add multiple inclusion guards to headers
[libav.git] / libavcodec / rangecoder.h
1 /*
2 * Range coder
3 * Copyright (c) 2004 Michael Niedermayer <michaelni@gmx.at>
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 *
21 */
22
23 /**
24 * @file rangecoder.h
25 * Range coder.
26 */
27
28 #ifndef AVCODEC_RANGECODER_H
29 #define AVCODEC_RANGECODER_H
30
31 #include <stdint.h>
32 #include <assert.h>
33 #include "common.h"
34
35 typedef struct RangeCoder{
36 int low;
37 int range;
38 int outstanding_count;
39 int outstanding_byte;
40 uint8_t zero_state[256];
41 uint8_t one_state[256];
42 uint8_t *bytestream_start;
43 uint8_t *bytestream;
44 uint8_t *bytestream_end;
45 }RangeCoder;
46
47 void ff_init_range_encoder(RangeCoder *c, uint8_t *buf, int buf_size);
48 void ff_init_range_decoder(RangeCoder *c, const uint8_t *buf, int buf_size);
49 int ff_rac_terminate(RangeCoder *c);
50 void ff_build_rac_states(RangeCoder *c, int factor, int max_p);
51
52 static inline void renorm_encoder(RangeCoder *c){
53 //FIXME optimize
54 while(c->range < 0x100){
55 if(c->outstanding_byte < 0){
56 c->outstanding_byte= c->low>>8;
57 }else if(c->low <= 0xFF00){
58 *c->bytestream++ = c->outstanding_byte;
59 for(;c->outstanding_count; c->outstanding_count--)
60 *c->bytestream++ = 0xFF;
61 c->outstanding_byte= c->low>>8;
62 }else if(c->low >= 0x10000){
63 *c->bytestream++ = c->outstanding_byte + 1;
64 for(;c->outstanding_count; c->outstanding_count--)
65 *c->bytestream++ = 0x00;
66 c->outstanding_byte= (c->low>>8) & 0xFF;
67 }else{
68 c->outstanding_count++;
69 }
70
71 c->low = (c->low & 0xFF)<<8;
72 c->range <<= 8;
73 }
74 }
75
76 static inline int get_rac_count(RangeCoder *c){
77 int x= c->bytestream - c->bytestream_start + c->outstanding_count;
78 if(c->outstanding_byte >= 0)
79 x++;
80 return 8*x - av_log2(c->range);
81 }
82
83 static inline void put_rac(RangeCoder *c, uint8_t * const state, int bit){
84 int range1= (c->range * (*state)) >> 8;
85
86 assert(*state);
87 assert(range1 < c->range);
88 assert(range1 > 0);
89 if(!bit){
90 c->range -= range1;
91 *state= c->zero_state[*state];
92 }else{
93 c->low += c->range - range1;
94 c->range = range1;
95 *state= c->one_state[*state];
96 }
97
98 renorm_encoder(c);
99 }
100
101 static inline void refill(RangeCoder *c){
102 if(c->range < 0x100){
103 c->range <<= 8;
104 c->low <<= 8;
105 if(c->bytestream < c->bytestream_end)
106 c->low+= c->bytestream[0];
107 c->bytestream++;
108 }
109 }
110
111 static inline int get_rac(RangeCoder *c, uint8_t * const state){
112 int range1= (c->range * (*state)) >> 8;
113 int av_unused one_mask;
114
115 c->range -= range1;
116 #if 1
117 if(c->low < c->range){
118 *state= c->zero_state[*state];
119 refill(c);
120 return 0;
121 }else{
122 c->low -= c->range;
123 *state= c->one_state[*state];
124 c->range = range1;
125 refill(c);
126 return 1;
127 }
128 #else
129 one_mask= (c->range - c->low-1)>>31;
130
131 c->low -= c->range & one_mask;
132 c->range += (range1 - c->range) & one_mask;
133
134 *state= c->zero_state[(*state) + (256&one_mask)];
135
136 refill(c);
137
138 return one_mask&1;
139 #endif
140 }
141
142 #endif