mirror of
https://github.com/godotengine/godot.git
synced 2024-11-25 21:52:51 +00:00
115 lines
3.1 KiB
C
115 lines
3.1 KiB
C
/********************************************************************
|
|
* *
|
|
* THIS FILE IS PART OF THE OggTheora SOFTWARE 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 OggTheora SOURCE CODE IS (C) COPYRIGHT 1994-2009 *
|
|
* by the Xiph.Org Foundation and contributors http://www.xiph.org/ *
|
|
* *
|
|
********************************************************************
|
|
|
|
function: packing variable sized words into an octet stream
|
|
last mod: $Id$
|
|
|
|
********************************************************************/
|
|
#include <string.h>
|
|
#include <stdlib.h>
|
|
#include "bitpack.h"
|
|
|
|
/*We're 'MSb' endian; if we write a word but read individual bits,
|
|
then we'll read the MSb first.*/
|
|
|
|
void oc_pack_readinit(oc_pack_buf *_b,unsigned char *_buf,long _bytes){
|
|
memset(_b,0,sizeof(*_b));
|
|
_b->ptr=_buf;
|
|
_b->stop=_buf+_bytes;
|
|
}
|
|
|
|
static oc_pb_window oc_pack_refill(oc_pack_buf *_b,int _bits){
|
|
const unsigned char *ptr;
|
|
const unsigned char *stop;
|
|
oc_pb_window window;
|
|
int available;
|
|
unsigned shift;
|
|
stop=_b->stop;
|
|
ptr=_b->ptr;
|
|
window=_b->window;
|
|
available=_b->bits;
|
|
shift=OC_PB_WINDOW_SIZE-available;
|
|
while(7<shift&&ptr<stop){
|
|
shift-=8;
|
|
window|=(oc_pb_window)*ptr++<<shift;
|
|
}
|
|
_b->ptr=ptr;
|
|
available=OC_PB_WINDOW_SIZE-shift;
|
|
if(_bits>available){
|
|
if(ptr>=stop){
|
|
_b->eof=1;
|
|
available=OC_LOTS_OF_BITS;
|
|
}
|
|
else window|=*ptr>>(available&7);
|
|
}
|
|
_b->bits=available;
|
|
return window;
|
|
}
|
|
|
|
int oc_pack_look1(oc_pack_buf *_b){
|
|
oc_pb_window window;
|
|
int available;
|
|
window=_b->window;
|
|
available=_b->bits;
|
|
if(available<1)_b->window=window=oc_pack_refill(_b,1);
|
|
return window>>OC_PB_WINDOW_SIZE-1;
|
|
}
|
|
|
|
void oc_pack_adv1(oc_pack_buf *_b){
|
|
_b->window<<=1;
|
|
_b->bits--;
|
|
}
|
|
|
|
/*Here we assume that 0<=_bits&&_bits<=32.*/
|
|
long oc_pack_read_c(oc_pack_buf *_b,int _bits){
|
|
oc_pb_window window;
|
|
int available;
|
|
long result;
|
|
window=_b->window;
|
|
available=_b->bits;
|
|
if(_bits==0)return 0;
|
|
if(available<_bits){
|
|
window=oc_pack_refill(_b,_bits);
|
|
available=_b->bits;
|
|
}
|
|
result=window>>OC_PB_WINDOW_SIZE-_bits;
|
|
available-=_bits;
|
|
window<<=1;
|
|
window<<=_bits-1;
|
|
_b->window=window;
|
|
_b->bits=available;
|
|
return result;
|
|
}
|
|
|
|
int oc_pack_read1_c(oc_pack_buf *_b){
|
|
oc_pb_window window;
|
|
int available;
|
|
int result;
|
|
window=_b->window;
|
|
available=_b->bits;
|
|
if(available<1){
|
|
window=oc_pack_refill(_b,1);
|
|
available=_b->bits;
|
|
}
|
|
result=window>>OC_PB_WINDOW_SIZE-1;
|
|
available--;
|
|
window<<=1;
|
|
_b->window=window;
|
|
_b->bits=available;
|
|
return result;
|
|
}
|
|
|
|
long oc_pack_bytes_left(oc_pack_buf *_b){
|
|
if(_b->eof)return -1;
|
|
return _b->stop-_b->ptr+(_b->bits>>3);
|
|
}
|