Merged r3211:3213 from branches/SDL-1.2: YUV MMX inline asm for GCC.
authorRyan C. Gordon <icculus@icculus.org>
Wed, 11 Jul 2007 07:39:01 +0000
changeset 2168 07f084fe97d0
parent 2167 8f2174e22cd5
child 2169 13cf2d5eda86
Merged r3211:3213 from branches/SDL-1.2: YUV MMX inline asm for GCC.
src/video/SDL_yuv_mmx.c
src/video/SDL_yuv_sw.c
--- a/src/video/SDL_yuv_mmx.c	Wed Jul 11 04:47:25 2007 +0000
+++ b/src/video/SDL_yuv_mmx.c	Wed Jul 11 07:39:01 2007 +0000
@@ -21,38 +21,37 @@
 */
 #include "SDL_config.h"
 
-/* *INDENT-OFF* */
-
-#if 0 /* FIXME: This code needs to be rewritten to reference the static data using relocatable addresses (e.g. http://www.gentoo.org/proj/en/hardened/pic-fix-guide.xml or http://nasm.sourceforge.net/doc/html/nasmdoc8.html#section-8.2) This code currently breaks on systems with readonly text segments (hardened Linux / Intel Mac) */
-#if defined(__GNUC__) && defined(__i386__) && SDL_ASSEMBLY_ROUTINES
+#if (__GNUC__ > 2) && defined(__i386__) && SDL_ASSEMBLY_ROUTINES
 
 #include "SDL_stdinc.h"
 
-#define ASM_ARRAY(x) x[] __asm__("_" #x) __attribute__((used))
- 
-static unsigned int  ASM_ARRAY(MMX_0080w)    = {0x00800080, 0x00800080};
-static unsigned int  ASM_ARRAY(MMX_00FFw)    = {0x00ff00ff, 0x00ff00ff};
-static unsigned int  ASM_ARRAY(MMX_FF00w)    = {0xff00ff00, 0xff00ff00};
+#include "mmx.h"
+
+/* *INDENT-OFF* */
 
-static unsigned short ASM_ARRAY(MMX_Ycoeff)  = {0x004a, 0x004a, 0x004a, 0x004a};
+static mmx_t MMX_0080w    = { .ud = {0x00800080, 0x00800080} };
+static mmx_t MMX_00FFw    = { .ud = {0x00ff00ff, 0x00ff00ff} };
+static mmx_t MMX_FF00w    = { .ud = {0xff00ff00, 0xff00ff00} };
 
-static unsigned short ASM_ARRAY(MMX_UbluRGB) = {0x0072, 0x0072, 0x0072, 0x0072};
-static unsigned short ASM_ARRAY(MMX_VredRGB) = {0x0059, 0x0059, 0x0059, 0x0059};
-static unsigned short ASM_ARRAY(MMX_UgrnRGB) = {0xffea, 0xffea, 0xffea, 0xffea};
-static unsigned short ASM_ARRAY(MMX_VgrnRGB) = {0xffd2, 0xffd2, 0xffd2, 0xffd2};
+static mmx_t MMX_Ycoeff   = { .uw = {0x004a, 0x004a, 0x004a, 0x004a} };
 
-static unsigned short ASM_ARRAY(MMX_Ublu5x5) = {0x0081, 0x0081, 0x0081, 0x0081};
-static unsigned short ASM_ARRAY(MMX_Vred5x5) = {0x0066, 0x0066, 0x0066, 0x0066};
-static unsigned short ASM_ARRAY(MMX_Ugrn555) = {0xffe7, 0xffe7, 0xffe7, 0xffe7};
-static unsigned short ASM_ARRAY(MMX_Vgrn555) = {0xffcc, 0xffcc, 0xffcc, 0xffcc};
-static unsigned short ASM_ARRAY(MMX_Ugrn565) = {0xffe8, 0xffe8, 0xffe8, 0xffe8};
-static unsigned short ASM_ARRAY(MMX_Vgrn565) = {0xffcd, 0xffcd, 0xffcd, 0xffcd};
+static mmx_t MMX_UbluRGB  = { .uw = {0x0072, 0x0072, 0x0072, 0x0072} };
+static mmx_t MMX_VredRGB  = { .uw = {0x0059, 0x0059, 0x0059, 0x0059} };
+static mmx_t MMX_UgrnRGB  = { .uw = {0xffea, 0xffea, 0xffea, 0xffea} };
+static mmx_t MMX_VgrnRGB  = { .uw = {0xffd2, 0xffd2, 0xffd2, 0xffd2} };
 
-static unsigned short ASM_ARRAY(MMX_red555)  = {0x7c00, 0x7c00, 0x7c00, 0x7c00};
-static unsigned short ASM_ARRAY(MMX_red565)  = {0xf800, 0xf800, 0xf800, 0xf800};
-static unsigned short ASM_ARRAY(MMX_grn555)  = {0x03e0, 0x03e0, 0x03e0, 0x03e0};
-static unsigned short ASM_ARRAY(MMX_grn565)  = {0x07e0, 0x07e0, 0x07e0, 0x07e0};
-static unsigned short ASM_ARRAY(MMX_blu5x5)  = {0x001f, 0x001f, 0x001f, 0x001f};
+static mmx_t MMX_Ublu5x5  = { .uw = {0x0081, 0x0081, 0x0081, 0x0081} };
+static mmx_t MMX_Vred5x5  = { .uw = {0x0066, 0x0066, 0x0066, 0x0066} };
+static mmx_t MMX_Ugrn555  = { .uw = {0xffe7, 0xffe7, 0xffe7, 0xffe7} };
+static mmx_t MMX_Vgrn555  = { .uw = {0xffcc, 0xffcc, 0xffcc, 0xffcc} };
+static mmx_t MMX_Ugrn565  = { .uw = {0xffe8, 0xffe8, 0xffe8, 0xffe8} };
+static mmx_t MMX_Vgrn565  = { .uw = {0xffcd, 0xffcd, 0xffcd, 0xffcd} };
+
+static mmx_t MMX_red555   = { .uw = {0x7c00, 0x7c00, 0x7c00, 0x7c00} };
+static mmx_t MMX_red565   = { .uw = {0xf800, 0xf800, 0xf800, 0xf800} };
+static mmx_t MMX_grn555   = { .uw = {0x03e0, 0x03e0, 0x03e0, 0x03e0} };
+static mmx_t MMX_grn565   = { .uw = {0x07e0, 0x07e0, 0x07e0, 0x07e0} };
+static mmx_t MMX_blu5x5   = { .uw = {0x001f, 0x001f, 0x001f, 0x001f} };
 
 /**
    This MMX assembler is my first assembler/MMX program ever.
@@ -92,147 +91,158 @@
     Uint32 *row2;
 
     unsigned char* y = lum +cols*rows;    // Pointer to the end
-    int x=0;
+    int x = 0;
     row1 = (Uint32 *)out;                 // 32 bit target
-    row2 = (Uint32 *)out+cols+mod;        // start of second row 
+    row2 = (Uint32 *)out+cols+mod;        // start of second row
     mod = (mod+cols+mod)*4;               // increment for row1 in byte
 
     __asm__ __volatile__ (
-/* We don't really care about PIC - the code should be rewritten to use
-   relative addressing for the static tables, so right now we take the
-   COW hit on the pages this code resides. Big deal.
-   This spill is just to reduce register pressure in the PIC case. */
-		 "pushl %%ebx\n"
-		 "movl %0, %%ebx\n"
+        // tap dance to workaround the inability to use %%ebx at will...
+        //  move one thing to the stack...
+        "pushl $0\n"  // save a slot on the stack.
+        "pushl %%ebx\n"  // save %%ebx.
+        "movl %0, %%ebx\n"  // put the thing in ebx.
+        "movl %%ebx,4(%%esp)\n"  // put the thing in the stack slot.
+        "popl %%ebx\n"  // get back %%ebx (the PIC register).
+
+        ".align 8\n"
+        "1:\n"
 
-	         ".align 8\n"
-		 "1:\n"
-		
-		 // create Cr (result in mm1)
-		 "movd (%%ebx), %%mm1\n"   //         0  0  0  0  v3 v2 v1 v0
-		 "pxor %%mm7,%%mm7\n"      //         00 00 00 00 00 00 00 00
-		 "movd (%2), %%mm2\n"           //    0  0  0  0 l3 l2 l1 l0
-		 "punpcklbw %%mm7,%%mm1\n" //         0  v3 0  v2 00 v1 00 v0
-		 "punpckldq %%mm1,%%mm1\n" //         00 v1 00 v0 00 v1 00 v0
-		 "psubw _MMX_0080w,%%mm1\n"  // mm1-128:r1 r1 r0 r0 r1 r1 r0 r0 
+        // create Cr (result in mm1)
+        "pushl %%ebx\n"
+        "movl 4(%%esp),%%ebx\n"
+        "movd (%%ebx),%%mm1\n"   //         0  0  0  0  v3 v2 v1 v0
+        "popl %%ebx\n"
+        "pxor %%mm7,%%mm7\n"      //         00 00 00 00 00 00 00 00
+        "movd (%2), %%mm2\n"           //    0  0  0  0 l3 l2 l1 l0
+        "punpcklbw %%mm7,%%mm1\n" //         0  v3 0  v2 00 v1 00 v0
+        "punpckldq %%mm1,%%mm1\n" //         00 v1 00 v0 00 v1 00 v0
+        "psubw %9,%%mm1\n"        // mm1-128:r1 r1 r0 r0 r1 r1 r0 r0
+
+        // create Cr_g (result in mm0)
+        "movq %%mm1,%%mm0\n"           // r1 r1 r0 r0 r1 r1 r0 r0
+        "pmullw %10,%%mm0\n"           // red*-46dec=0.7136*64
+        "pmullw %11,%%mm1\n"           // red*89dec=1.4013*64
+        "psraw  $6, %%mm0\n"           // red=red/64
+        "psraw  $6, %%mm1\n"           // red=red/64
 
-		 // create Cr_g (result in mm0)
-		 "movq %%mm1,%%mm0\n"           // r1 r1 r0 r0 r1 r1 r0 r0
-		 "pmullw _MMX_VgrnRGB,%%mm0\n"// red*-46dec=0.7136*64
-		 "pmullw _MMX_VredRGB,%%mm1\n"// red*89dec=1.4013*64
-		 "psraw  $6, %%mm0\n"           // red=red/64
-		 "psraw  $6, %%mm1\n"           // red=red/64
-		 
-		 // create L1 L2 (result in mm2,mm4)
-		 // L2=lum+cols
-		 "movq (%2,%4),%%mm3\n"         //    0  0  0  0 L3 L2 L1 L0
-		 "punpckldq %%mm3,%%mm2\n"      //   L3 L2 L1 L0 l3 l2 l1 l0
-		 "movq %%mm2,%%mm4\n"           //   L3 L2 L1 L0 l3 l2 l1 l0
-		 "pand _MMX_FF00w,%%mm2\n"      //   L3 0  L1  0 l3  0 l1  0
-		 "pand _MMX_00FFw,%%mm4\n"      //   0  L2  0 L0  0 l2  0 l0
-		 "psrlw $8,%%mm2\n"             //   0  L3  0 L1  0 l3  0 l1
+        // create L1 L2 (result in mm2,mm4)
+        // L2=lum+cols
+        "movq (%2,%4),%%mm3\n"         //    0  0  0  0 L3 L2 L1 L0
+        "punpckldq %%mm3,%%mm2\n"      //   L3 L2 L1 L0 l3 l2 l1 l0
+        "movq %%mm2,%%mm4\n"           //   L3 L2 L1 L0 l3 l2 l1 l0
+        "pand %12,%%mm2\n"             //   L3 0  L1  0 l3  0 l1  0
+        "pand %13,%%mm4\n"             //   0  L2  0 L0  0 l2  0 l0
+        "psrlw $8,%%mm2\n"             //   0  L3  0 L1  0 l3  0 l1
+
+        // create R (result in mm6)
+        "movq %%mm2,%%mm5\n"           //   0 L3  0 L1  0 l3  0 l1
+        "movq %%mm4,%%mm6\n"           //   0 L2  0 L0  0 l2  0 l0
+        "paddsw  %%mm1, %%mm5\n"       // lum1+red:x R3 x R1 x r3 x r1
+        "paddsw  %%mm1, %%mm6\n"       // lum1+red:x R2 x R0 x r2 x r0
+        "packuswb %%mm5,%%mm5\n"       //  R3 R1 r3 r1 R3 R1 r3 r1
+        "packuswb %%mm6,%%mm6\n"       //  R2 R0 r2 r0 R2 R0 r2 r0
+        "pxor %%mm7,%%mm7\n"      //         00 00 00 00 00 00 00 00
+        "punpcklbw %%mm5,%%mm6\n"      //  R3 R2 R1 R0 r3 r2 r1 r0
 
-		 // create R (result in mm6)
-		 "movq %%mm2,%%mm5\n"           //   0 L3  0 L1  0 l3  0 l1
-		 "movq %%mm4,%%mm6\n"           //   0 L2  0 L0  0 l2  0 l0
-		 "paddsw  %%mm1, %%mm5\n"       // lum1+red:x R3 x R1 x r3 x r1
-		 "paddsw  %%mm1, %%mm6\n"       // lum1+red:x R2 x R0 x r2 x r0
-		 "packuswb %%mm5,%%mm5\n"       //  R3 R1 r3 r1 R3 R1 r3 r1
-		 "packuswb %%mm6,%%mm6\n"       //  R2 R0 r2 r0 R2 R0 r2 r0
-		 "pxor %%mm7,%%mm7\n"      //         00 00 00 00 00 00 00 00
-		 "punpcklbw %%mm5,%%mm6\n"      //  R3 R2 R1 R0 r3 r2 r1 r0
+        // create Cb (result in mm1)
+        "movd (%1), %%mm1\n"      //         0  0  0  0  u3 u2 u1 u0
+        "punpcklbw %%mm7,%%mm1\n" //         0  u3 0  u2 00 u1 00 u0
+        "punpckldq %%mm1,%%mm1\n" //         00 u1 00 u0 00 u1 00 u0
+        "psubw %9,%%mm1\n"        // mm1-128:u1 u1 u0 u0 u1 u1 u0 u0
 
-		 // create Cb (result in mm1)
-		 "movd (%1), %%mm1\n"      //         0  0  0  0  u3 u2 u1 u0
-		 "punpcklbw %%mm7,%%mm1\n" //         0  u3 0  u2 00 u1 00 u0
-		 "punpckldq %%mm1,%%mm1\n" //         00 u1 00 u0 00 u1 00 u0
-		 "psubw _MMX_0080w,%%mm1\n"  // mm1-128:u1 u1 u0 u0 u1 u1 u0 u0 
-		 // create Cb_g (result in mm5)
-		 "movq %%mm1,%%mm5\n"            // u1 u1 u0 u0 u1 u1 u0 u0
-		 "pmullw _MMX_UgrnRGB,%%mm5\n"    // blue*-109dec=1.7129*64
-		 "pmullw _MMX_UbluRGB,%%mm1\n"    // blue*114dec=1.78125*64
-		 "psraw  $6, %%mm5\n"            // blue=red/64
-		 "psraw  $6, %%mm1\n"            // blue=blue/64
+        // create Cb_g (result in mm5)
+        "movq %%mm1,%%mm5\n"            // u1 u1 u0 u0 u1 u1 u0 u0
+        "pmullw %14,%%mm5\n"            // blue*-109dec=1.7129*64
+        "pmullw %15,%%mm1\n"            // blue*114dec=1.78125*64
+        "psraw  $6, %%mm5\n"            // blue=red/64
+        "psraw  $6, %%mm1\n"            // blue=blue/64
+
+        // create G (result in mm7)
+        "movq %%mm2,%%mm3\n"      //   0  L3  0 L1  0 l3  0 l1
+        "movq %%mm4,%%mm7\n"      //   0  L2  0 L0  0 l2  0 l1
+        "paddsw  %%mm5, %%mm3\n"  // lum1+Cb_g:x G3t x G1t x g3t x g1t
+        "paddsw  %%mm5, %%mm7\n"  // lum1+Cb_g:x G2t x G0t x g2t x g0t
+        "paddsw  %%mm0, %%mm3\n"  // lum1+Cr_g:x G3  x G1  x g3  x g1
+        "paddsw  %%mm0, %%mm7\n"  // lum1+blue:x G2  x G0  x g2  x g0
+        "packuswb %%mm3,%%mm3\n"  // G3 G1 g3 g1 G3 G1 g3 g1
+        "packuswb %%mm7,%%mm7\n"  // G2 G0 g2 g0 G2 G0 g2 g0
+        "punpcklbw %%mm3,%%mm7\n" // G3 G2 G1 G0 g3 g2 g1 g0
 
-		 // create G (result in mm7)
-		 "movq %%mm2,%%mm3\n"      //   0  L3  0 L1  0 l3  0 l1
-		 "movq %%mm4,%%mm7\n"      //   0  L2  0 L0  0 l2  0 l1
-		 "paddsw  %%mm5, %%mm3\n"  // lum1+Cb_g:x G3t x G1t x g3t x g1t
-		 "paddsw  %%mm5, %%mm7\n"  // lum1+Cb_g:x G2t x G0t x g2t x g0t
-		 "paddsw  %%mm0, %%mm3\n"  // lum1+Cr_g:x G3  x G1  x g3  x g1
-		 "paddsw  %%mm0, %%mm7\n"  // lum1+blue:x G2  x G0  x g2  x g0
-		 "packuswb %%mm3,%%mm3\n"  // G3 G1 g3 g1 G3 G1 g3 g1
-		 "packuswb %%mm7,%%mm7\n"  // G2 G0 g2 g0 G2 G0 g2 g0
-		 "punpcklbw %%mm3,%%mm7\n" // G3 G2 G1 G0 g3 g2 g1 g0
-		 
-		 // create B (result in mm5)
-		 "movq %%mm2,%%mm3\n"         //   0  L3  0 L1  0 l3  0 l1
-		 "movq %%mm4,%%mm5\n"         //   0  L2  0 L0  0 l2  0 l1
-		 "paddsw  %%mm1, %%mm3\n"     // lum1+blue:x B3 x B1 x b3 x b1
-		 "paddsw  %%mm1, %%mm5\n"     // lum1+blue:x B2 x B0 x b2 x b0
-		 "packuswb %%mm3,%%mm3\n"     // B3 B1 b3 b1 B3 B1 b3 b1
-		 "packuswb %%mm5,%%mm5\n"     // B2 B0 b2 b0 B2 B0 b2 b0
-		 "punpcklbw %%mm3,%%mm5\n"    // B3 B2 B1 B0 b3 b2 b1 b0
+        // create B (result in mm5)
+        "movq %%mm2,%%mm3\n"         //   0  L3  0 L1  0 l3  0 l1
+        "movq %%mm4,%%mm5\n"         //   0  L2  0 L0  0 l2  0 l1
+        "paddsw  %%mm1, %%mm3\n"     // lum1+blue:x B3 x B1 x b3 x b1
+        "paddsw  %%mm1, %%mm5\n"     // lum1+blue:x B2 x B0 x b2 x b0
+        "packuswb %%mm3,%%mm3\n"     // B3 B1 b3 b1 B3 B1 b3 b1
+        "packuswb %%mm5,%%mm5\n"     // B2 B0 b2 b0 B2 B0 b2 b0
+        "punpcklbw %%mm3,%%mm5\n"    // B3 B2 B1 B0 b3 b2 b1 b0
+
+        // fill destination row1 (needed are mm6=Rr,mm7=Gg,mm5=Bb)
+
+        "pxor %%mm2,%%mm2\n"           //  0  0  0  0  0  0  0  0
+        "pxor %%mm4,%%mm4\n"           //  0  0  0  0  0  0  0  0
+        "movq %%mm6,%%mm1\n"           // R3 R2 R1 R0 r3 r2 r1 r0
+        "movq %%mm5,%%mm3\n"           // B3 B2 B1 B0 b3 b2 b1 b0
 
-		 // fill destination row1 (needed are mm6=Rr,mm7=Gg,mm5=Bb)
+        // process lower lum
+        "punpcklbw %%mm4,%%mm1\n"      //  0 r3  0 r2  0 r1  0 r0
+        "punpcklbw %%mm4,%%mm3\n"      //  0 b3  0 b2  0 b1  0 b0
+        "movq %%mm1,%%mm2\n"           //  0 r3  0 r2  0 r1  0 r0
+        "movq %%mm3,%%mm0\n"           //  0 b3  0 b2  0 b1  0 b0
+        "punpcklwd %%mm1,%%mm3\n"      //  0 r1  0 b1  0 r0  0 b0
+        "punpckhwd %%mm2,%%mm0\n"      //  0 r3  0 b3  0 r2  0 b2
 
-		 "pxor %%mm2,%%mm2\n"           //  0  0  0  0  0  0  0  0
-		 "pxor %%mm4,%%mm4\n"           //  0  0  0  0  0  0  0  0
-		 "movq %%mm6,%%mm1\n"           // R3 R2 R1 R0 r3 r2 r1 r0
-		 "movq %%mm5,%%mm3\n"           // B3 B2 B1 B0 b3 b2 b1 b0
-		 // process lower lum
-		 "punpcklbw %%mm4,%%mm1\n"      //  0 r3  0 r2  0 r1  0 r0
-		 "punpcklbw %%mm4,%%mm3\n"      //  0 b3  0 b2  0 b1  0 b0
-		 "movq %%mm1,%%mm2\n"           //  0 r3  0 r2  0 r1  0 r0
-		 "movq %%mm3,%%mm0\n"           //  0 b3  0 b2  0 b1  0 b0
-		 "punpcklwd %%mm1,%%mm3\n"      //  0 r1  0 b1  0 r0  0 b0
-		 "punpckhwd %%mm2,%%mm0\n"      //  0 r3  0 b3  0 r2  0 b2
+        "pxor %%mm2,%%mm2\n"           //  0  0  0  0  0  0  0  0
+        "movq %%mm7,%%mm1\n"           // G3 G2 G1 G0 g3 g2 g1 g0
+        "punpcklbw %%mm1,%%mm2\n"      // g3  0 g2  0 g1  0 g0  0
+        "punpcklwd %%mm4,%%mm2\n"      //  0  0 g1  0  0  0 g0  0
+        "por %%mm3, %%mm2\n"          //  0 r1 g1 b1  0 r0 g0 b0
+        "movq %%mm2,(%3)\n"          // wrote out ! row1
+
+        "pxor %%mm2,%%mm2\n"           //  0  0  0  0  0  0  0  0
+        "punpcklbw %%mm1,%%mm4\n"      // g3  0 g2  0 g1  0 g0  0
+        "punpckhwd %%mm2,%%mm4\n"      //  0  0 g3  0  0  0 g2  0
+        "por %%mm0, %%mm4\n"          //  0 r3 g3 b3  0 r2 g2 b2
+        "movq %%mm4,8(%3)\n"         // wrote out ! row1
 
-		 "pxor %%mm2,%%mm2\n"           //  0  0  0  0  0  0  0  0
-		 "movq %%mm7,%%mm1\n"           // G3 G2 G1 G0 g3 g2 g1 g0
-		 "punpcklbw %%mm1,%%mm2\n"      // g3  0 g2  0 g1  0 g0  0
-		 "punpcklwd %%mm4,%%mm2\n"      //  0  0 g1  0  0  0 g0  0 
-		 "por  %%mm3, %%mm2\n"          //  0 r1 g1 b1  0 r0 g0 b0
-		 "movq   %%mm2,(%3)\n"          // wrote out ! row1
+        // fill destination row2 (needed are mm6=Rr,mm7=Gg,mm5=Bb)
+        // this can be done "destructive"
+        "pxor %%mm2,%%mm2\n"           //  0  0  0  0  0  0  0  0
+        "punpckhbw %%mm2,%%mm6\n"      //  0 R3  0 R2  0 R1  0 R0
+        "punpckhbw %%mm1,%%mm5\n"      // G3 B3 G2 B2 G1 B1 G0 B0
+        "movq %%mm5,%%mm1\n"           // G3 B3 G2 B2 G1 B1 G0 B0
+        "punpcklwd %%mm6,%%mm1\n"      //  0 R1 G1 B1  0 R0 G0 B0
+        "movq %%mm1,(%5)\n"          // wrote out ! row2
+        "punpckhwd %%mm6,%%mm5\n"      //  0 R3 G3 B3  0 R2 G2 B2
+        "movq %%mm5,8(%5)\n"         // wrote out ! row2
+
+        "addl $4,%2\n"            // lum+4
+        "leal 16(%3),%3\n"        // row1+16
+        "leal 16(%5),%5\n"        // row2+16
+        "addl $2,(%%esp)\n"        // cr+2
+        "addl $2,%1\n"           // cb+2
 
-		 "pxor %%mm2,%%mm2\n"           //  0  0  0  0  0  0  0  0
-		 "punpcklbw %%mm1,%%mm4\n"      // g3  0 g2  0 g1  0 g0  0
-		 "punpckhwd %%mm2,%%mm4\n"      //  0  0 g3  0  0  0 g2  0 
-		 "por  %%mm0, %%mm4\n"          //  0 r3 g3 b3  0 r2 g2 b2
-		 "movq   %%mm4,8(%3)\n"         // wrote out ! row1
-		 
-		 // fill destination row2 (needed are mm6=Rr,mm7=Gg,mm5=Bb)
-		 // this can be done "destructive"
-		 "pxor %%mm2,%%mm2\n"           //  0  0  0  0  0  0  0  0
-		 "punpckhbw %%mm2,%%mm6\n"      //  0 R3  0 R2  0 R1  0 R0
-		 "punpckhbw %%mm1,%%mm5\n"      // G3 B3 G2 B2 G1 B1 G0 B0
-		 "movq %%mm5,%%mm1\n"           // G3 B3 G2 B2 G1 B1 G0 B0
-		 "punpcklwd %%mm6,%%mm1\n"      //  0 R1 G1 B1  0 R0 G0 B0
-		 "movq   %%mm1,(%5)\n"          // wrote out ! row2
-		 "punpckhwd %%mm6,%%mm5\n"      //  0 R3 G3 B3  0 R2 G2 B2
-		 "movq   %%mm5,8(%5)\n"         // wrote out ! row2
-		 
-		 "addl  $4,%2\n"            // lum+4
-		 "leal  16(%3),%3\n"        // row1+16
-		 "leal  16(%5),%5\n"        // row2+16
-		 "addl  $2, %%ebx\n"        // cr+2
-		 "addl  $2, %1\n"           // cb+2
+        "addl $4,%6\n"            // x+4
+        "cmpl %4,%6\n"
 
-		 "addl  $4,%6\n"            // x+4
-		 "cmpl  %4,%6\n"
+        "jl 1b\n"
+        "addl %4,%2\n" // lum += cols
+        "addl %8,%3\n" // row1+= mod
+        "addl %8,%5\n" // row2+= mod
+        "movl $0,%6\n" // x=0
+        "cmpl %7,%2\n"
+        "jl 1b\n"
 
-		 "jl    1b\n"
-		 "addl           %4,     %2\n" // lum += cols 
-		 "addl           %8,     %3\n" // row1+= mod
-		 "addl           %8,     %5\n" // row2+= mod
-		 "movl           $0,     %6\n" // x=0
-		 "cmpl           %7,     %2\n"
-		 "jl             1b\n"
-		 "emms\n"
-		 "popl %%ebx\n"
-		 :
-		 : "m" (cr), "r"(cb),"r"(lum),
-		 "r"(row1),"r"(cols),"r"(row2),"m"(x),"m"(y),"m"(mod));
+        "addl $4,%%esp\n"  // get rid of the stack slot we reserved.
+        "emms\n"  // reset MMX registers.
+        :
+        : "m" (cr), "r"(cb),"r"(lum),
+          "r"(row1),"r"(cols),"r"(row2),"m"(x),"m"(y),"m"(mod),
+          "m"(MMX_0080w),"m"(MMX_VgrnRGB),"m"(MMX_VredRGB),
+          "m"(MMX_FF00w),"m"(MMX_00FFw),"m"(MMX_UgrnRGB),
+          "m"(MMX_UbluRGB)
+    );
 }
 
 void Color565DitherYV12MMX1X( int *colortab, Uint32 *rgb_2_pix,
@@ -244,173 +254,185 @@
     Uint16 *row2;
 
     unsigned char* y = lum +cols*rows;    /* Pointer to the end */
-    int x=0;
+    int x = 0;
     row1 = (Uint16 *)out;                 /* 16 bit target */
     row2 = (Uint16 *)out+cols+mod;        /* start of second row  */
     mod = (mod+cols+mod)*2;               /* increment for row1 in byte */
 
-
-      __asm__ __volatile__(
-         "pushl %%ebx\n"
-	 "movl %0, %%ebx\n"
+    __asm__ __volatile__(
+        // tap dance to workaround the inability to use %%ebx at will...
+        //  move one thing to the stack...
+        "pushl $0\n"  // save a slot on the stack.
+        "pushl %%ebx\n"  // save %%ebx.
+        "movl %0, %%ebx\n"  // put the thing in ebx.
+        "movl %%ebx, 4(%%esp)\n"  // put the thing in the stack slot.
+        "popl %%ebx\n"  // get back %%ebx (the PIC register).
 
-         ".align 8\n"
-         "1:\n"
-         "movd           (%1),                   %%mm0\n" // 4 Cb         0  0  0  0 u3 u2 u1 u0
-         "pxor           %%mm7,                  %%mm7\n"
-         "movd           (%%ebx),                %%mm1\n" // 4 Cr                0  0  0  0 v3 v2 v1 v0
-         "punpcklbw      %%mm7,                  %%mm0\n" // 4 W cb   0 u3  0 u2  0 u1  0 u0
-         "punpcklbw      %%mm7,                  %%mm1\n" // 4 W cr   0 v3  0 v2  0 v1  0 v0
-         "psubw          _MMX_0080w,             %%mm0\n"
-         "psubw          _MMX_0080w,             %%mm1\n"
-         "movq           %%mm0,                  %%mm2\n" // Cb                   0 u3  0 u2  0 u1  0 u0
-         "movq           %%mm1,                  %%mm3\n" // Cr
-         "pmullw         _MMX_Ugrn565,           %%mm2\n" // Cb2green 0 R3  0 R2  0 R1  0 R0
-         "movq           (%2),                   %%mm6\n" // L1      l7 L6 L5 L4 L3 L2 L1 L0
-         "pmullw         _MMX_Ublu5x5,           %%mm0\n" // Cb2blue
-         "pand           _MMX_00FFw,             %%mm6\n" // L1      00 L6 00 L4 00 L2 00 L0
-         "pmullw         _MMX_Vgrn565,           %%mm3\n" // Cr2green
-         "movq           (%2),                   %%mm7\n" // L2
-         "pmullw         _MMX_Vred5x5,           %%mm1\n" // Cr2red
-         "psrlw          $8,                     %%mm7\n"        // L2           00 L7 00 L5 00 L3 00 L1
-         "pmullw         _MMX_Ycoeff,            %%mm6\n" // lum1
-         "paddw          %%mm3,                  %%mm2\n" // Cb2green + Cr2green == green
-         "pmullw         _MMX_Ycoeff,            %%mm7\n" // lum2
+        ".align 8\n"
+        "1:\n"
+
+        "movd           (%1),                   %%mm0\n" // 4 Cb         0  0  0  0 u3 u2 u1 u0
+        "pxor           %%mm7,                  %%mm7\n"
+        "pushl %%ebx\n"
+        "movl 4(%%esp), %%ebx\n"
+        "movd (%%ebx), %%mm1\n"   // 4 Cr                0  0  0  0 v3 v2 v1 v0
+        "popl %%ebx\n"
 
-         "movq           %%mm6,                  %%mm4\n" // lum1
-         "paddw          %%mm0,                  %%mm6\n" // lum1 +blue 00 B6 00 B4 00 B2 00 B0
-         "movq           %%mm4,                  %%mm5\n" // lum1
-         "paddw          %%mm1,                  %%mm4\n" // lum1 +red  00 R6 00 R4 00 R2 00 R0
-         "paddw          %%mm2,                  %%mm5\n" // lum1 +green 00 G6 00 G4 00 G2 00 G0
-         "psraw          $6,                     %%mm4\n" // R1 0 .. 64
-         "movq           %%mm7,                  %%mm3\n" // lum2                       00 L7 00 L5 00 L3 00 L1
-         "psraw          $6,                     %%mm5\n" // G1  - .. +
-         "paddw          %%mm0,                  %%mm7\n" // Lum2 +blue 00 B7 00 B5 00 B3 00 B1
-         "psraw          $6,                     %%mm6\n" // B1         0 .. 64
-         "packuswb       %%mm4,                  %%mm4\n" // R1 R1
-         "packuswb       %%mm5,                  %%mm5\n" // G1 G1
-         "packuswb       %%mm6,                  %%mm6\n" // B1 B1
-         "punpcklbw      %%mm4,                  %%mm4\n"
-         "punpcklbw      %%mm5,                  %%mm5\n"
+        "punpcklbw      %%mm7,                  %%mm0\n" // 4 W cb   0 u3  0 u2  0 u1  0 u0
+        "punpcklbw      %%mm7,                  %%mm1\n" // 4 W cr   0 v3  0 v2  0 v1  0 v0
+        "psubw          %9,                     %%mm0\n"
+        "psubw          %9,                     %%mm1\n"
+        "movq           %%mm0,                  %%mm2\n" // Cb                   0 u3  0 u2  0 u1  0 u0
+        "movq           %%mm1,                  %%mm3\n" // Cr
+        "pmullw         %10,                    %%mm2\n" // Cb2green 0 R3  0 R2  0 R1  0 R0
+        "movq           (%2),                   %%mm6\n" // L1      l7 L6 L5 L4 L3 L2 L1 L0
+        "pmullw         %11,                    %%mm0\n" // Cb2blue
+        "pand           %12,                    %%mm6\n" // L1      00 L6 00 L4 00 L2 00 L0
+        "pmullw         %13,                    %%mm3\n" // Cr2green
+        "movq           (%2),                   %%mm7\n" // L2
+        "pmullw         %14,                    %%mm1\n" // Cr2red
+        "psrlw          $8,                     %%mm7\n"        // L2           00 L7 00 L5 00 L3 00 L1
+        "pmullw         %15,                    %%mm6\n" // lum1
+        "paddw          %%mm3,                  %%mm2\n" // Cb2green + Cr2green == green
+        "pmullw         %15,                    %%mm7\n" // lum2
 
-         "pand           _MMX_red565,            %%mm4\n"
-         "psllw          $3,                     %%mm5\n" // GREEN       1
-         "punpcklbw      %%mm6,                  %%mm6\n"
-         "pand           _MMX_grn565,            %%mm5\n"
-         "pand           _MMX_red565,            %%mm6\n"
-         "por            %%mm5,                  %%mm4\n" //
-         "psrlw          $11,                    %%mm6\n" // BLUE        1
-         "movq           %%mm3,                  %%mm5\n" // lum2
-         "paddw          %%mm1,                  %%mm3\n" // lum2 +red      00 R7 00 R5 00 R3 00 R1
-         "paddw          %%mm2,                  %%mm5\n" // lum2 +green 00 G7 00 G5 00 G3 00 G1
-         "psraw          $6,                     %%mm3\n" // R2
-         "por            %%mm6,                  %%mm4\n" // MM4
-         "psraw          $6,                     %%mm5\n" // G2
-         "movq           (%2, %4),               %%mm6\n" // L3 load lum2
-         "psraw          $6,                     %%mm7\n"
-         "packuswb       %%mm3,                  %%mm3\n"
-         "packuswb       %%mm5,                  %%mm5\n"
-         "packuswb       %%mm7,                  %%mm7\n"
-         "pand           _MMX_00FFw,             %%mm6\n" // L3
-         "punpcklbw      %%mm3,                  %%mm3\n"
-         "punpcklbw      %%mm5,                  %%mm5\n"
-         "pmullw         _MMX_Ycoeff,            %%mm6\n" // lum3
-         "punpcklbw      %%mm7,                  %%mm7\n"
-         "psllw          $3,                     %%mm5\n" // GREEN 2
-         "pand           _MMX_red565,            %%mm7\n"
-         "pand           _MMX_red565,            %%mm3\n"
-         "psrlw          $11,                    %%mm7\n" // BLUE  2
-         "pand           _MMX_grn565,            %%mm5\n"
-         "por            %%mm7,                  %%mm3\n"
-         "movq           (%2,%4),                %%mm7\n" // L4 load lum2
-         "por            %%mm5,                  %%mm3\n" //
-         "psrlw          $8,                     %%mm7\n" // L4
-         "movq           %%mm4,                  %%mm5\n"
-         "punpcklwd      %%mm3,                  %%mm4\n"
-         "pmullw         _MMX_Ycoeff,            %%mm7\n" // lum4
-         "punpckhwd      %%mm3,                  %%mm5\n"
+        "movq           %%mm6,                  %%mm4\n" // lum1
+        "paddw          %%mm0,                  %%mm6\n" // lum1 +blue 00 B6 00 B4 00 B2 00 B0
+        "movq           %%mm4,                  %%mm5\n" // lum1
+        "paddw          %%mm1,                  %%mm4\n" // lum1 +red  00 R6 00 R4 00 R2 00 R0
+        "paddw          %%mm2,                  %%mm5\n" // lum1 +green 00 G6 00 G4 00 G2 00 G0
+        "psraw          $6,                     %%mm4\n" // R1 0 .. 64
+        "movq           %%mm7,                  %%mm3\n" // lum2                       00 L7 00 L5 00 L3 00 L1
+        "psraw          $6,                     %%mm5\n" // G1  - .. +
+        "paddw          %%mm0,                  %%mm7\n" // Lum2 +blue 00 B7 00 B5 00 B3 00 B1
+        "psraw          $6,                     %%mm6\n" // B1         0 .. 64
+        "packuswb       %%mm4,                  %%mm4\n" // R1 R1
+        "packuswb       %%mm5,                  %%mm5\n" // G1 G1
+        "packuswb       %%mm6,                  %%mm6\n" // B1 B1
+        "punpcklbw      %%mm4,                  %%mm4\n"
+        "punpcklbw      %%mm5,                  %%mm5\n"
 
-         "movq           %%mm4,                  (%3)\n"  // write row1
-         "movq           %%mm5,                  8(%3)\n" // write row1
+        "pand           %16,                    %%mm4\n"
+        "psllw          $3,                     %%mm5\n" // GREEN       1
+        "punpcklbw      %%mm6,                  %%mm6\n"
+        "pand           %17,                    %%mm5\n"
+        "pand           %16,                    %%mm6\n"
+        "por            %%mm5,                  %%mm4\n" //
+        "psrlw          $11,                    %%mm6\n" // BLUE        1
+        "movq           %%mm3,                  %%mm5\n" // lum2
+        "paddw          %%mm1,                  %%mm3\n" // lum2 +red      00 R7 00 R5 00 R3 00 R1
+        "paddw          %%mm2,                  %%mm5\n" // lum2 +green 00 G7 00 G5 00 G3 00 G1
+        "psraw          $6,                     %%mm3\n" // R2
+        "por            %%mm6,                  %%mm4\n" // MM4
+        "psraw          $6,                     %%mm5\n" // G2
+        "movq           (%2, %4),               %%mm6\n" // L3 load lum2
+        "psraw          $6,                     %%mm7\n"
+        "packuswb       %%mm3,                  %%mm3\n"
+        "packuswb       %%mm5,                  %%mm5\n"
+        "packuswb       %%mm7,                  %%mm7\n"
+        "pand           %12,                    %%mm6\n" // L3
+        "punpcklbw      %%mm3,                  %%mm3\n"
+        "punpcklbw      %%mm5,                  %%mm5\n"
+        "pmullw         %15,                    %%mm6\n" // lum3
+        "punpcklbw      %%mm7,                  %%mm7\n"
+        "psllw          $3,                     %%mm5\n" // GREEN 2
+        "pand           %16,                    %%mm7\n"
+        "pand           %16,                    %%mm3\n"
+        "psrlw          $11,                    %%mm7\n" // BLUE  2
+        "pand           %17,                    %%mm5\n"
+        "por            %%mm7,                  %%mm3\n"
+        "movq           (%2,%4),                %%mm7\n" // L4 load lum2
+        "por            %%mm5,                  %%mm3\n" //
+        "psrlw          $8,                     %%mm7\n" // L4
+        "movq           %%mm4,                  %%mm5\n"
+        "punpcklwd      %%mm3,                  %%mm4\n"
+        "pmullw         %15,                    %%mm7\n" // lum4
+        "punpckhwd      %%mm3,                  %%mm5\n"
 
-         "movq           %%mm6,                  %%mm4\n" // Lum3
-         "paddw          %%mm0,                  %%mm6\n" // Lum3 +blue
+        "movq           %%mm4,                  (%3)\n"  // write row1
+        "movq           %%mm5,                  8(%3)\n" // write row1
+
+        "movq           %%mm6,                  %%mm4\n" // Lum3
+        "paddw          %%mm0,                  %%mm6\n" // Lum3 +blue
 
-         "movq           %%mm4,                  %%mm5\n" // Lum3
-         "paddw          %%mm1,                  %%mm4\n" // Lum3 +red
-         "paddw          %%mm2,                  %%mm5\n" // Lum3 +green
-         "psraw          $6,                     %%mm4\n"
-         "movq           %%mm7,                  %%mm3\n" // Lum4
-         "psraw          $6,                     %%mm5\n"
-         "paddw          %%mm0,                  %%mm7\n" // Lum4 +blue
-         "psraw          $6,                     %%mm6\n" // Lum3 +blue
-         "movq           %%mm3,                  %%mm0\n" // Lum4
-         "packuswb       %%mm4,                  %%mm4\n"
-         "paddw          %%mm1,                  %%mm3\n" // Lum4 +red
-         "packuswb       %%mm5,                  %%mm5\n"
-         "paddw          %%mm2,                  %%mm0\n" // Lum4 +green
-         "packuswb       %%mm6,                  %%mm6\n"
-         "punpcklbw      %%mm4,                  %%mm4\n"
-         "punpcklbw      %%mm5,                  %%mm5\n"
-         "punpcklbw      %%mm6,                  %%mm6\n"
-         "psllw          $3,                     %%mm5\n" // GREEN 3
-         "pand           _MMX_red565,            %%mm4\n"
-         "psraw          $6,                     %%mm3\n" // psr 6
-         "psraw          $6,                     %%mm0\n"
-         "pand           _MMX_red565,            %%mm6\n" // BLUE
-         "pand           _MMX_grn565,            %%mm5\n"
-         "psrlw          $11,                    %%mm6\n" // BLUE  3
-         "por            %%mm5,                  %%mm4\n"
-         "psraw          $6,                     %%mm7\n"
-         "por            %%mm6,                  %%mm4\n"
-         "packuswb       %%mm3,                  %%mm3\n"
-         "packuswb       %%mm0,                  %%mm0\n"
-         "packuswb       %%mm7,                  %%mm7\n"
-         "punpcklbw      %%mm3,                  %%mm3\n"
-         "punpcklbw      %%mm0,                  %%mm0\n"
-         "punpcklbw      %%mm7,                  %%mm7\n"
-         "pand           _MMX_red565,            %%mm3\n"
-         "pand           _MMX_red565,            %%mm7\n" // BLUE
-         "psllw          $3,                     %%mm0\n" // GREEN 4
-         "psrlw          $11,                    %%mm7\n"
-         "pand           _MMX_grn565,            %%mm0\n"
-         "por            %%mm7,                  %%mm3\n"
-         "por            %%mm0,                  %%mm3\n"
+        "movq           %%mm4,                  %%mm5\n" // Lum3
+        "paddw          %%mm1,                  %%mm4\n" // Lum3 +red
+        "paddw          %%mm2,                  %%mm5\n" // Lum3 +green
+        "psraw          $6,                     %%mm4\n"
+        "movq           %%mm7,                  %%mm3\n" // Lum4
+        "psraw          $6,                     %%mm5\n"
+        "paddw          %%mm0,                  %%mm7\n" // Lum4 +blue
+        "psraw          $6,                     %%mm6\n" // Lum3 +blue
+        "movq           %%mm3,                  %%mm0\n" // Lum4
+        "packuswb       %%mm4,                  %%mm4\n"
+        "paddw          %%mm1,                  %%mm3\n" // Lum4 +red
+        "packuswb       %%mm5,                  %%mm5\n"
+        "paddw          %%mm2,                  %%mm0\n" // Lum4 +green
+        "packuswb       %%mm6,                  %%mm6\n"
+        "punpcklbw      %%mm4,                  %%mm4\n"
+        "punpcklbw      %%mm5,                  %%mm5\n"
+        "punpcklbw      %%mm6,                  %%mm6\n"
+        "psllw          $3,                     %%mm5\n" // GREEN 3
+        "pand           %16,                    %%mm4\n"
+        "psraw          $6,                     %%mm3\n" // psr 6
+        "psraw          $6,                     %%mm0\n"
+        "pand           %16,                    %%mm6\n" // BLUE
+        "pand           %17,                    %%mm5\n"
+        "psrlw          $11,                    %%mm6\n" // BLUE  3
+        "por            %%mm5,                  %%mm4\n"
+        "psraw          $6,                     %%mm7\n"
+        "por            %%mm6,                  %%mm4\n"
+        "packuswb       %%mm3,                  %%mm3\n"
+        "packuswb       %%mm0,                  %%mm0\n"
+        "packuswb       %%mm7,                  %%mm7\n"
+        "punpcklbw      %%mm3,                  %%mm3\n"
+        "punpcklbw      %%mm0,                  %%mm0\n"
+        "punpcklbw      %%mm7,                  %%mm7\n"
+        "pand           %16,                    %%mm3\n"
+        "pand           %16,                    %%mm7\n" // BLUE
+        "psllw          $3,                     %%mm0\n" // GREEN 4
+        "psrlw          $11,                    %%mm7\n"
+        "pand           %17,                    %%mm0\n"
+        "por            %%mm7,                  %%mm3\n"
+        "por            %%mm0,                  %%mm3\n"
 
-         "movq           %%mm4,                  %%mm5\n"
+        "movq           %%mm4,                  %%mm5\n"
 
-         "punpcklwd      %%mm3,                  %%mm4\n"
-         "punpckhwd      %%mm3,                  %%mm5\n"
+        "punpcklwd      %%mm3,                  %%mm4\n"
+        "punpckhwd      %%mm3,                  %%mm5\n"
 
-         "movq           %%mm4,                  (%5)\n"
-	 "movq           %%mm5,                  8(%5)\n"
+        "movq           %%mm4,                  (%5)\n"
+        "movq           %%mm5,                  8(%5)\n"
 
-         "addl           $8,                     %6\n"
-         "addl           $8,                     %2\n"
-         "addl           $4,                     %%ebx\n"
-         "addl           $4,                     %1\n"
-         "cmpl           %4,                     %6\n"
-         "leal           16(%3),                 %3\n"
-	 "leal           16(%5),%5\n" // row2+16
-
+        "addl           $8,                     %6\n"
+        "addl           $8,                     %2\n"
+        "addl           $4,                     (%%esp)\n"
+        "addl           $4,                     %1\n"
+        "cmpl           %4,                     %6\n"
+        "leal           16(%3),                 %3\n"
+        "leal           16(%5),%5\n" // row2+16
 
-         "jl             1b\n"
-	 "addl           %4,     %2\n" // lum += cols 
-	 "addl           %8,     %3\n" // row1+= mod
-	 "addl           %8,     %5\n" // row2+= mod
-	 "movl           $0,     %6\n" // x=0
-	 "cmpl           %7,     %2\n"
-	 "jl             1b\n"
-         "emms\n"
-	 "popl %%ebx\n"
-         :
-         :"m" (cr), "r"(cb),"r"(lum),
-	 "r"(row1),"r"(cols),"r"(row2),"m"(x),"m"(y),"m"(mod));
+        "jl             1b\n"
+        "addl           %4,     %2\n" // lum += cols
+        "addl           %8,     %3\n" // row1+= mod
+        "addl           %8,     %5\n" // row2+= mod
+        "movl           $0,     %6\n" // x=0
+        "cmpl           %7,     %2\n"
+        "jl             1b\n"
+        "addl $4, %%esp\n"  // get rid of the stack slot we reserved.
+        "emms\n"
+        :
+        : "m" (cr), "r"(cb),"r"(lum),
+          "r"(row1),"r"(cols),"r"(row2),"m"(x),"m"(y),"m"(mod),
+          "m"(MMX_0080w),"m"(MMX_Ugrn565),"m"(MMX_Ublu5x5),
+          "m"(MMX_00FFw),"m"(MMX_Vgrn565),"m"(MMX_Vred5x5),
+          "m"(MMX_Ycoeff),"m"(MMX_red565),"m"(MMX_grn565)
+    );
 }
 
-#endif /* GCC i386 inline assembly */
-#endif /* 0 */
-
 /* *INDENT-ON* */
 
+#endif /* GCC3 i386 inline assembly */
+
 /* vi: set ts=4 sw=4 expandtab: */
+
--- a/src/video/SDL_yuv_sw.c	Wed Jul 11 04:47:25 2007 +0000
+++ b/src/video/SDL_yuv_sw.c	Wed Jul 11 07:39:01 2007 +0000
@@ -117,7 +117,7 @@
 
 /* The colorspace conversion functions */
 
-#if 0                           /*defined(__GNUC__) && defined(__i386__) && SDL_ASSEMBLY_ROUTINES */
+#if (__GNUC__ > 2) && defined(__i386__) && SDL_ASSEMBLY_ROUTINES
 extern void Color565DitherYV12MMX1X(int *colortab, Uint32 * rgb_2_pix,
                                     unsigned char *lum, unsigned char *cr,
                                     unsigned char *cb, unsigned char *out,
@@ -978,7 +978,7 @@
     case SDL_PIXELFORMAT_YV12:
     case SDL_PIXELFORMAT_IYUV:
         if (SDL_BYTESPERPIXEL(target_format) == 2) {
-#if 0                           /*defined(__GNUC__) && defined(__i386__) && SDL_ASSEMBLY_ROUTINES */
+#if (__GNUC__ > 2) && defined(__i386__) && SDL_ASSEMBLY_ROUTINES
             /* inline assembly functions */
             if (SDL_HasMMX() && (Rmask == 0xF800) &&
                 (Gmask == 0x07E0) && (Bmask == 0x001F) && (width & 15) == 0) {
@@ -998,7 +998,7 @@
             swdata->Display2X = Color24DitherYV12Mod2X;
         }
         if (SDL_BYTESPERPIXEL(target_format) == 4) {
-#if 0                           /*defined(__GNUC__) && defined(__i386__) && SDL_ASSEMBLY_ROUTINES */
+#if (__GNUC__ > 2) && defined(__i386__) && SDL_ASSEMBLY_ROUTINES
             /* inline assembly functions */
             if (SDL_HasMMX() && (Rmask == 0x00FF0000) &&
                 (Gmask == 0x0000FF00) &&