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X-Received-From: 2a00:1450:400c:c0c::241 Subject: [Qemu-devel] [PULL 14/22] fpu/softfloat: re-factor div X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Richard Henderson , =?utf-8?q?Alex_Benn?= =?utf-8?b?w6ll?= , qemu-devel@nongnu.org, Aurelien Jarno Errors-To: qemu-devel-bounces+patch=linaro.org@nongnu.org Sender: "Qemu-devel" We can now add float16_div and use the common decompose and canonicalize functions to have a single implementation for float16/32/64 versions. Signed-off-by: Alex Bennée Signed-off-by: Richard Henderson Reviewed-by: Peter Maydell -- 2.15.1 diff --git a/fpu/softfloat-macros.h b/fpu/softfloat-macros.h index 9cc6158cb4..c45a23193e 100644 --- a/fpu/softfloat-macros.h +++ b/fpu/softfloat-macros.h @@ -625,6 +625,54 @@ static uint64_t estimateDiv128To64( uint64_t a0, uint64_t a1, uint64_t b ) } +/* From the GNU Multi Precision Library - longlong.h __udiv_qrnnd + * (https://gmplib.org/repo/gmp/file/tip/longlong.h) + * + * Licensed under the GPLv2/LGPLv3 + */ +static uint64_t div128To64(uint64_t n0, uint64_t n1, uint64_t d) +{ + uint64_t d0, d1, q0, q1, r1, r0, m; + + d0 = (uint32_t)d; + d1 = d >> 32; + + r1 = n1 % d1; + q1 = n1 / d1; + m = q1 * d0; + r1 = (r1 << 32) | (n0 >> 32); + if (r1 < m) { + q1 -= 1; + r1 += d; + if (r1 >= d) { + if (r1 < m) { + q1 -= 1; + r1 += d; + } + } + } + r1 -= m; + + r0 = r1 % d1; + q0 = r1 / d1; + m = q0 * d0; + r0 = (r0 << 32) | (uint32_t)n0; + if (r0 < m) { + q0 -= 1; + r0 += d; + if (r0 >= d) { + if (r0 < m) { + q0 -= 1; + r0 += d; + } + } + } + r0 -= m; + + /* Return remainder in LSB */ + return (q1 << 32) | q0 | (r0 != 0); +} + /*---------------------------------------------------------------------------- | Returns an approximation to the square root of the 32-bit significand given | by `a'. Considered as an integer, `a' must be at least 2^31. If bit 0 of diff --git a/fpu/softfloat.c b/fpu/softfloat.c index 6d29e1a103..4a859b2721 100644 --- a/fpu/softfloat.c +++ b/fpu/softfloat.c @@ -816,6 +816,94 @@ float64 __attribute__((flatten)) float64_mul(float64 a, float64 b, return float64_round_pack_canonical(pr, status); } +/* + * Returns the result of dividing the floating-point value `a' by the + * corresponding value `b'. The operation is performed according to + * the IEC/IEEE Standard for Binary Floating-Point Arithmetic. + */ + +static FloatParts div_floats(FloatParts a, FloatParts b, float_status *s) +{ + bool sign = a.sign ^ b.sign; + + if (a.cls == float_class_normal && b.cls == float_class_normal) { + uint64_t temp_lo, temp_hi; + int exp = a.exp - b.exp; + if (a.frac < b.frac) { + exp -= 1; + shortShift128Left(0, a.frac, DECOMPOSED_BINARY_POINT + 1, + &temp_hi, &temp_lo); + } else { + shortShift128Left(0, a.frac, DECOMPOSED_BINARY_POINT, + &temp_hi, &temp_lo); + } + /* LSB of quot is set if inexact which roundandpack will use + * to set flags. Yet again we re-use a for the result */ + a.frac = div128To64(temp_lo, temp_hi, b.frac); + a.sign = sign; + a.exp = exp; + return a; + } + /* handle all the NaN cases */ + if (is_nan(a.cls) || is_nan(b.cls)) { + return pick_nan(a, b, s); + } + /* 0/0 or Inf/Inf */ + if (a.cls == b.cls + && + (a.cls == float_class_inf || a.cls == float_class_zero)) { + s->float_exception_flags |= float_flag_invalid; + a.cls = float_class_dnan; + return a; + } + /* Div 0 => Inf */ + if (b.cls == float_class_zero) { + s->float_exception_flags |= float_flag_divbyzero; + a.cls = float_class_inf; + a.sign = sign; + return a; + } + /* Inf / x or 0 / x */ + if (a.cls == float_class_inf || a.cls == float_class_zero) { + a.sign = sign; + return a; + } + /* Div by Inf */ + if (b.cls == float_class_inf) { + a.cls = float_class_zero; + a.sign = sign; + return a; + } + g_assert_not_reached(); +} + +float16 float16_div(float16 a, float16 b, float_status *status) +{ + FloatParts pa = float16_unpack_canonical(a, status); + FloatParts pb = float16_unpack_canonical(b, status); + FloatParts pr = div_floats(pa, pb, status); + + return float16_round_pack_canonical(pr, status); +} + +float32 float32_div(float32 a, float32 b, float_status *status) +{ + FloatParts pa = float32_unpack_canonical(a, status); + FloatParts pb = float32_unpack_canonical(b, status); + FloatParts pr = div_floats(pa, pb, status); + + return float32_round_pack_canonical(pr, status); +} + +float64 float64_div(float64 a, float64 b, float_status *status) +{ + FloatParts pa = float64_unpack_canonical(a, status); + FloatParts pb = float64_unpack_canonical(b, status); + FloatParts pr = div_floats(pa, pb, status); + + return float64_round_pack_canonical(pr, status); +} + /*---------------------------------------------------------------------------- | Takes a 64-bit fixed-point value `absZ' with binary point between bits 6 | and 7, and returns the properly rounded 32-bit integer corresponding to the @@ -2627,77 +2715,6 @@ float32 float32_round_to_int(float32 a, float_status *status) } - -/*---------------------------------------------------------------------------- -| Returns the result of dividing the single-precision floating-point value `a' -| by the corresponding value `b'. The operation is performed according to the -| IEC/IEEE Standard for Binary Floating-Point Arithmetic. -*----------------------------------------------------------------------------*/ - -float32 float32_div(float32 a, float32 b, float_status *status) -{ - flag aSign, bSign, zSign; - int aExp, bExp, zExp; - uint32_t aSig, bSig, zSig; - a = float32_squash_input_denormal(a, status); - b = float32_squash_input_denormal(b, status); - - aSig = extractFloat32Frac( a ); - aExp = extractFloat32Exp( a ); - aSign = extractFloat32Sign( a ); - bSig = extractFloat32Frac( b ); - bExp = extractFloat32Exp( b ); - bSign = extractFloat32Sign( b ); - zSign = aSign ^ bSign; - if ( aExp == 0xFF ) { - if (aSig) { - return propagateFloat32NaN(a, b, status); - } - if ( bExp == 0xFF ) { - if (bSig) { - return propagateFloat32NaN(a, b, status); - } - float_raise(float_flag_invalid, status); - return float32_default_nan(status); - } - return packFloat32( zSign, 0xFF, 0 ); - } - if ( bExp == 0xFF ) { - if (bSig) { - return propagateFloat32NaN(a, b, status); - } - return packFloat32( zSign, 0, 0 ); - } - if ( bExp == 0 ) { - if ( bSig == 0 ) { - if ( ( aExp | aSig ) == 0 ) { - float_raise(float_flag_invalid, status); - return float32_default_nan(status); - } - float_raise(float_flag_divbyzero, status); - return packFloat32( zSign, 0xFF, 0 ); - } - normalizeFloat32Subnormal( bSig, &bExp, &bSig ); - } - if ( aExp == 0 ) { - if ( aSig == 0 ) return packFloat32( zSign, 0, 0 ); - normalizeFloat32Subnormal( aSig, &aExp, &aSig ); - } - zExp = aExp - bExp + 0x7D; - aSig = ( aSig | 0x00800000 )<<7; - bSig = ( bSig | 0x00800000 )<<8; - if ( bSig <= ( aSig + aSig ) ) { - aSig >>= 1; - ++zExp; - } - zSig = ( ( (uint64_t) aSig )<<32 ) / bSig; - if ( ( zSig & 0x3F ) == 0 ) { - zSig |= ( (uint64_t) bSig * zSig != ( (uint64_t) aSig )<<32 ); - } - return roundAndPackFloat32(zSign, zExp, zSig, status); - -} - /*---------------------------------------------------------------------------- | Returns the remainder of the single-precision floating-point value `a' | with respect to the corresponding value `b'. The operation is performed @@ -4159,83 +4176,6 @@ float64 float64_trunc_to_int(float64 a, float_status *status) return res; } -/*---------------------------------------------------------------------------- -| Returns the result of dividing the double-precision floating-point value `a' -| by the corresponding value `b'. The operation is performed according to -| the IEC/IEEE Standard for Binary Floating-Point Arithmetic. -*----------------------------------------------------------------------------*/ - -float64 float64_div(float64 a, float64 b, float_status *status) -{ - flag aSign, bSign, zSign; - int aExp, bExp, zExp; - uint64_t aSig, bSig, zSig; - uint64_t rem0, rem1; - uint64_t term0, term1; - a = float64_squash_input_denormal(a, status); - b = float64_squash_input_denormal(b, status); - - aSig = extractFloat64Frac( a ); - aExp = extractFloat64Exp( a ); - aSign = extractFloat64Sign( a ); - bSig = extractFloat64Frac( b ); - bExp = extractFloat64Exp( b ); - bSign = extractFloat64Sign( b ); - zSign = aSign ^ bSign; - if ( aExp == 0x7FF ) { - if (aSig) { - return propagateFloat64NaN(a, b, status); - } - if ( bExp == 0x7FF ) { - if (bSig) { - return propagateFloat64NaN(a, b, status); - } - float_raise(float_flag_invalid, status); - return float64_default_nan(status); - } - return packFloat64( zSign, 0x7FF, 0 ); - } - if ( bExp == 0x7FF ) { - if (bSig) { - return propagateFloat64NaN(a, b, status); - } - return packFloat64( zSign, 0, 0 ); - } - if ( bExp == 0 ) { - if ( bSig == 0 ) { - if ( ( aExp | aSig ) == 0 ) { - float_raise(float_flag_invalid, status); - return float64_default_nan(status); - } - float_raise(float_flag_divbyzero, status); - return packFloat64( zSign, 0x7FF, 0 ); - } - normalizeFloat64Subnormal( bSig, &bExp, &bSig ); - } - if ( aExp == 0 ) { - if ( aSig == 0 ) return packFloat64( zSign, 0, 0 ); - normalizeFloat64Subnormal( aSig, &aExp, &aSig ); - } - zExp = aExp - bExp + 0x3FD; - aSig = ( aSig | LIT64( 0x0010000000000000 ) )<<10; - bSig = ( bSig | LIT64( 0x0010000000000000 ) )<<11; - if ( bSig <= ( aSig + aSig ) ) { - aSig >>= 1; - ++zExp; - } - zSig = estimateDiv128To64( aSig, 0, bSig ); - if ( ( zSig & 0x1FF ) <= 2 ) { - mul64To128( bSig, zSig, &term0, &term1 ); - sub128( aSig, 0, term0, term1, &rem0, &rem1 ); - while ( (int64_t) rem0 < 0 ) { - --zSig; - add128( rem0, rem1, 0, bSig, &rem0, &rem1 ); - } - zSig |= ( rem1 != 0 ); - } - return roundAndPackFloat64(zSign, zExp, zSig, status); - -} /*---------------------------------------------------------------------------- | Returns the remainder of the double-precision floating-point value `a' diff --git a/include/fpu/softfloat.h b/include/fpu/softfloat.h index 7fc63dd60f..85e4a74f1b 100644 --- a/include/fpu/softfloat.h +++ b/include/fpu/softfloat.h @@ -240,6 +240,7 @@ float64 float16_to_float64(float16 a, flag ieee, float_status *status); float16 float16_add(float16, float16, float_status *status); float16 float16_sub(float16, float16, float_status *status); float16 float16_mul(float16, float16, float_status *status); +float16 float16_div(float16, float16, float_status *status); int float16_is_quiet_nan(float16, float_status *status); int float16_is_signaling_nan(float16, float_status *status);