Revert two swscale commits.

Revert "swscale: update context offsets after removal of AlpMmxFilter."
(commit a95e3fa90b)
and
Revert "swscale: Remove some write-only variables related to alpha handling."
(commit 9d03cb9fc5).

They broke alpha handling - it's the evil inline asm that still uses that
variable, so it's not truely write-only.

libswscale/swscale_internal.h

@@ -352,10 +352,11 @@ typedef struct SwsContext {
 #define U_TEMP                "11*8+4*4*256*2+24"
 #define V_TEMP                "11*8+4*4*256*2+32"
 #define Y_TEMP                "11*8+4*4*256*2+40"
-#define UV_OFF_PX             "11*8+4*4*256*2+48"
-#define UV_OFF_BYTE           "11*8+4*4*256*2+56"
-#define DITHER16              "11*8+4*4*256*2+64"
-#define DITHER32              "11*8+4*4*256*2+80"
+#define ALP_MMX_FILTER_OFFSET "11*8+4*4*256*2+48"
+#define UV_OFF_PX             "11*8+4*4*256*3+48"
+#define UV_OFF_BYTE           "11*8+4*4*256*3+56"
+#define DITHER16              "11*8+4*4*256*3+64"
+#define DITHER32              "11*8+4*4*256*3+80"
 
     DECLARE_ALIGNED(8, uint64_t, redDither);
     DECLARE_ALIGNED(8, uint64_t, greenDither);
@@ -377,6 +378,7 @@ typedef struct SwsContext {
     DECLARE_ALIGNED(8, uint64_t, u_temp);
     DECLARE_ALIGNED(8, uint64_t, v_temp);
     DECLARE_ALIGNED(8, uint64_t, y_temp);
+    int32_t alpMmxFilter[4 * MAX_FILTER_SIZE];
     // alignment of these values is not necessary, but merely here
     // to maintain the same offset across x8632 and x86-64. Once we
     // use proper offset macros in the asm, they can be removed.

libswscale/x86/swscale_mmx.c

@@ -90,6 +90,7 @@ void updateMMXDitherTables(SwsContext *c, int dstY, int lumBufIndex, int chrBufI
     const int flags= c->flags;
     int16_t **lumPixBuf= c->lumPixBuf;
     int16_t **chrUPixBuf= c->chrUPixBuf;
+    int16_t **alpPixBuf= c->alpPixBuf;
     const int vLumBufSize= c->vLumBufSize;
     const int vChrBufSize= c->vChrBufSize;
     int16_t *vLumFilterPos= c->vLumFilterPos;
@@ -98,6 +99,7 @@ void updateMMXDitherTables(SwsContext *c, int dstY, int lumBufIndex, int chrBufI
     int16_t *vChrFilter= c->vChrFilter;
     int32_t *lumMmxFilter= c->lumMmxFilter;
     int32_t *chrMmxFilter= c->chrMmxFilter;
+    int32_t av_unused *alpMmxFilter= c->alpMmxFilter;
     const int vLumFilterSize= c->vLumFilterSize;
     const int vChrFilterSize= c->vChrFilterSize;
     const int chrDstY= dstY>>c->chrDstVSubSample;
@@ -113,6 +115,7 @@ void updateMMXDitherTables(SwsContext *c, int dstY, int lumBufIndex, int chrBufI
     if (dstY < dstH - 2) {
         const int16_t **lumSrcPtr= (const int16_t **) lumPixBuf + lumBufIndex + firstLumSrcY - lastInLumBuf + vLumBufSize;
         const int16_t **chrUSrcPtr= (const int16_t **) chrUPixBuf + chrBufIndex + firstChrSrcY - lastInChrBuf + vChrBufSize;
+        const int16_t **alpSrcPtr= (CONFIG_SWSCALE_ALPHA && alpPixBuf) ? (const int16_t **) alpPixBuf + lumBufIndex + firstLumSrcY - lastInLumBuf + vLumBufSize : NULL;
         int i;
         if (flags & SWS_ACCURATE_RND) {
             int s= APCK_SIZE / 8;
@@ -122,6 +125,12 @@ void updateMMXDitherTables(SwsContext *c, int dstY, int lumBufIndex, int chrBufI
                 lumMmxFilter[s*i+APCK_COEF/4  ]=
                 lumMmxFilter[s*i+APCK_COEF/4+1]= vLumFilter[dstY*vLumFilterSize + i    ]
                 + (vLumFilterSize>1 ? vLumFilter[dstY*vLumFilterSize + i + 1]<<16 : 0);
+                if (CONFIG_SWSCALE_ALPHA && alpPixBuf) {
+                    *(const void**)&alpMmxFilter[s*i              ]= alpSrcPtr[i  ];
+                    *(const void**)&alpMmxFilter[s*i+APCK_PTR2/4  ]= alpSrcPtr[i+(vLumFilterSize>1)];
+                    alpMmxFilter[s*i+APCK_COEF/4  ]=
+                    alpMmxFilter[s*i+APCK_COEF/4+1]= lumMmxFilter[s*i+APCK_COEF/4  ];
+                }
             }
             for (i=0; i<vChrFilterSize; i+=2) {
                 *(const void**)&chrMmxFilter[s*i              ]= chrUSrcPtr[i  ];
@@ -136,6 +145,11 @@ void updateMMXDitherTables(SwsContext *c, int dstY, int lumBufIndex, int chrBufI
                 lumMmxFilter[4*i+2]=
                 lumMmxFilter[4*i+3]=
                 ((uint16_t)vLumFilter[dstY*vLumFilterSize + i])*0x10001;
+                if (CONFIG_SWSCALE_ALPHA && alpPixBuf) {
+                    *(const void**)&alpMmxFilter[4*i+0]= alpSrcPtr[i];
+                    alpMmxFilter[4*i+2]=
+                    alpMmxFilter[4*i+3]= lumMmxFilter[4*i+2];
+                }
             }
             for (i=0; i<vChrFilterSize; i++) {
                 *(const void**)&chrMmxFilter[4*i+0]= chrUSrcPtr[i];

libswscale/x86/swscale_template.c

@@ -268,7 +268,7 @@ static void RENAME(yuv2rgb32_X_ar)(SwsContext *c, const int16_t *lumFilter,
         "movq                      %%mm2, "U_TEMP"(%0)  \n\t"
         "movq                      %%mm4, "V_TEMP"(%0)  \n\t"
         "movq                      %%mm5, "Y_TEMP"(%0)  \n\t"
-        YSCALEYUV2PACKEDX_ACCURATE_YA(LUM_MMX_FILTER_OFFSET)
+        YSCALEYUV2PACKEDX_ACCURATE_YA(ALP_MMX_FILTER_OFFSET)
         "movq               "Y_TEMP"(%0), %%mm5         \n\t"
         "psraw                        $3, %%mm1         \n\t"
         "psraw                        $3, %%mm7         \n\t"
@@ -298,7 +298,7 @@ static void RENAME(yuv2rgb32_X)(SwsContext *c, const int16_t *lumFilter,
     if (CONFIG_SWSCALE_ALPHA && c->alpPixBuf) {
         YSCALEYUV2PACKEDX
         YSCALEYUV2RGBX
-        YSCALEYUV2PACKEDX_YA(LUM_MMX_FILTER_OFFSET, %%mm0, %%mm3, %%mm6, %%mm1, %%mm7)
+        YSCALEYUV2PACKEDX_YA(ALP_MMX_FILTER_OFFSET, %%mm0, %%mm3, %%mm6, %%mm1, %%mm7)
         "psraw                        $3, %%mm1         \n\t"
         "psraw                        $3, %%mm7         \n\t"
         "packuswb                  %%mm7, %%mm1         \n\t"