, *tmpt, *tmpy; - /* can we use the fast multiplier? */ -#ifdef BN_FAST_S_MP_MUL_HIGH_DIGS_C - if (((a->used + b->used + 1) < MP_WARRAY) - && (MIN (a->used, b->used) < (1 << ((CHAR_BIT * sizeof(mp_word)) - (2 * DIGIT_BIT))))) { - return fast_s_mp_mul_high_digs (a, b, c, digs); - } -#endif + /* can we use the fast multiplier? */ + if (MP_HAS(S_MP_MUL_HIGH_DIGS_FAST) + && ((a->used + b->used + 1) < MP_WARRAY) + && (MP_MIN(a->used, b->used) < MP_MAXFAST)) { + return s_mp_mul_high_digs_fast(a, b, c, digs); + } - if ((res = mp_init_size (&t, a->used + b->used + 1)) != MP_OKAY) { - return res; - } - t.used = a->used + b->used + 1; + if ((err = mp_init_size(&t, a->used + b->used + 1)) != MP_OKAY) { + return err; + } + t.used = a->used + b->used + 1; - pa = a->used; - pb = b->used; - for (ix = 0; ix < pa; ix++) { - /* clear the carry */ - u = 0; + pa = a->used; + pb = b->used; + for (ix = 0; ix < pa; ix++) { + /* clear the carry */ + u = 0; - /* left hand side of A[ix] * B[iy] */ - tmpx = a->dp[ix]; + /* left hand side of A[ix] * B[iy] */ + tmpx = a->dp[ix]; - /* alias to the address of where the digits will be stored */ - tmpt = &(t.dp[digs]); + /* alias to the address of where the digits will be stored */ + tmpt = &(t.dp[digs]); - /* alias for where to read the right hand side from */ - tmpy = b->dp + (digs - ix); + /* alias for where to read the right hand side from */ + tmpy = b->dp + (digs - ix); - for (iy = digs - ix; iy < pb; iy++) { - /* calculate the double precision result */ - r = (mp_word)*tmpt + - ((mp_word)tmpx * (mp_word)*tmpy++) + - (mp_word)u; + for (iy = digs - ix; iy < pb; iy++) { + /* calculate the double precision result */ + r = (mp_word)*tmpt + + ((mp_word)tmpx * (mp_word)*tmpy++) + + (mp_word)u; - /* get the lower part */ - *tmpt++ = (mp_digit) (r & ((mp_word) MP_MASK)); + /* get the lower part */ + *tmpt++ = (mp_digit)(r & (mp_word)MP_MASK); - /* carry the carry */ - u = (mp_digit) (r >> ((mp_word) DIGIT_BIT)); - } - *tmpt = u; - } - mp_clamp (&t); - mp_exch (&t, c); - mp_clear (&t); - return MP_OKAY; + /* carry the carry */ + u = (mp_digit)(r >> (mp_word)MP_DIGIT_BIT); + } + *tmpt = u; + } + mp_clamp(&t); + mp_exch(&t, c); + mp_clear(&t); + return MP_OKAY; } #endif - -/* ref: $Format:%D$ */ -/* git commit: $Format:%H$ */ -/* commit time: $Format:%ai$ */ |