huffyuvdec: implement trick for BGR

Before:
179436 decicycles in rgb, 32735 runs, 33 skips
Stripped object size: 23188

After:
154861 decicycles in rgb, 32738 runs, 30 skips
Stripped object size: 22736
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/huffyuvdec.c

@@ -720,28 +720,89 @@ static void decode_gray_bitstream(HYuvContext *s, int count)
     CLOSE_READER(re, &s->gb);
 }
 
+#define GET_VLC_DUAL(dst0, dst1, name, gb, dtable, table1, table2,  \
+                     bits, max_depth, rsvd )                        \
+    do {                                                            \
+        unsigned int index = SHOW_UBITS(name, gb, bits);            \
+        int          code  = dtable[index][0];                      \
+        int          n     = dtable[index][1];                      \
+                                                                    \
+        if (code != rsvd && n>0) {                                  \
+            dst0 = code>>8;                                         \
+            dst1 = code;                                            \
+            LAST_SKIP_BITS(name, gb, n);                            \
+        } else {                                                    \
+            int nb_bits;                                            \
+            DUAL_INTERN(dst0, table1, gb, name, bits, max_depth);   \
+                                                                    \
+            UPDATE_CACHE(re, gb);                                   \
+            index = SHOW_UBITS(name, gb, bits);                     \
+            DUAL_INTERN(dst1, table2, gb, name, bits, max_depth);   \
+        }                                                           \
+    } while (0)
+
+#define READ_2PIX(dst0, dst1, plane1)\
+    UPDATE_CACHE(re, &s->gb); \
+    GET_VLC_DUAL(dst0, dst1, re, &s->gb, s->vlc[4+plane1].table, \
+                 s->vlc[0].table, s->vlc[plane1].table, \
+                 VLC_BITS, 3, 0xffff)
+
 static av_always_inline void decode_bgr_1(HYuvContext *s, int count,
                                           int decorrelate, int alpha)
 {
     int i;
+    OPEN_READER(re, &s->gb);
+
     for (i = 0; i < count; i++) {
-        int code = get_vlc2(&s->gb, s->vlc[4].table, VLC_BITS, 1);
+        unsigned int index;
+        int code, n;
+
+        UPDATE_CACHE(re, &s->gb);
+        index = SHOW_UBITS(re, &s->gb, VLC_BITS);
+        code  = s->vlc[4].table[index][0];
+        n     = s->vlc[4].table[index][1];
+
         if (code != -1) {
             *(uint32_t*)&s->temp[0][4 * i] = s->pix_bgr_map[code];
-        } else if(decorrelate) {
-            s->temp[0][4 * i + G] = get_vlc2(&s->gb, s->vlc[1].table, VLC_BITS, 3);
-            s->temp[0][4 * i + B] = get_vlc2(&s->gb, s->vlc[0].table, VLC_BITS, 3) +
-                                    s->temp[0][4 * i + G];
-            s->temp[0][4 * i + R] = get_vlc2(&s->gb, s->vlc[2].table, VLC_BITS, 3) +
-                                    s->temp[0][4 * i + G];
+            LAST_SKIP_BITS(re, &s->gb, n);
         } else {
-            s->temp[0][4 * i + B] = get_vlc2(&s->gb, s->vlc[0].table, VLC_BITS, 3);
-            s->temp[0][4 * i + G] = get_vlc2(&s->gb, s->vlc[1].table, VLC_BITS, 3);
-            s->temp[0][4 * i + R] = get_vlc2(&s->gb, s->vlc[2].table, VLC_BITS, 3);
+            int nb_bits;
+            if(decorrelate) {
+                DUAL_INTERN(s->temp[0][4 * i + G], s->vlc[1].table,
+                            &s->gb, re, VLC_BITS, 3);
+
+                UPDATE_CACHE(re, &s->gb);
+                index = SHOW_UBITS(re, &s->gb, VLC_BITS);
+                DUAL_INTERN(code, s->vlc[0].table, &s->gb, re, VLC_BITS, 3);
+                s->temp[0][4 * i + B] = code + s->temp[0][4 * i + G];
+
+                UPDATE_CACHE(re, &s->gb);
+                index = SHOW_UBITS(re, &s->gb, VLC_BITS);
+                DUAL_INTERN(code, s->vlc[2].table, &s->gb, re, VLC_BITS, 3);
+                s->temp[0][4 * i + R] = code + s->temp[0][4 * i + G];
+            } else {
+                DUAL_INTERN(s->temp[0][4 * i + B], s->vlc[0].table,
+                            &s->gb, re, VLC_BITS, 3);
+
+                UPDATE_CACHE(re, &s->gb);
+                index = SHOW_UBITS(re, &s->gb, VLC_BITS);
+                DUAL_INTERN(s->temp[0][4 * i + G], s->vlc[1].table,
+                            &s->gb, re, VLC_BITS, 3);
+
+                UPDATE_CACHE(re, &s->gb);
+                index = SHOW_UBITS(re, &s->gb, VLC_BITS);
+                DUAL_INTERN(s->temp[0][4 * i + R], s->vlc[2].table,
+                            &s->gb, re, VLC_BITS, 3);
+            }
+            if (alpha) {
+                UPDATE_CACHE(re, &s->gb);
+                index = SHOW_UBITS(re, &s->gb, VLC_BITS);
+                DUAL_INTERN(s->temp[0][4 * i + A], s->vlc[2].table,
+                            &s->gb, re, VLC_BITS, 3);
+            }
         }
-        if (alpha)
-            s->temp[0][4 * i + A] = get_vlc2(&s->gb, s->vlc[2].table, VLC_BITS, 3);
     }
+    CLOSE_READER(re, &s->gb);
 }
 
 static void decode_bgr_bitstream(HYuvContext *s, int count)