FFmpeg
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 static inline void flush_put_bits_le(PutBitContext *s)
123 {
124  while (s->bit_left < 32) {
125  av_assert0(s->buf_ptr < s->buf_end);
126  *s->buf_ptr++ = s->bit_buf;
127  s->bit_buf >>= 8;
128  s->bit_left += 8;
129  }
130  s->bit_left = 32;
131  s->bit_buf = 0;
132 }
133 
134 #ifdef BITSTREAM_WRITER_LE
135 #define avpriv_align_put_bits align_put_bits_unsupported_here
136 #define avpriv_put_string ff_put_string_unsupported_here
137 #define avpriv_copy_bits avpriv_copy_bits_unsupported_here
138 #else
139 /**
140  * Pad the bitstream with zeros up to the next byte boundary.
141  */
143 
144 /**
145  * Put the string string in the bitstream.
146  *
147  * @param terminate_string 0-terminates the written string if value is 1
148  */
149 void avpriv_put_string(PutBitContext *pb, const char *string,
150  int terminate_string);
151 
152 /**
153  * Copy the content of src to the bitstream.
154  *
155  * @param length the number of bits of src to copy
156  */
157 void avpriv_copy_bits(PutBitContext *pb, const uint8_t *src, int length);
158 #endif
159 
160 /**
161  * Write up to 31 bits into a bitstream.
162  * Use put_bits32 to write 32 bits.
163  */
164 static inline void put_bits(PutBitContext *s, int n, unsigned int value)
165 {
166  unsigned int bit_buf;
167  int bit_left;
168 
169  av_assert2(n <= 31 && value < (1U << n));
170 
171  bit_buf = s->bit_buf;
172  bit_left = s->bit_left;
173 
174  /* XXX: optimize */
175 #ifdef BITSTREAM_WRITER_LE
176  bit_buf |= value << (32 - bit_left);
177  if (n >= bit_left) {
178  if (3 < s->buf_end - s->buf_ptr) {
179  AV_WL32(s->buf_ptr, bit_buf);
180  s->buf_ptr += 4;
181  } else {
182  av_log(NULL, AV_LOG_ERROR, "Internal error, put_bits buffer too small\n");
183  av_assert2(0);
184  }
185  bit_buf = value >> bit_left;
186  bit_left += 32;
187  }
188  bit_left -= n;
189 #else
190  if (n < bit_left) {
191  bit_buf = (bit_buf << n) | value;
192  bit_left -= n;
193  } else {
194  bit_buf <<= bit_left;
195  bit_buf |= value >> (n - bit_left);
196  if (3 < s->buf_end - s->buf_ptr) {
197  AV_WB32(s->buf_ptr, bit_buf);
198  s->buf_ptr += 4;
199  } else {
200  av_log(NULL, AV_LOG_ERROR, "Internal error, put_bits buffer too small\n");
201  av_assert2(0);
202  }
203  bit_left += 32 - n;
204  bit_buf = value;
205  }
206 #endif
207 
208  s->bit_buf = bit_buf;
209  s->bit_left = bit_left;
210 }
211 
212 static inline void put_bits_le(PutBitContext *s, int n, unsigned int value)
213 {
214  unsigned int bit_buf;
215  int bit_left;
216 
217  av_assert2(n <= 31 && value < (1U << n));
218 
219  bit_buf = s->bit_buf;
220  bit_left = s->bit_left;
221 
222  bit_buf |= value << (32 - bit_left);
223  if (n >= bit_left) {
224  if (3 < s->buf_end - s->buf_ptr) {
225  AV_WL32(s->buf_ptr, bit_buf);
226  s->buf_ptr += 4;
227  } else {
228  av_log(NULL, AV_LOG_ERROR, "Internal error, put_bits buffer too small\n");
229  av_assert2(0);
230  }
231  bit_buf = value >> bit_left;
232  bit_left += 32;
233  }
234  bit_left -= n;
235 
236  s->bit_buf = bit_buf;
237  s->bit_left = bit_left;
238 }
239 
240 static inline void put_sbits(PutBitContext *pb, int n, int32_t value)
241 {
242  av_assert2(n >= 0 && n <= 31);
243 
244  put_bits(pb, n, av_mod_uintp2(value, n));
245 }
246 
247 /**
248  * Write exactly 32 bits into a bitstream.
249  */
250 static void av_unused put_bits32(PutBitContext *s, uint32_t value)
251 {
252  unsigned int bit_buf;
253  int bit_left;
254 
255  bit_buf = s->bit_buf;
256  bit_left = s->bit_left;
257 
258 #ifdef BITSTREAM_WRITER_LE
259  bit_buf |= value << (32 - bit_left);
260  if (3 < s->buf_end - s->buf_ptr) {
261  AV_WL32(s->buf_ptr, bit_buf);
262  s->buf_ptr += 4;
263  } else {
264  av_log(NULL, AV_LOG_ERROR, "Internal error, put_bits buffer too small\n");
265  av_assert2(0);
266  }
267  bit_buf = (uint64_t)value >> bit_left;
268 #else
269  bit_buf = (uint64_t)bit_buf << bit_left;
270  bit_buf |= value >> (32 - bit_left);
271  if (3 < s->buf_end - s->buf_ptr) {
272  AV_WB32(s->buf_ptr, bit_buf);
273  s->buf_ptr += 4;
274  } else {
275  av_log(NULL, AV_LOG_ERROR, "Internal error, put_bits buffer too small\n");
276  av_assert2(0);
277  }
278  bit_buf = value;
279 #endif
280 
281  s->bit_buf = bit_buf;
282  s->bit_left = bit_left;
283 }
284 
285 /**
286  * Write up to 64 bits into a bitstream.
287  */
288 static inline void put_bits64(PutBitContext *s, int n, uint64_t value)
289 {
290  av_assert2((n == 64) || (n < 64 && value < (UINT64_C(1) << n)));
291 
292  if (n < 32)
293  put_bits(s, n, value);
294  else if (n == 32)
295  put_bits32(s, value);
296  else if (n < 64) {
297  uint32_t lo = value & 0xffffffff;
298  uint32_t hi = value >> 32;
299 #ifdef BITSTREAM_WRITER_LE
300  put_bits32(s, lo);
301  put_bits(s, n - 32, hi);
302 #else
303  put_bits(s, n - 32, hi);
304  put_bits32(s, lo);
305 #endif
306  } else {
307  uint32_t lo = value & 0xffffffff;
308  uint32_t hi = value >> 32;
309 #ifdef BITSTREAM_WRITER_LE
310  put_bits32(s, lo);
311  put_bits32(s, hi);
312 #else
313  put_bits32(s, hi);
314  put_bits32(s, lo);
315 #endif
316 
317  }
318 }
319 
320 /**
321  * Return the pointer to the byte where the bitstream writer will put
322  * the next bit.
323  */
325 {
326  return s->buf_ptr;
327 }
328 
329 /**
330  * Skip the given number of bytes.
331  * PutBitContext must be flushed & aligned to a byte boundary before calling this.
332  */
333 static inline void skip_put_bytes(PutBitContext *s, int n)
334 {
335  av_assert2((put_bits_count(s) & 7) == 0);
336  av_assert2(s->bit_left == 32);
337  av_assert0(n <= s->buf_end - s->buf_ptr);
338  s->buf_ptr += n;
339 }
340 
341 /**
342  * Skip the given number of bits.
343  * Must only be used if the actual values in the bitstream do not matter.
344  * If n is 0 the behavior is undefined.
345  */
346 static inline void skip_put_bits(PutBitContext *s, int n)
347 {
348  s->bit_left -= n;
349  s->buf_ptr -= 4 * (s->bit_left >> 5);
350  s->bit_left &= 31;
351 }
352 
353 /**
354  * Change the end of the buffer.
355  *
356  * @param size the new size in bytes of the buffer where to put bits
357  */
358 static inline void set_put_bits_buffer_size(PutBitContext *s, int size)
359 {
360  av_assert0(size <= INT_MAX/8 - 32);
361  s->buf_end = s->buf + size;
362  s->size_in_bits = 8*size;
363 }
364 
365 #endif /* AVCODEC_PUT_BITS_H */
static void put_bits_le(PutBitContext *s, int n, unsigned int value)
Definition: put_bits.h:212
static void av_unused put_bits32(PutBitContext *s, uint32_t value)
Write exactly 32 bits into a bitstream.
Definition: put_bits.h:250
#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
static void put_sbits(PutBitContext *pb, int n, int32_t value)
Definition: put_bits.h:240
static void skip_put_bits(PutBitContext *s, int n)
Skip the given number of bits.
Definition: put_bits.h:346
#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
GLsizei GLboolean const GLfloat * value
Definition: opengl_enc.c:108
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:100
#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:288
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:324
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:114
static void put_bits(PutBitContext *s, int n, unsigned int value)
Write up to 31 bits into a bitstream.
Definition: put_bits.h:164
static int put_bits_count(PutBitContext *s)
Definition: put_bits.h:85
static void flush_put_bits_le(PutBitContext *s)
Definition: put_bits.h:122
static void skip_put_bytes(PutBitContext *s, int n)
Skip the given number of bytes.
Definition: put_bits.h:333
int32_t
#define s(width, name)
Definition: cbs_vp9.c:257
int n
Definition: avisynth_c.h:760
static void set_put_bits_buffer_size(PutBitContext *s, int size)
Change the end of the buffer.
Definition: put_bits.h:358
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:419
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:101
#define av_unused
Definition: attributes.h:125
#define AV_WL32(p, v)
Definition: intreadwrite.h:426