[Beignet] [PATCH] [PATCH]GBE: improve precision of remainder

[Zhigang Gong]

Thanks for the contribution, just pushed this and the previous 8 patches.

On Fri, Dec 20, 2013 at 03:54:05PM +0800, Lv Meng wrote:
> 
> Signed-off-by: Lv Meng <meng.lv at intel.com>
> ---
>  backend/src/ocl_stdlib.tmpl.h |   39 ++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 38 insertions(+), 1 deletion(-)
> 
> diff --git a/backend/src/ocl_stdlib.tmpl.h b/backend/src/ocl_stdlib.tmpl.h
> index fe26744..2345ecb 100755
> --- a/backend/src/ocl_stdlib.tmpl.h
> +++ b/backend/src/ocl_stdlib.tmpl.h
> @@ -1859,7 +1859,6 @@ INLINE_OVERLOADABLE float __gen_ocl_internal_round(float x) {
>  INLINE_OVERLOADABLE float __gen_ocl_internal_floor(float x) { return __gen_ocl_rndd(x); }
>  INLINE_OVERLOADABLE float __gen_ocl_internal_ceil(float x)  { return __gen_ocl_rndu(x); }
>  INLINE_OVERLOADABLE float powr(float x, float y) { return __gen_ocl_pow(x,y); }
> -INLINE_OVERLOADABLE float remainder(float x, float y) { return x-y*__gen_ocl_rnde(x/y); }
>  INLINE_OVERLOADABLE float __gen_ocl_internal_rint(float x) {
>    return __gen_ocl_rnde(x);
>  }
> @@ -2272,6 +2271,43 @@ INLINE_OVERLOADABLE float __gen_ocl_internal_cosh(float x) {
>    return huge*huge;
>  }
>  
> +INLINE_OVERLOADABLE float __gen_ocl_internal_remainder(float x, float p){
> +  //return x-y*__gen_ocl_rnde(x/y);
> +  float zero = 0.0;
> +  int hx,hp;
> +  unsigned sx;
> +  float p_half;
> +  GEN_OCL_GET_FLOAT_WORD(hx,x);
> +  GEN_OCL_GET_FLOAT_WORD(hp,p);
> +  sx = hx&0x80000000;
> +  hp &= 0x7fffffff;
> +  hx &= 0x7fffffff;
> +  /* purge off exception values */
> +  if(hp==0) return (x*p)/(x*p);	        /* p = 0 */
> +  if((hx>=0x7f800000)||               /* x not finite */
> +    ((hp>0x7f800000)))	               /* p is NaN */
> +    return (x*p)/(x*p);
> +  if (hp<=0x7effffff) x = __gen_ocl_internal_fmod(x,p+p); /* now x < 2p */
> +  if ((hx-hp)==0) return zero*x;
> +  x = __gen_ocl_fabs(x);
> +  p = __gen_ocl_fabs(p);
> +  if (hp<0x01000000) {
> +    if(x+x>p) {
> +      x-=p;
> +      if(x+x>=p) x -= p;
> +    }
> +  } else {
> +    p_half = (float)0.5*p;
> +    if(x>p_half) {
> +      x-=p;
> +      if(x>=p_half) x -= p;
> +    }
> +  }
> +  GEN_OCL_GET_FLOAT_WORD(hx,x);
> +  GEN_OCL_SET_FLOAT_WORD(x,hx^sx);
> +  return x;
> +}
> +
>  
>  // TODO use llvm intrinsics definitions
>  #define cos native_cos
> @@ -2301,6 +2337,7 @@ INLINE_OVERLOADABLE float __gen_ocl_internal_cosh(float x) {
>  #define erf __gen_ocl_internal_erf
>  #define erfc __gen_ocl_internal_erfc
>  #define fmod __gen_ocl_internal_fmod
> +#define remainder __gen_ocl_internal_remainder
>  PURE CONST float __gen_ocl_mad(float a, float b, float c);
>  INLINE_OVERLOADABLE float mad(float a, float b, float c) {
>    return __gen_ocl_mad(a, b, c);
> -- 
> 1.7.10.4
> 
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