new MMX blend code (Jose Fonseca)

2 files changed, 381 insertions, 341 deletions

diff --git a/src/mesa/swrast/s_blend.c b/src/mesa/swrast/s_blend.c
index 3fdb808abf0..845709a1119 100644
--- a/src/mesa/swrast/s_blend.c
+++ b/src/mesa/swrast/s_blend.c
@@ -1,4 +1,4 @@
-/* $Id: s_blend.c,v 1.18 2002/04/04 16:53:26 brianp Exp $ */
+/* $Id: s_blend.c,v 1.19 2002/04/10 16:32:32 brianp Exp $ */
 
 /*
  * Mesa 3-D graphics library
@@ -646,10 +646,8 @@ void _swrast_choose_blend_func( GLcontext *ctx )
       SWRAST_CONTEXT(ctx)->BlendFunc = blend_general;
    }
    else if (eq==GL_FUNC_ADD_EXT && srcRGB==GL_SRC_ALPHA
-            && dstRGB==GL_ONE_MINUS_SRC_ALPHA)
-   {
-      /* XXX It looks like the MMX blend code is broken.  Disable for now. */
-#if 0 && defined(USE_MMX_ASM)
+            && dstRGB==GL_ONE_MINUS_SRC_ALPHA) {
+#if defined(USE_MMX_ASM)
       if ( cpu_has_mmx ) {
          SWRAST_CONTEXT(ctx)->BlendFunc = _mesa_mmx_blend_transparency;
       }
diff --git a/src/mesa/x86/mmx_blend.S b/src/mesa/x86/mmx_blend.S
index c2be6812ec0..caf1f17ba44 100644
--- a/src/mesa/x86/mmx_blend.S
+++ b/src/mesa/x86/mmx_blend.S
@@ -1,8 +1,69 @@
+/*
+ * Written by Jos� Fonseca <[email protected]>
+ */
+
 #include "matypes.h"
 
+/*
+ * make the following approximation to the division (Sree)
+ *
+ *   rgb*a/255 ~= (rgb*(a+1)) >> 256
+ *
+ * which is the fastest method that satisfies the following OpenGL criteria
+ *
+ *   0*0 = 0 and 255*255 = 255
+ *
+ * note this one should be used alone
+ */
+#define GMBT_ALPHA_PLUS_ONE	0
+
+/*
+ * take the geometric series approximation to the division
+ *
+ *   t/255 = (t >> 8) + (t >> 16) + (t >> 24) ..
+ *
+ * in this case just the first two terms to fit in 16bit arithmetic
+ *
+ *   t/255 ~= (t + (t >> 8)) >> 8
+ *
+ * note that just by itself it doesn't satisfies the OpenGL criteria, as 255*255 = 254, 
+ * so the special case a = 255 must be accounted or roundoff must be used
+ */
+#define GMBT_GEOMETRIC_SERIES	1
+
+/*
+ * when using a geometric series division instead of truncating the result 
+ * use roundoff in the approximation (Jim Blinn)
+ *
+ *   t = rgb*a + 0x80
+ *
+ * achieving the exact results
+ */
+#define GMBT_ROUNDOFF		1
+
+/*
+ * do
+ *
+ *   s = (q - p)*a + q
+ *
+ * instead of
+ *
+ *   s = p*a + q*(1-a)
+ *
+ * this eliminates a multiply at the expense of
+ * complicating the roundoff but is generally worth it
+ */
+#define GMBT_SIGNED_ARITHMETIC	1
+
+#if GMBT_ROUNDOFF
+    SEG_DATA
 
-SEG_TEXT
+ALIGNDATA8
+const_80:
+	D_LONG 0x00800080, 0x00800080
+#endif 
 
+   SEG_TEXT
 
 ALIGNTEXT16
 GLOBL GLNAME(_mesa_mmx_blend_transparency)
@@ -17,344 +78,325 @@ GLOBL GLNAME(_mesa_mmx_blend_transparency)
  * Common transparency blending mode.
  */
 GLNAME( _mesa_mmx_blend_transparency ):
-    PUSH_L    ( EBP )
-    MOV_L     ( ESP, EBP )
-    SUB_L     ( CONST(52), ESP )
-    PUSH_L    ( EBX )
-
-    MOV_L     ( CONST(16711680), REGOFF(-8, EBP) )
-    MOV_L     ( CONST(16711680), REGOFF(-4, EBP) )
-    MOV_L     ( CONST(0), REGOFF(-16, EBP) )
-    MOV_L     ( CONST(-1), REGOFF(-12, EBP) )
-    MOV_L     ( CONST(-1), REGOFF(-24, EBP) )
-    MOV_L     ( CONST(0), REGOFF(-20, EBP) )
-    MOV_L     ( REGOFF(24, EBP), EAX )		/* rgba */
-    ADD_L     ( CONST(4), EAX )
-    MOV_L     ( EAX, EDX )
-    AND_L     ( REGOFF(20, EBP), EDX )		/* mask */
-    MOV_L     ( EDX, EAX )
-    AND_L     ( CONST(4), EAX )
-    CMP_L     ( CONST(8), EAX )
-    JNE       ( LLBL(GMBT_skip_runin) )
-    MOV_L     ( REGOFF(20, EBP), EAX )
-    ADD_L     ( CONST(3), EAX )
-    XOR_L     ( EDX, EDX )
-    MOV_B     ( REGIND(EAX), DL )
-    MOV_L     ( EDX, REGOFF(-32, EBP) )
-    MOV_L     ( CONST(255), EAX )
-    MOV_L     ( EAX, EBX )
-    SUB_L     ( REGOFF(-32, EBP), EBX )
-    MOV_L     ( EBX, REGOFF(-36, EBP) )
-    MOV_L     ( REGOFF(20, EBP), EAX )
-    XOR_L     ( EDX, EDX )
-    MOV_B     ( REGIND(EAX), DL )
-    MOV_L     ( EDX, EAX )
-    IMUL_L    ( REGOFF(-32, EBP), EAX )
-    MOV_L     ( REGOFF(24, EBP), EDX )
-    XOR_L     ( ECX, ECX )
-    MOV_B     ( REGIND(EDX), CL )
-    MOV_L     ( ECX, EDX )
-    IMUL_L    ( REGOFF(-36, EBP), EDX )
-    ADD_L     ( EDX, EAX )
-    MOV_L     ( EAX, EBX )
-    SAR_L     ( CONST(8), EBX )
-    MOV_L     ( EBX, REGOFF(-40, EBP) )
-    MOV_L     ( REGOFF(20, EBP), EAX )
-    INC_L     ( EAX )
-    XOR_L     ( EDX, EDX )
-    MOV_B     ( REGIND(EAX), DL )
-    MOV_L     ( EDX, EAX )
-    IMUL_L    ( REGOFF(-32, EBP), EAX )
-    MOV_L     ( REGOFF(24, EBP), EDX )
-    INC_L     ( EDX )
-    XOR_L     ( ECX, ECX )
-    MOV_B     ( REGIND(EDX), CL )
-    MOV_L     ( ECX, EDX )
-    IMUL_L    ( REGOFF(-36, EBP), EDX )
-    ADD_L     ( EDX, EAX )
-    MOV_L     ( EAX, EBX )
-    SAR_L     ( CONST(8), EBX )
-    MOV_L     ( EBX, REGOFF(-44, EBP) )
-    MOV_L     ( REGOFF(20, EBP), EAX )
-    ADD_L     ( CONST(2), EAX )
-    XOR_L     ( EDX, EDX )
-    MOV_B     ( REGIND(EAX), DL )
-    MOV_L     ( EDX, EAX )
-    IMUL_L    ( REGOFF(-32, EBP), EAX )
-    MOV_L     ( REGOFF(24, EBP), EDX )
-    ADD_L     ( CONST(2), EDX )
-    XOR_L     ( ECX, ECX )
-    MOV_B     ( REGIND(EDX), CL )
-    MOV_L     ( ECX, EDX )
-    IMUL_L    ( REGOFF(-36, EBP), EDX )
-    ADD_L     ( EDX, EAX )
-    MOV_L     ( EAX, EBX )
-    SAR_L     ( CONST(8), EBX )
-    MOV_L     ( EBX, REGOFF(-48, EBP) )
-    MOV_L     ( REGOFF(20, EBP), EAX )
-    ADD_L     ( CONST(3), EAX )
-    XOR_L     ( EDX, EDX )
-    MOV_B     ( REGIND(EAX), DL )
-    MOV_L     ( EDX, EAX )
-    IMUL_L    ( REGOFF(-32, EBP), EAX )
-    MOV_L     ( REGOFF(24, EBP), EDX )
-    ADD_L     ( CONST(3), EDX )
-    XOR_L     ( ECX, ECX )
-    MOV_B     ( REGIND(EDX), CL )
-    MOV_L     ( ECX, EDX )
-    IMUL_L    ( REGOFF(-36, EBP), EDX )
-    ADD_L     ( EDX, EAX )
-    MOV_L     ( EAX, EBX )
-    SAR_L     ( CONST(8), EBX )
-    MOV_L     ( EBX, REGOFF(-52, EBP) )
-    MOV_L     ( REGOFF(20, EBP), EAX )
-    MOV_B     ( REGOFF(-40, EBP), DL )
-    MOV_B     ( DL, REGIND(EAX) )
-    MOV_L     ( REGOFF(20, EBP), EAX )
-    INC_L     ( EAX )
-    MOV_B     ( REGOFF(-44, EBP), DL )
-    MOV_B     ( DL, REGIND(EAX) )
-    MOV_L     ( REGOFF(20, EBP), EAX )
-    ADD_L     ( CONST(2), EAX )
-    MOV_B     ( REGOFF(-48, EBP), DL )
-    MOV_B     ( DL, REGIND(EAX) )
-    MOV_L     ( REGOFF(20, EBP), EAX )
-    ADD_L     ( CONST(3), EAX )
-    MOV_B     ( REGOFF(-52, EBP), DL )
-    MOV_B     ( DL, REGIND(EAX) )
-    INC_L     ( REGOFF(16, EBP) )
-    ADD_L     ( CONST(4), REGOFF(20, EBP) )
-    ADD_L     ( CONST(4), REGOFF(24, EBP) )
-    DEC_L     ( REGOFF(12, EBP) )
-
-LLBL (GMBT_skip_runin):
-
-    CMP_L     ( CONST(0), REGOFF(12, EBP) )	/* n == 0 */
-    JE        ( LLBL(GMBT_runout) )
-    MOV_L     ( CONST(0), REGOFF(-28, EBP) )	
-
-ALIGNTEXT4
-LLBL (GMBT_main_loop):
-
-    MOV_L     ( REGOFF(12, EBP), EDX )
-    MOV_L     ( EDX, EAX )
-    SHR_L     ( CONST(1), EAX )			/* eax = n/2 */
-    CMP_L     ( EAX, REGOFF(-28, EBP) )
-    JB        ( LLBL(GMBT_no_jump) )
-    JMP       ( LLBL(GMBT_end_loop) )
 
-ALIGNTEXT16
-LLBL (GMBT_no_jump):
-
-    MOV_L     ( REGOFF(-28, EBP), EAX )		/* eax = i */
-    LEA_L     ( REGDIS(0,EAX,2), EDX )		/* edx = i*2 */
-    MOV_L     ( REGOFF(16, EBP), EAX )		/* eax = mask */
-    CMP_W     ( CONST(0), REGBI(EAX,EDX) )	/* ((unsigned *) mask)[i] == 0 */
-    JE        ( LLBL(GMBT_masked) )
-    MOV_L     ( REGOFF(-28, EBP), EAX )		/* eax = i */
-    MOV_L     ( EAX, EDX )
-    LEA_L     ( REGDIS(0,EDX,8), ECX )		/* ecx = i*8 */
-    MOV_L     ( ECX, EAX )
-    ADD_L     ( REGOFF(20, EBP), EAX )		
-    MOV_L     ( REGOFF(-28, EBP), EDX )
-    MOV_L     ( EDX, ECX )
-    LEA_L     ( REGDIS(0,ECX,8), EDX )
-    MOV_L     ( EDX, ECX )
-    ADD_L     ( REGOFF(24, EBP), ECX )
-
-    MOVQ      ( REGIND(EAX), MM4 )
-    PXOR      ( MM5, MM5 )			/* mm5 = 00 00 00 00 00 00 00 00 */
-    MOVQ      ( MM4, MM1 )
-    MOVQ      ( REGIND(ECX), MM7 )
-    PUNPCKLBW ( MM5, MM1 )
-    MOVQ      ( MM7, MM6 )
-    MOVQ      ( MM1, MM0 )
-    PUNPCKLBW ( MM5, MM6 )
-    MOVQ      ( MM1, MM2 )
-    PSRLQ     ( CONST(48), MM0 )
-    PUNPCKHBW ( MM5, MM4 )
-    PACKSSDW  ( MM0, MM0 )
-    MOVQ      ( MM0, MM3 )
-    PUNPCKHBW ( MM5, MM7 )
-    PSLLQ     ( CONST(16), MM3 )
-    POR       ( REGOFF(-8, EBP), MM0 )
-    PUNPCKLWD ( MM6, MM1 )
-    PSUBW     ( MM3, MM0 )
-    PUNPCKHWD ( MM6, MM2 )
-    MOVQ      ( MM4, MM3 )
-    PSRLQ     ( CONST(48), MM3 )
-    PACKSSDW  ( MM3, MM3 )
-    MOVQ      ( MM3, MM6 )
-    POR       ( REGOFF(-8, EBP), MM3 )
-    PSLLQ     ( CONST(16), MM6 )
-    PSUBW     ( MM6, MM3 )
-    MOVQ      ( MM4, MM5 )
-    PUNPCKLWD ( MM7, MM4 )
-    PUNPCKHWD ( MM7, MM5 )
-    PMADDWD   ( MM0, MM1 )
-    PMADDWD   ( MM3, MM4 )
-    PMADDWD   ( MM0, MM2 )
-    PMADDWD   ( MM3, MM5 )
-    PSRLD     ( CONST(8), MM1 )
-    PSRLD     ( CONST(8), MM2 )
-    PSRLD     ( CONST(8), MM4 )
-    PACKSSDW  ( MM2, MM1 )
-    PSRLD     ( CONST(8), MM5 )
-    PACKUSWB  ( MM1, MM1 )
-    PACKSSDW  ( MM5, MM4 )
-    PAND      ( REGOFF(-24, EBP), MM1 )
-    PACKUSWB  ( MM4, MM4 )
-    PAND      ( REGOFF(-16, EBP), MM4 )
-    POR       ( MM1, MM4 )
-    MOVQ      ( MM4, REGIND(EAX) )
-
-LLBL (GMBT_masked):
-
-    INC_L     ( REGOFF(-28, EBP) )
-    JMP       ( LLBL(GMBT_main_loop) )
+    PUSH_L     ( EBP )
+    MOV_L      ( ESP, EBP )
+    PUSH_L     ( ESI )
+    PUSH_L     ( EDI )
+    PUSH_L     ( EBX )
+
+    MOV_L      ( REGOFF(12, EBP), ECX )		/* n */
+    CMP_L      ( CONST(0), ECX)
+    JE         ( LLBL (GMBT_return) )
+
+    MOV_L      ( REGOFF(16, EBP), EBX )		/* mask */
+    MOV_L      ( REGOFF(20, EBP), EDI )         /* rgba */
+    MOV_L      ( REGOFF(24, EBP), ESI )         /* dest */
+    
+    TEST_L     ( CONST(4), EDI )		/* align rgba on an 8-byte boundary */
+    JZ         ( LLBL (GMBT_align_end) )
+
+    CMP_B      ( CONST(0), REGIND(EBX) )	/* *mask == 0 */
+    JE         ( LLBL (GMBT_align_continue) )
+
+    PXOR       ( MM0, MM0 )			/*   0x0000  |   0x0000  |   0x0000  |   0x0000  */
+
+    MOVD       ( REGIND(ESI), MM1 )		/*     |     |     |     | qa1 | qb1 | qg1 | qr1 */
+    MOVD       ( REGIND(EDI), MM2 )		/*     |     |     |     | pa1 | pb1 | pg1 | pr1 */
+
+    PUNPCKLBW  ( MM0, MM1 )			/*    qa1    |    qb1    |    qg1    |    qr1    */
+    PUNPCKLBW  ( MM0, MM2 )			/*    pa1    |    pb1    |    pg1    |    pr1    */
+
+    MOVQ       ( MM2, MM3 )
+
+    PUNPCKHWD  ( MM3, MM3 )			/*    pa1    |    pa1    |           |           */
+    PUNPCKHDQ  ( MM3, MM3 )                     /*    pa1    |    pa1    |    pa1    |    pa1    */
+
+#if GMBT_ALPHA_PLUS_ONE
+    PCMPEQW    ( MM4, MM4 )			/*   0xffff  |   0xffff  |   0xffff  |   0xffff  */
+
+    PSUBW      ( MM4, MM3 )                     /*   pa1 + 1 |   pa1 + 1 |   pa1 + 1 |   pa1 + 1 */
+#endif
+
+#if GMBT_SIGNED_ARITHMETIC
+    PSUBW      ( MM1, MM2 )                     /* pa1 - qa1 | pb1 - qb1 | pg1 - qg1 | pr1 - qr1 */
+
+    PSLLW      ( CONST(8), MM1 )		/*                    q1 << 8                    */
+
+#if GMBT_ROUNDOFF
+    MOVQ       ( MM2, MM4 )
+#endif
+
+    PMULLW     ( MM3, MM2 )			/*              t1 = (q1 - p1)*pa1               */
+
+#if GMBT_ROUNDOFF
+    PSRLW      ( CONST(15), MM4 )		/*                 q1 > p1 ? 1 : 0               */
+
+    PSLLW      ( CONST(8), MM4 )		/*             q1 > p1 ? 0x100 : 0               */
+
+    PSUBW      ( MM4, MM2 )                     /*                  t1 -=? 0x100                 */
+#endif
+
+#else
+    PCMPEQW    ( MM4, MM4 )			/*   0xffff  |   0xffff  |   0xffff  |   0xffff  */
+    PUNPCKLBW  ( MM0, MM4 )			/*   0x00ff  |   0x00ff  |   0x00ff  |   0x00ff  */
+    MOVQ       ( MM4, MM0 )
+    
+    PMULLW     ( MM3, MM2 )			/*                     p1*pa1                    */
+
+    PSUBW      ( MM3, MM0 )			/* 255 - pa1 | 255 - pa1 | 255 - pa1 | 255 - pa1 */
+
+    PMULLW     ( MM0, MM1 )			/*                  q1*(255 - pa1)               */
+
+    PADDW      ( MM1, MM2 )			/*           t1 = p1*pa1 + q1*(255 - pa1)        */
+#endif
+
+#if GMBT_ROUNDOFF
+    MOVQ       ( CONTENT(const_80), MM4 )
+
+    PADDW      ( MM4, MM2 )                     /*                 t1 += 0x80                    */
+#endif
+
+#if GMBT_GEOMETRIC_SERIES
+    MOVQ       ( MM2, MM3 )
+
+    PSRLW      ( CONST(8), MM3 )		/*                    t1 >> 8                    */
+
+    PADDW      ( MM3, MM2 )			/*        t1 + (t1 >> 8) ~= (t1/255) << 8        */
+#endif
+
+#if GMBT_SIGNED_ARITHMETIC
+    PADDW      ( MM1, MM2 )			/*              (t1/255 + q1) << 8               */
+#endif
+
+    PSRLW      ( CONST(8), MM2 )		/*    sa1    |    sb1    |    sg1    |    sr1    */
+    
+    PACKUSWB   ( MM0, MM2 )			/*     |     |     |     | sa1 | sb1 | sg1 | sr1 */
+    MOVD       ( MM2, REGIND(EDI) )
+
+LLBL (GMBT_align_continue):
+
+    DEC_L      ( ECX )				/* n -= 1 */
+    INC_L      ( EBX )		                /* mask += 1 */
+    ADD_L      ( CONST(4), EDI )		/* rgba += 1 */
+    ADD_L      ( CONST(4), ESI )		/* dest += 1 */ 
+
+LLBL (GMBT_align_end):
+
+    CMP_L      ( CONST(2), ECX)
+    JB         ( LLBL (GMBT_loop_end) )
 
 ALIGNTEXT16
-LLBL (GMBT_end_loop):
+LLBL (GMBT_loop_begin):
+
+    CMP_W      ( CONST(0), REGIND(EBX) )	/* *mask == 0 && *(mask + 1) == 0 */
+    JE         ( LLBL (GMBT_loop_continue) )
+
+    /* NOTE: the instruction pairing when multiple pipelines are available must be checked */
+
+    PXOR       ( MM0, MM0 )			/*   0x0000  |   0x0000  |   0x0000  |   0x0000  */
+
+    MOVQ       ( REGIND(ESI), MM7 )		/* qa2 | qb2 | qg2 | qr2 | qa1 | qb1 | qg1 | qr1 */
+    MOVQ       ( REGIND(EDI), MM6 )		/* pa2 | pb2 | pg2 | pr2 | pa1 | pb1 | pg1 | pr1 */
+
+    MOVQ       ( MM7, MM1 )
+    MOVQ       ( MM6, MM2 )
+
+    PUNPCKLBW  ( MM0, MM1 )			/*    qa1    |    qb1    |    qg1    |    qr1    */
+    PUNPCKHBW  ( MM0, MM7 )                     /*    qa2    |    qb2    |    qg2    |    qr2    */
+    PUNPCKLBW  ( MM0, MM2 )			/*    pa1    |    pb1    |    pg1    |    pr1    */
+    PUNPCKHBW  ( MM0, MM6 )                     /*    pa2    |    pb2    |    pg2    |    pr2    */
+
+    MOVQ       ( MM2, MM3 )
+    MOVQ       ( MM6, MM5 )
+
+    PUNPCKHWD  ( MM3, MM3 )			/*    pa1    |    pa1    |           |           */
+    PUNPCKHWD  ( MM5, MM5 )			/*    pa2    |    pa2    |           |           */
+    PUNPCKHDQ  ( MM3, MM3 )                     /*    pa1    |    pa1    |    pa1    |    pa1    */
+    PUNPCKHDQ  ( MM5, MM5 )                     /*    pa2    |    pa2    |    pa2    |    pa2    */
+
+#if GMBT_ALPHA_PLUS_ONE
+    PCMPEQW    ( MM4, MM4 )			/*   0xffff  |   0xffff  |   0xffff  |   0xffff  */
+
+    PSUBW      ( MM4, MM3 )                     /*   pa1 + 1 |   pa1 + 1 |   pa1 + 1 |   pa1 + 1 */
+    PSUBW      ( MM4, MM5 )                     /*   pa2 + 1 |   pa2 + 1 |   pa2 + 1 |   pa2 + 1 */
+#endif
+
+#if GMBT_SIGNED_ARITHMETIC
+    PSUBW      ( MM1, MM2 )                     /* pa1 - qa1 | pb1 - qb1 | pg1 - qg1 | pr1 - qr1 */
+    PSUBW      ( MM7, MM6 )                     /* pa2 - qa2 | pb2 - qb2 | pg2 - qg2 | pr2 - qr2 */
+
+    PSLLW      ( CONST(8), MM1 )		/*                    q1 << 8                    */
+    PSLLW      ( CONST(8), MM7 )		/*                    q2 << 8                    */
+
+#if GMBT_ROUNDOFF
+    MOVQ       ( MM2, MM0 )
+    MOVQ       ( MM6, MM4 )
+#endif
+
+    PMULLW     ( MM3, MM2 )			/*              t1 = (q1 - p1)*pa1               */
+    PMULLW     ( MM5, MM6 )			/*              t2 = (q2 - p2)*pa2               */
+
+#if GMBT_ROUNDOFF
+    PSRLW      ( CONST(15), MM0 )		/*                 q1 > p1 ? 1 : 0               */
+    PSRLW      ( CONST(15), MM4 )		/*                 q2 > q2 ? 1 : 0               */
+
+    PSLLW      ( CONST(8), MM0 )		/*             q1 > p1 ? 0x100 : 0               */
+    PSLLW      ( CONST(8), MM4 )		/*             q2 > q2 ? 0x100 : 0               */
+
+    PSUBW      ( MM0, MM2 )                     /*                  t1 -=? 0x100                 */
+    PSUBW      ( MM4, MM7 )                     /*                  t2 -=? 0x100                 */ 
+#endif
+
+#else
+    PCMPEQW    ( MM4, MM4 )			/*   0xffff  |   0xffff  |   0xffff  |   0xffff  */
+    PUNPCKLBW  ( MM0, MM4 )			/*   0x00ff  |   0x00ff  |   0x00ff  |   0x00ff  */
+    MOVQ       ( MM4, MM0 )
+    
+    PMULLW     ( MM3, MM2 )			/*                     p1*pa1                    */
+    PMULLW     ( MM5, MM6 )			/*                     p2*pa2                    */
+
+    PSUBW      ( MM3, MM0 )			/* 255 - pa1 | 255 - pa1 | 255 - pa1 | 255 - pa1 */
+    PSUBW      ( MM5, MM4 )			/* 255 - pa2 | 255 - pa2 | 255 - pa2 | 255 - pa2 */
+
+    PMULLW     ( MM0, MM1 )			/*                  q1*(255 - pa1)               */
+    PMULLW     ( MM4, MM7 )			/*                  q2*(255 - pa2)               */
+
+    PADDW      ( MM1, MM2 )			/*           t1 = p1*pa1 + q1*(255 - pa1)        */
+    PADDW      ( MM7, MM6 )			/*           t2 = p2*pa2 + q2*(255 - pa2)        */
+#endif
+
+#if GMBT_ROUNDOFF
+    MOVQ       ( CONTENT(const_80), MM4 )
+
+    PADDW      ( MM4, MM2 )                     /*                 t1 += 0x80                    */
+    PADDW      ( MM4, MM6 )                     /*                 t2 += 0x80                    */
+#endif
+
+#if GMBT_GEOMETRIC_SERIES
+    MOVQ       ( MM2, MM3 )
+    MOVQ       ( MM6, MM5 )
+
+    PSRLW      ( CONST(8), MM3 )		/*                    t1 >> 8                    */
+    PSRLW      ( CONST(8), MM5 )		/*                    t2 >> 8                    */
+
+    PADDW      ( MM3, MM2 )			/*        t1 + (t1 >> 8) ~= (t1/255) << 8        */
+    PADDW      ( MM5, MM6 )			/*        t2 + (t2 >> 8) ~= (t2/255) << 8        */
+#endif
+
+#if GMBT_SIGNED_ARITHMETIC
+    PADDW      ( MM1, MM2 )			/*              (t1/255 + q1) << 8               */
+    PADDW      ( MM7, MM6 )			/*              (t2/255 + q2) << 8               */
+#endif
+
+    PSRLW      ( CONST(8), MM2 )		/*    sa1    |    sb1    |    sg1    |    sr1    */
+    PSRLW      ( CONST(8), MM6 )		/*    sa2    |    sb2    |    sg2    |    sr2    */
+    
+    PACKUSWB   ( MM6, MM2 )			/* sa2 | sb2 | sg2 | sr2 | sa1 | sb1 | sg1 | sr1 */
+    MOVQ       ( MM2, REGIND(EDI) )
+
+LLBL (GMBT_loop_continue):
+
+    DEC_L      ( ECX )
+    DEC_L      ( ECX )				/* n -= 2 */
+    ADD_L      ( CONST(2), EBX )		/* mask += 2 */
+    ADD_L      ( CONST(8), EDI )		/* rgba += 2 */
+    ADD_L      ( CONST(8), ESI )		/* dest += 2 */ 
+    CMP_L      ( CONST(2), ECX )
+    JAE        ( LLBL (GMBT_loop_begin) )
+
+LLBL (GMBT_loop_end):
+
+    CMP_L      ( CONST(1), ECX )
+    JB         ( LLBL (GMBT_done) )
+
+    CMP_B      ( CONST(0), REGIND(EBX) )	/* *mask == 0 */
+    JE         ( LLBL (GMBT_done) )
+
+    PXOR       ( MM0, MM0 )			/*   0x0000  |   0x0000  |   0x0000  |   0x0000  */
+
+    MOVD       ( REGIND(ESI), MM1 )		/*     |     |     |     | qa1 | qb1 | qg1 | qr1 */
+    MOVD       ( REGIND(EDI), MM2 )		/*     |     |     |     | pa1 | pb1 | pg1 | pr1 */
+
+    PUNPCKLBW  ( MM0, MM1 )			/*    qa1    |    qb1    |    qg1    |    qr1    */
+    PUNPCKLBW  ( MM0, MM2 )			/*    pa1    |    pb1    |    pg1    |    pr1    */
+
+    MOVQ       ( MM2, MM3 )
+
+    PUNPCKHWD  ( MM3, MM3 )			/*    pa1    |    pa1    |           |           */
+    PUNPCKHDQ  ( MM3, MM3 )                     /*    pa1    |    pa1    |    pa1    |    pa1    */
+
+#if GMBT_ALPHA_PLUS_ONE
+    PCMPEQW    ( MM4, MM4 )			/*   0xffff  |   0xffff  |   0xffff  |   0xffff  */
+
+    PSUBW      ( MM4, MM3 )                     /*   pa1 + 1 |   pa1 + 1 |   pa1 + 1 |   pa1 + 1 */
+#endif
+
+#if GMBT_SIGNED_ARITHMETIC
+    PSUBW      ( MM1, MM2 )                     /* pa1 - qa1 | pb1 - qb1 | pg1 - qg1 | pr1 - qr1 */
+
+    PSLLW      ( CONST(8), MM1 )		/*                    q1 << 8                    */
+
+#if GMBT_ROUNDOFF
+    MOVQ       ( MM2, MM4 )
+#endif
+
+    PMULLW     ( MM3, MM2 )			/*              t1 = (q1 - p1)*pa1               */
+
+#if GMBT_ROUNDOFF
+    PSRLW      ( CONST(15), MM4 )		/*                 q1 > p1 ? 1 : 0               */
+
+    PSLLW      ( CONST(8), MM4 )		/*             q1 > p1 ? 0x100 : 0               */
+
+    PSUBW      ( MM4, MM2 )                     /*                  t1 -=? 0x100                 */
+#endif
+
+#else
+    PCMPEQW    ( MM4, MM4 )			/*   0xffff  |   0xffff  |   0xffff  |   0xffff  */
+    PUNPCKLBW  ( MM0, MM4 )			/*   0x00ff  |   0x00ff  |   0x00ff  |   0x00ff  */
+    MOVQ       ( MM4, MM0 )
+    
+    PMULLW     ( MM3, MM2 )			/*                     p1*pa1                    */
+
+    PSUBW      ( MM3, MM0 )			/* 255 - pa1 | 255 - pa1 | 255 - pa1 | 255 - pa1 */
+
+    PMULLW     ( MM0, MM1 )			/*                  q1*(255 - pa1)               */
+
+    PADDW      ( MM1, MM2 )			/*           t1 = p1*pa1 + q1*(255 - pa1)        */
+#endif
+
+#if GMBT_ROUNDOFF
+    MOVQ       ( CONTENT(const_80), MM4 )
+
+    PADDW      ( MM4, MM2 )                     /*                 t1 += 0x80                    */
+#endif
+
+#if GMBT_GEOMETRIC_SERIES
+    MOVQ       ( MM2, MM3 )
+
+    PSRLW      ( CONST(8), MM3 )		/*                    t1 >> 8                    */
+
+    PADDW      ( MM3, MM2 )			/*        t1 + (t1 >> 8) ~= (t1/255) << 8        */
+#endif
+
+#if GMBT_SIGNED_ARITHMETIC
+    PADDW      ( MM1, MM2 )			/*              (t1/255 + q1) << 8               */
+#endif
+
+    PSRLW      ( CONST(8), MM2 )		/*    sa1    |    sb1    |    sg1    |    sr1    */
+    
+    PACKUSWB   ( MM0, MM2 )			/*     |     |     |     | sa1 | sb1 | sg1 | sr1 */
+    MOVD       ( MM2, REGIND(EDI) )
+
+LLBL (GMBT_done):
+
     EMMS
 
-LLBL (GMBT_runout):
-
-    MOV_L     ( REGOFF(12, EBP), EAX )
-    AND_L     ( CONST(1), EAX )
-    TEST_L    ( EAX, EAX )
-    JE        ( LLBL(GMBT_skip_runout) )
-    MOV_L     ( REGOFF(12, EBP), EAX )
-    LEA_L     ( REGDIS(0,EAX,4), EDX )
-    MOV_L     ( EDX, EAX )
-    ADD_L     ( REGOFF(20, EBP), EAX )
-    LEA_L     ( REGOFF(-1, EAX), EDX )
-    XOR_L     ( EAX, EAX )
-    MOV_B     ( REGIND(EDX), AL )
-    MOV_L     ( EAX, REGOFF(-52, EBP) )
-    MOV_L     ( CONST(255), EAX )
-    MOV_L     ( EAX, EBX )
-    SUB_L     ( REGOFF(-52, EBP), EBX )
-    MOV_L     ( EBX, REGOFF(-48, EBP) )
-    MOV_L     ( REGOFF(12, EBP), EAX )
-    LEA_L     ( REGDIS(0,EAX,4), EDX )
-    MOV_L     ( EDX, EAX )
-    ADD_L     ( REGOFF(20, EBP), EAX )
-    LEA_L     ( REGOFF(-4, EAX), EDX )
-    XOR_L     ( ECX, ECX )
-    MOV_B     ( REGIND(EDX), CL )
-    MOV_L     ( ECX, EAX )
-    IMUL_L    ( REGOFF(-52, EBP), EAX )
-    MOV_L     ( REGOFF(12, EBP), EDX )
-    LEA_L     ( REGDIS(0,EDX,4), ECX )
-    MOV_L     ( ECX, EDX )
-    ADD_L     ( REGOFF(24, EBP), EDX )
-    LEA_L     ( REGOFF(-4, EDX), ECX )
-    XOR_L     ( EDX, EDX )
-    MOV_B     ( REGIND(ECX), DL )
-    MOV_L     ( EDX, ECX )
-    IMUL_L    ( REGOFF(-48, EBP), ECX )
-    ADD_L     ( ECX, EAX )
-    MOV_L     ( EAX, EBX )
-    SAR_L     ( CONST(8), EBX )
-    MOV_L     ( EBX, REGOFF(-44, EBP) )
-    MOV_L     ( REGOFF(12, EBP), EAX )
-    LEA_L     ( REGDIS(0,EAX,4), EDX )
-    MOV_L     ( EDX, EAX )
-    ADD_L     ( REGOFF(20, EBP), EAX )
-    LEA_L     ( REGOFF(-3, EAX), EDX )
-    XOR_L     ( ECX, ECX )
-    MOV_B     ( REGIND(EDX), CL )
-    MOV_L     ( ECX, EAX )
-    IMUL_L    ( REGOFF(-52, EBP), EAX )
-    MOV_L     ( REGOFF(12, EBP), EDX )
-    LEA_L     ( REGDIS(0,EDX,4), ECX )
-    MOV_L     ( ECX, EDX )
-    ADD_L     ( REGOFF(24, EBP), EDX )
-    LEA_L     ( REGOFF(-3, EDX), ECX )
-    XOR_L     ( EDX, EDX )
-    MOV_B     ( REGIND(ECX), DL )
-    MOV_L     ( EDX, ECX )
-    IMUL_L    ( REGOFF(-48, EBP), ECX )
-    ADD_L     ( ECX, EAX )
-    MOV_L     ( EAX, EBX )
-    SAR_L     ( CONST(8), EBX )
-    MOV_L     ( EBX, REGOFF(-40, EBP) )
-    MOV_L     ( REGOFF(12, EBP), EAX )
-    LEA_L     ( REGDIS(0,EAX,4), EDX )
-    MOV_L     ( EDX, EAX )
-    ADD_L     ( REGOFF(20, EBP), EAX )
-    LEA_L     ( REGOFF(-2, EAX), EDX )
-    XOR_L     ( ECX, ECX )
-    MOV_B     ( REGIND(EDX), CL )
-    MOV_L     ( ECX, EAX )
-    IMUL_L    ( REGOFF(-52, EBP), EAX )
-    MOV_L     ( REGOFF(12, EBP), EDX )
-    LEA_L     ( REGDIS(0,EDX,4), ECX )
-    MOV_L     ( ECX, EDX )
-    ADD_L     ( REGOFF(24, EBP), EDX )
-    LEA_L     ( REGOFF(-2, EDX), ECX )
-    XOR_L     ( EDX, EDX )
-    MOV_B     ( REGIND(ECX), DL )
-    MOV_L     ( EDX, ECX )
-    IMUL_L    ( REGOFF(-48, EBP), ECX )
-    ADD_L     ( ECX, EAX )
-    MOV_L     ( EAX, EBX )
-    SAR_L     ( CONST(8), EBX )
-    MOV_L     ( EBX, REGOFF(-36, EBP) )
-    MOV_L     ( REGOFF(12, EBP), EAX )
-    LEA_L     ( REGDIS(0,EAX,4), EDX )
-    MOV_L     ( EDX, EAX )
-    ADD_L     ( REGOFF(20, EBP), EAX )
-    LEA_L     ( REGOFF(-1, EAX), EDX )
-    XOR_L     ( ECX, ECX )
-    MOV_B     ( REGIND(EDX), CL )
-    MOV_L     ( ECX, EAX )
-    IMUL_L    ( REGOFF(-52, EBP), EAX )
-    MOV_L     ( REGOFF(12, EBP), EDX )
-    LEA_L     ( REGDIS(0,EDX,4), ECX )
-    MOV_L     ( ECX, EDX )
-    ADD_L     ( REGOFF(24, EBP), EDX )
-    LEA_L     ( REGOFF(-1, EDX), ECX )
-    XOR_L     ( EDX, EDX )
-    MOV_B     ( REGIND(ECX), DL )
-    MOV_L     ( EDX, ECX )
-    IMUL_L    ( REGOFF(-48, EBP), ECX )
-    ADD_L     ( ECX, EAX )
-    MOV_L     ( EAX, EBX )
-    SAR_L     ( CONST(8), EBX )
-    MOV_L     ( EBX, REGOFF(-32, EBP) )
-    MOV_L     ( REGOFF(12, EBP), EAX )
-    LEA_L     ( REGDIS(0,EAX,4), EDX )
-    MOV_L     ( EDX, EAX )
-    ADD_L     ( REGOFF(20, EBP), EAX )
-    LEA_L     ( REGOFF(-4, EAX), EDX )
-    MOV_B     ( REGOFF(-44, EBP), AL )
-    MOV_B     ( AL, REGIND(EDX) )
-    MOV_L     ( REGOFF(12, EBP), EAX )
-    LEA_L     ( REGDIS(0,EAX,4), EDX )
-    MOV_L     ( EDX, EAX )
-    ADD_L     ( REGOFF(20, EBP), EAX )
-    LEA_L     ( REGOFF(-3, EAX), EDX )
-    MOV_B     ( REGOFF(-40, EBP), AL )
-    MOV_B     ( AL, REGIND(EDX) )
-    MOV_L     ( REGOFF(12, EBP), EAX )
-    LEA_L     ( REGDIS(0,EAX,4), EDX )
-    MOV_L     ( EDX, EAX )
-    ADD_L     ( REGOFF(20, EBP), EAX )
-    LEA_L     ( REGOFF(-2, EAX), EDX )
-    MOV_B     ( REGOFF(-36, EBP), AL )
-    MOV_B     ( AL, REGIND(EDX) )
-    MOV_L     ( REGOFF(12, EBP), EAX )
-    LEA_L     ( REGDIS(0,EAX,4), EDX )
-    MOV_L     ( EDX, EAX )
-    ADD_L     ( REGOFF(20, EBP), EAX )
-    LEA_L     ( REGOFF(-1, EAX), EDX )
-    MOV_B     ( REGOFF(-32, EBP), AL )
-    MOV_B     ( AL, REGIND(EDX) )
-
-LLBL (GMBT_skip_runout):
-
-    MOV_L     ( REGOFF(-56, EBP), EBX )
-    MOV_L     ( EBP, ESP )
-    POP_L     ( EBP )
+LLBL (GMBT_return):
+
+    POP_L      ( EBX )
+    POP_L      ( EDI )
+    POP_L      ( ESI )
+    MOV_L      ( EBP, ESP )
+    POP_L      ( EBP )
     RET