Mercurial > hg > forks > libbpg
comparison libavcodec/put_bits.h @ 0:772086c29cc7
Initial import.
author | Matti Hamalainen <ccr@tnsp.org> |
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date | Wed, 16 Nov 2016 11:16:33 +0200 |
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-1:000000000000 | 0:772086c29cc7 |
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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 #include <assert.h> | |
32 | |
33 #include "libavutil/intreadwrite.h" | |
34 #include "libavutil/avassert.h" | |
35 | |
36 typedef struct PutBitContext { | |
37 uint32_t bit_buf; | |
38 int bit_left; | |
39 uint8_t *buf, *buf_ptr, *buf_end; | |
40 int size_in_bits; | |
41 } PutBitContext; | |
42 | |
43 /** | |
44 * Initialize the PutBitContext s. | |
45 * | |
46 * @param buffer the buffer where to put bits | |
47 * @param buffer_size the size in bytes of buffer | |
48 */ | |
49 static inline void init_put_bits(PutBitContext *s, uint8_t *buffer, | |
50 int buffer_size) | |
51 { | |
52 if (buffer_size < 0) { | |
53 buffer_size = 0; | |
54 buffer = NULL; | |
55 } | |
56 | |
57 s->size_in_bits = 8 * buffer_size; | |
58 s->buf = buffer; | |
59 s->buf_end = s->buf + buffer_size; | |
60 s->buf_ptr = s->buf; | |
61 s->bit_left = 32; | |
62 s->bit_buf = 0; | |
63 } | |
64 | |
65 /** | |
66 * Rebase the bit writer onto a reallocated buffer. | |
67 * | |
68 * @param buffer the buffer where to put bits | |
69 * @param buffer_size the size in bytes of buffer, | |
70 * must be larger than the previous size | |
71 */ | |
72 static inline void rebase_put_bits(PutBitContext *s, uint8_t *buffer, | |
73 int buffer_size) | |
74 { | |
75 av_assert0(8*buffer_size > s->size_in_bits); | |
76 | |
77 s->buf_end = buffer + buffer_size; | |
78 s->buf_ptr = buffer + (s->buf_ptr - s->buf); | |
79 s->buf = buffer; | |
80 s->size_in_bits = 8 * buffer_size; | |
81 } | |
82 | |
83 /** | |
84 * @return the total number of bits written to the bitstream. | |
85 */ | |
86 static inline int put_bits_count(PutBitContext *s) | |
87 { | |
88 return (s->buf_ptr - s->buf) * 8 + 32 - s->bit_left; | |
89 } | |
90 | |
91 /** | |
92 * @return the number of bits available in the bitstream. | |
93 */ | |
94 static inline int put_bits_left(PutBitContext* s) | |
95 { | |
96 return (s->buf_end - s->buf_ptr) * 8 - 32 + s->bit_left; | |
97 } | |
98 | |
99 /** | |
100 * Pad the end of the output stream with zeros. | |
101 */ | |
102 static inline void flush_put_bits(PutBitContext *s) | |
103 { | |
104 #ifndef BITSTREAM_WRITER_LE | |
105 if (s->bit_left < 32) | |
106 s->bit_buf <<= s->bit_left; | |
107 #endif | |
108 while (s->bit_left < 32) { | |
109 /* XXX: should test end of buffer */ | |
110 #ifdef BITSTREAM_WRITER_LE | |
111 *s->buf_ptr++ = s->bit_buf; | |
112 s->bit_buf >>= 8; | |
113 #else | |
114 *s->buf_ptr++ = s->bit_buf >> 24; | |
115 s->bit_buf <<= 8; | |
116 #endif | |
117 s->bit_left += 8; | |
118 } | |
119 s->bit_left = 32; | |
120 s->bit_buf = 0; | |
121 } | |
122 | |
123 #ifdef BITSTREAM_WRITER_LE | |
124 #define avpriv_align_put_bits align_put_bits_unsupported_here | |
125 #define avpriv_put_string ff_put_string_unsupported_here | |
126 #define avpriv_copy_bits avpriv_copy_bits_unsupported_here | |
127 #else | |
128 /** | |
129 * Pad the bitstream with zeros up to the next byte boundary. | |
130 */ | |
131 void avpriv_align_put_bits(PutBitContext *s); | |
132 | |
133 /** | |
134 * Put the string string in the bitstream. | |
135 * | |
136 * @param terminate_string 0-terminates the written string if value is 1 | |
137 */ | |
138 void avpriv_put_string(PutBitContext *pb, const char *string, | |
139 int terminate_string); | |
140 | |
141 /** | |
142 * Copy the content of src to the bitstream. | |
143 * | |
144 * @param length the number of bits of src to copy | |
145 */ | |
146 void avpriv_copy_bits(PutBitContext *pb, const uint8_t *src, int length); | |
147 #endif | |
148 | |
149 /** | |
150 * Write up to 31 bits into a bitstream. | |
151 * Use put_bits32 to write 32 bits. | |
152 */ | |
153 static inline void put_bits(PutBitContext *s, int n, unsigned int value) | |
154 { | |
155 unsigned int bit_buf; | |
156 int bit_left; | |
157 | |
158 av_assert2(n <= 31 && value < (1U << n)); | |
159 | |
160 bit_buf = s->bit_buf; | |
161 bit_left = s->bit_left; | |
162 | |
163 /* XXX: optimize */ | |
164 #ifdef BITSTREAM_WRITER_LE | |
165 bit_buf |= value << (32 - bit_left); | |
166 if (n >= bit_left) { | |
167 av_assert2(s->buf_ptr+3<s->buf_end); | |
168 AV_WL32(s->buf_ptr, bit_buf); | |
169 s->buf_ptr += 4; | |
170 bit_buf = (bit_left == 32) ? 0 : value >> bit_left; | |
171 bit_left += 32; | |
172 } | |
173 bit_left -= n; | |
174 #else | |
175 if (n < bit_left) { | |
176 bit_buf = (bit_buf << n) | value; | |
177 bit_left -= n; | |
178 } else { | |
179 bit_buf <<= bit_left; | |
180 bit_buf |= value >> (n - bit_left); | |
181 av_assert2(s->buf_ptr+3<s->buf_end); | |
182 AV_WB32(s->buf_ptr, bit_buf); | |
183 s->buf_ptr += 4; | |
184 bit_left += 32 - n; | |
185 bit_buf = value; | |
186 } | |
187 #endif | |
188 | |
189 s->bit_buf = bit_buf; | |
190 s->bit_left = bit_left; | |
191 } | |
192 | |
193 static inline void put_sbits(PutBitContext *pb, int n, int32_t value) | |
194 { | |
195 av_assert2(n >= 0 && n <= 31); | |
196 | |
197 put_bits(pb, n, value & ((1 << n) - 1)); | |
198 } | |
199 | |
200 /** | |
201 * Write exactly 32 bits into a bitstream. | |
202 */ | |
203 static void av_unused put_bits32(PutBitContext *s, uint32_t value) | |
204 { | |
205 int lo = value & 0xffff; | |
206 int hi = value >> 16; | |
207 #ifdef BITSTREAM_WRITER_LE | |
208 put_bits(s, 16, lo); | |
209 put_bits(s, 16, hi); | |
210 #else | |
211 put_bits(s, 16, hi); | |
212 put_bits(s, 16, lo); | |
213 #endif | |
214 } | |
215 | |
216 /** | |
217 * Return the pointer to the byte where the bitstream writer will put | |
218 * the next bit. | |
219 */ | |
220 static inline uint8_t *put_bits_ptr(PutBitContext *s) | |
221 { | |
222 return s->buf_ptr; | |
223 } | |
224 | |
225 /** | |
226 * Skip the given number of bytes. | |
227 * PutBitContext must be flushed & aligned to a byte boundary before calling this. | |
228 */ | |
229 static inline void skip_put_bytes(PutBitContext *s, int n) | |
230 { | |
231 av_assert2((put_bits_count(s) & 7) == 0); | |
232 av_assert2(s->bit_left == 32); | |
233 s->buf_ptr += n; | |
234 } | |
235 | |
236 /** | |
237 * Skip the given number of bits. | |
238 * Must only be used if the actual values in the bitstream do not matter. | |
239 * If n is 0 the behavior is undefined. | |
240 */ | |
241 static inline void skip_put_bits(PutBitContext *s, int n) | |
242 { | |
243 s->bit_left -= n; | |
244 s->buf_ptr -= 4 * (s->bit_left >> 5); | |
245 s->bit_left &= 31; | |
246 } | |
247 | |
248 /** | |
249 * Change the end of the buffer. | |
250 * | |
251 * @param size the new size in bytes of the buffer where to put bits | |
252 */ | |
253 static inline void set_put_bits_buffer_size(PutBitContext *s, int size) | |
254 { | |
255 s->buf_end = s->buf + size; | |
256 } | |
257 | |
258 #endif /* AVCODEC_PUT_BITS_H */ |