softfloat: Move div_floats to softfloat-parts.c.inc
Rename to parts$N_div. Implement float128_div with FloatParts128. Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson
parent
463e45dcb4
commit
ec961b81b4
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@ -539,3 +539,58 @@ static FloatPartsN *partsN(muladd)(FloatPartsN *a, FloatPartsN *b,
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parts_default_nan(a, s);
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return a;
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}
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/*
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* Returns the result of dividing the floating-point value `a' by the
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* corresponding value `b'. The operation is performed according to
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* the IEC/IEEE Standard for Binary Floating-Point Arithmetic.
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*/
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static FloatPartsN *partsN(div)(FloatPartsN *a, FloatPartsN *b,
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float_status *s)
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{
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int ab_mask = float_cmask(a->cls) | float_cmask(b->cls);
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bool sign = a->sign ^ b->sign;
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if (likely(ab_mask == float_cmask_normal)) {
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a->sign = sign;
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a->exp -= b->exp + frac_div(a, b);
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return a;
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}
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/* 0/0 or Inf/Inf => NaN */
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if (unlikely(ab_mask == float_cmask_zero) ||
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unlikely(ab_mask == float_cmask_inf)) {
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float_raise(float_flag_invalid, s);
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parts_default_nan(a, s);
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return a;
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}
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/* All the NaN cases */
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if (unlikely(ab_mask & float_cmask_anynan)) {
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return parts_pick_nan(a, b, s);
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}
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a->sign = sign;
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/* Inf / X */
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if (a->cls == float_class_inf) {
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return a;
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}
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/* 0 / X */
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if (a->cls == float_class_zero) {
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return a;
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}
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/* X / Inf */
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if (b->cls == float_class_inf) {
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a->cls = float_class_zero;
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return a;
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}
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/* X / 0 => Inf */
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g_assert(b->cls == float_class_zero);
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float_raise(float_flag_divbyzero, s);
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a->cls = float_class_inf;
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return a;
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}
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290
fpu/softfloat.c
290
fpu/softfloat.c
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@ -803,6 +803,14 @@ static FloatParts128 *parts128_muladd(FloatParts128 *a, FloatParts128 *b,
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#define parts_muladd(A, B, C, Z, S) \
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PARTS_GENERIC_64_128(muladd, A)(A, B, C, Z, S)
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static FloatParts64 *parts64_div(FloatParts64 *a, FloatParts64 *b,
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float_status *s);
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static FloatParts128 *parts128_div(FloatParts128 *a, FloatParts128 *b,
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float_status *s);
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#define parts_div(A, B, S) \
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PARTS_GENERIC_64_128(div, A)(A, B, S)
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/*
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* Helper functions for softfloat-parts.c.inc, per-size operations.
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*/
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@ -895,6 +903,87 @@ static void frac128_clear(FloatParts128 *a)
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#define frac_clear(A) FRAC_GENERIC_64_128(clear, A)(A)
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static bool frac64_div(FloatParts64 *a, FloatParts64 *b)
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{
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uint64_t n1, n0, r, q;
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bool ret;
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/*
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* We want a 2*N / N-bit division to produce exactly an N-bit
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* result, so that we do not lose any precision and so that we
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* do not have to renormalize afterward. If A.frac < B.frac,
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* then division would produce an (N-1)-bit result; shift A left
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* by one to produce the an N-bit result, and return true to
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* decrement the exponent to match.
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*
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* The udiv_qrnnd algorithm that we're using requires normalization,
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* i.e. the msb of the denominator must be set, which is already true.
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*/
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ret = a->frac < b->frac;
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if (ret) {
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n0 = a->frac;
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n1 = 0;
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} else {
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n0 = a->frac >> 1;
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n1 = a->frac << 63;
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}
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q = udiv_qrnnd(&r, n0, n1, b->frac);
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/* Set lsb if there is a remainder, to set inexact. */
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a->frac = q | (r != 0);
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return ret;
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}
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static bool frac128_div(FloatParts128 *a, FloatParts128 *b)
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{
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uint64_t q0, q1, a0, a1, b0, b1;
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uint64_t r0, r1, r2, r3, t0, t1, t2, t3;
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bool ret = false;
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a0 = a->frac_hi, a1 = a->frac_lo;
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b0 = b->frac_hi, b1 = b->frac_lo;
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ret = lt128(a0, a1, b0, b1);
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if (!ret) {
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a1 = shr_double(a0, a1, 1);
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a0 = a0 >> 1;
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}
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/* Use 128/64 -> 64 division as estimate for 192/128 -> 128 division. */
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q0 = estimateDiv128To64(a0, a1, b0);
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/*
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* Estimate is high because B1 was not included (unless B1 == 0).
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* Reduce quotient and increase remainder until remainder is non-negative.
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* This loop will execute 0 to 2 times.
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*/
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mul128By64To192(b0, b1, q0, &t0, &t1, &t2);
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sub192(a0, a1, 0, t0, t1, t2, &r0, &r1, &r2);
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while (r0 != 0) {
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q0--;
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add192(r0, r1, r2, 0, b0, b1, &r0, &r1, &r2);
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}
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/* Repeat using the remainder, producing a second word of quotient. */
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q1 = estimateDiv128To64(r1, r2, b0);
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mul128By64To192(b0, b1, q1, &t1, &t2, &t3);
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sub192(r1, r2, 0, t1, t2, t3, &r1, &r2, &r3);
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while (r1 != 0) {
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q1--;
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add192(r1, r2, r3, 0, b0, b1, &r1, &r2, &r3);
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}
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/* Any remainder indicates inexact; set sticky bit. */
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q1 |= (r2 | r3) != 0;
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a->frac_hi = q0;
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a->frac_lo = q1;
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return ret;
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}
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#define frac_div(A, B) FRAC_GENERIC_64_128(div, A)(A, B)
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static bool frac64_eqz(FloatParts64 *a)
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{
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return a->frac == 0;
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@ -1821,110 +1910,42 @@ float128 QEMU_FLATTEN float128_muladd(float128 a, float128 b, float128 c,
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}
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/*
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* Returns the result of dividing the floating-point value `a' by the
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* corresponding value `b'. The operation is performed according to
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* the IEC/IEEE Standard for Binary Floating-Point Arithmetic.
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* Division
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*/
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static FloatParts64 div_floats(FloatParts64 a, FloatParts64 b, float_status *s)
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{
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bool sign = a.sign ^ b.sign;
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if (a.cls == float_class_normal && b.cls == float_class_normal) {
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uint64_t n0, n1, q, r;
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int exp = a.exp - b.exp;
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/*
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* We want a 2*N / N-bit division to produce exactly an N-bit
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* result, so that we do not lose any precision and so that we
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* do not have to renormalize afterward. If A.frac < B.frac,
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* then division would produce an (N-1)-bit result; shift A left
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* by one to produce the an N-bit result, and decrement the
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* exponent to match.
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*
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* The udiv_qrnnd algorithm that we're using requires normalization,
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* i.e. the msb of the denominator must be set, which is already true.
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*/
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if (a.frac < b.frac) {
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exp -= 1;
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shift128Left(0, a.frac, DECOMPOSED_BINARY_POINT + 1, &n1, &n0);
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} else {
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shift128Left(0, a.frac, DECOMPOSED_BINARY_POINT, &n1, &n0);
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}
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q = udiv_qrnnd(&r, n1, n0, b.frac);
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/* Set lsb if there is a remainder, to set inexact. */
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a.frac = q | (r != 0);
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a.sign = sign;
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a.exp = exp;
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return a;
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}
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/* handle all the NaN cases */
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if (is_nan(a.cls) || is_nan(b.cls)) {
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return *parts_pick_nan(&a, &b, s);
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}
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/* 0/0 or Inf/Inf */
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if (a.cls == b.cls
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&&
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(a.cls == float_class_inf || a.cls == float_class_zero)) {
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float_raise(float_flag_invalid, s);
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parts_default_nan(&a, s);
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return a;
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}
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/* Inf / x or 0 / x */
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if (a.cls == float_class_inf || a.cls == float_class_zero) {
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a.sign = sign;
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return a;
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}
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/* Div 0 => Inf */
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if (b.cls == float_class_zero) {
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float_raise(float_flag_divbyzero, s);
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a.cls = float_class_inf;
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a.sign = sign;
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return a;
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}
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/* Div by Inf */
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if (b.cls == float_class_inf) {
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a.cls = float_class_zero;
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a.sign = sign;
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return a;
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}
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g_assert_not_reached();
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}
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float16 float16_div(float16 a, float16 b, float_status *status)
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{
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FloatParts64 pa, pb, pr;
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FloatParts64 pa, pb, *pr;
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float16_unpack_canonical(&pa, a, status);
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float16_unpack_canonical(&pb, b, status);
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pr = div_floats(pa, pb, status);
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pr = parts_div(&pa, &pb, status);
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return float16_round_pack_canonical(&pr, status);
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return float16_round_pack_canonical(pr, status);
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}
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static float32 QEMU_SOFTFLOAT_ATTR
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soft_f32_div(float32 a, float32 b, float_status *status)
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{
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FloatParts64 pa, pb, pr;
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FloatParts64 pa, pb, *pr;
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float32_unpack_canonical(&pa, a, status);
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float32_unpack_canonical(&pb, b, status);
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pr = div_floats(pa, pb, status);
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pr = parts_div(&pa, &pb, status);
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return float32_round_pack_canonical(&pr, status);
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return float32_round_pack_canonical(pr, status);
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}
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static float64 QEMU_SOFTFLOAT_ATTR
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soft_f64_div(float64 a, float64 b, float_status *status)
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{
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FloatParts64 pa, pb, pr;
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FloatParts64 pa, pb, *pr;
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float64_unpack_canonical(&pa, a, status);
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float64_unpack_canonical(&pb, b, status);
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pr = div_floats(pa, pb, status);
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pr = parts_div(&pa, &pb, status);
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return float64_round_pack_canonical(&pr, status);
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return float64_round_pack_canonical(pr, status);
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}
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static float hard_f32_div(float a, float b)
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@ -1985,20 +2006,28 @@ float64_div(float64 a, float64 b, float_status *s)
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f64_div_pre, f64_div_post);
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}
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/*
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* Returns the result of dividing the bfloat16
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* value `a' by the corresponding value `b'.
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*/
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bfloat16 bfloat16_div(bfloat16 a, bfloat16 b, float_status *status)
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bfloat16 QEMU_FLATTEN
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bfloat16_div(bfloat16 a, bfloat16 b, float_status *status)
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{
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FloatParts64 pa, pb, pr;
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FloatParts64 pa, pb, *pr;
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bfloat16_unpack_canonical(&pa, a, status);
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bfloat16_unpack_canonical(&pb, b, status);
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pr = div_floats(pa, pb, status);
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pr = parts_div(&pa, &pb, status);
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return bfloat16_round_pack_canonical(&pr, status);
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return bfloat16_round_pack_canonical(pr, status);
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}
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float128 QEMU_FLATTEN
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float128_div(float128 a, float128 b, float_status *status)
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{
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FloatParts128 pa, pb, *pr;
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float128_unpack_canonical(&pa, a, status);
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float128_unpack_canonical(&pb, b, status);
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pr = parts_div(&pa, &pb, status);
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return float128_round_pack_canonical(pr, status);
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}
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/*
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@ -7123,93 +7152,6 @@ float128 float128_round_to_int(float128 a, float_status *status)
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}
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/*----------------------------------------------------------------------------
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| Returns the result of dividing the quadruple-precision floating-point value
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| `a' by the corresponding value `b'. The operation is performed according to
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| the IEC/IEEE Standard for Binary Floating-Point Arithmetic.
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*----------------------------------------------------------------------------*/
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float128 float128_div(float128 a, float128 b, float_status *status)
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{
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bool aSign, bSign, zSign;
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int32_t aExp, bExp, zExp;
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uint64_t aSig0, aSig1, bSig0, bSig1, zSig0, zSig1, zSig2;
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uint64_t rem0, rem1, rem2, rem3, term0, term1, term2, term3;
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aSig1 = extractFloat128Frac1( a );
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aSig0 = extractFloat128Frac0( a );
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aExp = extractFloat128Exp( a );
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aSign = extractFloat128Sign( a );
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bSig1 = extractFloat128Frac1( b );
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bSig0 = extractFloat128Frac0( b );
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bExp = extractFloat128Exp( b );
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bSign = extractFloat128Sign( b );
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zSign = aSign ^ bSign;
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if ( aExp == 0x7FFF ) {
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if (aSig0 | aSig1) {
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return propagateFloat128NaN(a, b, status);
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}
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if ( bExp == 0x7FFF ) {
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if (bSig0 | bSig1) {
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return propagateFloat128NaN(a, b, status);
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}
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goto invalid;
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}
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return packFloat128( zSign, 0x7FFF, 0, 0 );
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}
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if ( bExp == 0x7FFF ) {
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if (bSig0 | bSig1) {
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return propagateFloat128NaN(a, b, status);
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}
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return packFloat128( zSign, 0, 0, 0 );
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}
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if ( bExp == 0 ) {
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if ( ( bSig0 | bSig1 ) == 0 ) {
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if ( ( aExp | aSig0 | aSig1 ) == 0 ) {
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invalid:
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float_raise(float_flag_invalid, status);
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return float128_default_nan(status);
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}
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float_raise(float_flag_divbyzero, status);
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return packFloat128( zSign, 0x7FFF, 0, 0 );
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}
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normalizeFloat128Subnormal( bSig0, bSig1, &bExp, &bSig0, &bSig1 );
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}
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if ( aExp == 0 ) {
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if ( ( aSig0 | aSig1 ) == 0 ) return packFloat128( zSign, 0, 0, 0 );
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normalizeFloat128Subnormal( aSig0, aSig1, &aExp, &aSig0, &aSig1 );
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}
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zExp = aExp - bExp + 0x3FFD;
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shortShift128Left(
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aSig0 | UINT64_C(0x0001000000000000), aSig1, 15, &aSig0, &aSig1 );
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shortShift128Left(
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bSig0 | UINT64_C(0x0001000000000000), bSig1, 15, &bSig0, &bSig1 );
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if ( le128( bSig0, bSig1, aSig0, aSig1 ) ) {
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shift128Right( aSig0, aSig1, 1, &aSig0, &aSig1 );
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++zExp;
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}
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zSig0 = estimateDiv128To64( aSig0, aSig1, bSig0 );
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mul128By64To192( bSig0, bSig1, zSig0, &term0, &term1, &term2 );
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sub192( aSig0, aSig1, 0, term0, term1, term2, &rem0, &rem1, &rem2 );
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while ( (int64_t) rem0 < 0 ) {
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--zSig0;
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add192( rem0, rem1, rem2, 0, bSig0, bSig1, &rem0, &rem1, &rem2 );
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}
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zSig1 = estimateDiv128To64( rem1, rem2, bSig0 );
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if ( ( zSig1 & 0x3FFF ) <= 4 ) {
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mul128By64To192( bSig0, bSig1, zSig1, &term1, &term2, &term3 );
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sub192( rem1, rem2, 0, term1, term2, term3, &rem1, &rem2, &rem3 );
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while ( (int64_t) rem1 < 0 ) {
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--zSig1;
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add192( rem1, rem2, rem3, 0, bSig0, bSig1, &rem1, &rem2, &rem3 );
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}
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zSig1 |= ( ( rem1 | rem2 | rem3 ) != 0 );
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}
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shift128ExtraRightJamming( zSig0, zSig1, 0, 15, &zSig0, &zSig1, &zSig2 );
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return roundAndPackFloat128(zSign, zExp, zSig0, zSig1, zSig2, status);
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}
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/*----------------------------------------------------------------------------
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| Returns the remainder of the quadruple-precision floating-point value `a'
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| with respect to the corresponding value `b'. The operation is performed
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