| Message ID | 20180109122252.17670-19-alex.bennee@linaro.org |
|---|---|
| State | Superseded |
| Headers | show |
| Series | re-factor softfloat and add fp16 functions | expand |
On 9 January 2018 at 12:22, Alex Bennée <alex.bennee@linaro.org> wrote: > This is one of the simpler manipulations you could make to a floating > point number. > > Signed-off-by: Alex Bennée <alex.bennee@linaro.org> > Reviewed-by: Richard Henderson <richard.henderson@linaro.org> > --- > fpu/softfloat.c | 104 +++++++++++++++--------------------------------- > include/fpu/softfloat.h | 1 + > 2 files changed, 32 insertions(+), 73 deletions(-) > > diff --git a/fpu/softfloat.c b/fpu/softfloat.c > index bb68d77f72..3647f6ca03 100644 > --- a/fpu/softfloat.c > +++ b/fpu/softfloat.c > @@ -1663,6 +1663,37 @@ float64 uint16_to_float64(uint16_t a, float_status *status) > return uint64_to_float64(a, status); > } > > +/* Multiply A by 2 raised to the power N. */ > +static decomposed_parts scalbn_decomposed(decomposed_parts a, int n, > + float_status *s) > +{ > + if (a.cls == float_class_normal) { > + a.exp += n; > + } > + return a; > +} > + > +float16 float16_scalbn(float16 a, int n, float_status *status) > +{ > + decomposed_parts pa = float16_unpack_canonical(a, status); > + decomposed_parts pr = scalbn_decomposed(pa, n, status); > + return float16_round_pack_canonical(pr, status); > +} > + > +float32 float32_scalbn(float32 a, int n, float_status *status) > +{ > + decomposed_parts pa = float32_unpack_canonical(a, status); > + decomposed_parts pr = scalbn_decomposed(pa, n, status); > + return float32_round_pack_canonical(pr, status); > +} > + > +float64 float64_scalbn(float64 a, int n, float_status *status) > +{ > + decomposed_parts pa = float64_unpack_canonical(a, status); > + decomposed_parts pr = scalbn_decomposed(pa, n, status); > + return float64_round_pack_canonical(pr, status); > +} The old code used propagateFloat32NaN(a, a, status) if the input was a NaN, to cause us to raise the invalid flag, maybe return a default NaN, maybe silence the NaN. I can't see where the new code is doing this? thanks -- PMM
Peter Maydell <peter.maydell@linaro.org> writes: > On 9 January 2018 at 12:22, Alex Bennée <alex.bennee@linaro.org> wrote: >> This is one of the simpler manipulations you could make to a floating >> point number. >> >> Signed-off-by: Alex Bennée <alex.bennee@linaro.org> >> Reviewed-by: Richard Henderson <richard.henderson@linaro.org> >> --- >> fpu/softfloat.c | 104 +++++++++++++++--------------------------------- >> include/fpu/softfloat.h | 1 + >> 2 files changed, 32 insertions(+), 73 deletions(-) >> >> diff --git a/fpu/softfloat.c b/fpu/softfloat.c >> index bb68d77f72..3647f6ca03 100644 >> --- a/fpu/softfloat.c >> +++ b/fpu/softfloat.c >> @@ -1663,6 +1663,37 @@ float64 uint16_to_float64(uint16_t a, float_status *status) >> return uint64_to_float64(a, status); >> } >> >> +/* Multiply A by 2 raised to the power N. */ >> +static decomposed_parts scalbn_decomposed(decomposed_parts a, int n, >> + float_status *s) >> +{ >> + if (a.cls == float_class_normal) { >> + a.exp += n; >> + } >> + return a; >> +} >> + >> +float16 float16_scalbn(float16 a, int n, float_status *status) >> +{ >> + decomposed_parts pa = float16_unpack_canonical(a, status); >> + decomposed_parts pr = scalbn_decomposed(pa, n, status); >> + return float16_round_pack_canonical(pr, status); >> +} >> + >> +float32 float32_scalbn(float32 a, int n, float_status *status) >> +{ >> + decomposed_parts pa = float32_unpack_canonical(a, status); >> + decomposed_parts pr = scalbn_decomposed(pa, n, status); >> + return float32_round_pack_canonical(pr, status); >> +} >> + >> +float64 float64_scalbn(float64 a, int n, float_status *status) >> +{ >> + decomposed_parts pa = float64_unpack_canonical(a, status); >> + decomposed_parts pr = scalbn_decomposed(pa, n, status); >> + return float64_round_pack_canonical(pr, status); >> +} > > The old code used propagateFloat32NaN(a, a, status) if the > input was a NaN, to cause us to raise the invalid flag, > maybe return a default NaN, maybe silence the NaN. I can't > see where the new code is doing this? invalid and setting msnan are done during the unpack stage when the input is canonicalized. NaN's may raise their signals when we round and pack any results. > > thanks > -- PMM -- Alex Bennée
diff --git a/fpu/softfloat.c b/fpu/softfloat.c index bb68d77f72..3647f6ca03 100644 --- a/fpu/softfloat.c +++ b/fpu/softfloat.c @@ -1663,6 +1663,37 @@ float64 uint16_to_float64(uint16_t a, float_status *status) return uint64_to_float64(a, status); } +/* Multiply A by 2 raised to the power N. */ +static decomposed_parts scalbn_decomposed(decomposed_parts a, int n, + float_status *s) +{ + if (a.cls == float_class_normal) { + a.exp += n; + } + return a; +} + +float16 float16_scalbn(float16 a, int n, float_status *status) +{ + decomposed_parts pa = float16_unpack_canonical(a, status); + decomposed_parts pr = scalbn_decomposed(pa, n, status); + return float16_round_pack_canonical(pr, status); +} + +float32 float32_scalbn(float32 a, int n, float_status *status) +{ + decomposed_parts pa = float32_unpack_canonical(a, status); + decomposed_parts pr = scalbn_decomposed(pa, n, status); + return float32_round_pack_canonical(pr, status); +} + +float64 float64_scalbn(float64 a, int n, float_status *status) +{ + decomposed_parts pa = float64_unpack_canonical(a, status); + decomposed_parts pr = scalbn_decomposed(pa, n, 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 @@ -6992,79 +7023,6 @@ MINMAX(32) MINMAX(64) -/* Multiply A by 2 raised to the power N. */ -float32 float32_scalbn(float32 a, int n, float_status *status) -{ - flag aSign; - int16_t aExp; - uint32_t aSig; - - a = float32_squash_input_denormal(a, status); - aSig = extractFloat32Frac( a ); - aExp = extractFloat32Exp( a ); - aSign = extractFloat32Sign( a ); - - if ( aExp == 0xFF ) { - if ( aSig ) { - return propagateFloat32NaN(a, a, status); - } - return a; - } - if (aExp != 0) { - aSig |= 0x00800000; - } else if (aSig == 0) { - return a; - } else { - aExp++; - } - - if (n > 0x200) { - n = 0x200; - } else if (n < -0x200) { - n = -0x200; - } - - aExp += n - 1; - aSig <<= 7; - return normalizeRoundAndPackFloat32(aSign, aExp, aSig, status); -} - -float64 float64_scalbn(float64 a, int n, float_status *status) -{ - flag aSign; - int16_t aExp; - uint64_t aSig; - - a = float64_squash_input_denormal(a, status); - aSig = extractFloat64Frac( a ); - aExp = extractFloat64Exp( a ); - aSign = extractFloat64Sign( a ); - - if ( aExp == 0x7FF ) { - if ( aSig ) { - return propagateFloat64NaN(a, a, status); - } - return a; - } - if (aExp != 0) { - aSig |= LIT64( 0x0010000000000000 ); - } else if (aSig == 0) { - return a; - } else { - aExp++; - } - - if (n > 0x1000) { - n = 0x1000; - } else if (n < -0x1000) { - n = -0x1000; - } - - aExp += n - 1; - aSig <<= 10; - return normalizeRoundAndPackFloat64(aSign, aExp, aSig, status); -} - floatx80 floatx80_scalbn(floatx80 a, int n, float_status *status) { flag aSign; diff --git a/include/fpu/softfloat.h b/include/fpu/softfloat.h index aa9e30d254..41338184d5 100644 --- a/include/fpu/softfloat.h +++ b/include/fpu/softfloat.h @@ -326,6 +326,7 @@ float16 float16_sub(float16, float16, float_status *status); float16 float16_mul(float16, float16, float_status *status); float16 float16_muladd(float16, float16, float16, int, float_status *status); float16 float16_div(float16, float16, float_status *status); +float16 float16_scalbn(float16, int, float_status *status); int float16_is_quiet_nan(float16, float_status *status); int float16_is_signaling_nan(float16, float_status *status);