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FS #6848 - optimizations of Huffman decoding in Tremor.

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git-svn-id: svn://svn.rockbox.org/rockbox/trunk@12903 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Tomasz Malesinski 2007-03-24 14:06:56 +00:00
parent 25046aac17
commit 7d9ff93b79
2 changed files with 101 additions and 12 deletions
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103
apps/codecs/Tremor/codebook.c
View file

@ -154,9 +154,9 @@ static inline long decode_packed_entry_number(codebook *book,
long lo,hi;
long lok = oggpack_look(b,book->dec_firsttablen);
if (lok >= 0) {
if (EXPECT(lok >= 0, 1)) {
long entry = book->dec_firsttable[lok];
if(entry&0x80000000UL){
if(EXPECT(entry&0x80000000UL, 0)){
lo=(entry>>15)&0x7fff;
hi=book->used_entries-(entry&0x7fff);
}else{
@ -195,6 +195,78 @@ static inline long decode_packed_entry_number(codebook *book,
return(-1);
}
static inline long decode_packed_block(codebook *book, oggpack_buffer *b,
long *buf, int n){
long *bufptr = buf;
long *bufend = buf + n;
while (bufptr<bufend) {
if (b->headend > 8) {
ogg_uint32_t *ptr;
unsigned long bit, bitend;
unsigned long adr;
ogg_uint32_t cache = 0;
int cachesize = 0;
adr = (unsigned long)b->headptr;
bit = (adr&3)*8+b->headbit;
ptr = (ogg_uint32_t *)(adr&~3);
bitend = ((adr&3)+b->headend)*8;
while (bufptr<bufend){
long entry, lo, hi;
if (EXPECT(cachesize<book->dec_maxlength, 0)) {
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));
cachesize=32;
bit+=32;
}
entry=book->dec_firsttable[cache&((1<<book->dec_firsttablen)-1)];
if(EXPECT(entry&0x80000000UL, 0)){
lo=(entry>>15)&0x7fff;
hi=book->used_entries-(entry&0x7fff);
{
ogg_uint32_t testword=bitreverse((ogg_uint32_t)cache);
while(EXPECT(hi-lo>1, 1)){
long p=(hi-lo)>>1;
if (book->codelist[lo+p]>testword)
hi-=p;
else
lo+=p;
}
entry=lo;
}
}else
entry--;
*bufptr++=entry;
{
int l=book->dec_codelengths[entry];
cachesize-=l;
cache>>=l;
}
}
adr=(unsigned long)b->headptr;
bit-=(adr&3)*8+cachesize;
b->headend-=(bit/8);
b->headptr+=bit/8;
b->headbit=bit%8;
} else {
long r = decode_packed_entry_number(book, b);
if (r == -1) return bufptr-buf;
*bufptr++ = r;
}
}
return n;
}
/* Decode side is specced and easier, because we don't need to find
matches using different criteria; we simply read and map. There are
two things we need to do 'depending':
@ -310,17 +382,20 @@ long vorbis_book_decodev_set(codebook *book,ogg_int32_t *a,
long vorbis_book_decodevv_add(codebook *book,ogg_int32_t **a,
long offset,int ch,
oggpack_buffer *b,int n,int point){
long i,j,entry;
long i,j,k,chunk,read;
int chptr=0;
int shift=point-book->binarypoint;
long entries[32];
if(shift>=0){
for(i=offset;i<offset+n;){
entry = decode_packed_entry_number(book,b);
if(entry==-1)return(-1);
{
const ogg_int32_t *t = book->valuelist+entry*book->dim;
chunk=32;
if (chunk*book->dim>(offset+n-i)*ch)
chunk=((offset+n-i)*ch+book->dim-1)/book->dim;
read = decode_packed_block(book,b,entries,chunk);
for(k=0;k<read;k++){
const ogg_int32_t *t = book->valuelist+entries[k]*book->dim;
for (j=0;j<book->dim;j++){
a[chptr++][i]+=t[j]>>shift;
if(chptr==ch){
@ -329,14 +404,17 @@ long vorbis_book_decodevv_add(codebook *book,ogg_int32_t **a,
}
}
}
if (read<chunk)return-1;
}
}else{
shift = -shift;
for(i=offset;i<offset+n;){
entry = decode_packed_entry_number(book,b);
if(entry==-1)return(-1);
{
const ogg_int32_t *t = book->valuelist+entry*book->dim;
chunk=32;
if (chunk*book->dim>(offset+n-i)*ch)
chunk=((offset+n-i)*ch+book->dim-1)/book->dim;
read = decode_packed_block(book,b,entries,chunk);
for(k=0;k<read;k++){
const ogg_int32_t *t = book->valuelist+entries[k]*book->dim;
for (j=0;j<book->dim;j++){
a[chptr++][i]+=t[j]<<shift;
if(chptr==ch){
@ -345,6 +423,7 @@ long vorbis_book_decodevv_add(codebook *book,ogg_int32_t **a,
}
}
}
if (read<chunk)return-1;
}
}
return(0);

10
apps/codecs/Tremor/misc.h
View file

@ -275,6 +275,16 @@ static inline ogg_int32_t VFLOAT_ADD(ogg_int32_t a,ogg_int32_t ap,
return(a);
}
#ifdef __GNUC__
#if __GNUC__ >= 3
#define EXPECT(a, b) __builtin_expect((a), (b))
#else
#define EXPECT(a, b) (a)
#endif
#else
#define EXPECT(a, b) (a)
#endif
#endif