FFmpeg coverage

Directory: ../../../ffmpeg/
File: src/libavutil/fifo.c
Date: 2026-09-29 11:16:21
Exec Total Coverage
Lines: 131 141 92.9%
Functions: 17 18 94.4%
Branches: 63 74 85.1%
Line Branch Exec Source
1 /*
2 * a very simple circular buffer FIFO implementation
3 * Copyright (c) 2000, 2001, 2002 Fabrice Bellard
4 * Copyright (c) 2006 Roman Shaposhnik
5 *
6 * This file is part of FFmpeg.
7 *
8 * FFmpeg is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; either
11 * version 2.1 of the License, or (at your option) any later version.
12 *
13 * FFmpeg is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Lesser General Public License for more details.
17 *
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with FFmpeg; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21 */
22
23 #include <stdint.h>
24 #include <string.h>
25
26 #include "avassert.h"
27 #include "error.h"
28 #include "fifo.h"
29 #include "macros.h"
30 #include "mem.h"
31
32 // by default the FIFO can be auto-grown to 1MB
33 #define AUTO_GROW_DEFAULT_BYTES (1024 * 1024)
34
35 struct AVFifo {
36 uint8_t *buffer;
37
38 size_t elem_size, nb_elems;
39 size_t offset_r, offset_w;
40 // distinguishes the ambiguous situation offset_r == offset_w
41 int is_empty;
42
43 unsigned int flags;
44 size_t auto_grow_limit;
45 };
46
47 94981 AVFifo *av_fifo_alloc2(size_t nb_elems, size_t elem_size,
48 unsigned int flags)
49 {
50 AVFifo *f;
51 94981 void *buffer = NULL;
52
53
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 94981 if (!elem_size)
54 ✗ return NULL;
55
56
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 94981 if (nb_elems) {
57 94981 buffer = av_realloc_array(NULL, nb_elems, elem_size);
58
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 94981 if (!buffer)
59 ✗ return NULL;
60 }
61 94981 f = av_mallocz(sizeof(*f));
62
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 94981 if (!f) {
63 ✗ av_free(buffer);
64 ✗ return NULL;
65 }
66 94981 f->buffer = buffer;
67 94981 f->nb_elems = nb_elems;
68 94981 f->elem_size = elem_size;
69 94981 f->is_empty = 1;
70
71 94981 f->flags = flags;
72 94981 f->auto_grow_limit = FFMAX(AUTO_GROW_DEFAULT_BYTES / elem_size, 1);
73
74 94981 return f;
75 }
76
77 5 void av_fifo_auto_grow_limit(AVFifo *f, size_t max_elems)
78 {
79 5 f->auto_grow_limit = max_elems;
80 5 }
81
82 1 size_t av_fifo_elem_size(const AVFifo *f)
83 {
84 1 return f->elem_size;
85 }
86
87 15552303 size_t av_fifo_can_read(const AVFifo *f)
88 {
89
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 15552303 if (f->offset_w <= f->offset_r && !f->is_empty)
90 5791003 return f->nb_elems - f->offset_r + f->offset_w;
91 9761300 return f->offset_w - f->offset_r;
92 }
93
94 4103828 size_t av_fifo_can_write(const AVFifo *f)
95 {
96 4103828 return f->nb_elems - av_fifo_can_read(f);
97 }
98
99 18979 int av_fifo_grow2(AVFifo *f, size_t inc)
100 {
101 uint8_t *tmp;
102
103
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 18979 if (inc > SIZE_MAX - f->nb_elems)
104 ✗ return AVERROR(EINVAL);
105
106 18979 tmp = av_realloc_array(f->buffer, f->nb_elems + inc, f->elem_size);
107
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 18979 if (!tmp)
108 ✗ return AVERROR(ENOMEM);
109 18979 f->buffer = tmp;
110
111 // move the data from the beginning of the ring buffer
112 // to the newly allocated space
113
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 18979 if (f->offset_w <= f->offset_r && !f->is_empty) {
114 18954 const size_t copy = FFMIN(inc, f->offset_w);
115 18954 memcpy(tmp + f->nb_elems * f->elem_size, tmp, copy * f->elem_size);
116
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 18954 if (copy < f->offset_w) {
117 132 memmove(tmp, tmp + copy * f->elem_size,
118 132 (f->offset_w - copy) * f->elem_size);
119 132 f->offset_w -= copy;
120 } else
121
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 18822 f->offset_w = copy == inc ? 0 : f->nb_elems + copy;
122 }
123
124 18979 f->nb_elems += inc;
125
126 18979 return 0;
127 }
128
129 4083547 static int fifo_check_space(AVFifo *f, size_t to_write)
130 {
131 4083547 const size_t can_write = av_fifo_can_write(f);
132
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 4083547 const size_t need_grow = to_write > can_write ? to_write - can_write : 0;
133 size_t can_grow;
134
135
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 4083547 if (!need_grow)
136 4064797 return 0;
137
138 37500 can_grow = f->auto_grow_limit > f->nb_elems ?
139
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 18750 f->auto_grow_limit - f->nb_elems : 0;
140
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 18750 if ((f->flags & AV_FIFO_FLAG_AUTO_GROW) && need_grow <= can_grow) {
141 // allocate a bit more than necessary, if we can
142
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 18749 const size_t inc = (need_grow < can_grow / 2 ) ? need_grow * 2 : can_grow;
143 18749 return av_fifo_grow2(f, inc);
144 }
145
146 1 return AVERROR(ENOSPC);
147 }
148
149 4083547 static int fifo_write_common(AVFifo *f, const uint8_t *buf, size_t *nb_elems,
150 AVFifoCB read_cb, void *opaque)
151 {
152 4083547 size_t to_write = *nb_elems;
153 size_t offset_w;
154 4083547 int ret = 0;
155
156 4083547 ret = fifo_check_space(f, to_write);
157
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 4083547 if (ret < 0)
158 1 return ret;
159
160 4083546 offset_w = f->offset_w;
161
162
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 8161824 while (to_write > 0) {
163 4078310 size_t len = FFMIN(f->nb_elems - offset_w, to_write);
164 4078310 uint8_t *wptr = f->buffer + offset_w * f->elem_size;
165
166
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 4078310 if (read_cb) {
167 69 ret = read_cb(opaque, wptr, &len);
168
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 69 if (ret < 0 || len == 0)
169 break;
170 } else {
171 4078241 memcpy(wptr, buf, len * f->elem_size);
172 4078241 buf += len * f->elem_size;
173 }
174 4078278 offset_w += len;
175
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 4078278 if (offset_w >= f->nb_elems)
176 1756718 offset_w = 0;
177 4078278 to_write -= len;
178 }
179 4083546 f->offset_w = offset_w;
180
181
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 4083546 if (*nb_elems != to_write)
182 4073567 f->is_empty = 0;
183 4083546 *nb_elems -= to_write;
184
185 4083546 return ret;
186 }
187
188 4083515 int av_fifo_write(AVFifo *f, const void *buf, size_t nb_elems)
189 {
190 4083515 return fifo_write_common(f, buf, &nb_elems, NULL, NULL);
191 }
192
193 32 int av_fifo_write_from_cb(AVFifo *f, AVFifoCB read_cb,
194 void *opaque, size_t *nb_elems)
195 {
196 32 return fifo_write_common(f, NULL, nb_elems, read_cb, opaque);
197 }
198
199 5881114 static int fifo_peek_common(const AVFifo *f, uint8_t *buf, size_t *nb_elems,
200 size_t offset, AVFifoCB write_cb, void *opaque)
201 {
202 5881114 size_t to_read = *nb_elems;
203 5881114 size_t offset_r = f->offset_r;
204 5881114 size_t can_read = av_fifo_can_read(f);
205 5881114 int ret = 0;
206
207
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 5881114 if (offset > can_read || to_read > can_read - offset) {
208 1268532 *nb_elems = 0;
209 1268532 return AVERROR(EINVAL);
210 }
211
212
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 4612582 if (offset_r >= f->nb_elems - offset)
213 6 offset_r -= f->nb_elems - offset;
214 else
215 4612576 offset_r += offset;
216
217
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 9229899 while (to_read > 0) {
218 4617380 size_t len = FFMIN(f->nb_elems - offset_r, to_read);
219 4617380 uint8_t *rptr = f->buffer + offset_r * f->elem_size;
220
221
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 4617380 if (write_cb) {
222 13025 ret = write_cb(opaque, rptr, &len);
223
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 13025 if (ret < 0 || len == 0)
224 break;
225 } else {
226 4604355 memcpy(buf, rptr, len * f->elem_size);
227 4604355 buf += len * f->elem_size;
228 }
229 4617317 offset_r += len;
230
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 4617317 if (offset_r >= f->nb_elems)
231 1922274 offset_r = 0;
232 4617317 to_read -= len;
233 }
234
235 4612582 *nb_elems -= to_read;
236
237 4612582 return ret;
238 }
239
240 5279265 int av_fifo_read(AVFifo *f, void *buf, size_t nb_elems)
241 {
242 5279265 int ret = fifo_peek_common(f, buf, &nb_elems, 0, NULL, NULL);
243 5279265 av_fifo_drain2(f, nb_elems);
244 5279265 return ret;
245 }
246
247 8196 int av_fifo_read_to_cb(AVFifo *f, AVFifoCB write_cb,
248 void *opaque, size_t *nb_elems)
249 {
250 8196 int ret = fifo_peek_common(f, NULL, nb_elems, 0, write_cb, opaque);
251 8196 av_fifo_drain2(f, *nb_elems);
252 8196 return ret;
253 }
254
255 593622 int av_fifo_peek(const AVFifo *f, void *buf, size_t nb_elems, size_t offset)
256 {
257 593622 return fifo_peek_common(f, buf, &nb_elems, offset, NULL, NULL);
258 }
259
260 31 int av_fifo_peek_to_cb(const AVFifo *f, AVFifoCB write_cb, void *opaque,
261 size_t *nb_elems, size_t offset)
262 {
263 31 return fifo_peek_common(f, NULL, nb_elems, offset, write_cb, opaque);
264 }
265
266 5287551 void av_fifo_drain2(AVFifo *f, size_t size)
267 {
268 5287551 const size_t cur_size = av_fifo_can_read(f);
269
270
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 5287551 av_assert0(cur_size >= size);
271
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 5287551 if (cur_size == size)
272 3647927 f->is_empty = 1;
273
274
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 5287551 if (f->offset_r >= f->nb_elems - size)
275 1731469 f->offset_r -= f->nb_elems - size;
276 else
277 3556082 f->offset_r += size;
278 5287551 }
279
280 ✗ void av_fifo_reset2(AVFifo *f)
281 {
282 ✗ f->offset_r = f->offset_w = 0;
283 ✗ f->is_empty = 1;
284 ✗ }
285
286 95321 void av_fifo_freep2(AVFifo **f)
287 {
288
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 95321 if (*f) {
289 94981 av_freep(&(*f)->buffer);
290 94981 av_freep(f);
291 }
292 95321 }
293