3 * Copyright (c) 2004 Michael Niedermayer <michaelni@gmx.at>
5 * This file is part of FFmpeg.
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.
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.
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
27 #ifndef AVCODEC_RANGECODER_H
28 #define AVCODEC_RANGECODER_H
32 #include "libavutil/common.h"
34 typedef struct RangeCoder{
37 int outstanding_count;
39 uint8_t zero_state[256];
40 uint8_t one_state[256];
41 uint8_t *bytestream_start;
43 uint8_t *bytestream_end;
46 void ff_init_range_encoder(RangeCoder *c, uint8_t *buf, int buf_size);
47 void ff_init_range_decoder(RangeCoder *c, const uint8_t *buf, int buf_size);
48 int ff_rac_terminate(RangeCoder *c);
49 void ff_build_rac_states(RangeCoder *c, int factor, int max_p);
51 static inline void renorm_encoder(RangeCoder *c){
53 while(c->range < 0x100){
54 if(c->outstanding_byte < 0){
55 c->outstanding_byte= c->low>>8;
56 }else if(c->low <= 0xFF00){
57 *c->bytestream++ = c->outstanding_byte;
58 for(;c->outstanding_count; c->outstanding_count--)
59 *c->bytestream++ = 0xFF;
60 c->outstanding_byte= c->low>>8;
61 }else if(c->low >= 0x10000){
62 *c->bytestream++ = c->outstanding_byte + 1;
63 for(;c->outstanding_count; c->outstanding_count--)
64 *c->bytestream++ = 0x00;
65 c->outstanding_byte= (c->low>>8) & 0xFF;
67 c->outstanding_count++;
70 c->low = (c->low & 0xFF)<<8;
75 static inline int get_rac_count(RangeCoder *c){
76 int x= c->bytestream - c->bytestream_start + c->outstanding_count;
77 if(c->outstanding_byte >= 0)
79 return 8*x - av_log2(c->range);
82 static inline void put_rac(RangeCoder *c, uint8_t * const state, int bit){
83 int range1= (c->range * (*state)) >> 8;
86 assert(range1 < c->range);
90 *state= c->zero_state[*state];
92 c->low += c->range - range1;
94 *state= c->one_state[*state];
100 static inline void refill(RangeCoder *c){
101 if(c->range < 0x100){
104 if(c->bytestream < c->bytestream_end)
105 c->low+= c->bytestream[0];
110 static inline int get_rac(RangeCoder *c, uint8_t * const state){
111 int range1= (c->range * (*state)) >> 8;
112 int av_unused one_mask;
116 if(c->low < c->range){
117 *state= c->zero_state[*state];
122 *state= c->one_state[*state];
128 one_mask= (c->range - c->low-1)>>31;
130 c->low -= c->range & one_mask;
131 c->range += (range1 - c->range) & one_mask;
133 *state= c->zero_state[(*state) + (256&one_mask)];
141 #endif /* AVCODEC_RANGECODER_H */