gif

commit dcb739a2a1f61d96d7f34daf691928d651da48ff
parent c0a4d61d695927b2b275db24e43dd690eb4b9697
Author: phoebos <ben@bvnf.space>
Date:   Sat, 28 Aug 2021 11:53:17 +0100

fix bug when GCT has 256 colours

Diffstat:
M
gif.c
 | 
7
++++---

1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/gif.c b/gif.c
@@ -29,8 +29,8 @@ struct Gif {
                          */
     unsigned char background; /* color index in GCT of screen background */
     unsigned char aspect_ratio; /* 89a+ only */
-    rgb colortable[255];
-    int colortable_len;
+    rgb colortable[256];
+    int colortable_len; /* 2 - 256 */
     unsigned char *pixels; /* array of indices to colors */
 };
 
@@ -63,7 +63,8 @@ gif_decode(unsigned char *buf, size_t len){
     g.background = *buf++;
     g.aspect_ratio = *buf++;
 
-    g.colortable_len = (int)pow(2.0, (double) (g.flags & 7) + 1);
+    g.colortable_len = (int)pow(2.0, (double) (g.flags & 7U) + 1);
+    fprintf(stderr, "%d colors in GCT\n", g.colortable_len);
 
     /* if GCT... */
     if (g.flags & 0x80) {