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 #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;
42  uint8_t *buf, *buf_ptr, *buf_end;
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 void flush_put_bits(PutBitContext *s)
79 {
80 #ifndef BITSTREAM_WRITER_LE
81  if (s->bit_left < 32)
82  s->bit_buf<<= s->bit_left;
83 #endif
84  while (s->bit_left < 32) {
85  /* XXX: should test end of buffer */
86 #ifdef BITSTREAM_WRITER_LE
87  *s->buf_ptr++=s->bit_buf;
88  s->bit_buf>>=8;
89 #else
90  *s->buf_ptr++=s->bit_buf >> 24;
91  s->bit_buf<<=8;
92 #endif
93  s->bit_left+=8;
94  }
95  s->bit_left=32;
96  s->bit_buf=0;
97 }
98 
99 #ifdef BITSTREAM_WRITER_LE
100 #define avpriv_align_put_bits align_put_bits_unsupported_here
101 #define ff_put_string ff_put_string_unsupported_here
102 #define avpriv_copy_bits avpriv_copy_bits_unsupported_here
103 #else
104 
108 
114 void ff_put_string(PutBitContext *pb, const char *string, int terminate_string);
115 
121 void avpriv_copy_bits(PutBitContext *pb, const uint8_t *src, int length);
122 #endif
123 
128 static inline void put_bits(PutBitContext *s, int n, unsigned int value)
129 {
130  unsigned int bit_buf;
131  int bit_left;
132 
133  // printf("put_bits=%d %x\n", n, value);
134  assert(n <= 31 && value < (1U << n));
135 
136  bit_buf = s->bit_buf;
137  bit_left = s->bit_left;
138 
139  // printf("n=%d value=%x cnt=%d buf=%x\n", n, value, bit_cnt, bit_buf);
140  /* XXX: optimize */
141 #ifdef BITSTREAM_WRITER_LE
142  bit_buf |= value << (32 - bit_left);
143  if (n >= bit_left) {
144  AV_WL32(s->buf_ptr, bit_buf);
145  s->buf_ptr+=4;
146  bit_buf = (bit_left==32)?0:value >> bit_left;
147  bit_left+=32;
148  }
149  bit_left-=n;
150 #else
151  if (n < bit_left) {
152  bit_buf = (bit_buf<<n) | value;
153  bit_left-=n;
154  } else {
155  bit_buf<<=bit_left;
156  bit_buf |= value >> (n - bit_left);
157  AV_WB32(s->buf_ptr, bit_buf);
158  //printf("bitbuf = %08x\n", bit_buf);
159  s->buf_ptr+=4;
160  bit_left+=32 - n;
161  bit_buf = value;
162  }
163 #endif
164 
165  s->bit_buf = bit_buf;
166  s->bit_left = bit_left;
167 }
168 
169 static inline void put_sbits(PutBitContext *pb, int n, int32_t value)
170 {
171  assert(n >= 0 && n <= 31);
172 
173  put_bits(pb, n, value & ((1<<n)-1));
174 }
175 
179 static void av_unused put_bits32(PutBitContext *s, uint32_t value)
180 {
181  int lo = value & 0xffff;
182  int hi = value >> 16;
183 #ifdef BITSTREAM_WRITER_LE
184  put_bits(s, 16, lo);
185  put_bits(s, 16, hi);
186 #else
187  put_bits(s, 16, hi);
188  put_bits(s, 16, lo);
189 #endif
190 }
191 
196 static inline uint8_t* put_bits_ptr(PutBitContext *s)
197 {
198  return s->buf_ptr;
199 }
200 
205 static inline void skip_put_bytes(PutBitContext *s, int n)
206 {
207  assert((put_bits_count(s)&7)==0);
208  assert(s->bit_left==32);
209  s->buf_ptr += n;
210 }
211 
217 static inline void skip_put_bits(PutBitContext *s, int n)
218 {
219  s->bit_left -= n;
220  s->buf_ptr-= 4*(s->bit_left>>5);
221  s->bit_left &= 31;
222 }
223 
229 static inline void set_put_bits_buffer_size(PutBitContext *s, int size)
230 {
231  s->buf_end= s->buf + size;
232 }
233 
234 #endif /* AVCODEC_PUT_BITS_H */