diff options
Diffstat (limited to 'fpu')
| -rw-r--r-- | fpu/softfloat-parts.c.inc | 55 | ||||
| -rw-r--r-- | fpu/softfloat.c | 290 |
2 files changed, 171 insertions, 174 deletions
diff --git a/fpu/softfloat-parts.c.inc b/fpu/softfloat-parts.c.inc index a203811299..f8165d92f9 100644 --- a/fpu/softfloat-parts.c.inc +++ b/fpu/softfloat-parts.c.inc @@ -539,3 +539,58 @@ static FloatPartsN *partsN(muladd)(FloatPartsN *a, FloatPartsN *b, parts_default_nan(a, s); return a; } + +/* + * 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 FloatPartsN *partsN(div)(FloatPartsN *a, FloatPartsN *b, + float_status *s) +{ + int ab_mask = float_cmask(a->cls) | float_cmask(b->cls); + bool sign = a->sign ^ b->sign; + + if (likely(ab_mask == float_cmask_normal)) { + a->sign = sign; + a->exp -= b->exp + frac_div(a, b); + return a; + } + + /* 0/0 or Inf/Inf => NaN */ + if (unlikely(ab_mask == float_cmask_zero) || + unlikely(ab_mask == float_cmask_inf)) { + float_raise(float_flag_invalid, s); + parts_default_nan(a, s); + return a; + } + + /* All the NaN cases */ + if (unlikely(ab_mask & float_cmask_anynan)) { + return parts_pick_nan(a, b, s); + } + + a->sign = sign; + + /* Inf / X */ + if (a->cls == float_class_inf) { + return a; + } + + /* 0 / X */ + if (a->cls == float_class_zero) { + return a; + } + + /* X / Inf */ + if (b->cls == float_class_inf) { + a->cls = float_class_zero; + return a; + } + + /* X / 0 => Inf */ + g_assert(b->cls == float_class_zero); + float_raise(float_flag_divbyzero, s); + a->cls = float_class_inf; + return a; +} diff --git a/fpu/softfloat.c b/fpu/softfloat.c index 34689959a9..a6dbb1dabf 100644 --- a/fpu/softfloat.c +++ b/fpu/softfloat.c @@ -803,6 +803,14 @@ static FloatParts128 *parts128_muladd(FloatParts128 *a, FloatParts128 *b, #define parts_muladd(A, B, C, Z, S) \ PARTS_GENERIC_64_128(muladd, A)(A, B, C, Z, S) +static FloatParts64 *parts64_div(FloatParts64 *a, FloatParts64 *b, + float_status *s); +static FloatParts128 *parts128_div(FloatParts128 *a, FloatParts128 *b, + float_status *s); + +#define parts_div(A, B, S) \ + PARTS_GENERIC_64_128(div, A)(A, B, S) + /* * Helper functions for softfloat-parts.c.inc, per-size operations. */ @@ -895,6 +903,87 @@ static void frac128_clear(FloatParts128 *a) #define frac_clear(A) FRAC_GENERIC_64_128(clear, A)(A) +static bool frac64_div(FloatParts64 *a, FloatParts64 *b) +{ + uint64_t n1, n0, r, q; + bool ret; + + /* + * We want a 2*N / N-bit division to produce exactly an N-bit + * result, so that we do not lose any precision and so that we + * do not have to renormalize afterward. If A.frac < B.frac, + * then division would produce an (N-1)-bit result; shift A left + * by one to produce the an N-bit result, and return true to + * decrement the exponent to match. + * + * The udiv_qrnnd algorithm that we're using requires normalization, + * i.e. the msb of the denominator must be set, which is already true. + */ + ret = a->frac < b->frac; + if (ret) { + n0 = a->frac; + n1 = 0; + } else { + n0 = a->frac >> 1; + n1 = a->frac << 63; + } + q = udiv_qrnnd(&r, n0, n1, b->frac); + + /* Set lsb if there is a remainder, to set inexact. */ + a->frac = q | (r != 0); + + return ret; +} + +static bool frac128_div(FloatParts128 *a, FloatParts128 *b) +{ + uint64_t q0, q1, a0, a1, b0, b1; + uint64_t r0, r1, r2, r3, t0, t1, t2, t3; + bool ret = false; + + a0 = a->frac_hi, a1 = a->frac_lo; + b0 = b->frac_hi, b1 = b->frac_lo; + + ret = lt128(a0, a1, b0, b1); + if (!ret) { + a1 = shr_double(a0, a1, 1); + a0 = a0 >> 1; + } + + /* Use 128/64 -> 64 division as estimate for 192/128 -> 128 division. */ + q0 = estimateDiv128To64(a0, a1, b0); + + /* + * Estimate is high because B1 was not included (unless B1 == 0). + * Reduce quotient and increase remainder until remainder is non-negative. + * This loop will execute 0 to 2 times. + */ + mul128By64To192(b0, b1, q0, &t0, &t1, &t2); + sub192(a0, a1, 0, t0, t1, t2, &r0, &r1, &r2); + while (r0 != 0) { + q0--; + add192(r0, r1, r2, 0, b0, b1, &r0, &r1, &r2); + } + + /* Repeat using the remainder, producing a second word of quotient. */ + q1 = estimateDiv128To64(r1, r2, b0); + mul128By64To192(b0, b1, q1, &t1, &t2, &t3); + sub192(r1, r2, 0, t1, t2, t3, &r1, &r2, &r3); + while (r1 != 0) { + q1--; + add192(r1, r2, r3, 0, b0, b1, &r1, &r2, &r3); + } + + /* Any remainder indicates inexact; set sticky bit. */ + q1 |= (r2 | r3) != 0; + + a->frac_hi = q0; + a->frac_lo = q1; + return ret; +} + +#define frac_div(A, B) FRAC_GENERIC_64_128(div, A)(A, B) + static bool frac64_eqz(FloatParts64 *a) { return a->frac == 0; @@ -1821,110 +1910,42 @@ float128 QEMU_FLATTEN float128_muladd(float128 a, float128 b, float128 c, } /* - * 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. + * Division */ -static FloatParts64 div_floats(FloatParts64 a, FloatParts64 b, float_status *s) -{ - bool sign = a.sign ^ b.sign; - - if (a.cls == float_class_normal && b.cls == float_class_normal) { - uint64_t n0, n1, q, r; - int exp = a.exp - b.exp; - - /* - * We want a 2*N / N-bit division to produce exactly an N-bit - * result, so that we do not lose any precision and so that we - * do not have to renormalize afterward. If A.frac < B.frac, - * then division would produce an (N-1)-bit result; shift A left - * by one to produce the an N-bit result, and decrement the - * exponent to match. - * - * The udiv_qrnnd algorithm that we're using requires normalization, - * i.e. the msb of the denominator must be set, which is already true. - */ - if (a.frac < b.frac) { - exp -= 1; - shift128Left(0, a.frac, DECOMPOSED_BINARY_POINT + 1, &n1, &n0); - } else { - shift128Left(0, a.frac, DECOMPOSED_BINARY_POINT, &n1, &n0); - } - q = udiv_qrnnd(&r, n1, n0, b.frac); - - /* Set lsb if there is a remainder, to set inexact. */ - a.frac = q | (r != 0); - a.sign = sign; - a.exp = exp; - return a; - } - /* handle all the NaN cases */ - if (is_nan(a.cls) || is_nan(b.cls)) { - return *parts_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)) { - float_raise(float_flag_invalid, s); - parts_default_nan(&a, s); - return a; - } - /* Inf / x or 0 / x */ - if (a.cls == float_class_inf || a.cls == float_class_zero) { - a.sign = sign; - return a; - } - /* Div 0 => Inf */ - if (b.cls == float_class_zero) { - float_raise(float_flag_divbyzero, s); - a.cls = float_class_inf; - 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) { - FloatParts64 pa, pb, pr; + FloatParts64 pa, pb, *pr; float16_unpack_canonical(&pa, a, status); float16_unpack_canonical(&pb, b, status); - pr = div_floats(pa, pb, status); + pr = parts_div(&pa, &pb, status); - return float16_round_pack_canonical(&pr, status); + return float16_round_pack_canonical(pr, status); } static float32 QEMU_SOFTFLOAT_ATTR soft_f32_div(float32 a, float32 b, float_status *status) { - FloatParts64 pa, pb, pr; + FloatParts64 pa, pb, *pr; float32_unpack_canonical(&pa, a, status); float32_unpack_canonical(&pb, b, status); - pr = div_floats(pa, pb, status); + pr = parts_div(&pa, &pb, status); - return float32_round_pack_canonical(&pr, status); + return float32_round_pack_canonical(pr, status); } static float64 QEMU_SOFTFLOAT_ATTR soft_f64_div(float64 a, float64 b, float_status *status) { - FloatParts64 pa, pb, pr; + FloatParts64 pa, pb, *pr; float64_unpack_canonical(&pa, a, status); float64_unpack_canonical(&pb, b, status); - pr = div_floats(pa, pb, status); + pr = parts_div(&pa, &pb, status); - return float64_round_pack_canonical(&pr, status); + return float64_round_pack_canonical(pr, status); } static float hard_f32_div(float a, float b) @@ -1985,20 +2006,28 @@ float64_div(float64 a, float64 b, float_status *s) f64_div_pre, f64_div_post); } -/* - * Returns the result of dividing the bfloat16 - * value `a' by the corresponding value `b'. - */ - -bfloat16 bfloat16_div(bfloat16 a, bfloat16 b, float_status *status) +bfloat16 QEMU_FLATTEN +bfloat16_div(bfloat16 a, bfloat16 b, float_status *status) { - FloatParts64 pa, pb, pr; + FloatParts64 pa, pb, *pr; bfloat16_unpack_canonical(&pa, a, status); bfloat16_unpack_canonical(&pb, b, status); - pr = div_floats(pa, pb, status); + pr = parts_div(&pa, &pb, status); - return bfloat16_round_pack_canonical(&pr, status); + return bfloat16_round_pack_canonical(pr, status); +} + +float128 QEMU_FLATTEN +float128_div(float128 a, float128 b, float_status *status) +{ + FloatParts128 pa, pb, *pr; + + float128_unpack_canonical(&pa, a, status); + float128_unpack_canonical(&pb, b, status); + pr = parts_div(&pa, &pb, status); + + return float128_round_pack_canonical(pr, status); } /* @@ -7124,93 +7153,6 @@ float128 float128_round_to_int(float128 a, float_status *status) } /*---------------------------------------------------------------------------- -| Returns the result of dividing the quadruple-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. -*----------------------------------------------------------------------------*/ - -float128 float128_div(float128 a, float128 b, float_status *status) -{ - bool aSign, bSign, zSign; - int32_t aExp, bExp, zExp; - uint64_t aSig0, aSig1, bSig0, bSig1, zSig0, zSig1, zSig2; - uint64_t rem0, rem1, rem2, rem3, term0, term1, term2, term3; - - aSig1 = extractFloat128Frac1( a ); - aSig0 = extractFloat128Frac0( a ); - aExp = extractFloat128Exp( a ); - aSign = extractFloat128Sign( a ); - bSig1 = extractFloat128Frac1( b ); - bSig0 = extractFloat128Frac0( b ); - bExp = extractFloat128Exp( b ); - bSign = extractFloat128Sign( b ); - zSign = aSign ^ bSign; - if ( aExp == 0x7FFF ) { - if (aSig0 | aSig1) { - return propagateFloat128NaN(a, b, status); - } - if ( bExp == 0x7FFF ) { - if (bSig0 | bSig1) { - return propagateFloat128NaN(a, b, status); - } - goto invalid; - } - return packFloat128( zSign, 0x7FFF, 0, 0 ); - } - if ( bExp == 0x7FFF ) { - if (bSig0 | bSig1) { - return propagateFloat128NaN(a, b, status); - } - return packFloat128( zSign, 0, 0, 0 ); - } - if ( bExp == 0 ) { - if ( ( bSig0 | bSig1 ) == 0 ) { - if ( ( aExp | aSig0 | aSig1 ) == 0 ) { - invalid: - float_raise(float_flag_invalid, status); - return float128_default_nan(status); - } - float_raise(float_flag_divbyzero, status); - return packFloat128( zSign, 0x7FFF, 0, 0 ); - } - normalizeFloat128Subnormal( bSig0, bSig1, &bExp, &bSig0, &bSig1 ); - } - if ( aExp == 0 ) { - if ( ( aSig0 | aSig1 ) == 0 ) return packFloat128( zSign, 0, 0, 0 ); - normalizeFloat128Subnormal( aSig0, aSig1, &aExp, &aSig0, &aSig1 ); - } - zExp = aExp - bExp + 0x3FFD; - shortShift128Left( - aSig0 | UINT64_C(0x0001000000000000), aSig1, 15, &aSig0, &aSig1 ); - shortShift128Left( - bSig0 | UINT64_C(0x0001000000000000), bSig1, 15, &bSig0, &bSig1 ); - if ( le128( bSig0, bSig1, aSig0, aSig1 ) ) { - shift128Right( aSig0, aSig1, 1, &aSig0, &aSig1 ); - ++zExp; - } - zSig0 = estimateDiv128To64( aSig0, aSig1, bSig0 ); - mul128By64To192( bSig0, bSig1, zSig0, &term0, &term1, &term2 ); - sub192( aSig0, aSig1, 0, term0, term1, term2, &rem0, &rem1, &rem2 ); - while ( (int64_t) rem0 < 0 ) { - --zSig0; - add192( rem0, rem1, rem2, 0, bSig0, bSig1, &rem0, &rem1, &rem2 ); - } - zSig1 = estimateDiv128To64( rem1, rem2, bSig0 ); - if ( ( zSig1 & 0x3FFF ) <= 4 ) { - mul128By64To192( bSig0, bSig1, zSig1, &term1, &term2, &term3 ); - sub192( rem1, rem2, 0, term1, term2, term3, &rem1, &rem2, &rem3 ); - while ( (int64_t) rem1 < 0 ) { - --zSig1; - add192( rem1, rem2, rem3, 0, bSig0, bSig1, &rem1, &rem2, &rem3 ); - } - zSig1 |= ( ( rem1 | rem2 | rem3 ) != 0 ); - } - shift128ExtraRightJamming( zSig0, zSig1, 0, 15, &zSig0, &zSig1, &zSig2 ); - return roundAndPackFloat128(zSign, zExp, zSig0, zSig1, zSig2, status); - -} - -/*---------------------------------------------------------------------------- | Returns the remainder of the quadruple-precision floating-point value `a' | with respect to the corresponding value `b'. The operation is performed | according to the IEC/IEEE Standard for Binary Floating-Point Arithmetic. |