simplify 4-point transform part a bit

Originally committed as revision 11559 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/vc1dsp.c

@@ -194,15 +194,13 @@ static void vc1_inv_trans_8x4_c(uint8_t *dest, int linesize, DCTELEM *block)
     for(i = 0; i < 8; i++){
         t1 = 17 * (src[ 0] + src[16]) + 64;
         t2 = 17 * (src[ 0] - src[16]) + 64;
-        t3 = 22 * src[ 8];
-        t4 = 22 * src[24];
-        t5 = 10 * src[ 8];
-        t6 = 10 * src[24];
+        t3 = 22 * src[ 8] + 10 * src[24];
+        t4 = 22 * src[24] - 10 * src[ 8];
 
-        dest[0*linesize] = cm[dest[0*linesize] + ((t1 + t3 + t6) >> 7)];
-        dest[1*linesize] = cm[dest[1*linesize] + ((t2 - t4 + t5) >> 7)];
-        dest[2*linesize] = cm[dest[2*linesize] + ((t2 + t4 - t5) >> 7)];
-        dest[3*linesize] = cm[dest[3*linesize] + ((t1 - t3 - t6) >> 7)];
+        dest[0*linesize] = cm[dest[0*linesize] + ((t1 + t3) >> 7)];
+        dest[1*linesize] = cm[dest[1*linesize] + ((t2 - t4) >> 7)];
+        dest[2*linesize] = cm[dest[2*linesize] + ((t2 + t4) >> 7)];
+        dest[3*linesize] = cm[dest[3*linesize] + ((t1 - t3) >> 7)];
 
         src ++;
         dest++;
@@ -223,15 +221,13 @@ static void vc1_inv_trans_4x8_c(uint8_t *dest, int linesize, DCTELEM *block)
     for(i = 0; i < 8; i++){
         t1 = 17 * (src[0] + src[2]) + 4;
         t2 = 17 * (src[0] - src[2]) + 4;
-        t3 = 22 * src[1];
-        t4 = 22 * src[3];
-        t5 = 10 * src[1];
-        t6 = 10 * src[3];
+        t3 = 22 * src[1] + 10 * src[3];
+        t4 = 22 * src[3] - 10 * src[1];
 
-        dst[0] = (t1 + t3 + t6) >> 3;
-        dst[1] = (t2 - t4 + t5) >> 3;
-        dst[2] = (t2 + t4 - t5) >> 3;
-        dst[3] = (t1 - t3 - t6) >> 3;
+        dst[0] = (t1 + t3) >> 3;
+        dst[1] = (t2 - t4) >> 3;
+        dst[2] = (t2 + t4) >> 3;
+        dst[3] = (t1 - t3) >> 3;
 
         src += 8;
         dst += 8;
@@ -273,7 +269,7 @@ static void vc1_inv_trans_4x8_c(uint8_t *dest, int linesize, DCTELEM *block)
 static void vc1_inv_trans_4x4_c(uint8_t *dest, int linesize, DCTELEM *block)
 {
     int i;
-    register int t1,t2,t3,t4,t5,t6;
+    register int t1,t2,t3,t4;
     DCTELEM *src, *dst;
     const uint8_t *cm = ff_cropTbl + MAX_NEG_CROP;
 
@@ -282,15 +278,13 @@ static void vc1_inv_trans_4x4_c(uint8_t *dest, int linesize, DCTELEM *block)
     for(i = 0; i < 4; i++){
         t1 = 17 * (src[0] + src[2]) + 4;
         t2 = 17 * (src[0] - src[2]) + 4;
-        t3 = 22 * src[1];
-        t4 = 22 * src[3];
-        t5 = 10 * src[1];
-        t6 = 10 * src[3];
+        t3 = 22 * src[1] + 10 * src[3];
+        t4 = 22 * src[3] - 10 * src[1];
 
-        dst[0] = (t1 + t3 + t6) >> 3;
-        dst[1] = (t2 - t4 + t5) >> 3;
-        dst[2] = (t2 + t4 - t5) >> 3;
-        dst[3] = (t1 - t3 - t6) >> 3;
+        dst[0] = (t1 + t3) >> 3;
+        dst[1] = (t2 - t4) >> 3;
+        dst[2] = (t2 + t4) >> 3;
+        dst[3] = (t1 - t3) >> 3;
 
         src += 8;
         dst += 8;
@@ -300,15 +294,13 @@ static void vc1_inv_trans_4x4_c(uint8_t *dest, int linesize, DCTELEM *block)
     for(i = 0; i < 4; i++){
         t1 = 17 * (src[ 0] + src[16]) + 64;
         t2 = 17 * (src[ 0] - src[16]) + 64;
-        t3 = 22 * src[ 8];
-        t4 = 22 * src[24];
-        t5 = 10 * src[ 8];
-        t6 = 10 * src[24];
-
-        dest[0*linesize] = cm[dest[0*linesize] + ((t1 + t3 + t6) >> 7)];
-        dest[1*linesize] = cm[dest[1*linesize] + ((t2 - t4 + t5) >> 7)];
-        dest[2*linesize] = cm[dest[2*linesize] + ((t2 + t4 - t5) >> 7)];
-        dest[3*linesize] = cm[dest[3*linesize] + ((t1 - t3 - t6) >> 7)];
+        t3 = 22 * src[ 8] + 10 * src[24];
+        t4 = 22 * src[24] - 10 * src[ 8];
+
+        dest[0*linesize] = cm[dest[0*linesize] + ((t1 + t3) >> 7)];
+        dest[1*linesize] = cm[dest[1*linesize] + ((t2 - t4) >> 7)];
+        dest[2*linesize] = cm[dest[2*linesize] + ((t2 + t4) >> 7)];
+        dest[3*linesize] = cm[dest[3*linesize] + ((t1 - t3) >> 7)];
 
         src ++;
         dest++;