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libtremor: tweak a hot function for codebook decoding, mostly moving pointer lookups outside the loop. Speeds up decoding by 3-6% on Coldfire and a small speedup on arm too

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git-svn-id: svn://svn.rockbox.org/rockbox/trunk@28419 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Nils Wallménius 2010-10-31 14:48:40 +00:00
parent a177e13ee0
commit dfac9503eb
1 changed files with 20 additions and 13 deletions
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33
apps/codecs/libtremor/codebook.c
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@ -277,7 +277,6 @@ static long decode_packed_block(codebook *book, oggpack_buffer *b,
long *buf, int n){
long *bufptr = buf;
long *bufend = buf + n;
const unsigned int cachemask = (1<<book->dec_firsttablen)-1;
while (bufptr<bufend) {
if (b->headend > 8) {
@ -286,34 +285,42 @@ static long decode_packed_block(codebook *book, oggpack_buffer *b,
unsigned long adr;
ogg_uint32_t cache = 0;
int cachesize = 0;
const unsigned int cachemask = (1<<book->dec_firsttablen)-1;
const int book_dec_maxlength = book->dec_maxlength;
const ogg_uint32_t *book_dec_firsttable = book->dec_firsttable;
const long book_used_entries = book->used_entries;
const ogg_uint32_t *book_codelist = book->codelist;
const char *book_dec_codelengths = book->dec_codelengths;
adr = (unsigned long)b->headptr;
bit = (adr&3)*8+b->headbit;
ptr = (ogg_uint32_t *)(adr&~3);
ptr = (ogg_uint32_t*)(adr&~3);
bitend = ((adr&3)+b->headend)*8;
while (bufptr<bufend){
if (UNLIKELY(cachesize<book->dec_maxlength)) {
if (UNLIKELY(cachesize<book_dec_maxlength)) {
if (bit-cachesize+32>=bitend)
break;
bit-=cachesize;
cache=letoh32(ptr[bit>>5]) >> (bit&31);
if (bit&31)
cache|=letoh32(ptr[(bit>>5)+1]) << (32-(bit&31));
cache = letoh32(ptr[bit>>5]);
if (bit&31) {
cache >>= (bit&31);
cache |= letoh32(ptr[(bit>>5)+1]) << (32-(bit&31));
}
cachesize=32;
bit+=32;
}
ogg_int32_t entry = book->dec_firsttable[cache&cachemask];
ogg_int32_t entry = book_dec_firsttable[cache&cachemask];
if(UNLIKELY(entry < 0)){
const long lo = (entry>>15)&0x7fff, hi = book->used_entries-(entry&0x7fff);
entry = bisect_codelist(lo, hi, cache, book->codelist);
const long lo = (entry>>15)&0x7fff, hi = book_used_entries-(entry&0x7fff);
entry = bisect_codelist(lo, hi, cache, book_codelist);
}else
entry--;
*bufptr++=entry;
int l=book->dec_codelengths[entry];
cachesize-=l;
cache>>=l;
*bufptr++ = entry;
int l = book_dec_codelengths[entry];
cachesize -= l;
cache >>= l;
}
adr=(unsigned long)b->headptr;