Commit | Line | Data |
---|---|---|
2ba45a60 DM |
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 | ||
f6fa7814 DM |
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 | ||
2ba45a60 DM |
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 */ |