put_bits: fix invalid shift by 32 in flush_put_bits()
[libav.git] / libavcodec / put_bits.h
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1/*
2 * copyright (c) 2004 Michael Niedermayer <michaelni@gmx.at>
3 *
2912e87a 4 * This file is part of Libav.
b2755007 5 *
2912e87a 6 * Libav is free software; you can redistribute it and/or
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7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
10 *
2912e87a 11 * Libav is distributed in the hope that it will be useful,
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12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public
2912e87a 17 * License along with Libav; if not, write to the Free Software
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18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 */
20
21/**
ba87f080 22 * @file
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23 * bitstream writer API
24 */
25
26#ifndef AVCODEC_PUT_BITS_H
27#define AVCODEC_PUT_BITS_H
28
29#include <stdint.h>
30#include <stdlib.h>
31#include <assert.h>
32#include "libavutil/bswap.h"
33#include "libavutil/common.h"
34#include "libavutil/intreadwrite.h"
35#include "libavutil/log.h"
36#include "mathops.h"
8d459acc 37#include "config.h"
b2755007 38
b2755007 39typedef struct PutBitContext {
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40 uint32_t bit_buf;
41 int bit_left;
42 uint8_t *buf, *buf_ptr, *buf_end;
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43 int size_in_bits;
44} PutBitContext;
45
46/**
49bd8e4b 47 * Initialize the PutBitContext s.
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48 *
49 * @param buffer the buffer where to put bits
bf7e799c 50 * @param buffer_size the size in bytes of buffer
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51 */
52static inline void init_put_bits(PutBitContext *s, uint8_t *buffer, int buffer_size)
53{
54 if(buffer_size < 0) {
55 buffer_size = 0;
56 buffer = NULL;
57 }
58
59 s->size_in_bits= 8*buffer_size;
60 s->buf = buffer;
61 s->buf_end = s->buf + buffer_size;
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62 s->buf_ptr = s->buf;
63 s->bit_left=32;
64 s->bit_buf=0;
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65}
66
67/**
49bd8e4b 68 * @return the total number of bits written to the bitstream.
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69 */
70static inline int put_bits_count(PutBitContext *s)
71{
b2755007 72 return (s->buf_ptr - s->buf) * 8 + 32 - s->bit_left;
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73}
74
75/**
49bd8e4b 76 * Pad the end of the output stream with zeros.
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77 */
78static inline void flush_put_bits(PutBitContext *s)
79{
b2755007 80#ifndef BITSTREAM_WRITER_LE
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81 if (s->bit_left < 32)
82 s->bit_buf<<= s->bit_left;
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83#endif
84 while (s->bit_left < 32) {
85 /* XXX: should test end of buffer */
86#ifdef BITSTREAM_WRITER_LE
87 *s->buf_ptr++=s->bit_buf;
88 s->bit_buf>>=8;
89#else
90 *s->buf_ptr++=s->bit_buf >> 24;
91 s->bit_buf<<=8;
92#endif
93 s->bit_left+=8;
94 }
95 s->bit_left=32;
96 s->bit_buf=0;
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97}
98
0d5c349a 99#ifdef BITSTREAM_WRITER_LE
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100#define align_put_bits align_put_bits_unsupported_here
101#define ff_put_string ff_put_string_unsupported_here
102#define ff_copy_bits ff_copy_bits_unsupported_here
103#else
b2755007 104/**
49bd8e4b 105 * Pad the bitstream with zeros up to the next byte boundary.
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106 */
107void align_put_bits(PutBitContext *s);
108
109/**
49bd8e4b 110 * Put the string string in the bitstream.
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111 *
112 * @param terminate_string 0-terminates the written string if value is 1
113 */
587edd6a 114void ff_put_string(PutBitContext *pb, const char *string, int terminate_string);
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115
116/**
49bd8e4b 117 * Copy the content of src to the bitstream.
b2755007 118 *
bf7e799c 119 * @param length the number of bits of src to copy
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120 */
121void ff_copy_bits(PutBitContext *pb, const uint8_t *src, int length);
7f6458a7 122#endif
b2755007 123
43d7c611 124/**
49bd8e4b 125 * Write up to 31 bits into a bitstream.
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126 * Use put_bits32 to write 32 bits.
127 */
b2755007 128static inline void put_bits(PutBitContext *s, int n, unsigned int value)
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129{
130 unsigned int bit_buf;
131 int bit_left;
132
133 // printf("put_bits=%d %x\n", n, value);
43d7c611 134 assert(n <= 31 && value < (1U << n));
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135
136 bit_buf = s->bit_buf;
137 bit_left = s->bit_left;
138
139 // printf("n=%d value=%x cnt=%d buf=%x\n", n, value, bit_cnt, bit_buf);
140 /* XXX: optimize */
141#ifdef BITSTREAM_WRITER_LE
142 bit_buf |= value << (32 - bit_left);
143 if (n >= bit_left) {
30b05520 144 AV_WL32(s->buf_ptr, bit_buf);
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145 s->buf_ptr+=4;
146 bit_buf = (bit_left==32)?0:value >> bit_left;
147 bit_left+=32;
148 }
149 bit_left-=n;
150#else
151 if (n < bit_left) {
152 bit_buf = (bit_buf<<n) | value;
153 bit_left-=n;
154 } else {
155 bit_buf<<=bit_left;
156 bit_buf |= value >> (n - bit_left);
30b05520 157 AV_WB32(s->buf_ptr, bit_buf);
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158 //printf("bitbuf = %08x\n", bit_buf);
159 s->buf_ptr+=4;
160 bit_left+=32 - n;
161 bit_buf = value;
162 }
163#endif
164
165 s->bit_buf = bit_buf;
166 s->bit_left = bit_left;
167}
b2755007 168
5f1836a7 169static inline void put_sbits(PutBitContext *pb, int n, int32_t value)
b2755007 170{
5f1836a7 171 assert(n >= 0 && n <= 31);
b2755007 172
5f1836a7 173 put_bits(pb, n, value & ((1<<n)-1));
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174}
175
53bd67ec 176/**
49bd8e4b 177 * Write exactly 32 bits into a bitstream.
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178 */
179static void av_unused put_bits32(PutBitContext *s, uint32_t value)
180{
181 int lo = value & 0xffff;
182 int hi = value >> 16;
28f2db96 183#ifdef BITSTREAM_WRITER_LE
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184 put_bits(s, 16, lo);
185 put_bits(s, 16, hi);
186#else
187 put_bits(s, 16, hi);
188 put_bits(s, 16, lo);
189#endif
190}
191
192/**
49bd8e4b 193 * Return the pointer to the byte where the bitstream writer will put
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194 * the next bit.
195 */
fb53b4a0 196static inline uint8_t* put_bits_ptr(PutBitContext *s)
b2755007 197{
b2755007 198 return s->buf_ptr;
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199}
200
201/**
49bd8e4b 202 * Skip the given number of bytes.
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203 * PutBitContext must be flushed & aligned to a byte boundary before calling this.
204 */
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205static inline void skip_put_bytes(PutBitContext *s, int n)
206{
b2755007 207 assert((put_bits_count(s)&7)==0);
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208 assert(s->bit_left==32);
209 s->buf_ptr += n;
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210}
211
212/**
49bd8e4b 213 * Skip the given number of bits.
b2755007 214 * Must only be used if the actual values in the bitstream do not matter.
bf7e799c 215 * If n is 0 the behavior is undefined.
b2755007 216 */
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217static inline void skip_put_bits(PutBitContext *s, int n)
218{
b2755007 219 s->bit_left -= n;
ad25b954 220 s->buf_ptr-= 4*(s->bit_left>>5);
b2755007 221 s->bit_left &= 31;
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222}
223
224/**
49bd8e4b 225 * Change the end of the buffer.
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226 *
227 * @param size the new size in bytes of the buffer where to put bits
228 */
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229static inline void set_put_bits_buffer_size(PutBitContext *s, int size)
230{
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231 s->buf_end= s->buf + size;
232}
233
234#endif /* AVCODEC_PUT_BITS_H */