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minor optimizations to FLAC__bitreader_read_rice_signed_block()

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This commit is contained in:
Josh Coalson
2007-03-22 03:19:19 +00:00
parent db55c40fd3
commit c9212fa01b
1 changed files with 14 additions and 1 deletions
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15
src/libFLAC/bitreader.c
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@@ -824,6 +824,7 @@ FLAC__bool FLAC__bitreader_read_rice_signed_block(FLAC__BitReader *br, int vals[
* bitwriter functions that use them, and before returning */
register unsigned cwords;
register unsigned cbits;
unsigned ucbits; /* keep track of the number of unconsumed bits in the buffer */
FLAC__ASSERT(0 != br);
FLAC__ASSERT(0 != br->buffer);
@@ -837,6 +838,7 @@ FLAC__bool FLAC__bitreader_read_rice_signed_block(FLAC__BitReader *br, int vals[
cbits = br->consumed_bits;
cwords = br->consumed_words;
ucbits = (br->words-cwords)*FLAC__BITS_PER_WORD + br->bytes*8 - cbits;
while(1) {
@@ -910,13 +912,21 @@ FLAC__bool FLAC__bitreader_read_rice_signed_block(FLAC__BitReader *br, int vals[
if(!bitreader_read_from_client_(br))
return false;
cwords = br->consumed_words;
ucbits = (br->words-cwords)*FLAC__BITS_PER_WORD + br->bytes*8 - cbits + uval;
/* + uval to offset our count by the # of unary bits already
* consumed before the read, because we will add these back
* in all at once at break1
*/
}
break1:
ucbits -= uval;
ucbits--; /* account for stop bit */
/* read binary part */
FLAC__ASSERT(cwords <= br->words);
if(bits) {
while((br->words-cwords)*FLAC__BITS_PER_WORD + br->bytes*8 - cbits < bits) {
while(ucbits < bits) {
/* flush registers and read; bitreader_read_from_client_() does
* not touch br->consumed_bits at all but we still need to set
* it in case it fails and we have to return false.
@@ -926,6 +936,7 @@ break1:
if(!bitreader_read_from_client_(br))
return false;
cwords = br->consumed_words;
ucbits = (br->words-cwords)*FLAC__BITS_PER_WORD + br->bytes*8 - cbits;
}
if(cwords < br->words) { /* if we've not consumed up to a partial tail word... */
if(cbits) {
@@ -980,6 +991,8 @@ break1:
}
}
break2:
ucbits -= parameter;
/* compose the value */
*vals = (int)(uval >> 1 ^ -(int)(uval & 1));