2 * a very simple circular buffer FIFO implementation
3 * Copyright (c) 2000, 2001, 2002 Fabrice Bellard
4 * Copyright (c) 2006 Roman Shaposhnik
6 * This file is part of FFmpeg.
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.
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.
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
25 AVFifoBuffer *av_fifo_alloc(unsigned int size)
27 AVFifoBuffer *f = av_mallocz(sizeof(AVFifoBuffer));
30 f->buffer = av_malloc(size);
31 f->end = f->buffer + size;
38 void av_fifo_free(AVFifoBuffer *f)
46 void av_fifo_reset(AVFifoBuffer *f)
48 f->wptr = f->rptr = f->buffer;
49 f->wndx = f->rndx = 0;
52 int av_fifo_size(AVFifoBuffer *f)
54 return (uint32_t)(f->wndx - f->rndx);
57 int av_fifo_space(AVFifoBuffer *f)
59 return f->end - f->buffer - av_fifo_size(f);
62 int av_fifo_realloc2(AVFifoBuffer *f, unsigned int new_size)
64 unsigned int old_size = f->end - f->buffer;
66 if (old_size < new_size) {
67 int len = av_fifo_size(f);
68 AVFifoBuffer *f2 = av_fifo_alloc(new_size);
71 return AVERROR(ENOMEM);
72 av_fifo_generic_read(f, f2->buffer, len, NULL);
82 int av_fifo_grow(AVFifoBuffer *f, unsigned int size)
84 unsigned int old_size = f->end - f->buffer;
85 if(size + (unsigned)av_fifo_size(f) < size)
86 return AVERROR(EINVAL);
88 size += av_fifo_size(f);
91 return av_fifo_realloc2(f, FFMAX(size, 2*size));
95 /* src must NOT be const as it can be a context for func that may need
96 * updating (like a pointer or byte counter) */
97 int av_fifo_generic_write(AVFifoBuffer *f, void *src, int size,
98 int (*func)(void *, void *, int))
101 uint32_t wndx= f->wndx;
102 uint8_t *wptr= f->wptr;
105 int len = FFMIN(f->end - wptr, size);
107 if (func(src, wptr, len) <= 0)
110 memcpy(wptr, src, len);
111 src = (uint8_t *)src + len;
113 // Write memory barrier needed for SMP here in theory
125 int av_fifo_generic_read(AVFifoBuffer *f, void *dest, int buf_size,
126 void (*func)(void *, void *, int))
128 // Read memory barrier needed for SMP here in theory
130 int len = FFMIN(f->end - f->rptr, buf_size);
132 func(dest, f->rptr, len);
134 memcpy(dest, f->rptr, len);
135 dest = (uint8_t *)dest + len;
137 // memory barrier needed for SMP here in theory
138 av_fifo_drain(f, len);
140 } while (buf_size > 0);
144 /** Discard data from the FIFO. */
145 void av_fifo_drain(AVFifoBuffer *f, int size)
148 if (f->rptr >= f->end)
149 f->rptr -= f->end - f->buffer;
157 /* create a FIFO buffer */
158 AVFifoBuffer *fifo = av_fifo_alloc(13 * sizeof(int));
162 for (i = 0; av_fifo_space(fifo) >= sizeof(int); i++)
163 av_fifo_generic_write(fifo, &i, sizeof(int), NULL);
166 n = av_fifo_size(fifo) / sizeof(int);
167 for (i = -n + 1; i < n; i++) {
168 int *v = (int *)av_fifo_peek2(fifo, i * sizeof(int));
169 printf("%d: %d\n", i, *v);
174 for (i = 0; av_fifo_size(fifo) >= sizeof(int); i++) {
175 av_fifo_generic_read(fifo, &j, sizeof(int), NULL);