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dv: simplify bitstream splicing in dv_decode_ac()

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This is simpler and fixes some overflow checker warnings.

Signed-off-by: Mans Rullgard <mans@mansr.com>
This commit is contained in:
Mans Rullgard
2011-11-26 18:48:16 +00:00
parent b02aa3a8ea
commit b6ae086682
1 changed files with 3 additions and 4 deletions
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7
libavcodec/dv.c
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@@ -364,7 +364,7 @@ typedef struct BlockInfo {
uint8_t pos; /* position in block */ uint8_t pos; /* position in block */
void (*idct_put)(uint8_t *dest, int line_size, DCTELEM *block); void (*idct_put)(uint8_t *dest, int line_size, DCTELEM *block);
uint8_t partial_bit_count; uint8_t partial_bit_count;
uint16_t partial_bit_buffer; uint32_t partial_bit_buffer;
int shift_offset; int shift_offset;
} BlockInfo; } BlockInfo;
@@ -392,8 +392,7 @@ static void dv_decode_ac(GetBitContext *gb, BlockInfo *mb, DCTELEM *block)
/* if we must parse a partial VLC, we do it here */ /* if we must parse a partial VLC, we do it here */
if (partial_bit_count > 0) { if (partial_bit_count > 0) {
re_cache = ((unsigned)re_cache >> partial_bit_count) | re_cache = re_cache >> partial_bit_count | mb->partial_bit_buffer;
(mb->partial_bit_buffer << (sizeof(re_cache) * 8 - partial_bit_count));
re_index -= partial_bit_count; re_index -= partial_bit_count;
mb->partial_bit_count = 0; mb->partial_bit_count = 0;
} }
@@ -416,7 +415,7 @@ static void dv_decode_ac(GetBitContext *gb, BlockInfo *mb, DCTELEM *block)
if (re_index + vlc_len > last_index) { if (re_index + vlc_len > last_index) {
/* should be < 16 bits otherwise a codeword could have been parsed */ /* should be < 16 bits otherwise a codeword could have been parsed */
mb->partial_bit_count = last_index - re_index; mb->partial_bit_count = last_index - re_index;
mb->partial_bit_buffer = NEG_USR32(re_cache, mb->partial_bit_count); mb->partial_bit_buffer = re_cache & ~(-1u >> mb->partial_bit_count);
re_index = last_index; re_index = last_index;
break; break;
} }