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 <stdlib.h>
31 #include <assert.h>
32 
33 #include "libavutil/bswap.h"
34 #include "libavutil/common.h"
35 #include "libavutil/intreadwrite.h"
36 #include "libavutil/log.h"
37 #include "mathops.h"
38 #include "config.h"
39 
40 typedef struct PutBitContext {
41  uint32_t bit_buf;
42  int bit_left;
46 
53 static inline void init_put_bits(PutBitContext *s, uint8_t *buffer,
54  int buffer_size)
55 {
56  if (buffer_size < 0) {
57  buffer_size = 0;
58  buffer = NULL;
59  }
60 
61  s->size_in_bits = 8 * buffer_size;
62  s->buf = buffer;
63  s->buf_end = s->buf + buffer_size;
64  s->buf_ptr = s->buf;
65  s->bit_left = 32;
66  s->bit_buf = 0;
67 }
68 
72 static inline int put_bits_count(PutBitContext *s)
73 {
74  return (s->buf_ptr - s->buf) * 8 + 32 - s->bit_left;
75 }
76 
80 static inline int put_bits_left(PutBitContext* s)
81 {
82  return (s->buf_end - s->buf_ptr) * 8 - 32 + s->bit_left;
83 }
84 
88 static inline void flush_put_bits(PutBitContext *s)
89 {
90 #ifndef BITSTREAM_WRITER_LE
91  if (s->bit_left < 32)
92  s->bit_buf <<= s->bit_left;
93 #endif
94  while (s->bit_left < 32) {
95  /* XXX: should test end of buffer */
96 #ifdef BITSTREAM_WRITER_LE
97  *s->buf_ptr++ = s->bit_buf;
98  s->bit_buf >>= 8;
99 #else
100  *s->buf_ptr++ = s->bit_buf >> 24;
101  s->bit_buf <<= 8;
102 #endif
103  s->bit_left += 8;
104  }
105  s->bit_left = 32;
106  s->bit_buf = 0;
107 }
108 
109 #ifdef BITSTREAM_WRITER_LE
110 #define avpriv_align_put_bits align_put_bits_unsupported_here
111 #define avpriv_put_string ff_put_string_unsupported_here
112 #define avpriv_copy_bits avpriv_copy_bits_unsupported_here
113 #else
114 
118 
124 void avpriv_put_string(PutBitContext *pb, const char *string,
125  int terminate_string);
126 
132 void avpriv_copy_bits(PutBitContext *pb, const uint8_t *src, int length);
133 #endif
134 
139 static inline void put_bits(PutBitContext *s, int n, unsigned int value)
140 {
141  unsigned int bit_buf;
142  int bit_left;
143 
144  assert(n <= 31 && value < (1U << n));
145 
146  bit_buf = s->bit_buf;
147  bit_left = s->bit_left;
148 
149  /* XXX: optimize */
150 #ifdef BITSTREAM_WRITER_LE
151  bit_buf |= value << (32 - bit_left);
152  if (n >= bit_left) {
153  AV_WL32(s->buf_ptr, bit_buf);
154  s->buf_ptr += 4;
155  bit_buf = (bit_left == 32) ? 0 : value >> bit_left;
156  bit_left += 32;
157  }
158  bit_left -= n;
159 #else
160  if (n < bit_left) {
161  bit_buf = (bit_buf << n) | value;
162  bit_left -= n;
163  } else {
164  bit_buf <<= bit_left;
165  bit_buf |= value >> (n - bit_left);
166  AV_WB32(s->buf_ptr, bit_buf);
167  s->buf_ptr += 4;
168  bit_left += 32 - n;
169  bit_buf = value;
170  }
171 #endif
172 
173  s->bit_buf = bit_buf;
174  s->bit_left = bit_left;
175 }
176 
177 static inline void put_sbits(PutBitContext *pb, int n, int32_t value)
178 {
179  assert(n >= 0 && n <= 31);
180 
181  put_bits(pb, n, value & ((1 << n) - 1));
182 }
183 
187 static void av_unused put_bits32(PutBitContext *s, uint32_t value)
188 {
189  int lo = value & 0xffff;
190  int hi = value >> 16;
191 #ifdef BITSTREAM_WRITER_LE
192  put_bits(s, 16, lo);
193  put_bits(s, 16, hi);
194 #else
195  put_bits(s, 16, hi);
196  put_bits(s, 16, lo);
197 #endif
198 }
199 
205 {
206  return s->buf_ptr;
207 }
208 
213 static inline void skip_put_bytes(PutBitContext *s, int n)
214 {
215  assert((put_bits_count(s) & 7) == 0);
216  assert(s->bit_left == 32);
217  s->buf_ptr += n;
218 }
219 
225 static inline void skip_put_bits(PutBitContext *s, int n)
226 {
227  s->bit_left -= n;
228  s->buf_ptr -= 4 * (s->bit_left >> 5);
229  s->bit_left &= 31;
230 }
231 
237 static inline void set_put_bits_buffer_size(PutBitContext *s, int size)
238 {
239  s->buf_end = s->buf + size;
240 }
241 
242 #endif /* AVCODEC_PUT_BITS_H */