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/*
bitwindow class
Copyright (C) 2000 Martin Vogt
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU Library General Public License as published by
the Free Software Foundation.
For more information look at the file COPYRIGHT in this package
*/
#ifndef __MPEGBITWINDOW_H
#define __MPEGBITWINDOW_H
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#ifndef WORDS_BIGENDIAN
#define _KEY 0
#else
#define _KEY 3
#endif
#define WINDOWSIZE 4096
#define BITWINDOWSIZE (WINDOWSIZE*8)
class MpegAudioBitWindow {
int point,bitindex;
char buffer[2*WINDOWSIZE];
public:
MpegAudioBitWindow(){bitindex=point=0;}
inline void initialize(void) {bitindex=point=0;}
inline int gettotalbit(void) const {return bitindex;}
inline void putbyte(int c) {buffer[point&(WINDOWSIZE-1)]=c;point++;}
void wrap(void);
inline void rewind(int bits) {bitindex-=bits;}
inline void forward(int bits) {bitindex+=bits;}
// returns number of bits which can safley read
int getCanReadBits();
//
// Ugly bitgetting inline functions for higher speed
//
inline int getbits(int bits) {
union
{
char store[4];
int current;
}u;
int bi;
if(!bits)return 0;
u.current=0;
bi=(bitindex&7);
u.store[_KEY]=buffer[(bitindex>>3)&(WINDOWSIZE-1)]<<bi;
//u.store[_KEY]=buffer[bitindex>>3]<<bi;
bi=8-bi;
bitindex+=bi;
while(bits) {
if(!bi) {
u.store[_KEY]=buffer[(bitindex>>3)&(WINDOWSIZE-1)];
//u.store[_KEY]=buffer[bitindex>>3];
bitindex+=8;
bi=8;
}
if(bits>=bi) {
u.current<<=bi;
bits-=bi;
bi=0;
}
else {
u.current<<=bits;
bi-=bits;
bits=0;
}
}
bitindex-=bi;
return (u.current>>8);
}
int getbit(void) {
int r=(buffer[(bitindex>>3)&(WINDOWSIZE-1)]>>(7-(bitindex&7)))&1;
//int r=(buffer[bitindex>>3]>>(7-(bitindex&7)))&1;
bitindex++;
return r;
}
// no range check version
inline int getbits9_f(int bits) {
unsigned short a;
{
int offset=bitindex>>3;
a=(((unsigned char)buffer[offset])<<8)|((unsigned char)buffer[offset+1]);
}
a<<=(bitindex&7);
bitindex+=bits;
return (int)((unsigned int)(a>>(16-bits)));
}
// range check version
int getbits9(int bits) {
unsigned short a;
{
int offset=(bitindex>>3)&(WINDOWSIZE-1);
a=(((unsigned char)buffer[offset])<<8)|((unsigned char)buffer[offset+1]);
}
a<<=(bitindex&7);
bitindex+=bits;
return (int)((unsigned int)(a>>(16-bits)));
}
int peek8() {
int offset = (bitindex>>3)&(WINDOWSIZE-1), a;
a=(((unsigned char)buffer[offset])<<8) | ((unsigned char)buffer[offset+1]);
return (a >> (8-(bitindex&7))) & 0xff;
}
};
#endif
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