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fix big-endian VP8LWriteBits

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bits would be lost if n_bits was > 17

Change-Id: Id315d075075338a08e10c04faa91cab347a53591
This commit is contained in:
James Zern 2012-07-01 13:49:44 -07:00
parent 4c3975792b
commit f56a369ab0
1 changed files with 3 additions and 2 deletions
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5
src/utils/bit_writer.c
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@ -230,7 +230,7 @@ void VP8LWriteBits(VP8LBitWriter* const bw, int n_bits, uint32_t bits) {
if (n_bits < 1) return; if (n_bits < 1) return;
#if !defined(__BIG_ENDIAN__) #if !defined(__BIG_ENDIAN__)
// Technically, this branch of the code can write up to 25 bits at a time, // Technically, this branch of the code can write up to 25 bits at a time,
// but in deflate, the maximum number of bits written is 16 at a time. // but in prefix encoding, the maximum number of bits written is 18 at a time.
{ {
uint8_t* p = &bw->buf_[bw->bit_pos_ >> 3]; uint8_t* p = &bw->buf_[bw->bit_pos_ >> 3];
uint32_t v = *(const uint32_t*)(p); uint32_t v = *(const uint32_t*)(p);
@ -251,7 +251,8 @@ void VP8LWriteBits(VP8LBitWriter* const bw, int n_bits, uint32_t bits) {
*p++ = bits >> (16 - bits_reserved_in_first_byte); *p++ = bits >> (16 - bits_reserved_in_first_byte);
} }
} }
*p = 0; assert(n_bits <= 25);
*p = bits >> (24 - bits_reserved_in_first_byte);
bw->bit_pos_ += n_bits; bw->bit_pos_ += n_bits;
} }
#endif // BIG_ENDIAN #endif // BIG_ENDIAN