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fpu/softfloat: re-factor mul 

We can now add float16_mul and use the common decompose and
canonicalize functions to have a single implementation for
float16/32/64 versions.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
This commit is contained in:
Alex Bennée 2017-12-07 18:56:50 +00:00
parent 6fff216769
commit 74d707e2cc
2 changed files with 82 additions and 128 deletions
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209
fpu/softfloat.c
View File

@ -735,6 +735,87 @@ float64 __attribute__((flatten)) float64_sub(float64 a, float64 b,
return float64_round_pack_canonical(pr, status);
}
/*
* Returns the result of multiplying the floating-point values `a' and
* `b'. The operation is performed according to the IEC/IEEE Standard
* for Binary Floating-Point Arithmetic.
*/
static FloatParts mul_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 hi, lo;
int exp = a.exp + b.exp;
mul64To128(a.frac, b.frac, &hi, &lo);
shift128RightJamming(hi, lo, DECOMPOSED_BINARY_POINT, &hi, &lo);
if (lo & DECOMPOSED_OVERFLOW_BIT) {
shift64RightJamming(lo, 1, &lo);
exp += 1;
}
/* Re-use a */
a.exp = exp;
a.sign = sign;
a.frac = lo;
return a;
}
/* handle all the NaN cases */
if (is_nan(a.cls) || is_nan(b.cls)) {
return pick_nan(a, b, s);
}
/* Inf * Zero == NaN */
if ((a.cls == float_class_inf && b.cls == float_class_zero) ||
(a.cls == float_class_zero && b.cls == float_class_inf)) {
s->float_exception_flags |= float_flag_invalid;
a.cls = float_class_dnan;
a.sign = sign;
return a;
}
/* Multiply by 0 or Inf */
if (a.cls == float_class_inf || a.cls == float_class_zero) {
a.sign = sign;
return a;
}
if (b.cls == float_class_inf || b.cls == float_class_zero) {
b.sign = sign;
return b;
}
g_assert_not_reached();
}
float16 __attribute__((flatten)) float16_mul(float16 a, float16 b,
float_status *status)
{
FloatParts pa = float16_unpack_canonical(a, status);
FloatParts pb = float16_unpack_canonical(b, status);
FloatParts pr = mul_floats(pa, pb, status);
return float16_round_pack_canonical(pr, status);
}
float32 __attribute__((flatten)) float32_mul(float32 a, float32 b,
float_status *status)
{
FloatParts pa = float32_unpack_canonical(a, status);
FloatParts pb = float32_unpack_canonical(b, status);
FloatParts pr = mul_floats(pa, pb, status);
return float32_round_pack_canonical(pr, status);
}
float64 __attribute__((flatten)) float64_mul(float64 a, float64 b,
float_status *status)
{
FloatParts pa = float64_unpack_canonical(a, status);
FloatParts pb = float64_unpack_canonical(b, status);
FloatParts pr = mul_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
@ -2546,70 +2627,6 @@ float32 float32_round_to_int(float32 a, float_status *status)
}
/*----------------------------------------------------------------------------
| Returns the result of multiplying the single-precision floating-point values
| `a' and `b'. The operation is performed according to the IEC/IEEE Standard
| for Binary Floating-Point Arithmetic.
*----------------------------------------------------------------------------*/
float32 float32_mul(float32 a, float32 b, float_status *status)
{
flag aSign, bSign, zSign;
int aExp, bExp, zExp;
uint32_t aSig, bSig;
uint64_t zSig64;
uint32_t 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 || ( ( bExp == 0xFF ) && bSig ) ) {
return propagateFloat32NaN(a, b, status);
}
if ( ( bExp | bSig ) == 0 ) {
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);
}
if ( ( aExp | aSig ) == 0 ) {
float_raise(float_flag_invalid, status);
return float32_default_nan(status);
}
return packFloat32( zSign, 0xFF, 0 );
}
if ( aExp == 0 ) {
if ( aSig == 0 ) return packFloat32( zSign, 0, 0 );
normalizeFloat32Subnormal( aSig, &aExp, &aSig );
}
if ( bExp == 0 ) {
if ( bSig == 0 ) return packFloat32( zSign, 0, 0 );
normalizeFloat32Subnormal( bSig, &bExp, &bSig );
}
zExp = aExp + bExp - 0x7F;
aSig = ( aSig | 0x00800000 )<<7;
bSig = ( bSig | 0x00800000 )<<8;
shift64RightJamming( ( (uint64_t) aSig ) * bSig, 32, &zSig64 );
zSig = zSig64;
if ( 0 <= (int32_t) ( zSig<<1 ) ) {
zSig <<= 1;
--zExp;
}
return roundAndPackFloat32(zSign, zExp, zSig, status);
}
/*----------------------------------------------------------------------------
| Returns the result of dividing the single-precision floating-point value `a'
@ -4142,70 +4159,6 @@ float64 float64_trunc_to_int(float64 a, float_status *status)
return res;
}
/*----------------------------------------------------------------------------
| Returns the result of multiplying the double-precision floating-point values
| `a' and `b'. The operation is performed according to the IEC/IEEE Standard
| for Binary Floating-Point Arithmetic.
*----------------------------------------------------------------------------*/
float64 float64_mul(float64 a, float64 b, float_status *status)
{
flag aSign, bSign, zSign;
int aExp, bExp, zExp;
uint64_t aSig, bSig, zSig0, zSig1;
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 || ( ( bExp == 0x7FF ) && bSig ) ) {
return propagateFloat64NaN(a, b, status);
}
if ( ( bExp | bSig ) == 0 ) {
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);
}
if ( ( aExp | aSig ) == 0 ) {
float_raise(float_flag_invalid, status);
return float64_default_nan(status);
}
return packFloat64( zSign, 0x7FF, 0 );
}
if ( aExp == 0 ) {
if ( aSig == 0 ) return packFloat64( zSign, 0, 0 );
normalizeFloat64Subnormal( aSig, &aExp, &aSig );
}
if ( bExp == 0 ) {
if ( bSig == 0 ) return packFloat64( zSign, 0, 0 );
normalizeFloat64Subnormal( bSig, &bExp, &bSig );
}
zExp = aExp + bExp - 0x3FF;
aSig = ( aSig | LIT64( 0x0010000000000000 ) )<<10;
bSig = ( bSig | LIT64( 0x0010000000000000 ) )<<11;
mul64To128( aSig, bSig, &zSig0, &zSig1 );
zSig0 |= ( zSig1 != 0 );
if ( 0 <= (int64_t) ( zSig0<<1 ) ) {
zSig0 <<= 1;
--zExp;
}
return roundAndPackFloat64(zSign, zExp, zSig0, status);
}
/*----------------------------------------------------------------------------
| Returns the result of dividing the double-precision floating-point value `a'
| by the corresponding value `b'. The operation is performed according to

1
include/fpu/softfloat.h
View File

@ -239,6 +239,7 @@ 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);
int float16_is_quiet_nan(float16, float_status *status);
int float16_is_signaling_nan(float16, float_status *status);