stb_image: Fast path for matches with dist=1 (runs) in stbi__parse_huffman_block.

2014-12-13 18:07:00 -08:00 · 2014-12-13 18:07:00 -08:00 · cdc230598e
parent 92b9e262b7
commit cdc230598e
1 changed files with 6 additions and 2 deletions
--- a/stb_image.h
+++ b/stb_image.h
@ -2210,8 +2210,12 @@ static int stbi__parse_huffman_block(stbi__zbuf *a)
            zout = a->zout;
         }
         p = (stbi_uc *) (zout - dist);
-         while (len--)
-            *zout++ = *p++;
+         if (dist == 1) { // run of one byte; common in images.
+            stbi_uc v = *p;
+            do *zout++ = v; while (--len);
+         } else {
+            do *zout++ = *p++; while (--len);
+         }
      }
   }
 }