mirror of https://git.ffmpeg.org/ffmpeg.git
293 lines
7.5 KiB
C
293 lines
7.5 KiB
C
/*
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* a very simple circular buffer FIFO implementation
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* Copyright (c) 2000, 2001, 2002 Fabrice Bellard
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* Copyright (c) 2006 Roman Shaposhnik
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include <stdint.h>
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#include <string.h>
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#include "avassert.h"
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#include "error.h"
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#include "fifo.h"
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#include "macros.h"
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#include "mem.h"
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// by default the FIFO can be auto-grown to 1MB
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#define AUTO_GROW_DEFAULT_BYTES (1024 * 1024)
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struct AVFifo {
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uint8_t *buffer;
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size_t elem_size, nb_elems;
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size_t offset_r, offset_w;
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// distinguishes the ambiguous situation offset_r == offset_w
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int is_empty;
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unsigned int flags;
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size_t auto_grow_limit;
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};
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AVFifo *av_fifo_alloc2(size_t nb_elems, size_t elem_size,
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unsigned int flags)
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{
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AVFifo *f;
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void *buffer = NULL;
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if (!elem_size)
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return NULL;
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if (nb_elems) {
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buffer = av_realloc_array(NULL, nb_elems, elem_size);
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if (!buffer)
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return NULL;
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}
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f = av_mallocz(sizeof(*f));
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if (!f) {
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av_free(buffer);
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return NULL;
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}
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f->buffer = buffer;
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f->nb_elems = nb_elems;
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f->elem_size = elem_size;
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f->is_empty = 1;
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f->flags = flags;
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f->auto_grow_limit = FFMAX(AUTO_GROW_DEFAULT_BYTES / elem_size, 1);
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return f;
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}
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void av_fifo_auto_grow_limit(AVFifo *f, size_t max_elems)
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{
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f->auto_grow_limit = max_elems;
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}
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size_t av_fifo_elem_size(const AVFifo *f)
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{
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return f->elem_size;
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}
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size_t av_fifo_can_read(const AVFifo *f)
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{
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if (f->offset_w <= f->offset_r && !f->is_empty)
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return f->nb_elems - f->offset_r + f->offset_w;
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return f->offset_w - f->offset_r;
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}
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size_t av_fifo_can_write(const AVFifo *f)
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{
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return f->nb_elems - av_fifo_can_read(f);
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}
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int av_fifo_grow2(AVFifo *f, size_t inc)
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{
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uint8_t *tmp;
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if (inc > SIZE_MAX - f->nb_elems)
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return AVERROR(EINVAL);
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tmp = av_realloc_array(f->buffer, f->nb_elems + inc, f->elem_size);
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if (!tmp)
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return AVERROR(ENOMEM);
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f->buffer = tmp;
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// move the data from the beginning of the ring buffer
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// to the newly allocated space
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if (f->offset_w <= f->offset_r && !f->is_empty) {
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const size_t copy = FFMIN(inc, f->offset_w);
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memcpy(tmp + f->nb_elems * f->elem_size, tmp, copy * f->elem_size);
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if (copy < f->offset_w) {
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memmove(tmp, tmp + copy * f->elem_size,
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(f->offset_w - copy) * f->elem_size);
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f->offset_w -= copy;
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} else
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f->offset_w = copy == inc ? 0 : f->nb_elems + copy;
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}
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f->nb_elems += inc;
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return 0;
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}
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static int fifo_check_space(AVFifo *f, size_t to_write)
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{
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const size_t can_write = av_fifo_can_write(f);
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const size_t need_grow = to_write > can_write ? to_write - can_write : 0;
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size_t can_grow;
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if (!need_grow)
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return 0;
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can_grow = f->auto_grow_limit > f->nb_elems ?
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f->auto_grow_limit - f->nb_elems : 0;
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if ((f->flags & AV_FIFO_FLAG_AUTO_GROW) && need_grow <= can_grow) {
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// allocate a bit more than necessary, if we can
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const size_t inc = (need_grow < can_grow / 2 ) ? need_grow * 2 : can_grow;
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return av_fifo_grow2(f, inc);
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}
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return AVERROR(ENOSPC);
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}
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static int fifo_write_common(AVFifo *f, const uint8_t *buf, size_t *nb_elems,
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AVFifoCB read_cb, void *opaque)
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{
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size_t to_write = *nb_elems;
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size_t offset_w;
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int ret = 0;
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ret = fifo_check_space(f, to_write);
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if (ret < 0)
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return ret;
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offset_w = f->offset_w;
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while (to_write > 0) {
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size_t len = FFMIN(f->nb_elems - offset_w, to_write);
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uint8_t *wptr = f->buffer + offset_w * f->elem_size;
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if (read_cb) {
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ret = read_cb(opaque, wptr, &len);
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if (ret < 0 || len == 0)
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break;
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} else {
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memcpy(wptr, buf, len * f->elem_size);
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buf += len * f->elem_size;
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}
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offset_w += len;
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if (offset_w >= f->nb_elems)
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offset_w = 0;
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to_write -= len;
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}
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f->offset_w = offset_w;
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if (*nb_elems != to_write)
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f->is_empty = 0;
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*nb_elems -= to_write;
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return ret;
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}
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int av_fifo_write(AVFifo *f, const void *buf, size_t nb_elems)
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{
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return fifo_write_common(f, buf, &nb_elems, NULL, NULL);
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}
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int av_fifo_write_from_cb(AVFifo *f, AVFifoCB read_cb,
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void *opaque, size_t *nb_elems)
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{
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return fifo_write_common(f, NULL, nb_elems, read_cb, opaque);
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}
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static int fifo_peek_common(const AVFifo *f, uint8_t *buf, size_t *nb_elems,
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size_t offset, AVFifoCB write_cb, void *opaque)
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{
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size_t to_read = *nb_elems;
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size_t offset_r = f->offset_r;
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size_t can_read = av_fifo_can_read(f);
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int ret = 0;
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if (offset > can_read || to_read > can_read - offset) {
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*nb_elems = 0;
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return AVERROR(EINVAL);
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}
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if (offset_r >= f->nb_elems - offset)
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offset_r -= f->nb_elems - offset;
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else
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offset_r += offset;
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while (to_read > 0) {
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size_t len = FFMIN(f->nb_elems - offset_r, to_read);
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uint8_t *rptr = f->buffer + offset_r * f->elem_size;
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if (write_cb) {
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ret = write_cb(opaque, rptr, &len);
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if (ret < 0 || len == 0)
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break;
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} else {
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memcpy(buf, rptr, len * f->elem_size);
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buf += len * f->elem_size;
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}
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offset_r += len;
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if (offset_r >= f->nb_elems)
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offset_r = 0;
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to_read -= len;
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}
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*nb_elems -= to_read;
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return ret;
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}
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int av_fifo_read(AVFifo *f, void *buf, size_t nb_elems)
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{
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int ret = fifo_peek_common(f, buf, &nb_elems, 0, NULL, NULL);
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av_fifo_drain2(f, nb_elems);
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return ret;
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}
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int av_fifo_read_to_cb(AVFifo *f, AVFifoCB write_cb,
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void *opaque, size_t *nb_elems)
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{
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int ret = fifo_peek_common(f, NULL, nb_elems, 0, write_cb, opaque);
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av_fifo_drain2(f, *nb_elems);
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return ret;
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}
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int av_fifo_peek(const AVFifo *f, void *buf, size_t nb_elems, size_t offset)
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{
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return fifo_peek_common(f, buf, &nb_elems, offset, NULL, NULL);
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}
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int av_fifo_peek_to_cb(const AVFifo *f, AVFifoCB write_cb, void *opaque,
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size_t *nb_elems, size_t offset)
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{
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return fifo_peek_common(f, NULL, nb_elems, offset, write_cb, opaque);
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}
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void av_fifo_drain2(AVFifo *f, size_t size)
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{
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const size_t cur_size = av_fifo_can_read(f);
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av_assert0(cur_size >= size);
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if (cur_size == size)
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f->is_empty = 1;
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if (f->offset_r >= f->nb_elems - size)
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f->offset_r -= f->nb_elems - size;
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else
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f->offset_r += size;
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}
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void av_fifo_reset2(AVFifo *f)
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{
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f->offset_r = f->offset_w = 0;
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f->is_empty = 1;
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}
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void av_fifo_freep2(AVFifo **f)
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{
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if (*f) {
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av_freep(&(*f)->buffer);
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av_freep(f);
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}
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}
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