FFmpeg coverage

Directory: ../../../ffmpeg/
File: src/libavutil/fifo.c
Date: 2026-04-24 05:04:01
Exec Total Coverage
Lines: 126 141 89.4%
Functions: 16 18 88.9%
Branches: 59 74 79.7%
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 92709 AVFifo *av_fifo_alloc2(size_t nb_elems, size_t elem_size,
48 unsigned int flags)
49 {
50 AVFifo *f;
51 92709 void *buffer = NULL;
52
53
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 92709 if (!elem_size)
54 ✗ return NULL;
55
56
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 92709 if (nb_elems) {
57 92709 buffer = av_realloc_array(NULL, nb_elems, elem_size);
58
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 92709 if (!buffer)
59 ✗ return NULL;
60 }
61 92709 f = av_mallocz(sizeof(*f));
62
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 92709 if (!f) {
63 ✗ av_free(buffer);
64 ✗ return NULL;
65 }
66 92709 f->buffer = buffer;
67 92709 f->nb_elems = nb_elems;
68 92709 f->elem_size = elem_size;
69 92709 f->is_empty = 1;
70
71 92709 f->flags = flags;
72 92709 f->auto_grow_limit = FFMAX(AUTO_GROW_DEFAULT_BYTES / elem_size, 1);
73
74 92709 return f;
75 }
76
77 ✗ void av_fifo_auto_grow_limit(AVFifo *f, size_t max_elems)
78 {
79 ✗ f->auto_grow_limit = max_elems;
80 ✗ }
81
82 1 size_t av_fifo_elem_size(const AVFifo *f)
83 {
84 1 return f->elem_size;
85 }
86
87 23729253 size_t av_fifo_can_read(const AVFifo *f)
88 {
89
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 23729253 if (f->offset_w <= f->offset_r && !f->is_empty)
90 8622771 return f->nb_elems - f->offset_r + f->offset_w;
91 15106482 return f->offset_w - f->offset_r;
92 }
93
94 6630874 size_t av_fifo_can_write(const AVFifo *f)
95 {
96 6630874 return f->nb_elems - av_fifo_can_read(f);
97 }
98
99 39867 int av_fifo_grow2(AVFifo *f, size_t inc)
100 {
101 uint8_t *tmp;
102
103
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 39867 if (inc > SIZE_MAX - f->nb_elems)
104 ✗ return AVERROR(EINVAL);
105
106 39867 tmp = av_realloc_array(f->buffer, f->nb_elems + inc, f->elem_size);
107
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 39867 if (!tmp)
108 ✗ return AVERROR(ENOMEM);
109 39867 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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 39867 if (f->offset_w <= f->offset_r && !f->is_empty) {
114 39842 const size_t copy = FFMIN(inc, f->offset_w);
115 39842 memcpy(tmp + f->nb_elems * f->elem_size, tmp, copy * f->elem_size);
116
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 39842 if (copy < f->offset_w) {
117 273 memmove(tmp, tmp + copy * f->elem_size,
118 273 (f->offset_w - copy) * f->elem_size);
119 273 f->offset_w -= copy;
120 } else
121
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 39569 f->offset_w = copy == inc ? 0 : f->nb_elems + copy;
122 }
123
124 39867 f->nb_elems += inc;
125
126 39867 return 0;
127 }
128
129 4020311 static int fifo_check_space(AVFifo *f, size_t to_write)
130 {
131 4020311 const size_t can_write = av_fifo_can_write(f);
132
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 4020311 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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 4020311 if (!need_grow)
136 3980702 return 0;
137
138 79218 can_grow = f->auto_grow_limit > f->nb_elems ?
139
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 39609 f->auto_grow_limit - f->nb_elems : 0;
140
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 39609 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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 39609 const size_t inc = (need_grow < can_grow / 2 ) ? need_grow * 2 : can_grow;
143 39609 return av_fifo_grow2(f, inc);
144 }
145
146 ✗ return AVERROR(ENOSPC);
147 }
148
149 4020311 static int fifo_write_common(AVFifo *f, const uint8_t *buf, size_t *nb_elems,
150 AVFifoCB read_cb, void *opaque)
151 {
152 4020311 size_t to_write = *nb_elems;
153 size_t offset_w;
154 4020311 int ret = 0;
155
156 4020311 ret = fifo_check_space(f, to_write);
157
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 4020311 if (ret < 0)
158 ✗ return ret;
159
160 4020311 offset_w = f->offset_w;
161
162
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 8035348 while (to_write > 0) {
163 4015069 size_t len = FFMIN(f->nb_elems - offset_w, to_write);
164 4015069 uint8_t *wptr = f->buffer + offset_w * f->elem_size;
165
166
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 4015069 if (read_cb) {
167 63 ret = read_cb(opaque, wptr, &len);
168
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 63 if (ret < 0 || len == 0)
169 break;
170 } else {
171 4015006 memcpy(wptr, buf, len * f->elem_size);
172 4015006 buf += len * f->elem_size;
173 }
174 4015037 offset_w += len;
175
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 4015037 if (offset_w >= f->nb_elems)
176 1310736 offset_w = 0;
177 4015037 to_write -= len;
178 }
179 4020311 f->offset_w = offset_w;
180
181
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 4020311 if (*nb_elems != to_write)
182 4010328 f->is_empty = 0;
183 4020311 *nb_elems -= to_write;
184
185 4020311 return ret;
186 }
187
188 4020279 int av_fifo_write(AVFifo *f, const void *buf, size_t nb_elems)
189 {
190 4020279 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 5694956 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 5694956 size_t to_read = *nb_elems;
203 5694956 size_t offset_r = f->offset_r;
204 5694956 size_t can_read = av_fifo_can_read(f);
205 5694956 int ret = 0;
206
207
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 5694956 if (offset > can_read || to_read > can_read - offset) {
208 1166113 *nb_elems = 0;
209 1166113 return AVERROR(EINVAL);
210 }
211
212
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 4528843 if (offset_r >= f->nb_elems - offset)
213 4 offset_r -= f->nb_elems - offset;
214 else
215 4528839 offset_r += offset;
216
217
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 9062427 while (to_read > 0) {
218 4533646 size_t len = FFMIN(f->nb_elems - offset_r, to_read);
219 4533646 uint8_t *rptr = f->buffer + offset_r * f->elem_size;
220
221
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 4533646 if (write_cb) {
222 13028 ret = write_cb(opaque, rptr, &len);
223
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 13028 if (ret < 0 || len == 0)
224 break;
225 } else {
226 4520618 memcpy(buf, rptr, len * f->elem_size);
227 4520618 buf += len * f->elem_size;
228 }
229 4533584 offset_r += len;
230
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 4533584 if (offset_r >= f->nb_elems)
231 1455432 offset_r = 0;
232 4533584 to_read -= len;
233 }
234
235 4528843 *nb_elems -= to_read;
236
237 4528843 return ret;
238 }
239
240 5095029 int av_fifo_read(AVFifo *f, void *buf, size_t nb_elems)
241 {
242 5095029 int ret = fifo_peek_common(f, buf, &nb_elems, 0, NULL, NULL);
243 5095029 av_fifo_drain2(f, nb_elems);
244 5095029 return ret;
245 }
246
247 8194 int av_fifo_read_to_cb(AVFifo *f, AVFifoCB write_cb,
248 void *opaque, size_t *nb_elems)
249 {
250 8194 int ret = fifo_peek_common(f, NULL, nb_elems, 0, write_cb, opaque);
251 8194 av_fifo_drain2(f, *nb_elems);
252 8194 return ret;
253 }
254
255 591702 int av_fifo_peek(const AVFifo *f, void *buf, size_t nb_elems, size_t offset)
256 {
257 591702 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 5103313 void av_fifo_drain2(AVFifo *f, size_t size)
267 {
268 5103313 const size_t cur_size = av_fifo_can_read(f);
269
270
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 5103313 av_assert0(cur_size >= size);
271
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 5103313 if (cur_size == size)
272 3342199 f->is_empty = 1;
273
274
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 5103313 if (f->offset_r >= f->nb_elems - size)
275 1264646 f->offset_r -= f->nb_elems - size;
276 else
277 3838667 f->offset_r += size;
278 5103313 }
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 92997 void av_fifo_freep2(AVFifo **f)
287 {
288
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 92997 if (*f) {
289 92709 av_freep(&(*f)->buffer);
290 92709 av_freep(f);
291 }
292 92997 }
293