fifo.h 3.52 KB
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/*
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 * This file is part of Libav.
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 *
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 * Libav is free software; you can redistribute it and/or
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 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
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 * Libav is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
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 * License along with Libav; 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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 * @file
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 * a very simple circular buffer FIFO implementation
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 */

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#ifndef AVUTIL_FIFO_H
#define AVUTIL_FIFO_H
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#include <stdint.h>

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typedef struct AVFifoBuffer {
    uint8_t *buffer;
    uint8_t *rptr, *wptr, *end;
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    uint32_t rndx, wndx;
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} AVFifoBuffer;

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/**
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 * Initialize an AVFifoBuffer.
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 * @param size of FIFO
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 * @return AVFifoBuffer or NULL in case of memory allocation failure
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 */
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AVFifoBuffer *av_fifo_alloc(unsigned int size);
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/**
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 * Free an AVFifoBuffer.
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 * @param *f AVFifoBuffer to free
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 */
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void av_fifo_free(AVFifoBuffer *f);
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/**
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 * Reset the AVFifoBuffer to the state right after av_fifo_alloc, in particular it is emptied.
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 * @param *f AVFifoBuffer to reset
 */
void av_fifo_reset(AVFifoBuffer *f);

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/**
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 * Return the amount of data in bytes in the AVFifoBuffer, that is the
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 * amount of data you can read from it.
 * @param *f AVFifoBuffer to read from
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 * @return size
 */
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int av_fifo_size(AVFifoBuffer *f);
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/**
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 * Return the amount of space in bytes in the AVFifoBuffer, that is the
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 * amount of data you can write into it.
 * @param *f AVFifoBuffer to write into
 * @return size
 */
int av_fifo_space(AVFifoBuffer *f);

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/**
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 * Feed data from an AVFifoBuffer to a user-supplied callback.
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 * @param *f AVFifoBuffer to read from
 * @param buf_size number of bytes to read
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 * @param *func generic read function
 * @param *dest data destination
 */
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int av_fifo_generic_read(AVFifoBuffer *f, void *dest, int buf_size, void (*func)(void*, void*, int));
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/**
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 * Feed data from a user-supplied callback to an AVFifoBuffer.
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 * @param *f AVFifoBuffer to write to
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 * @param *src data source; non-const since it may be used as a
 * modifiable context by the function defined in func
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 * @param size number of bytes to write
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 * @param *func generic write function; the first parameter is src,
 * the second is dest_buf, the third is dest_buf_size.
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 * func must return the number of bytes written to dest_buf, or <= 0 to
 * indicate no more data available to write.
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 * If func is NULL, src is interpreted as a simple byte array for source data.
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 * @return the number of bytes written to the FIFO
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 */
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int av_fifo_generic_write(AVFifoBuffer *f, void *src, int size, int (*func)(void*, void*, int));
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/**
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 * Resize an AVFifoBuffer.
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 * @param *f AVFifoBuffer to resize
 * @param size new AVFifoBuffer size in bytes
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 * @return <0 for failure, >=0 otherwise
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 */
int av_fifo_realloc2(AVFifoBuffer *f, unsigned int size);

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/**
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 * Read and discard the specified amount of data from an AVFifoBuffer.
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 * @param *f AVFifoBuffer to read from
 * @param size amount of data to read in bytes
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 */
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void av_fifo_drain(AVFifoBuffer *f, int size);

static inline uint8_t av_fifo_peek(AVFifoBuffer *f, int offs)
{
    uint8_t *ptr = f->rptr + offs;
    if (ptr >= f->end)
        ptr -= f->end - f->buffer;
    return *ptr;
}
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#endif /* AVUTIL_FIFO_H */