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authorRichard Henderson <richard.henderson@linaro.org>2020-11-21 16:40:57 -0800
committerRichard Henderson <richard.henderson@linaro.org>2021-06-03 14:09:02 -0700
commitc1b6299be12d744f3baeb53f84ab5e018ec642b8 (patch)
tree1b50ee5a679617bec182b3eb7d8db1f85c99e977 /fpu/softfloat.c
parent7ccae4ce7e4bb7c2f873986b6b6b0fc680e0a8bd (diff)
softfloat: Convert floatx80_add/sub to FloatParts
Since this is the first such, this includes all of the packing and unpacking routines as well. Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Diffstat (limited to 'fpu/softfloat.c')
-rw-r--r--fpu/softfloat.c339
1 files changed, 136 insertions, 203 deletions
diff --git a/fpu/softfloat.c b/fpu/softfloat.c
index b6a50e5e95..737f5d7701 100644
--- a/fpu/softfloat.c
+++ b/fpu/softfloat.c
@@ -578,14 +578,14 @@ typedef struct {
} FloatFmt;
/* Expand fields based on the size of exponent and fraction */
-#define FLOAT_PARAMS_(E, F) \
+#define FLOAT_PARAMS_(E) \
.exp_size = E, \
.exp_bias = ((1 << E) - 1) >> 1, \
- .exp_max = (1 << E) - 1, \
- .frac_size = F
+ .exp_max = (1 << E) - 1
#define FLOAT_PARAMS(E, F) \
- FLOAT_PARAMS_(E, F), \
+ FLOAT_PARAMS_(E), \
+ .frac_size = F, \
.frac_shift = (-F - 1) & 63, \
.round_mask = (1ull << ((-F - 1) & 63)) - 1
@@ -614,6 +614,18 @@ static const FloatFmt float128_params = {
FLOAT_PARAMS(15, 112)
};
+#define FLOATX80_PARAMS(R) \
+ FLOAT_PARAMS_(15), \
+ .frac_size = R == 64 ? 63 : R, \
+ .frac_shift = 0, \
+ .round_mask = R == 64 ? -1 : (1ull << ((-R - 1) & 63)) - 1
+
+static const FloatFmt floatx80_params[3] = {
+ [floatx80_precision_s] = { FLOATX80_PARAMS(23) },
+ [floatx80_precision_d] = { FLOATX80_PARAMS(52) },
+ [floatx80_precision_x] = { FLOATX80_PARAMS(64) },
+};
+
/* Unpack a float to parts, but do not canonicalize. */
static void unpack_raw64(FloatParts64 *r, const FloatFmt *fmt, uint64_t raw)
{
@@ -648,6 +660,16 @@ static inline void float64_unpack_raw(FloatParts64 *p, float64 f)
unpack_raw64(p, &float64_params, f);
}
+static void floatx80_unpack_raw(FloatParts128 *p, floatx80 f)
+{
+ *p = (FloatParts128) {
+ .cls = float_class_unclassified,
+ .sign = extract32(f.high, 15, 1),
+ .exp = extract32(f.high, 0, 15),
+ .frac_hi = f.low
+ };
+}
+
static void float128_unpack_raw(FloatParts128 *p, float128 f)
{
const int f_size = float128_params.frac_size - 64;
@@ -1536,6 +1558,92 @@ static float128 float128_round_pack_canonical(FloatParts128 *p,
return float128_pack_raw(p);
}
+/* Returns false if the encoding is invalid. */
+static bool floatx80_unpack_canonical(FloatParts128 *p, floatx80 f,
+ float_status *s)
+{
+ /* Ensure rounding precision is set before beginning. */
+ switch (s->floatx80_rounding_precision) {
+ case floatx80_precision_x:
+ case floatx80_precision_d:
+ case floatx80_precision_s:
+ break;
+ default:
+ g_assert_not_reached();
+ }
+
+ if (unlikely(floatx80_invalid_encoding(f))) {
+ float_raise(float_flag_invalid, s);
+ return false;
+ }
+
+ floatx80_unpack_raw(p, f);
+
+ if (likely(p->exp != floatx80_params[floatx80_precision_x].exp_max)) {
+ parts_canonicalize(p, s, &floatx80_params[floatx80_precision_x]);
+ } else {
+ /* The explicit integer bit is ignored, after invalid checks. */
+ p->frac_hi &= MAKE_64BIT_MASK(0, 63);
+ p->cls = (p->frac_hi == 0 ? float_class_inf
+ : parts_is_snan_frac(p->frac_hi, s)
+ ? float_class_snan : float_class_qnan);
+ }
+ return true;
+}
+
+static floatx80 floatx80_round_pack_canonical(FloatParts128 *p,
+ float_status *s)
+{
+ const FloatFmt *fmt = &floatx80_params[s->floatx80_rounding_precision];
+ uint64_t frac;
+ int exp;
+
+ switch (p->cls) {
+ case float_class_normal:
+ if (s->floatx80_rounding_precision == floatx80_precision_x) {
+ parts_uncanon_normal(p, s, fmt);
+ frac = p->frac_hi;
+ exp = p->exp;
+ } else {
+ FloatParts64 p64;
+
+ p64.sign = p->sign;
+ p64.exp = p->exp;
+ frac_truncjam(&p64, p);
+ parts_uncanon_normal(&p64, s, fmt);
+ frac = p64.frac;
+ exp = p64.exp;
+ }
+ if (exp != fmt->exp_max) {
+ break;
+ }
+ /* rounded to inf -- fall through to set frac correctly */
+
+ case float_class_inf:
+ /* x86 and m68k differ in the setting of the integer bit. */
+ frac = floatx80_infinity_low;
+ exp = fmt->exp_max;
+ break;
+
+ case float_class_zero:
+ frac = 0;
+ exp = 0;
+ break;
+
+ case float_class_snan:
+ case float_class_qnan:
+ /* NaNs have the integer bit set. */
+ frac = p->frac_hi | (1ull << 63);
+ exp = fmt->exp_max;
+ break;
+
+ default:
+ g_assert_not_reached();
+ }
+
+ return packFloatx80(p->sign, exp, frac);
+}
+
/*
* Addition and subtraction
*/
@@ -1725,6 +1833,30 @@ float128 float128_sub(float128 a, float128 b, float_status *status)
return float128_addsub(a, b, status, true);
}
+static floatx80 QEMU_FLATTEN
+floatx80_addsub(floatx80 a, floatx80 b, float_status *status, bool subtract)
+{
+ FloatParts128 pa, pb, *pr;
+
+ if (!floatx80_unpack_canonical(&pa, a, status) ||
+ !floatx80_unpack_canonical(&pb, b, status)) {
+ return floatx80_default_nan(status);
+ }
+
+ pr = parts_addsub(&pa, &pb, status, subtract);
+ return floatx80_round_pack_canonical(pr, status);
+}
+
+floatx80 floatx80_add(floatx80 a, floatx80 b, float_status *status)
+{
+ return floatx80_addsub(a, b, status, false);
+}
+
+floatx80 floatx80_sub(floatx80 a, floatx80 b, float_status *status)
+{
+ return floatx80_addsub(a, b, status, true);
+}
+
/*
* Multiplication
*/
@@ -5732,205 +5864,6 @@ floatx80 floatx80_round_to_int(floatx80 a, float_status *status)
}
/*----------------------------------------------------------------------------
-| Returns the result of adding the absolute values of the extended double-
-| 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 floatx80 addFloatx80Sigs(floatx80 a, floatx80 b, bool zSign,
- float_status *status)
-{
- int32_t aExp, bExp, zExp;
- uint64_t aSig, bSig, zSig0, zSig1;
- int32_t expDiff;
-
- aSig = extractFloatx80Frac( a );
- aExp = extractFloatx80Exp( a );
- bSig = extractFloatx80Frac( b );
- bExp = extractFloatx80Exp( b );
- expDiff = aExp - bExp;
- if ( 0 < expDiff ) {
- if ( aExp == 0x7FFF ) {
- if ((uint64_t)(aSig << 1)) {
- return propagateFloatx80NaN(a, b, status);
- }
- return a;
- }
- if ( bExp == 0 ) --expDiff;
- shift64ExtraRightJamming( bSig, 0, expDiff, &bSig, &zSig1 );
- zExp = aExp;
- }
- else if ( expDiff < 0 ) {
- if ( bExp == 0x7FFF ) {
- if ((uint64_t)(bSig << 1)) {
- return propagateFloatx80NaN(a, b, status);
- }
- return packFloatx80(zSign,
- floatx80_infinity_high,
- floatx80_infinity_low);
- }
- if ( aExp == 0 ) ++expDiff;
- shift64ExtraRightJamming( aSig, 0, - expDiff, &aSig, &zSig1 );
- zExp = bExp;
- }
- else {
- if ( aExp == 0x7FFF ) {
- if ( (uint64_t) ( ( aSig | bSig )<<1 ) ) {
- return propagateFloatx80NaN(a, b, status);
- }
- return a;
- }
- zSig1 = 0;
- zSig0 = aSig + bSig;
- if ( aExp == 0 ) {
- if ((aSig | bSig) & UINT64_C(0x8000000000000000) && zSig0 < aSig) {
- /* At least one of the values is a pseudo-denormal,
- * and there is a carry out of the result. */
- zExp = 1;
- goto shiftRight1;
- }
- if (zSig0 == 0) {
- return packFloatx80(zSign, 0, 0);
- }
- normalizeFloatx80Subnormal( zSig0, &zExp, &zSig0 );
- goto roundAndPack;
- }
- zExp = aExp;
- goto shiftRight1;
- }
- zSig0 = aSig + bSig;
- if ( (int64_t) zSig0 < 0 ) goto roundAndPack;
- shiftRight1:
- shift64ExtraRightJamming( zSig0, zSig1, 1, &zSig0, &zSig1 );
- zSig0 |= UINT64_C(0x8000000000000000);
- ++zExp;
- roundAndPack:
- return roundAndPackFloatx80(status->floatx80_rounding_precision,
- zSign, zExp, zSig0, zSig1, status);
-}
-
-/*----------------------------------------------------------------------------
-| Returns the result of subtracting the absolute values of the extended
-| double-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 floatx80 subFloatx80Sigs(floatx80 a, floatx80 b, bool zSign,
- float_status *status)
-{
- int32_t aExp, bExp, zExp;
- uint64_t aSig, bSig, zSig0, zSig1;
- int32_t expDiff;
-
- aSig = extractFloatx80Frac( a );
- aExp = extractFloatx80Exp( a );
- bSig = extractFloatx80Frac( b );
- bExp = extractFloatx80Exp( b );
- expDiff = aExp - bExp;
- if ( 0 < expDiff ) goto aExpBigger;
- if ( expDiff < 0 ) goto bExpBigger;
- if ( aExp == 0x7FFF ) {
- if ( (uint64_t) ( ( aSig | bSig )<<1 ) ) {
- return propagateFloatx80NaN(a, b, status);
- }
- float_raise(float_flag_invalid, status);
- return floatx80_default_nan(status);
- }
- if ( aExp == 0 ) {
- aExp = 1;
- bExp = 1;
- }
- zSig1 = 0;
- if ( bSig < aSig ) goto aBigger;
- if ( aSig < bSig ) goto bBigger;
- return packFloatx80(status->float_rounding_mode == float_round_down, 0, 0);
- bExpBigger:
- if ( bExp == 0x7FFF ) {
- if ((uint64_t)(bSig << 1)) {
- return propagateFloatx80NaN(a, b, status);
- }
- return packFloatx80(zSign ^ 1, floatx80_infinity_high,
- floatx80_infinity_low);
- }
- if ( aExp == 0 ) ++expDiff;
- shift128RightJamming( aSig, 0, - expDiff, &aSig, &zSig1 );
- bBigger:
- sub128( bSig, 0, aSig, zSig1, &zSig0, &zSig1 );
- zExp = bExp;
- zSign ^= 1;
- goto normalizeRoundAndPack;
- aExpBigger:
- if ( aExp == 0x7FFF ) {
- if ((uint64_t)(aSig << 1)) {
- return propagateFloatx80NaN(a, b, status);
- }
- return a;
- }
- if ( bExp == 0 ) --expDiff;
- shift128RightJamming( bSig, 0, expDiff, &bSig, &zSig1 );
- aBigger:
- sub128( aSig, 0, bSig, zSig1, &zSig0, &zSig1 );
- zExp = aExp;
- normalizeRoundAndPack:
- return normalizeRoundAndPackFloatx80(status->floatx80_rounding_precision,
- zSign, zExp, zSig0, zSig1, status);
-}
-
-/*----------------------------------------------------------------------------
-| Returns the result of adding the extended double-precision floating-point
-| values `a' and `b'. The operation is performed according to the IEC/IEEE
-| Standard for Binary Floating-Point Arithmetic.
-*----------------------------------------------------------------------------*/
-
-floatx80 floatx80_add(floatx80 a, floatx80 b, float_status *status)
-{
- bool aSign, bSign;
-
- if (floatx80_invalid_encoding(a) || floatx80_invalid_encoding(b)) {
- float_raise(float_flag_invalid, status);
- return floatx80_default_nan(status);
- }
- aSign = extractFloatx80Sign( a );
- bSign = extractFloatx80Sign( b );
- if ( aSign == bSign ) {
- return addFloatx80Sigs(a, b, aSign, status);
- }
- else {
- return subFloatx80Sigs(a, b, aSign, status);
- }
-
-}
-
-/*----------------------------------------------------------------------------
-| Returns the result of subtracting the extended double-precision floating-
-| point values `a' and `b'. The operation is performed according to the
-| IEC/IEEE Standard for Binary Floating-Point Arithmetic.
-*----------------------------------------------------------------------------*/
-
-floatx80 floatx80_sub(floatx80 a, floatx80 b, float_status *status)
-{
- bool aSign, bSign;
-
- if (floatx80_invalid_encoding(a) || floatx80_invalid_encoding(b)) {
- float_raise(float_flag_invalid, status);
- return floatx80_default_nan(status);
- }
- aSign = extractFloatx80Sign( a );
- bSign = extractFloatx80Sign( b );
- if ( aSign == bSign ) {
- return subFloatx80Sigs(a, b, aSign, status);
- }
- else {
- return addFloatx80Sigs(a, b, aSign, status);
- }
-
-}
-
-/*----------------------------------------------------------------------------
| Returns the result of multiplying the extended double-precision floating-
| point values `a' and `b'. The operation is performed according to the
| IEC/IEEE Standard for Binary Floating-Point Arithmetic.