X-Git-Url: https://git.sesse.net/?p=fjl;a=blobdiff_plain;f=driver.c;h=fcd9f7fb9aed2c1fa8629a2913ddb3b7df2117dc;hp=cda257e3c90ba023ed8b465eeedf2e1417768aff;hb=bbe665e5ef6a103657f4d921ddd4b540f38daf3d;hpb=1cfb04470add4e31406785980e7ce14a8e9d0672

diff --git a/driver.c b/driver.c
index cda257e..fcd9f7f 100644
--- a/driver.c
+++ b/driver.c
@@ -116,20 +116,16 @@ void read_sof(struct byte_source* source, struct jpeg_image* image)
 
 void decode_ac_coefficients(const struct huffman_table* tbl, struct bit_source* bits, int16_t* coeff)
 {
-	for (unsigned i = 1; i < DCTSIZE2; ++i) {
+	for (unsigned i = 0; i < DCTSIZE2 - 1; ) {
 		possibly_refill(bits, DEHUF_AC_TABLE_BITS);
 		unsigned lookup = peek_bits(bits, DEHUF_AC_TABLE_BITS);
 		int code = tbl->ac_table_codes[lookup];
-		int length = tbl->ac_table_length[lookup];
-		int r = tbl->ac_table_skip[lookup];
-
-		assert(length == AC_DEHUF_SLOW_PATH || (length > 0 && length <= DEHUF_AC_TABLE_BITS));
 
 		if (__builtin_expect(code == AC_DEHUF_SLOW_PATH, 0)) {
 			unsigned rs = read_huffman_symbol_no_refill(tbl, bits);
 			unsigned r = rs >> 4;
 			unsigned s = rs & 0xf;
-			i += r;
+			i += r + 1;
 			possibly_refill(bits, s);
 
 			if (rs == 0x00) {
@@ -145,7 +141,9 @@ void decode_ac_coefficients(const struct huffman_table* tbl, struct bit_source*
 
 			coeff[unzigzag[i]] = extend(read_bits(bits, s), s);
 		} else {
-			assert(r >= 0);
+			unsigned length = tbl->ac_table_length[lookup];
+			int r = tbl->ac_table_skip[lookup];
+			assert(r >= 1);
 			i += r;
 			assert(bits->bits_available >= length);
 			read_bits(bits, length);