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Jose's latest patch (GMBT_GEOMETRIC_CORRECTION)

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Brian Paul 2002-04-12 21:56:42 +00:00
parent 8c598cfd82
commit cffb351a62
1 changed files with 17 additions and 1 deletions
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18
src/mesa/x86/mmx_blend.S
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@ -39,7 +39,15 @@
*
* achieving the exact results
*/
#define GMBT_ROUNDOFF 1
#define GMBT_ROUNDOFF 0
/* instead of the roundoff this adds a small correction to satisfy the OpenGL criteria
*
* t/255 ~= (t + (t >> 8) + (t >> 15)) >> 8
*
* note that although is faster than rounding off it doesn't give always the exact results
*/
#define GMBT_GEOMETRIC_CORRECTION 1
/*
* do
@ -282,6 +290,14 @@ LLBL (GMBT_loop_begin):
PADDW ( MM3, MM2 ) /* t1 + (t1 >> 8) ~= (t1/255) << 8 */
PADDW ( MM5, MM6 ) /* t2 + (t2 >> 8) ~= (t2/255) << 8 */
#if GMBT_GEOMETRIC_CORRECTION
PSRLW ( CONST(7), MM3 ) /* t1 >> 15 */
PSRLW ( CONST(7), MM5 ) /* t2 >> 15 */
PADDW ( MM3, MM2 ) /* t1 + (t1 >> 8) + (t1 >>15) ~= (t1/255) << 8 */
PADDW ( MM5, MM6 ) /* t2 + (t2 >> 8) + (t2 >>15) ~= (t2/255) << 8 */
#endif
#endif
#if GMBT_SIGNED_ARITHMETIC