| /* |
| * Copyright(c) 2019-2021 Qualcomm Innovation Center, Inc. All Rights Reserved. |
| * |
| * This program 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 of the License, or |
| * (at your option) any later version. |
| * |
| * This program 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 this program; if not, see <http://www.gnu.org/licenses/>. |
| */ |
| |
| #include "qemu/osdep.h" |
| #include "qemu/int128.h" |
| #include "fpu/softfloat.h" |
| #include "macros.h" |
| #include "conv_emu.h" |
| #include "fma_emu.h" |
| |
| #define DF_INF_EXP 0x7ff |
| #define DF_BIAS 1023 |
| #define DF_MANTBITS 52 |
| #define DF_NAN 0xffffffffffffffffULL |
| #define DF_INF 0x7ff0000000000000ULL |
| #define DF_MINUS_INF 0xfff0000000000000ULL |
| #define DF_MAXF 0x7fefffffffffffffULL |
| #define DF_MINUS_MAXF 0xffefffffffffffffULL |
| |
| #define SF_INF_EXP 0xff |
| #define SF_BIAS 127 |
| #define SF_MANTBITS 23 |
| #define SF_INF 0x7f800000 |
| #define SF_MINUS_INF 0xff800000 |
| #define SF_MAXF 0x7f7fffff |
| #define SF_MINUS_MAXF 0xff7fffff |
| |
| #define HF_INF_EXP 0x1f |
| #define HF_BIAS 15 |
| |
| #define WAY_BIG_EXP 4096 |
| |
| typedef union { |
| double f; |
| uint64_t i; |
| struct { |
| uint64_t mant:52; |
| uint64_t exp:11; |
| uint64_t sign:1; |
| }; |
| } Double; |
| |
| typedef union { |
| float f; |
| uint32_t i; |
| struct { |
| uint32_t mant:23; |
| uint32_t exp:8; |
| uint32_t sign:1; |
| }; |
| } Float; |
| |
| static inline uint64_t float64_getmant(float64 f64) |
| { |
| Double a = { .i = f64 }; |
| if (float64_is_normal(f64)) { |
| return a.mant | 1ULL << 52; |
| } |
| if (float64_is_zero(f64)) { |
| return 0; |
| } |
| if (float64_is_denormal(f64)) { |
| return a.mant; |
| } |
| return ~0ULL; |
| } |
| |
| int32_t float64_getexp(float64 f64) |
| { |
| Double a = { .i = f64 }; |
| if (float64_is_normal(f64)) { |
| return a.exp; |
| } |
| if (float64_is_denormal(f64)) { |
| return a.exp + 1; |
| } |
| return -1; |
| } |
| |
| static inline uint64_t float32_getmant(float32 f32) |
| { |
| Float a = { .i = f32 }; |
| if (float32_is_normal(f32)) { |
| return a.mant | 1ULL << 23; |
| } |
| if (float32_is_zero(f32)) { |
| return 0; |
| } |
| if (float32_is_denormal(f32)) { |
| return a.mant; |
| } |
| return ~0ULL; |
| } |
| |
| int32_t float32_getexp(float32 f32) |
| { |
| Float a = { .i = f32 }; |
| if (float32_is_normal(f32)) { |
| return a.exp; |
| } |
| if (float32_is_denormal(f32)) { |
| return a.exp + 1; |
| } |
| return -1; |
| } |
| |
| static inline uint32_t int128_getw0(Int128 x) |
| { |
| return int128_getlo(x); |
| } |
| |
| static inline uint32_t int128_getw1(Int128 x) |
| { |
| return int128_getlo(x) >> 32; |
| } |
| |
| static inline Int128 int128_mul_6464(uint64_t ai, uint64_t bi) |
| { |
| Int128 a, b; |
| uint64_t pp0, pp1a, pp1b, pp1s, pp2; |
| |
| a = int128_make64(ai); |
| b = int128_make64(bi); |
| pp0 = (uint64_t)int128_getw0(a) * (uint64_t)int128_getw0(b); |
| pp1a = (uint64_t)int128_getw1(a) * (uint64_t)int128_getw0(b); |
| pp1b = (uint64_t)int128_getw1(b) * (uint64_t)int128_getw0(a); |
| pp2 = (uint64_t)int128_getw1(a) * (uint64_t)int128_getw1(b); |
| |
| pp1s = pp1a + pp1b; |
| if ((pp1s < pp1a) || (pp1s < pp1b)) { |
| pp2 += (1ULL << 32); |
| } |
| uint64_t ret_low = pp0 + (pp1s << 32); |
| if ((ret_low < pp0) || (ret_low < (pp1s << 32))) { |
| pp2 += 1; |
| } |
| |
| return int128_make128(ret_low, pp2 + (pp1s >> 32)); |
| } |
| |
| static inline Int128 int128_sub_borrow(Int128 a, Int128 b, int borrow) |
| { |
| Int128 ret = int128_sub(a, b); |
| if (borrow != 0) { |
| ret = int128_sub(ret, int128_one()); |
| } |
| return ret; |
| } |
| |
| typedef struct { |
| Int128 mant; |
| int32_t exp; |
| uint8_t sign; |
| uint8_t guard; |
| uint8_t round; |
| uint8_t sticky; |
| } Accum; |
| |
| static inline void accum_init(Accum *p) |
| { |
| p->mant = int128_zero(); |
| p->exp = 0; |
| p->sign = 0; |
| p->guard = 0; |
| p->round = 0; |
| p->sticky = 0; |
| } |
| |
| static inline Accum accum_norm_left(Accum a) |
| { |
| a.exp--; |
| a.mant = int128_lshift(a.mant, 1); |
| a.mant = int128_or(a.mant, int128_make64(a.guard)); |
| a.guard = a.round; |
| a.round = a.sticky; |
| return a; |
| } |
| |
| static inline Accum accum_norm_right(Accum a, int amt) |
| { |
| if (amt > 130) { |
| a.sticky |= |
| a.round | a.guard | int128_nz(a.mant); |
| a.guard = a.round = 0; |
| a.mant = int128_zero(); |
| a.exp += amt; |
| return a; |
| |
| } |
| while (amt >= 64) { |
| a.sticky |= a.round | a.guard | (int128_getlo(a.mant) != 0); |
| a.guard = (int128_getlo(a.mant) >> 63) & 1; |
| a.round = (int128_getlo(a.mant) >> 62) & 1; |
| a.mant = int128_make64(int128_gethi(a.mant)); |
| a.exp += 64; |
| amt -= 64; |
| } |
| while (amt > 0) { |
| a.exp++; |
| a.sticky |= a.round; |
| a.round = a.guard; |
| a.guard = int128_getlo(a.mant) & 1; |
| a.mant = int128_rshift(a.mant, 1); |
| amt--; |
| } |
| return a; |
| } |
| |
| /* |
| * On the add/sub, we need to be able to shift out lots of bits, but need a |
| * sticky bit for what was shifted out, I think. |
| */ |
| static Accum accum_add(Accum a, Accum b); |
| |
| static inline Accum accum_sub(Accum a, Accum b, int negate) |
| { |
| Accum ret; |
| accum_init(&ret); |
| int borrow; |
| |
| if (a.sign != b.sign) { |
| b.sign = !b.sign; |
| return accum_add(a, b); |
| } |
| if (b.exp > a.exp) { |
| /* small - big == - (big - small) */ |
| return accum_sub(b, a, !negate); |
| } |
| if ((b.exp == a.exp) && (int128_gt(b.mant, a.mant))) { |
| /* small - big == - (big - small) */ |
| return accum_sub(b, a, !negate); |
| } |
| |
| while (a.exp > b.exp) { |
| /* Try to normalize exponents: shrink a exponent and grow mantissa */ |
| if (int128_gethi(a.mant) & (1ULL << 62)) { |
| /* Can't grow a any more */ |
| break; |
| } else { |
| a = accum_norm_left(a); |
| } |
| } |
| |
| while (a.exp > b.exp) { |
| /* Try to normalize exponents: grow b exponent and shrink mantissa */ |
| /* Keep around shifted out bits... we might need those later */ |
| b = accum_norm_right(b, a.exp - b.exp); |
| } |
| |
| if ((int128_gt(b.mant, a.mant))) { |
| return accum_sub(b, a, !negate); |
| } |
| |
| /* OK, now things should be normalized! */ |
| ret.sign = a.sign; |
| ret.exp = a.exp; |
| assert(!int128_gt(b.mant, a.mant)); |
| borrow = (b.round << 2) | (b.guard << 1) | b.sticky; |
| ret.mant = int128_sub_borrow(a.mant, b.mant, (borrow != 0)); |
| borrow = 0 - borrow; |
| ret.guard = (borrow >> 2) & 1; |
| ret.round = (borrow >> 1) & 1; |
| ret.sticky = (borrow >> 0) & 1; |
| if (negate) { |
| ret.sign = !ret.sign; |
| } |
| return ret; |
| } |
| |
| static Accum accum_add(Accum a, Accum b) |
| { |
| Accum ret; |
| accum_init(&ret); |
| if (a.sign != b.sign) { |
| b.sign = !b.sign; |
| return accum_sub(a, b, 0); |
| } |
| if (b.exp > a.exp) { |
| /* small + big == (big + small) */ |
| return accum_add(b, a); |
| } |
| if ((b.exp == a.exp) && int128_gt(b.mant, a.mant)) { |
| /* small + big == (big + small) */ |
| return accum_add(b, a); |
| } |
| |
| while (a.exp > b.exp) { |
| /* Try to normalize exponents: shrink a exponent and grow mantissa */ |
| if (int128_gethi(a.mant) & (1ULL << 62)) { |
| /* Can't grow a any more */ |
| break; |
| } else { |
| a = accum_norm_left(a); |
| } |
| } |
| |
| while (a.exp > b.exp) { |
| /* Try to normalize exponents: grow b exponent and shrink mantissa */ |
| /* Keep around shifted out bits... we might need those later */ |
| b = accum_norm_right(b, a.exp - b.exp); |
| } |
| |
| /* OK, now things should be normalized! */ |
| if (int128_gt(b.mant, a.mant)) { |
| return accum_add(b, a); |
| }; |
| ret.sign = a.sign; |
| ret.exp = a.exp; |
| assert(!int128_gt(b.mant, a.mant)); |
| ret.mant = int128_add(a.mant, b.mant); |
| ret.guard = b.guard; |
| ret.round = b.round; |
| ret.sticky = b.sticky; |
| return ret; |
| } |
| |
| /* Return an infinity with requested sign */ |
| static inline float64 infinite_float64(uint8_t sign) |
| { |
| if (sign) { |
| return make_float64(DF_MINUS_INF); |
| } else { |
| return make_float64(DF_INF); |
| } |
| } |
| |
| /* Return a maximum finite value with requested sign */ |
| static inline float64 maxfinite_float64(uint8_t sign) |
| { |
| if (sign) { |
| return make_float64(DF_MINUS_MAXF); |
| } else { |
| return make_float64(DF_MAXF); |
| } |
| } |
| |
| /* Return a zero value with requested sign */ |
| static inline float64 zero_float64(uint8_t sign) |
| { |
| if (sign) { |
| return make_float64(0x8000000000000000); |
| } else { |
| return float64_zero; |
| } |
| } |
| |
| /* Return an infinity with the requested sign */ |
| float32 infinite_float32(uint8_t sign) |
| { |
| if (sign) { |
| return make_float32(SF_MINUS_INF); |
| } else { |
| return make_float32(SF_INF); |
| } |
| } |
| |
| /* Return a maximum finite value with the requested sign */ |
| static inline float32 maxfinite_float32(uint8_t sign) |
| { |
| if (sign) { |
| return make_float32(SF_MINUS_MAXF); |
| } else { |
| return make_float32(SF_MAXF); |
| } |
| } |
| |
| /* Return a zero value with requested sign */ |
| static inline float32 zero_float32(uint8_t sign) |
| { |
| if (sign) { |
| return make_float32(0x80000000); |
| } else { |
| return float32_zero; |
| } |
| } |
| |
| #define GEN_XF_ROUND(SUFFIX, MANTBITS, INF_EXP, INTERNAL_TYPE) \ |
| static inline SUFFIX accum_round_##SUFFIX(Accum a, float_status * fp_status) \ |
| { \ |
| if ((int128_gethi(a.mant) == 0) && (int128_getlo(a.mant) == 0) \ |
| && ((a.guard | a.round | a.sticky) == 0)) { \ |
| /* result zero */ \ |
| switch (fp_status->float_rounding_mode) { \ |
| case float_round_down: \ |
| return zero_##SUFFIX(1); \ |
| default: \ |
| return zero_##SUFFIX(0); \ |
| } \ |
| } \ |
| /* Normalize right */ \ |
| /* We want MANTBITS bits of mantissa plus the leading one. */ \ |
| /* That means that we want MANTBITS+1 bits, or 0x000000000000FF_FFFF */ \ |
| /* So we need to normalize right while the high word is non-zero and \ |
| * while the low word is nonzero when masked with 0xffe0_0000_0000_0000 */ \ |
| while ((int128_gethi(a.mant) != 0) || \ |
| ((int128_getlo(a.mant) >> (MANTBITS + 1)) != 0)) { \ |
| a = accum_norm_right(a, 1); \ |
| } \ |
| /* \ |
| * OK, now normalize left \ |
| * We want to normalize left until we have a leading one in bit 24 \ |
| * Theoretically, we only need to shift a maximum of one to the left if we \ |
| * shifted out lots of bits from B, or if we had no shift / 1 shift sticky \ |
| * shoudl be 0 \ |
| */ \ |
| while ((int128_getlo(a.mant) & (1ULL << MANTBITS)) == 0) { \ |
| a = accum_norm_left(a); \ |
| } \ |
| /* \ |
| * OK, now we might need to denormalize because of potential underflow. \ |
| * We need to do this before rounding, and rounding might make us normal \ |
| * again \ |
| */ \ |
| while (a.exp <= 0) { \ |
| a = accum_norm_right(a, 1 - a.exp); \ |
| /* \ |
| * Do we have underflow? \ |
| * That's when we get an inexact answer because we ran out of bits \ |
| * in a denormal. \ |
| */ \ |
| if (a.guard || a.round || a.sticky) { \ |
| float_raise(float_flag_underflow, fp_status); \ |
| } \ |
| } \ |
| /* OK, we're relatively canonical... now we need to round */ \ |
| if (a.guard || a.round || a.sticky) { \ |
| float_raise(float_flag_inexact, fp_status); \ |
| switch (fp_status->float_rounding_mode) { \ |
| case float_round_to_zero: \ |
| /* Chop and we're done */ \ |
| break; \ |
| case float_round_up: \ |
| if (a.sign == 0) { \ |
| a.mant = int128_add(a.mant, int128_one()); \ |
| } \ |
| break; \ |
| case float_round_down: \ |
| if (a.sign != 0) { \ |
| a.mant = int128_add(a.mant, int128_one()); \ |
| } \ |
| break; \ |
| default: \ |
| if (a.round || a.sticky) { \ |
| /* round up if guard is 1, down if guard is zero */ \ |
| a.mant = int128_add(a.mant, int128_make64(a.guard)); \ |
| } else if (a.guard) { \ |
| /* exactly .5, round up if odd */ \ |
| a.mant = int128_add(a.mant, int128_and(a.mant, int128_one())); \ |
| } \ |
| break; \ |
| } \ |
| } \ |
| /* \ |
| * OK, now we might have carried all the way up. \ |
| * So we might need to shr once \ |
| * at least we know that the lsb should be zero if we rounded and \ |
| * got a carry out... \ |
| */ \ |
| if ((int128_getlo(a.mant) >> (MANTBITS + 1)) != 0) { \ |
| a = accum_norm_right(a, 1); \ |
| } \ |
| /* Overflow? */ \ |
| if (a.exp >= INF_EXP) { \ |
| /* Yep, inf result */ \ |
| float_raise(float_flag_overflow, fp_status); \ |
| float_raise(float_flag_inexact, fp_status); \ |
| switch (fp_status->float_rounding_mode) { \ |
| case float_round_to_zero: \ |
| return maxfinite_##SUFFIX(a.sign); \ |
| case float_round_up: \ |
| if (a.sign == 0) { \ |
| return infinite_##SUFFIX(a.sign); \ |
| } else { \ |
| return maxfinite_##SUFFIX(a.sign); \ |
| } \ |
| case float_round_down: \ |
| if (a.sign != 0) { \ |
| return infinite_##SUFFIX(a.sign); \ |
| } else { \ |
| return maxfinite_##SUFFIX(a.sign); \ |
| } \ |
| default: \ |
| return infinite_##SUFFIX(a.sign); \ |
| } \ |
| } \ |
| /* Underflow? */ \ |
| if (int128_getlo(a.mant) & (1ULL << MANTBITS)) { \ |
| /* Leading one means: No, we're normal. So, we should be done... */ \ |
| INTERNAL_TYPE ret; \ |
| ret.i = 0; \ |
| ret.sign = a.sign; \ |
| ret.exp = a.exp; \ |
| ret.mant = int128_getlo(a.mant); \ |
| return ret.i; \ |
| } \ |
| assert(a.exp == 1); \ |
| INTERNAL_TYPE ret; \ |
| ret.i = 0; \ |
| ret.sign = a.sign; \ |
| ret.exp = 0; \ |
| ret.mant = int128_getlo(a.mant); \ |
| return ret.i; \ |
| } |
| |
| GEN_XF_ROUND(float64, DF_MANTBITS, DF_INF_EXP, Double) |
| GEN_XF_ROUND(float32, SF_MANTBITS, SF_INF_EXP, Float) |
| |
| static bool is_inf_prod(float64 a, float64 b) |
| { |
| return ((float64_is_infinity(a) && float64_is_infinity(b)) || |
| (float64_is_infinity(a) && is_finite(b) && (!float64_is_zero(b))) || |
| (float64_is_infinity(b) && is_finite(a) && (!float64_is_zero(a)))); |
| } |
| |
| static inline float64 special_fma(float64 a, float64 b, float64 c, |
| float_status *fp_status) |
| { |
| float64 ret = make_float64(0); |
| |
| /* |
| * If A multiplied by B is an exact infinity and C is also an infinity |
| * but with the opposite sign, FMA returns NaN and raises invalid. |
| */ |
| uint8_t a_sign = float64_is_neg(a); |
| uint8_t b_sign = float64_is_neg(b); |
| uint8_t c_sign = float64_is_neg(c); |
| if (is_inf_prod(a, b) && float64_is_infinity(c)) { |
| if ((a_sign ^ b_sign) != c_sign) { |
| ret = make_float64(DF_NAN); |
| float_raise(float_flag_invalid, fp_status); |
| return ret; |
| } |
| } |
| if ((float64_is_infinity(a) && float64_is_zero(b)) || |
| (float64_is_zero(a) && float64_is_infinity(b))) { |
| ret = make_float64(DF_NAN); |
| float_raise(float_flag_invalid, fp_status); |
| return ret; |
| } |
| /* |
| * If none of the above checks are true and C is a NaN, |
| * a NaN shall be returned |
| * If A or B are NaN, a NAN shall be returned. |
| */ |
| if (float64_is_any_nan(a) || |
| float64_is_any_nan(b) || |
| float64_is_any_nan(c)) { |
| if (float64_is_any_nan(a) && (fGETBIT(51, a) == 0)) { |
| float_raise(float_flag_invalid, fp_status); |
| } |
| if (float64_is_any_nan(b) && (fGETBIT(51, b) == 0)) { |
| float_raise(float_flag_invalid, fp_status); |
| } |
| if (float64_is_any_nan(c) && (fGETBIT(51, c) == 0)) { |
| float_raise(float_flag_invalid, fp_status); |
| } |
| ret = make_float64(DF_NAN); |
| return ret; |
| } |
| /* |
| * We have checked for adding opposite-signed infinities. |
| * Other infinities return infinity with the correct sign |
| */ |
| if (float64_is_infinity(c)) { |
| ret = infinite_float64(c_sign); |
| return ret; |
| } |
| if (float64_is_infinity(a) || float64_is_infinity(b)) { |
| ret = infinite_float64(a_sign ^ b_sign); |
| return ret; |
| } |
| g_assert_not_reached(); |
| } |
| |
| static inline float32 special_fmaf(float32 a, float32 b, float32 c, |
| float_status *fp_status) |
| { |
| float64 aa, bb, cc; |
| aa = float32_to_float64(a, fp_status); |
| bb = float32_to_float64(b, fp_status); |
| cc = float32_to_float64(c, fp_status); |
| return float64_to_float32(special_fma(aa, bb, cc, fp_status), fp_status); |
| } |
| |
| float32 internal_fmafx(float32 a, float32 b, float32 c, int scale, |
| float_status *fp_status) |
| { |
| Accum prod; |
| Accum acc; |
| Accum result; |
| accum_init(&prod); |
| accum_init(&acc); |
| accum_init(&result); |
| |
| uint8_t a_sign = float32_is_neg(a); |
| uint8_t b_sign = float32_is_neg(b); |
| uint8_t c_sign = float32_is_neg(c); |
| if (float32_is_infinity(a) || |
| float32_is_infinity(b) || |
| float32_is_infinity(c)) { |
| return special_fmaf(a, b, c, fp_status); |
| } |
| if (float32_is_any_nan(a) || |
| float32_is_any_nan(b) || |
| float32_is_any_nan(c)) { |
| return special_fmaf(a, b, c, fp_status); |
| } |
| if ((scale == 0) && (float32_is_zero(a) || float32_is_zero(b))) { |
| float32 tmp = float32_mul(a, b, fp_status); |
| tmp = float32_add(tmp, c, fp_status); |
| return tmp; |
| } |
| |
| /* (a * 2**b) * (c * 2**d) == a*c * 2**(b+d) */ |
| prod.mant = int128_mul_6464(float32_getmant(a), float32_getmant(b)); |
| |
| /* |
| * Note: extracting the mantissa into an int is multiplying by |
| * 2**23, so adjust here |
| */ |
| prod.exp = float32_getexp(a) + float32_getexp(b) - SF_BIAS - 23; |
| prod.sign = a_sign ^ b_sign; |
| if (float32_is_zero(a) || float32_is_zero(b)) { |
| prod.exp = -2 * WAY_BIG_EXP; |
| } |
| if ((scale > 0) && float32_is_denormal(c)) { |
| acc.mant = int128_mul_6464(0, 0); |
| acc.exp = -WAY_BIG_EXP; |
| acc.sign = c_sign; |
| acc.sticky = 1; |
| result = accum_add(prod, acc); |
| } else if (!float32_is_zero(c)) { |
| acc.mant = int128_mul_6464(float32_getmant(c), 1); |
| acc.exp = float32_getexp(c); |
| acc.sign = c_sign; |
| result = accum_add(prod, acc); |
| } else { |
| result = prod; |
| } |
| result.exp += scale; |
| return accum_round_float32(result, fp_status); |
| } |
| |
| float32 internal_mpyf(float32 a, float32 b, float_status *fp_status) |
| { |
| if (float32_is_zero(a) || float32_is_zero(b)) { |
| return float32_mul(a, b, fp_status); |
| } |
| return internal_fmafx(a, b, float32_zero, 0, fp_status); |
| } |
| |
| float64 internal_mpyhh(float64 a, float64 b, |
| unsigned long long int accumulated, |
| float_status *fp_status) |
| { |
| Accum x; |
| unsigned long long int prod; |
| unsigned int sticky; |
| uint8_t a_sign, b_sign; |
| |
| sticky = accumulated & 1; |
| accumulated >>= 1; |
| accum_init(&x); |
| if (float64_is_zero(a) || |
| float64_is_any_nan(a) || |
| float64_is_infinity(a)) { |
| return float64_mul(a, b, fp_status); |
| } |
| if (float64_is_zero(b) || |
| float64_is_any_nan(b) || |
| float64_is_infinity(b)) { |
| return float64_mul(a, b, fp_status); |
| } |
| x.mant = int128_mul_6464(accumulated, 1); |
| x.sticky = sticky; |
| prod = fGETUWORD(1, float64_getmant(a)) * fGETUWORD(1, float64_getmant(b)); |
| x.mant = int128_add(x.mant, int128_mul_6464(prod, 0x100000000ULL)); |
| x.exp = float64_getexp(a) + float64_getexp(b) - DF_BIAS - 20; |
| if (!float64_is_normal(a) || !float64_is_normal(b)) { |
| /* crush to inexact zero */ |
| x.sticky = 1; |
| x.exp = -4096; |
| } |
| a_sign = float64_is_neg(a); |
| b_sign = float64_is_neg(b); |
| x.sign = a_sign ^ b_sign; |
| return accum_round_float64(x, fp_status); |
| } |
