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mlp: split simple inline function that xors 4 bytes into one.

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Originally committed as revision 14747 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Ramiro Polla 2008-08-14 03:58:05 +00:00
parent 3c9769a008
commit a7cc783d71
3 changed files with 10 additions and 6 deletions
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3
libavcodec/mlp.c
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@ -110,8 +110,7 @@ uint8_t ff_mlp_calculate_parity(const uint8_t *buf, unsigned int buf_size)
for (; buf < buf_end - 3; buf += 4) for (; buf < buf_end - 3; buf += 4)
scratch ^= *((const uint32_t*)buf); scratch ^= *((const uint32_t*)buf);
scratch ^= scratch >> 16; scratch = xor_32_to_8(scratch);
scratch ^= scratch >> 8;
for (; buf < buf_end; buf++) for (; buf < buf_end; buf++)
scratch ^= *buf; scratch ^= *buf;

8
libavcodec/mlp.h
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@ -107,4 +107,12 @@ int ff_mlp_init_crc2D(AVCodecParserContext *s);
void ff_mlp_init_crc(); void ff_mlp_init_crc();
/** XOR four bytes into one. */
static inline uint8_t xor_32_to_8(uint32_t value)
{
value ^= value >> 16;
value ^= value >> 8;
return value;
}
#endif /* FFMPEG_MLP_H */ #endif /* FFMPEG_MLP_H */

5
libavcodec/mlpdec.c
View File

@ -364,10 +364,7 @@ static int read_restart_header(MLPDecodeContext *m, GetBitContext *gbp,
lossless_check = get_bits(gbp, 8); lossless_check = get_bits(gbp, 8);
if (substr == m->max_decoded_substream if (substr == m->max_decoded_substream
&& s->lossless_check_data != 0xffffffff) { && s->lossless_check_data != 0xffffffff) {
tmp = s->lossless_check_data; tmp = xor_32_to_8(s->lossless_check_data);
tmp ^= tmp >> 16;
tmp ^= tmp >> 8;
tmp &= 0xff;
if (tmp != lossless_check) if (tmp != lossless_check)
av_log(m->avctx, AV_LOG_WARNING, av_log(m->avctx, AV_LOG_WARNING,
"Lossless check failed - expected %02x, calculated %02x.\n", "Lossless check failed - expected %02x, calculated %02x.\n",