blob: f7a2f64cb3f6c60e1a33246d9408e86f4a9c09e4 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
|
/*
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) {
register int r=(buffer[(bitindex>>3)&(WINDOWSIZE-1)]>>(7-(bitindex&7)))&1;
//register int r=(buffer[bitindex>>3]>>(7-(bitindex&7)))&1;
bitindex++;
return r;
}
// no range check version
inline int getbits9_f(int bits) {
register 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) {
register 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
|
