Re: [Qemu-devel] [PATCH v2 4/6] softfloat: Correctly handle NaNs in float16_to_float32()

[Aurelien Jarno <aurelien@aurel32.net>]

On Wed, Feb 09, 2011 at 04:27:28PM +0000, Peter Maydell wrote:
> Correctly handle NaNs in float16_to_float32(), by defining and
> using a float16ToCommonNaN() function, as we do with the other formats.
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
>  fpu/softfloat-specialize.h |   17 +++++++++++++++++
>  fpu/softfloat.c            |    4 +---
>  2 files changed, 18 insertions(+), 3 deletions(-)

Reviewed-by: Aurelien Jarno <aurelien@aurel32.net>

> diff --git a/fpu/softfloat-specialize.h b/fpu/softfloat-specialize.h
> index 4907484..af82359 100644
> --- a/fpu/softfloat-specialize.h
> +++ b/fpu/softfloat-specialize.h
> @@ -116,6 +116,23 @@ float16 float16_maybe_silence_nan(float16 a)
>  }
>  
>  /*----------------------------------------------------------------------------
> +| Returns the result of converting the half-precision floating-point NaN
> +| `a' to the canonical NaN format.  If `a' is a signaling NaN, the invalid
> +| exception is raised.
> +*----------------------------------------------------------------------------*/
> +
> +static commonNaNT float16ToCommonNaN( float16 a STATUS_PARAM )
> +{
> +    commonNaNT z;
> +
> +    if ( float16_is_signaling_nan( a ) ) float_raise( float_flag_invalid STATUS_VAR );
> +    z.sign = a >> 15;
> +    z.low = 0;
> +    z.high = ((bits64) a)<<54;
> +    return z;
> +}
> +
> +/*----------------------------------------------------------------------------
>  | Returns the result of converting the canonical NaN `a' to the half-
>  | precision floating-point format.
>  *----------------------------------------------------------------------------*/
> diff --git a/fpu/softfloat.c b/fpu/softfloat.c
> index 4d51428..735db38 100644
> --- a/fpu/softfloat.c
> +++ b/fpu/softfloat.c
> @@ -2733,9 +2733,7 @@ float32 float16_to_float32(float16 a, flag ieee STATUS_PARAM)
>  
>      if (aExp == 0x1f && ieee) {
>          if (aSig) {
> -            /* Make sure correct exceptions are raised.  */
> -            float32ToCommonNaN(a STATUS_VAR);
> -            aSig |= 0x200;
> +            return commonNaNToFloat32(float16ToCommonNaN(a STATUS_VAR) STATUS_VAR);
>          }
>          return packFloat32(aSign, 0xff, aSig << 13);
>      }
> -- 
> 1.7.1
> 
> 
> 

-- 
Aurelien Jarno                          GPG: 1024D/F1BCDB73
aurelien@aurel32.net                 http://www.aurel32.net