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/********************************************************************
* *
* THIS FILE IS PART OF THE OggVorbis 'TREMOR' CODEC SOURCE CODE. *
* *
* USE, DISTRIBUTION AND REPRODUCTION OF THIS LIBRARY SOURCE IS *
* GOVERNED BY A BSD-STYLE SOURCE LICENSE INCLUDED WITH THIS SOURCE *
* IN 'COPYING'. PLEASE READ THESE TERMS BEFORE DISTRIBUTING. *
* *
* THE OggVorbis 'TREMOR' SOURCE CODE IS (C) COPYRIGHT 1994-2002 *
* BY THE Xiph.Org FOUNDATION http://www.xiph.org/ *
* *
********************************************************************
function: packing variable sized words into an octet stream
********************************************************************/
/* We're 'LSb' endian; if we write a word but read individual bits,
then we'll read the lsb first */
#include "config-tremor.h"
#include <string.h>
#include "ogg.h"
const unsigned long oggpack_mask[] ICONST_ATTR =
{0x00000000,0x00000001,0x00000003,0x00000007,0x0000000f,
0x0000001f,0x0000003f,0x0000007f,0x000000ff,0x000001ff,
0x000003ff,0x000007ff,0x00000fff,0x00001fff,0x00003fff,
0x00007fff,0x0000ffff,0x0001ffff,0x0003ffff,0x0007ffff,
0x000fffff,0x001fffff,0x003fffff,0x007fffff,0x00ffffff,
0x01ffffff,0x03ffffff,0x07ffffff,0x0fffffff,0x1fffffff,
0x3fffffff,0x7fffffff,0xffffffff };
void oggpack_readinit(oggpack_buffer *b,ogg_reference *r){
memset(b,0,sizeof(*b));
b->tail=b->head=r;
b->count=0;
b->headptr=b->head->buffer->data+b->head->begin;
b->headend=b->head->length;
_span(b);
}
#define _lookspan() while(!end){\
head=head->next;\
if(!head) return -1;\
ptr=head->buffer->data + head->begin;\
end=head->length;\
}
/* Read in bits without advancing the bitptr; bits <= 32 */
long oggpack_look_full(oggpack_buffer *b,int bits) ICODE_ATTR_TREMOR_NOT_MDCT;
long oggpack_look_full(oggpack_buffer *b,int bits){
unsigned long m=oggpack_mask[bits];
unsigned long ret=-1;
bits+=b->headbit;
if(bits >= b->headend<<3){
int end=b->headend;
unsigned char *ptr=b->headptr;
ogg_reference *head=b->head;
if(end<0)return -1;
if(bits){
_lookspan();
ret=*ptr++>>b->headbit;
if(bits>8){
--end;
_lookspan();
ret|=*ptr++<<(8-b->headbit);
if(bits>16){
--end;
_lookspan();
ret|=*ptr++<<(16-b->headbit);
if(bits>24){
--end;
_lookspan();
ret|=*ptr++<<(24-b->headbit);
if(bits>32 && b->headbit){
--end;
_lookspan();
ret|=*ptr<<(32-b->headbit);
}
}
}
}
}
}else{
/* make this a switch jump-table */
ret=b->headptr[0]>>b->headbit;
if(bits>8){
ret|=b->headptr[1]<<(8-b->headbit);
if(bits>16){
ret|=b->headptr[2]<<(16-b->headbit);
if(bits>24){
ret|=b->headptr[3]<<(24-b->headbit);
if(bits>32 && b->headbit)
ret|=b->headptr[4]<<(32-b->headbit);
}
}
}
}
ret&=m;
return ret;
}
/* spans forward and finds next byte. Never halts */
static void _span_one(oggpack_buffer *b){
while(b->headend<1){
if(b->head->next){
b->count+=b->head->length;
b->head=b->head->next;
b->headptr=b->head->buffer->data+b->head->begin;
b->headend=b->head->length;
}else
break;
}
}
static int _halt_one(oggpack_buffer *b){
if(b->headend<1){
_adv_halt(b);
return -1;
}
return 0;
}
/* bits <= 32 */
long oggpack_read(oggpack_buffer *b,register int bits) ICODE_ATTR_TREMOR_NOT_MDCT;
long oggpack_read(oggpack_buffer *b,register int bits){
unsigned long m=oggpack_mask[bits];
ogg_uint32_t ret=-1;
bits+=b->headbit;
if(bits >= b->headend<<3){
if(b->headend<0)return -1;
if(bits){
if (_halt_one(b)) return -1;
ret=*b->headptr>>b->headbit;
if(bits>=8){
++b->headptr;
--b->headend;
_span_one(b);
if(bits>8){
if (_halt_one(b)) return -1;
ret|=*b->headptr<<(8-b->headbit);
if(bits>=16){
++b->headptr;
--b->headend;
_span_one(b);
if(bits>16){
if (_halt_one(b)) return -1;
ret|=*b->headptr<<(16-b->headbit);
if(bits>=24){
++b->headptr;
--b->headend;
_span_one(b);
if(bits>24){
if (_halt_one(b)) return -1;
ret|=*b->headptr<<(24-b->headbit);
if(bits>=32){
++b->headptr;
--b->headend;
_span_one(b);
if(bits>32){
if (_halt_one(b)) return -1;
if(b->headbit)ret|=*b->headptr<<(32-b->headbit);
}
}
}
}
}
}
}
}
}
}else{
ret=b->headptr[0]>>b->headbit;
if(bits>8){
ret|=b->headptr[1]<<(8-b->headbit);
if(bits>16){
ret|=b->headptr[2]<<(16-b->headbit);
if(bits>24){
ret|=b->headptr[3]<<(24-b->headbit);
if(bits>32 && b->headbit){
ret|=b->headptr[4]<<(32-b->headbit);
}
}
}
}
b->headptr+=((unsigned)bits)/8;
b->headend-=((unsigned)bits)/8;
}
ret&=m;
b->headbit=bits&7;
return ret;
}
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