MMX/MMXEXT iDCT support, using external functions currently defined in libmpeg2

Gives average 13-20% mpeg decoding speedup on x86 systems.


Originally committed as revision 30 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/dsputil.c

@@ -21,6 +21,7 @@
 #include "avcodec.h"
 #include "dsputil.h"
 
+void (*ff_idct)(DCTELEM *block);
 void (*get_pixels)(DCTELEM *block, const UINT8 *pixels, int line_size);
 void (*put_pixels_clamped)(const DCTELEM *block, UINT8 *pixels, int line_size);
 void (*add_pixels_clamped)(const DCTELEM *block, UINT8 *pixels, int line_size);
@@ -363,6 +364,7 @@ void dsputil_init(void)
         squareTbl[i] = (i - 256) * (i - 256);
     }
 
+    ff_idct = j_rev_dct;
     get_pixels = get_pixels_c;
     put_pixels_clamped = put_pixels_clamped_c;
     add_pixels_clamped = add_pixels_clamped_c;

libavcodec/dsputil.h

@@ -25,6 +25,7 @@ void dsputil_init(void);
 
 /* pixel ops : interface with DCT */
 
+extern void (*ff_idct)(DCTELEM *block);
 extern void (*get_pixels)(DCTELEM *block, const UINT8 *pixels, int line_size);
 extern void (*put_pixels_clamped)(const DCTELEM *block, UINT8 *pixels, int line_size);
 extern void (*add_pixels_clamped)(const DCTELEM *block, UINT8 *pixels, int line_size);

libavcodec/i386/dsputil_mmx.c

@@ -29,6 +29,16 @@ int pix_abs16x16_x2_mmx(UINT8 *blk1, UINT8 *blk2, int lx, int h);
 int pix_abs16x16_y2_mmx(UINT8 *blk1, UINT8 *blk2, int lx, int h);
 int pix_abs16x16_xy2_mmx(UINT8 *blk1, UINT8 *blk2, int lx, int h);
 
+#ifdef USE_MMX_IDCT
+/* external functions, defined in libmpeg2 */
+void mmx_idct(DCTELEM *block);
+void mmxext_idct(DCTELEM *block);
+/* this should be in dsputil.h?  -- A'rpi   */
+extern UINT8 ff_alternate_horizontal_scan[64];
+extern UINT8 ff_alternate_vertical_scan[64];
+extern UINT8 zigzag_direct[64];
+#endif
+
 /* pixel operations */
 static const unsigned long long int mm_wone __attribute__ ((aligned(8))) = 0x0001000100010001;
 static const unsigned long long int mm_wtwo __attribute__ ((aligned(8))) = 0x0002000200020002;
@@ -1039,5 +1049,23 @@ void dsputil_init_mmx(void)
             sub_pixels_tab[1] = sub_pixels_x2_3dnow;
             sub_pixels_tab[2] = sub_pixels_y2_3dnow;
         }
+
+#ifdef USE_MMX_IDCT
+	/* use MMX / MMXEXT iDCT code from libmpeg2 */
+	//printf("LIBAVCODEC: Using MMX%s iDCT code\n",(mm_flags & MM_MMXEXT)?"EXT":"");
+	ff_idct = (mm_flags & MM_MMXEXT) ? mmxext_idct : mmx_idct;
+	/* the mmx/mmxext idct uses a reordered input, so we patch scan tables */
+	{   int i,j;
+	    for (i = 0; i < 64; i++) {
+		j = zigzag_direct[i];
+		zigzag_direct[i] = (j & 0x38) | ((j & 6) >> 1) | ((j & 1) << 2);
+		j = ff_alternate_horizontal_scan[i];
+		ff_alternate_horizontal_scan[i] =  (j & 0x38) | ((j & 6) >> 1) | ((j & 1) << 2);
+		j = ff_alternate_vertical_scan[i];
+		ff_alternate_vertical_scan[i] =  (j & 0x38) | ((j & 6) >> 1) | ((j & 1) << 2);
+	    }
+	}
+#endif
+
     }
 }

libavcodec/mpeg12data.h

@@ -331,7 +331,8 @@ static const UINT8 mbMotionVectorTable[17][2] = {
 { 0xc, 10 },
 };
 
-const UINT8 zigzag_direct[64] = {
+//const 
+UINT8 zigzag_direct[64] = {
     0, 1, 8, 16, 9, 2, 3, 10,
     17, 24, 32, 25, 18, 11, 4, 5,
     12, 19, 26, 33, 40, 48, 41, 34,

libavcodec/mpegvideo.c

@@ -634,7 +634,7 @@ static inline void put_dct(MpegEncContext *s,
 {
     if (!s->mpeg2)
         s->dct_unquantize(s, block, i, s->qscale);
-    j_rev_dct (block);
+    ff_idct (block);
     put_pixels_clamped(block, dest, line_size);
 }
 
@@ -645,7 +645,7 @@ static inline void add_dct(MpegEncContext *s,
     if (s->block_last_index[i] >= 0) {
         if (!s->mpeg2)
             s->dct_unquantize(s, block, i, s->qscale);
-        j_rev_dct (block);
+        ff_idct (block);
         add_pixels_clamped(block, dest, line_size);
     }
 }

libavcodec/mpegvideo.h

@@ -179,7 +179,8 @@ typedef struct MpegEncContext {
                            DCTELEM *block, int n, int qscale);
 } MpegEncContext;
 
-extern const UINT8 zigzag_direct[64];
+//const 
+extern UINT8 zigzag_direct[64];
 
 int MPV_common_init(MpegEncContext *s);
 void MPV_common_end(MpegEncContext *s);