Libav
put_bits.h
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1 /*
2  * copyright (c) 2004 Michael Niedermayer <michaelni@gmx.at>
3  *
4  * This file is part of Libav.
5  *
6  * Libav 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  * Libav 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 Libav; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
26 #ifndef AVCODEC_PUT_BITS_H
27 #define AVCODEC_PUT_BITS_H
28 
29 #include <stdint.h>
30 #include <stddef.h>
31 #include <assert.h>
32 
33 #include "libavutil/intreadwrite.h"
34 
35 typedef struct PutBitContext {
36  uint32_t bit_buf;
37  int bit_left;
41 
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 
67 static inline int put_bits_count(PutBitContext *s)
68 {
69  return (s->buf_ptr - s->buf) * 8 + 32 - s->bit_left;
70 }
71 
75 static inline int put_bits_left(PutBitContext* s)
76 {
77  return (s->buf_end - s->buf_ptr) * 8 - 32 + s->bit_left;
78 }
79 
83 static inline void flush_put_bits(PutBitContext *s)
84 {
85 #ifndef BITSTREAM_WRITER_LE
86  if (s->bit_left < 32)
87  s->bit_buf <<= s->bit_left;
88 #endif
89  while (s->bit_left < 32) {
90  /* XXX: should test end of buffer */
91 #ifdef BITSTREAM_WRITER_LE
92  *s->buf_ptr++ = s->bit_buf;
93  s->bit_buf >>= 8;
94 #else
95  *s->buf_ptr++ = s->bit_buf >> 24;
96  s->bit_buf <<= 8;
97 #endif
98  s->bit_left += 8;
99  }
100  s->bit_left = 32;
101  s->bit_buf = 0;
102 }
103 
104 #ifdef BITSTREAM_WRITER_LE
105 #define avpriv_align_put_bits align_put_bits_unsupported_here
106 #define avpriv_put_string ff_put_string_unsupported_here
107 #define avpriv_copy_bits avpriv_copy_bits_unsupported_here
108 #else
109 
113 
119 void avpriv_put_string(PutBitContext *pb, const char *string,
120  int terminate_string);
121 
127 void avpriv_copy_bits(PutBitContext *pb, const uint8_t *src, int length);
128 #endif
129 
134 static inline void put_bits(PutBitContext *s, int n, unsigned int value)
135 {
136  unsigned int bit_buf;
137  int bit_left;
138 
139  assert(n <= 31 && value < (1U << n));
140 
141  bit_buf = s->bit_buf;
142  bit_left = s->bit_left;
143 
144  /* XXX: optimize */
145 #ifdef BITSTREAM_WRITER_LE
146  bit_buf |= value << (32 - bit_left);
147  if (n >= bit_left) {
148  AV_WL32(s->buf_ptr, bit_buf);
149  s->buf_ptr += 4;
150  bit_buf = (bit_left == 32) ? 0 : value >> bit_left;
151  bit_left += 32;
152  }
153  bit_left -= n;
154 #else
155  if (n < bit_left) {
156  bit_buf = (bit_buf << n) | value;
157  bit_left -= n;
158  } else {
159  bit_buf <<= bit_left;
160  bit_buf |= value >> (n - bit_left);
161  AV_WB32(s->buf_ptr, bit_buf);
162  s->buf_ptr += 4;
163  bit_left += 32 - n;
164  bit_buf = value;
165  }
166 #endif
167 
168  s->bit_buf = bit_buf;
169  s->bit_left = bit_left;
170 }
171 
172 static inline void put_sbits(PutBitContext *pb, int n, int32_t value)
173 {
174  assert(n >= 0 && n <= 31);
175 
176  put_bits(pb, n, value & ((1 << n) - 1));
177 }
178 
182 static void av_unused put_bits32(PutBitContext *s, uint32_t value)
183 {
184  int lo = value & 0xffff;
185  int hi = value >> 16;
186 #ifdef BITSTREAM_WRITER_LE
187  put_bits(s, 16, lo);
188  put_bits(s, 16, hi);
189 #else
190  put_bits(s, 16, hi);
191  put_bits(s, 16, lo);
192 #endif
193 }
194 
200 {
201  return s->buf_ptr;
202 }
203 
208 static inline void skip_put_bytes(PutBitContext *s, int n)
209 {
210  assert((put_bits_count(s) & 7) == 0);
211  assert(s->bit_left == 32);
212  s->buf_ptr += n;
213 }
214 
220 static inline void skip_put_bits(PutBitContext *s, int n)
221 {
222  s->bit_left -= n;
223  s->buf_ptr -= 4 * (s->bit_left >> 5);
224  s->bit_left &= 31;
225 }
226 
232 static inline void set_put_bits_buffer_size(PutBitContext *s, int size)
233 {
234  s->buf_end = s->buf + size;
235 }
236 
237 #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:182
void avpriv_put_string(PutBitContext *pb, const char *string, int terminate_string)
Put the string string in the bitstream.
Definition: bitstream.c:50
int size
static void put_sbits(PutBitContext *pb, int n, int32_t value)
Definition: put_bits.h:172
static void skip_put_bits(PutBitContext *s, int n)
Skip the given number of bits.
Definition: put_bits.h:220
uint8_t
#define AV_WB32(p, d)
Definition: intreadwrite.h:239
#define AV_WL32(p, d)
Definition: intreadwrite.h:255
int size_in_bits
Definition: put_bits.h:39
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:199
static int put_bits_left(PutBitContext *s)
Definition: put_bits.h:75
uint8_t * buf
Definition: put_bits.h:38
static void put_bits(PutBitContext *s, int n, unsigned int value)
Write up to 31 bits into a bitstream.
Definition: put_bits.h:134
static int put_bits_count(PutBitContext *s)
Definition: put_bits.h:67
static void skip_put_bytes(PutBitContext *s, int n)
Skip the given number of bytes.
Definition: put_bits.h:208
int32_t
static char buffer[20]
Definition: seek-test.c:31
static void set_put_bits_buffer_size(PutBitContext *s, int size)
Change the end of the buffer.
Definition: put_bits.h:232
NULL
Definition: eval.c:55
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:61
void avpriv_align_put_bits(PutBitContext *s)
Pad the bitstream with zeros up to the next byte boundary.
Definition: bitstream.c:45
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:83
static void init_put_bits(PutBitContext *s, uint8_t *buffer, int buffer_size)
Initialize the PutBitContext s.
Definition: put_bits.h:48
#define av_unused
Definition: attributes.h:86
Definition: vf_drawbox.c:37