put_bits.h
Go to the documentation of this file.
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 #include "libavutil/bswap.h"
33 #include "libavutil/common.h"
34 #include "libavutil/intreadwrite.h"
35 #include "libavutil/log.h"
36 #include "mathops.h"
37 #include "config.h"
38 
39 typedef struct PutBitContext {
40  uint32_t bit_buf;
41  int bit_left;
45 
52 static 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;
62  s->buf_ptr = s->buf;
63  s->bit_left=32;
64  s->bit_buf=0;
65 }
66 
70 static inline int put_bits_count(PutBitContext *s)
71 {
72  return (s->buf_ptr - s->buf) * 8 + 32 - s->bit_left;
73 }
74 
78 static inline int put_bits_left(PutBitContext* s)
79 {
80  return (s->buf_end - s->buf_ptr) * 8 - 32 + s->bit_left;
81 }
82 
86 static inline void flush_put_bits(PutBitContext *s)
87 {
88 #ifndef BITSTREAM_WRITER_LE
89  if (s->bit_left < 32)
90  s->bit_buf<<= s->bit_left;
91 #endif
92  while (s->bit_left < 32) {
93  /* XXX: should test end of buffer */
94 #ifdef BITSTREAM_WRITER_LE
95  *s->buf_ptr++=s->bit_buf;
96  s->bit_buf>>=8;
97 #else
98  *s->buf_ptr++=s->bit_buf >> 24;
99  s->bit_buf<<=8;
100 #endif
101  s->bit_left+=8;
102  }
103  s->bit_left=32;
104  s->bit_buf=0;
105 }
106 
107 #ifdef BITSTREAM_WRITER_LE
108 #define avpriv_align_put_bits align_put_bits_unsupported_here
109 #define avpriv_put_string ff_put_string_unsupported_here
110 #define avpriv_copy_bits avpriv_copy_bits_unsupported_here
111 #else
112 
116 
122 void avpriv_put_string(PutBitContext *pb, const char *string, int terminate_string);
123 
129 void avpriv_copy_bits(PutBitContext *pb, const uint8_t *src, int length);
130 #endif
131 
136 static inline void put_bits(PutBitContext *s, int n, unsigned int value)
137 {
138  unsigned int bit_buf;
139  int bit_left;
140 
141  assert(n <= 31 && value < (1U << n));
142 
143  bit_buf = s->bit_buf;
144  bit_left = s->bit_left;
145 
146  /* XXX: optimize */
147 #ifdef BITSTREAM_WRITER_LE
148  bit_buf |= value << (32 - bit_left);
149  if (n >= bit_left) {
150  AV_WL32(s->buf_ptr, bit_buf);
151  s->buf_ptr+=4;
152  bit_buf = (bit_left==32)?0:value >> bit_left;
153  bit_left+=32;
154  }
155  bit_left-=n;
156 #else
157  if (n < bit_left) {
158  bit_buf = (bit_buf<<n) | value;
159  bit_left-=n;
160  } else {
161  bit_buf<<=bit_left;
162  bit_buf |= value >> (n - bit_left);
163  AV_WB32(s->buf_ptr, bit_buf);
164  s->buf_ptr+=4;
165  bit_left+=32 - n;
166  bit_buf = value;
167  }
168 #endif
169 
170  s->bit_buf = bit_buf;
171  s->bit_left = bit_left;
172 }
173 
174 static inline void put_sbits(PutBitContext *pb, int n, int32_t value)
175 {
176  assert(n >= 0 && n <= 31);
177 
178  put_bits(pb, n, value & ((1<<n)-1));
179 }
180 
184 static void av_unused put_bits32(PutBitContext *s, uint32_t value)
185 {
186  int lo = value & 0xffff;
187  int hi = value >> 16;
188 #ifdef BITSTREAM_WRITER_LE
189  put_bits(s, 16, lo);
190  put_bits(s, 16, hi);
191 #else
192  put_bits(s, 16, hi);
193  put_bits(s, 16, lo);
194 #endif
195 }
196 
202 {
203  return s->buf_ptr;
204 }
205 
210 static inline void skip_put_bytes(PutBitContext *s, int n)
211 {
212  assert((put_bits_count(s)&7)==0);
213  assert(s->bit_left==32);
214  s->buf_ptr += n;
215 }
216 
222 static inline void skip_put_bits(PutBitContext *s, int n)
223 {
224  s->bit_left -= n;
225  s->buf_ptr-= 4*(s->bit_left>>5);
226  s->bit_left &= 31;
227 }
228 
234 static inline void set_put_bits_buffer_size(PutBitContext *s, int size)
235 {
236  s->buf_end= s->buf + size;
237 }
238 
239 #endif /* AVCODEC_PUT_BITS_H */