On Wed, Feb 09, 2011 at 04:27:25PM +0000, Peter Maydell wrote: > Add a float16 type to softfloat, rather than using bits16 directly. > Also add the missing functions float16_is_quiet_nan(), > float16_is_signaling_nan() and float16_maybe_silence_nan(), > which are needed for the float16 conversion routines. > > Signed-off-by: Peter Maydell <peter.mayd...@linaro.org> > --- > fpu/softfloat-specialize.h | 59 > ++++++++++++++++++++++++++++++++++++++++++++ > fpu/softfloat.c | 8 +++--- > fpu/softfloat.h | 12 +++++++- > 3 files changed, 73 insertions(+), 6 deletions(-) > > diff --git a/fpu/softfloat-specialize.h b/fpu/softfloat-specialize.h > index eb644b2..bc9a66c 100644 > --- a/fpu/softfloat-specialize.h > +++ b/fpu/softfloat-specialize.h > @@ -57,6 +57,65 @@ typedef struct { > } commonNaNT; > > > /*---------------------------------------------------------------------------- > +| The pattern for a default generated half-precision NaN. > +*----------------------------------------------------------------------------*/ > +#if defined(TARGET_ARM) > +#define float16_default_nan 0x7E00 > +#elif SNAN_BIT_IS_ONE > +#define float16_default_nan 0x7DFF > +#else > +#define float16_default_nan 0xFE00 > +#endif > + > +/*---------------------------------------------------------------------------- > +| Returns 1 if the half-precision floating-point value `a' is a quiet > +| NaN; otherwise returns 0. > +*----------------------------------------------------------------------------*/ > + > +int float16_is_quiet_nan(float16 a) > +{ > +#if SNAN_BIT_IS_ONE > + return (((a >> 9) & 0x3F) == 0x3E) && (a & 0x1FF); > +#else > + return ((a & ~0x8000) >= 0x7c80); > +#endif > +} > + > +/*---------------------------------------------------------------------------- > +| Returns 1 if the half-precision floating-point value `a' is a signaling > +| NaN; otherwise returns 0. > +*----------------------------------------------------------------------------*/ > + > +int float16_is_signaling_nan(float16 a) > +{ > +#if SNAN_BIT_IS_ONE > + return ((a & ~0x8000) >= 0x7c80); > +#else > + return (((a >> 9) & 0x3F) == 0x3E) && (a & 0x1FF); > +#endif > +} > + > +/*---------------------------------------------------------------------------- > +| Returns a quiet NaN if the half-precision floating point value `a' is a > +| signaling NaN; otherwise returns `a'. > +*----------------------------------------------------------------------------*/ > +float16 float16_maybe_silence_nan(float16 a) > +{ > + if (float16_is_signaling_nan(a)) { > +#if SNAN_BIT_IS_ONE > +# if defined(TARGET_MIPS) || defined(TARGET_SH4) > + return float16_default_nan; > +# else > +# error Rules for silencing a signaling NaN are target-specific > +# endif > +#else > + a |= (1 << 9); > +#endif > + } > + return a; > +} > + > +/*---------------------------------------------------------------------------- > | The pattern for a default generated single-precision NaN. > > *----------------------------------------------------------------------------*/ > #if defined(TARGET_SPARC) > diff --git a/fpu/softfloat.c b/fpu/softfloat.c > index 17842f4..dc4492a 100644 > --- a/fpu/softfloat.c > +++ b/fpu/softfloat.c > @@ -2713,15 +2713,15 @@ float32 float64_to_float32( float64 a STATUS_PARAM ) > | than the desired result exponent whenever `zSig' is a complete, normalized > | significand. > > *----------------------------------------------------------------------------*/ > -static bits16 packFloat16(flag zSign, int16 zExp, bits16 zSig) > +static float16 packFloat16(flag zSign, int16 zExp, bits16 zSig) > { > return (((bits32)zSign) << 15) + (((bits32)zExp) << 10) + zSig; > } > > /* Half precision floats come in two formats: standard IEEE and "ARM" format. > The latter gains extra exponent range by omitting the NaN/Inf encodings. > */ > - > -float32 float16_to_float32( bits16 a, flag ieee STATUS_PARAM ) > + > +float32 float16_to_float32(float16 a, flag ieee STATUS_PARAM) > { > flag aSign; > int16 aExp; > @@ -2753,7 +2753,7 @@ float32 float16_to_float32( bits16 a, flag ieee > STATUS_PARAM ) > return packFloat32( aSign, aExp + 0x70, aSig << 13); > } > > -bits16 float32_to_float16( float32 a, flag ieee STATUS_PARAM) > +float16 float32_to_float16(float32 a, flag ieee STATUS_PARAM) > { > flag aSign; > int16 aExp; > diff --git a/fpu/softfloat.h b/fpu/softfloat.h > index 4a5345c..f773d67 100644 > --- a/fpu/softfloat.h > +++ b/fpu/softfloat.h > @@ -118,6 +118,7 @@ enum { > sane ABI should be able to see though these structs. However > x86/gcc 3.x seems to struggle a bit, so leave them disabled by default. > */ > //#define USE_SOFTFLOAT_STRUCT_TYPES > +typedef uint16_t float16; > #ifdef USE_SOFTFLOAT_STRUCT_TYPES > typedef struct { > uint32_t v;
You should also add it in the USE_SOFTFLOAT_STRUCT_TYPES case, so that we can check the type correctness. Last time I tried, it was not compiling in this mode, but it's probably worth having it anyway so that 16-bit floating points values are tested. > @@ -253,8 +254,15 @@ float128 int64_to_float128( int64_t STATUS_PARAM ); > > /*---------------------------------------------------------------------------- > | Software half-precision conversion routines. > > *----------------------------------------------------------------------------*/ > -bits16 float32_to_float16( float32, flag STATUS_PARAM ); > -float32 float16_to_float32( bits16, flag STATUS_PARAM ); > +float16 float32_to_float16( float32, flag STATUS_PARAM ); > +float32 float16_to_float32( float16, flag STATUS_PARAM ); > + > +/*---------------------------------------------------------------------------- > +| Software half-precision operations. > +*----------------------------------------------------------------------------*/ > +int float16_is_quiet_nan( float16 ); > +int float16_is_signaling_nan( float16 ); > +float16 float16_maybe_silence_nan( float16 ); > > > /*---------------------------------------------------------------------------- > | Software IEC/IEEE single-precision conversion routines. Otherwise looks pretty good. -- Aurelien Jarno GPG: 1024D/F1BCDB73 aurel...@aurel32.net http://www.aurel32.net