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Diffstat (limited to 'libgcc/config/libbid/bid128_sqrt.c')
-rw-r--r-- | libgcc/config/libbid/bid128_sqrt.c | 278 |
1 files changed, 278 insertions, 0 deletions
diff --git a/libgcc/config/libbid/bid128_sqrt.c b/libgcc/config/libbid/bid128_sqrt.c new file mode 100644 index 00000000000..bae395f60d3 --- /dev/null +++ b/libgcc/config/libbid/bid128_sqrt.c @@ -0,0 +1,278 @@ +/* Copyright (C) 2007 Free Software Foundation, Inc. + +This file is part of GCC. + +GCC is free software; you can redistribute it and/or modify it under +the terms of the GNU General Public License as published by the Free +Software Foundation; either version 2, or (at your option) any later +version. + +In addition to the permissions in the GNU General Public License, the +Free Software Foundation gives you unlimited permission to link the +compiled version of this file into combinations with other programs, +and to distribute those combinations without any restriction coming +from the use of this file. (The General Public License restrictions +do apply in other respects; for example, they cover modification of +the file, and distribution when not linked into a combine +executable.) + +GCC is distributed in the hope that it will be useful, but WITHOUT ANY +WARRANTY; without even the implied warranty of MERCHANTABILITY or +FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License +for more details. + +You should have received a copy of the GNU General Public License +along with GCC; see the file COPYING. If not, write to the Free +Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA +02110-1301, USA. */ + +#define BID_128RES +#include "sqrt_macros.h" + +BID128_FUNCTION_ARG1(__bid128_sqrt, x) + + UINT256 M256, C256, C4, C8; + UINT128 CX, CX1, CX2, A10, S2, T128, TP128, CS, CSM, res; + UINT64 sign_x, Carry; + SINT64 D; + int_float fx, f64; + int exponent_x = 0, bin_expon_cx; + int digits, scale, exponent_q; + + // unpack arguments, check for NaN or Infinity + if (!unpack_BID128_value (&sign_x, &exponent_x, &CX, x)) { + res.w[1] = x.w[1]; + res.w[0] = x.w[0]; + // NaN ? + if ((x.w[1] & 0x7c00000000000000ull) == 0x7c00000000000000ull) { +#ifdef SET_STATUS_FLAGS + if ((x.w[1] & 0x7e00000000000000ull) == 0x7e00000000000000ull) // sNaN + __set_status_flags (pfpsf, INVALID_EXCEPTION); +#endif + res.w[1] &= QUIET_MASK64; + BID_RETURN (res); + } + // x is Infinity? + if ((x.w[1] & 0x7800000000000000ull) == 0x7800000000000000ull) { + if (sign_x) { + // -Inf, return NaN + res.w[1] = 0x7c00000000000000ull; +#ifdef SET_STATUS_FLAGS + __set_status_flags (pfpsf, INVALID_EXCEPTION); +#endif + } + BID_RETURN (res); + } + // x is 0 otherwise + + res.w[1] = + sign_x | + ((((UINT64) (exponent_x + DECIMAL_EXPONENT_BIAS_128)) >> 1) << + 49); + BID_RETURN (res); + } + if (sign_x) { + res.w[1] = 0x7c00000000000000ull; + res.w[0] = 0; +#ifdef SET_STATUS_FLAGS + __set_status_flags (pfpsf, INVALID_EXCEPTION); +#endif + BID_RETURN (res); + } + // 2^64 + f64.i = 0x5f800000; + + // fx ~ CX + fx.d = (float) CX.w[1] * f64.d + (float) CX.w[0]; + bin_expon_cx = ((fx.i >> 23) & 0xff) - 0x7f; + digits = __bid_estimate_decimal_digits[bin_expon_cx]; + + A10 = CX; + if (exponent_x & 1) { + A10.w[1] = (CX.w[1] << 3) | (CX.w[0] >> 61); + A10.w[0] = CX.w[0] << 3; + CX2.w[1] = (CX.w[1] << 1) | (CX.w[0] >> 63); + CX2.w[0] = CX.w[0] << 1; + __add_128_128 (A10, A10, CX2); + } + + CS.w[0] = short_sqrt128 (A10); + CS.w[1] = 0; + // check for exact result + if (CS.w[0] * CS.w[0] == A10.w[0]) { + __mul_64x64_to_128_fast (S2, CS.w[0], CS.w[0]); + if (S2.w[1] == A10.w[1]) // && S2.w[0]==A10.w[0]) + { + get_BID128_very_fast (&res, 0, + (exponent_x + + DECIMAL_EXPONENT_BIAS_128) >> 1, CS); + BID_RETURN (res); + } + } + // get number of digits in CX + D = CX.w[1] - __bid_power10_index_binexp_128[bin_expon_cx].w[1]; + if (D > 0 + || (!D && CX.w[0] >= __bid_power10_index_binexp_128[bin_expon_cx].w[0])) + digits++; + + // if exponent is odd, scale coefficient by 10 + scale = 67 - digits; + exponent_q = exponent_x - scale; + scale += (exponent_q & 1); // exp. bias is even + + if (scale > 38) { + T128 = __bid_power10_table_128[scale - 37]; + __mul_128x128_low (CX1, CX, T128); + + TP128 = __bid_power10_table_128[37]; + __mul_128x128_to_256 (C256, CX1, TP128); + } else { + T128 = __bid_power10_table_128[scale]; + __mul_128x128_to_256 (C256, CX, T128); + } + + + // 4*C256 + C4.w[3] = (C256.w[3] << 2) | (C256.w[2] >> 62); + C4.w[2] = (C256.w[2] << 2) | (C256.w[1] >> 62); + C4.w[1] = (C256.w[1] << 2) | (C256.w[0] >> 62); + C4.w[0] = C256.w[0] << 2; + + long_sqrt128 (&CS, C256); + +#ifndef IEEE_ROUND_NEAREST +#ifndef IEEE_ROUND_NEAREST_TIES_AWAY + if (!((rnd_mode) & 3)) { +#endif +#endif + // compare to midpoints + CSM.w[1] = (CS.w[1] << 1) | (CS.w[0] >> 63); + CSM.w[0] = (CS.w[0] + CS.w[0]) | 1; + // CSM^2 + //__mul_128x128_to_256(M256, CSM, CSM); + __sqr128_to_256 (M256, CSM); + + if (C4.w[3] > M256.w[3] + || (C4.w[3] == M256.w[3] + && (C4.w[2] > M256.w[2] + || (C4.w[2] == M256.w[2] + && (C4.w[1] > M256.w[1] + || (C4.w[1] == M256.w[1] + && C4.w[0] > M256.w[0])))))) { + // round up + CS.w[0]++; + if (!CS.w[0]) + CS.w[1]++; + } else { + C8.w[1] = (CS.w[1] << 3) | (CS.w[0] >> 61); + C8.w[0] = CS.w[0] << 3; + // M256 - 8*CSM + __sub_borrow_out (M256.w[0], Carry, M256.w[0], C8.w[0]); + __sub_borrow_in_out (M256.w[1], Carry, M256.w[1], C8.w[1], Carry); + __sub_borrow_in_out (M256.w[2], Carry, M256.w[2], 0, Carry); + M256.w[3] = M256.w[3] - Carry; + + // if CSM' > C256, round up + if (M256.w[3] > C4.w[3] + || (M256.w[3] == C4.w[3] + && (M256.w[2] > C4.w[2] + || (M256.w[2] == C4.w[2] + && (M256.w[1] > C4.w[1] + || (M256.w[1] == C4.w[1] + && M256.w[0] > C4.w[0])))))) { + // round down + if (!CS.w[0]) + CS.w[1]--; + CS.w[0]--; + } + } +#ifndef IEEE_ROUND_NEAREST +#ifndef IEEE_ROUND_NEAREST_TIES_AWAY + } else { + __sqr128_to_256 (M256, CS); + C8.w[1] = (CS.w[1] << 1) | (CS.w[0] >> 63); + C8.w[0] = CS.w[0] << 1; + if (M256.w[3] > C256.w[3] + || (M256.w[3] == C256.w[3] + && (M256.w[2] > C256.w[2] + || (M256.w[2] == C256.w[2] + && (M256.w[1] > C256.w[1] + || (M256.w[1] == C256.w[1] + && M256.w[0] > C256.w[0])))))) { + __sub_borrow_out (M256.w[0], Carry, M256.w[0], C8.w[0]); + __sub_borrow_in_out (M256.w[1], Carry, M256.w[1], C8.w[1], Carry); + __sub_borrow_in_out (M256.w[2], Carry, M256.w[2], 0, Carry); + M256.w[3] = M256.w[3] - Carry; + M256.w[0]++; + if (!M256.w[0]) { + M256.w[1]++; + if (!M256.w[1]) { + M256.w[2]++; + if (!M256.w[2]) + M256.w[3]++; + } + } + + if (!CS.w[0]) + CS.w[1]--; + CS.w[0]--; + + if (M256.w[3] > C256.w[3] + || (M256.w[3] == C256.w[3] + && (M256.w[2] > C256.w[2] + || (M256.w[2] == C256.w[2] + && (M256.w[1] > C256.w[1] + || (M256.w[1] == C256.w[1] + && M256.w[0] > C256.w[0])))))) { + + if (!CS.w[0]) + CS.w[1]--; + CS.w[0]--; + } + } + + else { + __add_carry_out (M256.w[0], Carry, M256.w[0], C8.w[0]); + __add_carry_in_out (M256.w[1], Carry, M256.w[1], C8.w[1], Carry); + __add_carry_in_out (M256.w[2], Carry, M256.w[2], 0, Carry); + M256.w[3] = M256.w[3] + Carry; + M256.w[0]++; + if (!M256.w[0]) { + M256.w[1]++; + if (!M256.w[1]) { + M256.w[2]++; + if (!M256.w[2]) + M256.w[3]++; + } + } + if (M256.w[3] < C256.w[3] + || (M256.w[3] == C256.w[3] + && (M256.w[2] < C256.w[2] + || (M256.w[2] == C256.w[2] + && (M256.w[1] < C256.w[1] + || (M256.w[1] == C256.w[1] + && M256.w[0] <= C256.w[0])))))) { + + CS.w[0]++; + if (!CS.w[0]) + CS.w[1]++; + } + } + // RU? + if ((rnd_mode) == ROUNDING_UP) { + CS.w[0]++; + if (!CS.w[0]) + CS.w[1]++; + } + + } +#endif +#endif + +#ifdef SET_STATUS_FLAGS + __set_status_flags (pfpsf, INEXACT_EXCEPTION); +#endif + get_BID128_fast (&res, 0, + (exponent_q + DECIMAL_EXPONENT_BIAS_128) >> 1, CS); + BID_RETURN (res); +} |