avoid i++ in decode_block()

Originally committed as revision 5238 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/mjpeg.c

@@ -894,14 +894,24 @@ typedef struct MJpegDecodeContext {
 static int mjpeg_decode_dht(MJpegDecodeContext *s);
 
 static int build_vlc(VLC *vlc, const uint8_t *bits_table, const uint8_t *val_table,
-                      int nb_codes, int use_static)
+                      int nb_codes, int use_static, int is_ac)
 {
-    uint8_t huff_size[256];
-    uint16_t huff_code[256];
+    uint8_t huff_size[256+16];
+    uint16_t huff_code[256+16];
+
+    assert(nb_codes <= 256);
 
     memset(huff_size, 0, sizeof(huff_size));
     build_huffman_codes(huff_size, huff_code, bits_table, val_table);
 
+    if(is_ac){
+        memmove(huff_size+16, huff_size, sizeof(uint8_t)*nb_codes);
+        memmove(huff_code+16, huff_code, sizeof(uint16_t)*nb_codes);
+        memset(huff_size, 0, sizeof(uint8_t)*16);
+        memset(huff_code, 0, sizeof(uint16_t)*16);
+        nb_codes += 16;
+    }
+
     return init_vlc(vlc, 9, nb_codes, huff_size, 1, 1, huff_code, 2, 2, use_static);
 }
 
@@ -930,10 +940,10 @@ static int mjpeg_decode_init(AVCodecContext *avctx)
     s->first_picture = 1;
     s->org_height = avctx->coded_height;
 
-    build_vlc(&s->vlcs[0][0], bits_dc_luminance, val_dc_luminance, 12, 0);
-    build_vlc(&s->vlcs[0][1], bits_dc_chrominance, val_dc_chrominance, 12, 0);
-    build_vlc(&s->vlcs[1][0], bits_ac_luminance, val_ac_luminance, 251, 0);
-    build_vlc(&s->vlcs[1][1], bits_ac_chrominance, val_ac_chrominance, 251, 0);
+    build_vlc(&s->vlcs[0][0], bits_dc_luminance, val_dc_luminance, 12, 0, 0);
+    build_vlc(&s->vlcs[0][1], bits_dc_chrominance, val_dc_chrominance, 12, 0, 0);
+    build_vlc(&s->vlcs[1][0], bits_ac_luminance, val_ac_luminance, 251, 0, 1);
+    build_vlc(&s->vlcs[1][1], bits_ac_chrominance, val_ac_chrominance, 251, 0, 1);
 
     if (avctx->flags & CODEC_FLAG_EXTERN_HUFF)
     {
@@ -1084,7 +1094,7 @@ static int mjpeg_decode_dht(MJpegDecodeContext *s)
         free_vlc(&s->vlcs[class][index]);
         dprintf("class=%d index=%d nb_codes=%d\n",
                class, index, code_max + 1);
-        if(build_vlc(&s->vlcs[class][index], bits_table, val_table, code_max + 1, 0) < 0){
+        if(build_vlc(&s->vlcs[class][index], bits_table, val_table, code_max + 1, 0, class > 0) < 0){
             return -1;
         }
     }
@@ -1262,16 +1272,16 @@ static int decode_block(MJpegDecodeContext *s, DCTELEM *block,
     block[0] = val;
     /* AC coefs */
     ac_vlc = &s->vlcs[1][ac_index];
-    i = 1;
+    i = 0;
     OPEN_READER(re, &s->gb)
     for(;;) {
         UPDATE_CACHE(re, &s->gb);
         GET_VLC(code, re, &s->gb, s->vlcs[1][ac_index].table, 9, 2)
 
         /* EOB */
-        if (code == 0)
+        if (code == 0x10)
             break;
-        if (code == 0xf0) {
+        if (code == 0x100) {
             i += 16;
         } else {
             i += ((unsigned)code) >> 4;
@@ -1293,8 +1303,7 @@ static int decode_block(MJpegDecodeContext *s, DCTELEM *block,
             }
             j = s->scantable.permutated[i];
             block[j] = level * quant_matrix[j];
-            i++;
-            if (i >= 64)
+            if (i >= 63)
                 break;
         }
     }