fifo.c 3.41 KB
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/*
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 * a very simple circular buffer FIFO implementation
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 * Copyright (c) 2000, 2001, 2002 Fabrice Bellard
 * Copyright (c) 2006 Roman Shaposhnik
 *
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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
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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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 * 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
 */
#include "common.h"
#include "fifo.h"

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AVFifoBuffer *av_fifo_alloc(unsigned int size)
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{
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    AVFifoBuffer *f= av_mallocz(sizeof(AVFifoBuffer));
    if(!f)
        return NULL;
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    f->buffer = av_malloc(size);
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    f->end = f->buffer + size;
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    av_fifo_reset(f);
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    if (!f->buffer)
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        av_freep(&f);
    return f;
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}

void av_fifo_free(AVFifoBuffer *f)
{
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    if(f){
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        av_free(f->buffer);
        av_free(f);
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    }
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}

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void av_fifo_reset(AVFifoBuffer *f)
{
    f->wptr = f->rptr = f->buffer;
    f->wndx = f->rndx = 0;
}

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int av_fifo_size(AVFifoBuffer *f)
{
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    return (uint32_t)(f->wndx - f->rndx);
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}

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int av_fifo_space(AVFifoBuffer *f)
{
    return f->end - f->buffer - av_fifo_size(f);
}

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int av_fifo_realloc2(AVFifoBuffer *f, unsigned int new_size) {
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    unsigned int old_size= f->end - f->buffer;

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    if(old_size < new_size){
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        int len= av_fifo_size(f);
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        AVFifoBuffer *f2= av_fifo_alloc(new_size);
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        if (!f2)
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            return -1;
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        av_fifo_generic_read(f, f2->buffer, len, NULL);
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        f2->wptr += len;
        f2->wndx += len;
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        av_free(f->buffer);
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        *f= *f2;
        av_free(f2);
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    }
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    return 0;
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}

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// src must NOT be const as it can be a context for func that may need updating (like a pointer or byte counter)
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int av_fifo_generic_write(AVFifoBuffer *f, void *src, int size, int (*func)(void*, void*, int))
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{
    int total = size;
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    do {
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        int len = FFMIN(f->end - f->wptr, size);
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        if(func) {
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            if(func(src, f->wptr, len) <= 0)
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                break;
        } else {
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            memcpy(f->wptr, src, len);
            src = (uint8_t*)src + len;
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        }
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// Write memory barrier needed for SMP here in theory
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        f->wptr += len;
        if (f->wptr >= f->end)
            f->wptr = f->buffer;
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        f->wndx += len;
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        size -= len;
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    } while (size > 0);
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    return total - size;
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}


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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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// Read memory barrier needed for SMP here in theory
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    do {
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        int len = FFMIN(f->end - f->rptr, buf_size);
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        if(func) func(dest, f->rptr, len);
        else{
            memcpy(dest, f->rptr, len);
            dest = (uint8_t*)dest + len;
        }
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// memory barrier needed for SMP here in theory
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        av_fifo_drain(f, len);
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        buf_size -= len;
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    } while (buf_size > 0);
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    return 0;
}

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/** Discard data from the FIFO. */
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void av_fifo_drain(AVFifoBuffer *f, int size)
{
    f->rptr += size;
    if (f->rptr >= f->end)
        f->rptr -= f->end - f->buffer;
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    f->rndx += size;
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}