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 Libav.
8 * Libav 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 * Libav 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 Libav; 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 /* src must NOT be const as it can be a context for func that may need
83 * updating (like a pointer or byte counter) */
84 int av_fifo_generic_write(AVFifoBuffer *f, void *src, int size,
85 int (*func)(void *, void *, int))
89 int len = FFMIN(f->end - f->wptr, size);
91 if (func(src, f->wptr, len) <= 0)
94 memcpy(f->wptr, src, len);
95 src = (uint8_t *)src + len;
97 // Write memory barrier needed for SMP here in theory
99 if (f->wptr >= f->end)
107 int av_fifo_generic_read(AVFifoBuffer *f, void *dest, int buf_size,
108 void (*func)(void *, void *, int))
110 // Read memory barrier needed for SMP here in theory
112 int len = FFMIN(f->end - f->rptr, buf_size);
114 func(dest, f->rptr, len);
116 memcpy(dest, f->rptr, len);
117 dest = (uint8_t *)dest + len;
119 // memory barrier needed for SMP here in theory
120 av_fifo_drain(f, len);
122 } while (buf_size > 0);
126 /** Discard data from the FIFO. */
127 void av_fifo_drain(AVFifoBuffer *f, int size)
130 if (f->rptr >= f->end)
131 f->rptr -= f->end - f->buffer;