| Message ID | 20180109122252.17670-7-alex.bennee@linaro.org |
|---|---|
| State | Superseded |
| Headers | show |
| Series | re-factor softfloat and add fp16 functions | expand |
Hi Alex, On 01/09/2018 09:22 AM, Alex Bennée wrote: > This defines the same set of common constants for float 16 as defined > for 32 and 64 bit floats. These are often used by target helper > functions. I've also removed constants that are not used by anybody. > > Signed-off-by: Alex Bennée <alex.bennee@linaro.org> > > --- > v2 > - fixup constants, remove unused onces > --- > include/fpu/softfloat.h | 8 +++++--- > 1 file changed, 5 insertions(+), 3 deletions(-) > > diff --git a/include/fpu/softfloat.h b/include/fpu/softfloat.h > index 8ab5d0df47..e64bf62f3d 100644 > --- a/include/fpu/softfloat.h > +++ b/include/fpu/softfloat.h > @@ -368,6 +368,11 @@ static inline float16 float16_set_sign(float16 a, int sign) > return make_float16((float16_val(a) & 0x7fff) | (sign << 15)); > } > > +#define float16_zero make_float16(0) > +#define float16_one make_float16(0x3a00) I still disagree with this one, it seems your bits 9/10 are inverted (mantissa msb with biased exponent lsb). S EEEEE TTTTTTTTTT 0x3a00 = 0 01110 1000000000 having: S=0 E=0b01110=14 T=0b1000000000=512 I get: (-1)^0 * 2^(14-15) * (1 + (2^-10) * 512) = 1 * 0.5 * (1 + 0.5) = 0.75 With 0x3c00 I get: S EEEEE TTTTTTTTTT 0x3c00 = 0 01111 0000000000 S=0 E=0b01111=15 T=0b0000000000=0 (-1)^0 * 2^(15-15) * (1 + (2^-10) * 0) = 1 * 2^0 * (1 + 0) = 1 The rest is OK. Changing by "#define float16_one make_float16(0x3c00)": Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org> > +#define float16_half make_float16(0x3800) > +#define float16_infinity make_float16(0x7c00) > + > /*---------------------------------------------------------------------------- > | The pattern for a default generated half-precision NaN. > *----------------------------------------------------------------------------*/ > @@ -474,8 +479,6 @@ static inline float32 float32_set_sign(float32 a, int sign) > > #define float32_zero make_float32(0) > #define float32_one make_float32(0x3f800000) > -#define float32_ln2 make_float32(0x3f317218) > -#define float32_pi make_float32(0x40490fdb) > #define float32_half make_float32(0x3f000000) > #define float32_infinity make_float32(0x7f800000) > > @@ -588,7 +591,6 @@ static inline float64 float64_set_sign(float64 a, int sign) > #define float64_zero make_float64(0) > #define float64_one make_float64(0x3ff0000000000000LL) > #define float64_ln2 make_float64(0x3fe62e42fefa39efLL) > -#define float64_pi make_float64(0x400921fb54442d18LL) > #define float64_half make_float64(0x3fe0000000000000LL) > #define float64_infinity make_float64(0x7ff0000000000000LL) > >
Philippe Mathieu-Daudé <f4bug@amsat.org> writes: > Hi Alex, > > On 01/09/2018 09:22 AM, Alex Bennée wrote: >> This defines the same set of common constants for float 16 as defined >> for 32 and 64 bit floats. These are often used by target helper >> functions. I've also removed constants that are not used by anybody. >> >> Signed-off-by: Alex Bennée <alex.bennee@linaro.org> >> >> --- >> v2 >> - fixup constants, remove unused onces >> --- >> include/fpu/softfloat.h | 8 +++++--- >> 1 file changed, 5 insertions(+), 3 deletions(-) >> >> diff --git a/include/fpu/softfloat.h b/include/fpu/softfloat.h >> index 8ab5d0df47..e64bf62f3d 100644 >> --- a/include/fpu/softfloat.h >> +++ b/include/fpu/softfloat.h >> @@ -368,6 +368,11 @@ static inline float16 float16_set_sign(float16 a, int sign) >> return make_float16((float16_val(a) & 0x7fff) | (sign << 15)); >> } >> >> +#define float16_zero make_float16(0) >> +#define float16_one make_float16(0x3a00) > > I still disagree with this one, it seems your bits 9/10 are inverted > (mantissa msb with biased exponent lsb). > > S EEEEE TTTTTTTTTT > 0x3a00 = 0 01110 1000000000 > > having: > S=0 > E=0b01110=14 > T=0b1000000000=512 > > I get: > (-1)^0 * 2^(14-15) * (1 + (2^-10) * 512) = 1 * 0.5 * (1 + 0.5) = 0.75 > > With 0x3c00 I get: > > S EEEEE TTTTTTTTTT > 0x3c00 = 0 01111 0000000000 > S=0 > E=0b01111=15 > T=0b0000000000=0 > > (-1)^0 * 2^(15-15) * (1 + (2^-10) * 0) = 1 * 2^0 * (1 + 0) = 1 > > The rest is OK. > > Changing by "#define float16_one make_float16(0x3c00)": > Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org> Dam it, I thought I'd fixed them all. Thanks for the catch. > >> +#define float16_half make_float16(0x3800) >> +#define float16_infinity make_float16(0x7c00) >> + >> /*---------------------------------------------------------------------------- >> | The pattern for a default generated half-precision NaN. >> *----------------------------------------------------------------------------*/ >> @@ -474,8 +479,6 @@ static inline float32 float32_set_sign(float32 a, int sign) >> >> #define float32_zero make_float32(0) >> #define float32_one make_float32(0x3f800000) >> -#define float32_ln2 make_float32(0x3f317218) >> -#define float32_pi make_float32(0x40490fdb) >> #define float32_half make_float32(0x3f000000) >> #define float32_infinity make_float32(0x7f800000) >> >> @@ -588,7 +591,6 @@ static inline float64 float64_set_sign(float64 a, int sign) >> #define float64_zero make_float64(0) >> #define float64_one make_float64(0x3ff0000000000000LL) >> #define float64_ln2 make_float64(0x3fe62e42fefa39efLL) >> -#define float64_pi make_float64(0x400921fb54442d18LL) >> #define float64_half make_float64(0x3fe0000000000000LL) >> #define float64_infinity make_float64(0x7ff0000000000000LL) >> >> -- Alex Bennée
On 9 January 2018 at 12:22, Alex Bennée <alex.bennee@linaro.org> wrote: > This defines the same set of common constants for float 16 as defined > for 32 and 64 bit floats. These are often used by target helper > functions. I've also removed constants that are not used by anybody. > > Signed-off-by: Alex Bennée <alex.bennee@linaro.org> With the fix to the value for float16_one that Philippe suggests: Reviewed-by: Peter Maydell <peter.maydell@linaro.org> thanks -- PMM
diff --git a/include/fpu/softfloat.h b/include/fpu/softfloat.h index 8ab5d0df47..e64bf62f3d 100644 --- a/include/fpu/softfloat.h +++ b/include/fpu/softfloat.h @@ -368,6 +368,11 @@ static inline float16 float16_set_sign(float16 a, int sign) return make_float16((float16_val(a) & 0x7fff) | (sign << 15)); } +#define float16_zero make_float16(0) +#define float16_one make_float16(0x3a00) +#define float16_half make_float16(0x3800) +#define float16_infinity make_float16(0x7c00) + /*---------------------------------------------------------------------------- | The pattern for a default generated half-precision NaN. *----------------------------------------------------------------------------*/ @@ -474,8 +479,6 @@ static inline float32 float32_set_sign(float32 a, int sign) #define float32_zero make_float32(0) #define float32_one make_float32(0x3f800000) -#define float32_ln2 make_float32(0x3f317218) -#define float32_pi make_float32(0x40490fdb) #define float32_half make_float32(0x3f000000) #define float32_infinity make_float32(0x7f800000) @@ -588,7 +591,6 @@ static inline float64 float64_set_sign(float64 a, int sign) #define float64_zero make_float64(0) #define float64_one make_float64(0x3ff0000000000000LL) #define float64_ln2 make_float64(0x3fe62e42fefa39efLL) -#define float64_pi make_float64(0x400921fb54442d18LL) #define float64_half make_float64(0x3fe0000000000000LL) #define float64_infinity make_float64(0x7ff0000000000000LL)
This defines the same set of common constants for float 16 as defined for 32 and 64 bit floats. These are often used by target helper functions. I've also removed constants that are not used by anybody. Signed-off-by: Alex Bennée <alex.bennee@linaro.org> --- v2 - fixup constants, remove unused onces --- include/fpu/softfloat.h | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) -- 2.15.1