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put_bits.h
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1 /*
2  * copyright (c) 2004 Michael Niedermayer <michaelni@gmx.at>
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg is free software; you can redistribute it and/or
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  *
11  * FFmpeg is distributed in the hope that it will be useful,
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
17  * License along with FFmpeg; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 /**
22  * @file
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 <stddef.h>
31 
32 #include "libavutil/intreadwrite.h"
33 #include "libavutil/avassert.h"
34 
35 typedef struct PutBitContext {
36  uint32_t bit_buf;
37  int bit_left;
41 
42 /**
43  * Initialize the PutBitContext s.
44  *
45  * @param buffer the buffer where to put bits
46  * @param buffer_size the size in bytes of buffer
47  */
48 static inline void init_put_bits(PutBitContext *s, uint8_t *buffer,
49  int buffer_size)
50 {
51  if (buffer_size < 0) {
52  buffer_size = 0;
53  buffer = NULL;
54  }
55 
56  s->size_in_bits = 8 * buffer_size;
57  s->buf = buffer;
58  s->buf_end = s->buf + buffer_size;
59  s->buf_ptr = s->buf;
60  s->bit_left = 32;
61  s->bit_buf = 0;
62 }
63 
64 /**
65  * Rebase the bit writer onto a reallocated buffer.
66  *
67  * @param buffer the buffer where to put bits
68  * @param buffer_size the size in bytes of buffer,
69  * must be larger than the previous size
70  */
72  int buffer_size)
73 {
74  av_assert0(8*buffer_size > s->size_in_bits);
75 
76  s->buf_end = buffer + buffer_size;
77  s->buf_ptr = buffer + (s->buf_ptr - s->buf);
78  s->buf = buffer;
79  s->size_in_bits = 8 * buffer_size;
80 }
81 
82 /**
83  * @return the total number of bits written to the bitstream.
84  */
85 static inline int put_bits_count(PutBitContext *s)
86 {
87  return (s->buf_ptr - s->buf) * 8 + 32 - s->bit_left;
88 }
89 
90 /**
91  * @return the number of bits available in the bitstream.
92  */
93 static inline int put_bits_left(PutBitContext* s)
94 {
95  return (s->buf_end - s->buf_ptr) * 8 - 32 + s->bit_left;
96 }
97 
98 /**
99  * Pad the end of the output stream with zeros.
100  */
101 static inline void flush_put_bits(PutBitContext *s)
102 {
103 #ifndef BITSTREAM_WRITER_LE
104  if (s->bit_left < 32)
105  s->bit_buf <<= s->bit_left;
106 #endif
107  while (s->bit_left < 32) {
108  av_assert0(s->buf_ptr < s->buf_end);
109 #ifdef BITSTREAM_WRITER_LE
110  *s->buf_ptr++ = s->bit_buf;
111  s->bit_buf >>= 8;
112 #else
113  *s->buf_ptr++ = s->bit_buf >> 24;
114  s->bit_buf <<= 8;
115 #endif
116  s->bit_left += 8;
117  }
118  s->bit_left = 32;
119  s->bit_buf = 0;
120 }
121 
122 #ifdef BITSTREAM_WRITER_LE
123 #define avpriv_align_put_bits align_put_bits_unsupported_here
124 #define avpriv_put_string ff_put_string_unsupported_here
125 #define avpriv_copy_bits avpriv_copy_bits_unsupported_here
126 #else
127 /**
128  * Pad the bitstream with zeros up to the next byte boundary.
129  */
131 
132 /**
133  * Put the string string in the bitstream.
134  *
135  * @param terminate_string 0-terminates the written string if value is 1
136  */
137 void avpriv_put_string(PutBitContext *pb, const char *string,
138  int terminate_string);
139 
140 /**
141  * Copy the content of src to the bitstream.
142  *
143  * @param length the number of bits of src to copy
144  */
145 void avpriv_copy_bits(PutBitContext *pb, const uint8_t *src, int length);
146 #endif
147 
148 /**
149  * Write up to 31 bits into a bitstream.
150  * Use put_bits32 to write 32 bits.
151  */
152 static inline void put_bits(PutBitContext *s, int n, unsigned int value)
153 {
154  unsigned int bit_buf;
155  int bit_left;
156 
157  av_assert2(n <= 31 && value < (1U << n));
158 
159  bit_buf = s->bit_buf;
160  bit_left = s->bit_left;
161 
162  /* XXX: optimize */
163 #ifdef BITSTREAM_WRITER_LE
164  bit_buf |= value << (32 - bit_left);
165  if (n >= bit_left) {
166  if (3 < s->buf_end - s->buf_ptr) {
167  AV_WL32(s->buf_ptr, bit_buf);
168  s->buf_ptr += 4;
169  } else {
170  av_log(NULL, AV_LOG_ERROR, "Internal error, put_bits buffer too small\n");
171  av_assert2(0);
172  }
173  bit_buf = value >> bit_left;
174  bit_left += 32;
175  }
176  bit_left -= n;
177 #else
178  if (n < bit_left) {
179  bit_buf = (bit_buf << n) | value;
180  bit_left -= n;
181  } else {
182  bit_buf <<= bit_left;
183  bit_buf |= value >> (n - bit_left);
184  if (3 < s->buf_end - s->buf_ptr) {
185  AV_WB32(s->buf_ptr, bit_buf);
186  s->buf_ptr += 4;
187  } else {
188  av_log(NULL, AV_LOG_ERROR, "Internal error, put_bits buffer too small\n");
189  av_assert2(0);
190  }
191  bit_left += 32 - n;
192  bit_buf = value;
193  }
194 #endif
195 
196  s->bit_buf = bit_buf;
197  s->bit_left = bit_left;
198 }
199 
200 static inline void put_sbits(PutBitContext *pb, int n, int32_t value)
201 {
202  av_assert2(n >= 0 && n <= 31);
203 
204  put_bits(pb, n, av_mod_uintp2(value, n));
205 }
206 
207 /**
208  * Write exactly 32 bits into a bitstream.
209  */
210 static void av_unused put_bits32(PutBitContext *s, uint32_t value)
211 {
212  unsigned int bit_buf;
213  int bit_left;
214 
215  bit_buf = s->bit_buf;
216  bit_left = s->bit_left;
217 
218 #ifdef BITSTREAM_WRITER_LE
219  bit_buf |= value << (32 - bit_left);
220  if (3 < s->buf_end - s->buf_ptr) {
221  AV_WL32(s->buf_ptr, bit_buf);
222  s->buf_ptr += 4;
223  } else {
224  av_log(NULL, AV_LOG_ERROR, "Internal error, put_bits buffer too small\n");
225  av_assert2(0);
226  }
227  bit_buf = (uint64_t)value >> bit_left;
228 #else
229  bit_buf = (uint64_t)bit_buf << bit_left;
230  bit_buf |= value >> (32 - bit_left);
231  if (3 < s->buf_end - s->buf_ptr) {
232  AV_WB32(s->buf_ptr, bit_buf);
233  s->buf_ptr += 4;
234  } else {
235  av_log(NULL, AV_LOG_ERROR, "Internal error, put_bits buffer too small\n");
236  av_assert2(0);
237  }
238  bit_buf = value;
239 #endif
240 
241  s->bit_buf = bit_buf;
242  s->bit_left = bit_left;
243 }
244 
245 /**
246  * Write up to 64 bits into a bitstream.
247  */
248 static inline void put_bits64(PutBitContext *s, int n, uint64_t value)
249 {
250  av_assert2((n == 64) || (n < 64 && value < (UINT64_C(1) << n)));
251 
252  if (n < 32)
253  put_bits(s, n, value);
254  else if (n == 32)
255  put_bits32(s, value);
256  else if (n < 64) {
257  uint32_t lo = value & 0xffffffff;
258  uint32_t hi = value >> 32;
259 #ifdef BITSTREAM_WRITER_LE
260  put_bits32(s, lo);
261  put_bits(s, n - 32, hi);
262 #else
263  put_bits(s, n - 32, hi);
264  put_bits32(s, lo);
265 #endif
266  } else {
267  uint32_t lo = value & 0xffffffff;
268  uint32_t hi = value >> 32;
269 #ifdef BITSTREAM_WRITER_LE
270  put_bits32(s, lo);
271  put_bits32(s, hi);
272 #else
273  put_bits32(s, hi);
274  put_bits32(s, lo);
275 #endif
276 
277  }
278 }
279 
280 /**
281  * Return the pointer to the byte where the bitstream writer will put
282  * the next bit.
283  */
285 {
286  return s->buf_ptr;
287 }
288 
289 /**
290  * Skip the given number of bytes.
291  * PutBitContext must be flushed & aligned to a byte boundary before calling this.
292  */
293 static inline void skip_put_bytes(PutBitContext *s, int n)
294 {
295  av_assert2((put_bits_count(s) & 7) == 0);
296  av_assert2(s->bit_left == 32);
297  av_assert0(n <= s->buf_end - s->buf_ptr);
298  s->buf_ptr += n;
299 }
300 
301 /**
302  * Skip the given number of bits.
303  * Must only be used if the actual values in the bitstream do not matter.
304  * If n is 0 the behavior is undefined.
305  */
306 static inline void skip_put_bits(PutBitContext *s, int n)
307 {
308  s->bit_left -= n;
309  s->buf_ptr -= 4 * (s->bit_left >> 5);
310  s->bit_left &= 31;
311 }
312 
313 /**
314  * Change the end of the buffer.
315  *
316  * @param size the new size in bytes of the buffer where to put bits
317  */
318 static inline void set_put_bits_buffer_size(PutBitContext *s, int size)
319 {
320  av_assert0(size <= INT_MAX/8 - 32);
321  s->buf_end = s->buf + size;
322  s->size_in_bits = 8*size;
323 }
324 
325 #endif /* AVCODEC_PUT_BITS_H */
static void av_unused put_bits32(PutBitContext *s, uint32_t value)
Write exactly 32 bits into a bitstream.
Definition: put_bits.h:210
#define NULL
Definition: coverity.c:32
void avpriv_put_string(PutBitContext *pb, const char *string, int terminate_string)
Put the string string in the bitstream.
Definition: bitstream.c:53
const char * s
Definition: avisynth_c.h:768
static void put_sbits(PutBitContext *pb, int n, int32_t value)
Definition: put_bits.h:200
static void skip_put_bits(PutBitContext *s, int n)
Skip the given number of bits.
Definition: put_bits.h:306
#define src
Definition: vp8dsp.c:254
#define av_assert0(cond)
assert() equivalent, that is always enabled.
Definition: avassert.h:37
uint8_t
#define av_assert2(cond)
assert() equivalent, that does lie in speed critical code.
Definition: avassert.h:64
static void rebase_put_bits(PutBitContext *s, uint8_t *buffer, int buffer_size)
Rebase the bit writer onto a reallocated buffer.
Definition: put_bits.h:71
ptrdiff_t size
Definition: opengl_enc.c:101
#define av_log(a,...)
#define U(x)
Definition: vp56_arith.h:37
static void put_bits64(PutBitContext *s, int n, uint64_t value)
Write up to 64 bits into a bitstream.
Definition: put_bits.h:248
int size_in_bits
Definition: put_bits.h:39
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:176
static uint8_t * put_bits_ptr(PutBitContext *s)
Return the pointer to the byte where the bitstream writer will put the next bit.
Definition: put_bits.h:284
static int put_bits_left(PutBitContext *s)
Definition: put_bits.h:93
uint8_t * buf
Definition: put_bits.h:38
simple assert() macros that are a bit more flexible than ISO C assert().
GLsizei GLsizei * length
Definition: opengl_enc.c:115
static void put_bits(PutBitContext *s, int n, unsigned int value)
Write up to 31 bits into a bitstream.
Definition: put_bits.h:152
static int put_bits_count(PutBitContext *s)
Definition: put_bits.h:85
static void skip_put_bytes(PutBitContext *s, int n)
Skip the given number of bytes.
Definition: put_bits.h:293
GLsizei GLboolean const GLfloat * value
Definition: opengl_enc.c:109
int32_t
int n
Definition: avisynth_c.h:684
static void set_put_bits_buffer_size(PutBitContext *s, int size)
Change the end of the buffer.
Definition: put_bits.h:318
int bit_left
Definition: put_bits.h:37
uint8_t * buf_end
Definition: put_bits.h:38
uint8_t * buf_ptr
Definition: put_bits.h:38
void avpriv_copy_bits(PutBitContext *pb, const uint8_t *src, int length)
Copy the content of src to the bitstream.
Definition: bitstream.c:64
#define AV_WB32(p, v)
Definition: intreadwrite.h:424
void avpriv_align_put_bits(PutBitContext *s)
Pad the bitstream with zeros up to the next byte boundary.
Definition: bitstream.c:48
uint32_t bit_buf
Definition: put_bits.h:36
static void flush_put_bits(PutBitContext *s)
Pad the end of the output stream with zeros.
Definition: put_bits.h:101
static void init_put_bits(PutBitContext *s, uint8_t *buffer, int buffer_size)
Initialize the PutBitContext s.
Definition: put_bits.h:48
GLuint buffer
Definition: opengl_enc.c:102
#define av_unused
Definition: attributes.h:125
#define AV_WL32(p, v)
Definition: intreadwrite.h:431