From 3ff49e56a7294e1b0d29ee62250a877838f4a1eb Mon Sep 17 00:00:00 2001 From: Richard Henderson Date: Fri, 23 Oct 2020 19:22:50 -0700 Subject: [PATCH] softfloat: Implement float128_add/sub via parts MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Replace the existing Berkeley implementation with the FloatParts implementation. Reviewed-by: Alex Bennée Signed-off-by: Richard Henderson --- fpu/softfloat.c | 257 +++++++----------------------------------------- 1 file changed, 36 insertions(+), 221 deletions(-) diff --git a/fpu/softfloat.c b/fpu/softfloat.c index afeef00097..8f734f6020 100644 --- a/fpu/softfloat.c +++ b/fpu/softfloat.c @@ -1046,6 +1046,20 @@ static float64 float64_round_pack_canonical(FloatParts64 *p, return float64_pack_raw(p); } +static void float128_unpack_canonical(FloatParts128 *p, float128 f, + float_status *s) +{ + float128_unpack_raw(p, f); + parts_canonicalize(p, s, &float128_params); +} + +static float128 float128_round_pack_canonical(FloatParts128 *p, + float_status *s) +{ + parts_uncanon(p, s, &float128_params); + return float128_pack_raw(p); +} + /* * Addition and subtraction */ @@ -1213,6 +1227,28 @@ bfloat16 bfloat16_sub(bfloat16 a, bfloat16 b, float_status *status) return bfloat16_addsub(a, b, status, true); } +static float128 QEMU_FLATTEN +float128_addsub(float128 a, float128 b, float_status *status, bool subtract) +{ + FloatParts128 pa, pb, *pr; + + float128_unpack_canonical(&pa, a, status); + float128_unpack_canonical(&pb, b, status); + pr = parts_addsub(&pa, &pb, status, subtract); + + return float128_round_pack_canonical(pr, status); +} + +float128 float128_add(float128 a, float128 b, float_status *status) +{ + return float128_addsub(a, b, status, false); +} + +float128 float128_sub(float128 a, float128 b, float_status *status) +{ + return float128_addsub(a, b, status, true); +} + /* * Returns the result of multiplying the floating-point values `a' and * `b'. The operation is performed according to the IEC/IEEE Standard @@ -7032,227 +7068,6 @@ float128 float128_round_to_int(float128 a, float_status *status) } -/*---------------------------------------------------------------------------- -| Returns the result of adding the absolute values of the quadruple-precision -| floating-point values `a' and `b'. If `zSign' is 1, the sum is negated -| before being returned. `zSign' is ignored if the result is a NaN. -| The addition is performed according to the IEC/IEEE Standard for Binary -| Floating-Point Arithmetic. -*----------------------------------------------------------------------------*/ - -static float128 addFloat128Sigs(float128 a, float128 b, bool zSign, - float_status *status) -{ - int32_t aExp, bExp, zExp; - uint64_t aSig0, aSig1, bSig0, bSig1, zSig0, zSig1, zSig2; - int32_t expDiff; - - aSig1 = extractFloat128Frac1( a ); - aSig0 = extractFloat128Frac0( a ); - aExp = extractFloat128Exp( a ); - bSig1 = extractFloat128Frac1( b ); - bSig0 = extractFloat128Frac0( b ); - bExp = extractFloat128Exp( b ); - expDiff = aExp - bExp; - if ( 0 < expDiff ) { - if ( aExp == 0x7FFF ) { - if (aSig0 | aSig1) { - return propagateFloat128NaN(a, b, status); - } - return a; - } - if ( bExp == 0 ) { - --expDiff; - } - else { - bSig0 |= UINT64_C(0x0001000000000000); - } - shift128ExtraRightJamming( - bSig0, bSig1, 0, expDiff, &bSig0, &bSig1, &zSig2 ); - zExp = aExp; - } - else if ( expDiff < 0 ) { - if ( bExp == 0x7FFF ) { - if (bSig0 | bSig1) { - return propagateFloat128NaN(a, b, status); - } - return packFloat128( zSign, 0x7FFF, 0, 0 ); - } - if ( aExp == 0 ) { - ++expDiff; - } - else { - aSig0 |= UINT64_C(0x0001000000000000); - } - shift128ExtraRightJamming( - aSig0, aSig1, 0, - expDiff, &aSig0, &aSig1, &zSig2 ); - zExp = bExp; - } - else { - if ( aExp == 0x7FFF ) { - if ( aSig0 | aSig1 | bSig0 | bSig1 ) { - return propagateFloat128NaN(a, b, status); - } - return a; - } - add128( aSig0, aSig1, bSig0, bSig1, &zSig0, &zSig1 ); - if ( aExp == 0 ) { - if (status->flush_to_zero) { - if (zSig0 | zSig1) { - float_raise(float_flag_output_denormal, status); - } - return packFloat128(zSign, 0, 0, 0); - } - return packFloat128( zSign, 0, zSig0, zSig1 ); - } - zSig2 = 0; - zSig0 |= UINT64_C(0x0002000000000000); - zExp = aExp; - goto shiftRight1; - } - aSig0 |= UINT64_C(0x0001000000000000); - add128( aSig0, aSig1, bSig0, bSig1, &zSig0, &zSig1 ); - --zExp; - if ( zSig0 < UINT64_C(0x0002000000000000) ) goto roundAndPack; - ++zExp; - shiftRight1: - shift128ExtraRightJamming( - zSig0, zSig1, zSig2, 1, &zSig0, &zSig1, &zSig2 ); - roundAndPack: - return roundAndPackFloat128(zSign, zExp, zSig0, zSig1, zSig2, status); - -} - -/*---------------------------------------------------------------------------- -| Returns the result of subtracting the absolute values of the quadruple- -| precision floating-point values `a' and `b'. If `zSign' is 1, the -| difference is negated before being returned. `zSign' is ignored if the -| result is a NaN. The subtraction is performed according to the IEC/IEEE -| Standard for Binary Floating-Point Arithmetic. -*----------------------------------------------------------------------------*/ - -static float128 subFloat128Sigs(float128 a, float128 b, bool zSign, - float_status *status) -{ - int32_t aExp, bExp, zExp; - uint64_t aSig0, aSig1, bSig0, bSig1, zSig0, zSig1; - int32_t expDiff; - - aSig1 = extractFloat128Frac1( a ); - aSig0 = extractFloat128Frac0( a ); - aExp = extractFloat128Exp( a ); - bSig1 = extractFloat128Frac1( b ); - bSig0 = extractFloat128Frac0( b ); - bExp = extractFloat128Exp( b ); - expDiff = aExp - bExp; - shortShift128Left( aSig0, aSig1, 14, &aSig0, &aSig1 ); - shortShift128Left( bSig0, bSig1, 14, &bSig0, &bSig1 ); - if ( 0 < expDiff ) goto aExpBigger; - if ( expDiff < 0 ) goto bExpBigger; - if ( aExp == 0x7FFF ) { - if ( aSig0 | aSig1 | bSig0 | bSig1 ) { - return propagateFloat128NaN(a, b, status); - } - float_raise(float_flag_invalid, status); - return float128_default_nan(status); - } - if ( aExp == 0 ) { - aExp = 1; - bExp = 1; - } - if ( bSig0 < aSig0 ) goto aBigger; - if ( aSig0 < bSig0 ) goto bBigger; - if ( bSig1 < aSig1 ) goto aBigger; - if ( aSig1 < bSig1 ) goto bBigger; - return packFloat128(status->float_rounding_mode == float_round_down, - 0, 0, 0); - bExpBigger: - if ( bExp == 0x7FFF ) { - if (bSig0 | bSig1) { - return propagateFloat128NaN(a, b, status); - } - return packFloat128( zSign ^ 1, 0x7FFF, 0, 0 ); - } - if ( aExp == 0 ) { - ++expDiff; - } - else { - aSig0 |= UINT64_C(0x4000000000000000); - } - shift128RightJamming( aSig0, aSig1, - expDiff, &aSig0, &aSig1 ); - bSig0 |= UINT64_C(0x4000000000000000); - bBigger: - sub128( bSig0, bSig1, aSig0, aSig1, &zSig0, &zSig1 ); - zExp = bExp; - zSign ^= 1; - goto normalizeRoundAndPack; - aExpBigger: - if ( aExp == 0x7FFF ) { - if (aSig0 | aSig1) { - return propagateFloat128NaN(a, b, status); - } - return a; - } - if ( bExp == 0 ) { - --expDiff; - } - else { - bSig0 |= UINT64_C(0x4000000000000000); - } - shift128RightJamming( bSig0, bSig1, expDiff, &bSig0, &bSig1 ); - aSig0 |= UINT64_C(0x4000000000000000); - aBigger: - sub128( aSig0, aSig1, bSig0, bSig1, &zSig0, &zSig1 ); - zExp = aExp; - normalizeRoundAndPack: - --zExp; - return normalizeRoundAndPackFloat128(zSign, zExp - 14, zSig0, zSig1, - status); - -} - -/*---------------------------------------------------------------------------- -| Returns the result of adding the quadruple-precision floating-point values -| `a' and `b'. The operation is performed according to the IEC/IEEE Standard -| for Binary Floating-Point Arithmetic. -*----------------------------------------------------------------------------*/ - -float128 float128_add(float128 a, float128 b, float_status *status) -{ - bool aSign, bSign; - - aSign = extractFloat128Sign( a ); - bSign = extractFloat128Sign( b ); - if ( aSign == bSign ) { - return addFloat128Sigs(a, b, aSign, status); - } - else { - return subFloat128Sigs(a, b, aSign, status); - } - -} - -/*---------------------------------------------------------------------------- -| Returns the result of subtracting the quadruple-precision floating-point -| values `a' and `b'. The operation is performed according to the IEC/IEEE -| Standard for Binary Floating-Point Arithmetic. -*----------------------------------------------------------------------------*/ - -float128 float128_sub(float128 a, float128 b, float_status *status) -{ - bool aSign, bSign; - - aSign = extractFloat128Sign( a ); - bSign = extractFloat128Sign( b ); - if ( aSign == bSign ) { - return subFloat128Sigs(a, b, aSign, status); - } - else { - return addFloat128Sigs(a, b, aSign, status); - } - -} - /*---------------------------------------------------------------------------- | Returns the result of multiplying the quadruple-precision floating-point | values `a' and `b'. The operation is performed according to the IEC/IEEE