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/*

 * a very simple circular buffer FIFO implementation

 * Copyright (c) 2000, 2001, 2002 Fabrice Bellard

 * Copyright (c) 2006 Roman Shaposhnik

 *

 * This file is part of FFmpeg.

 *

 * FFmpeg is free software; you can redistribute it and/or

 * 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.

 *

 * FFmpeg is distributed in the hope that it will be useful,

 * 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

 * License along with FFmpeg; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

 */

#include "avassert.h"

#include "common.h"

#include "fifo.h"

AVFifoBuffer *av_fifo_alloc(unsigned int size)

{

    AVFifoBuffer *f = av_mallocz(sizeof(AVFifoBuffer));

    if (!f)

        return NULL;

    f->buffer = av_malloc(size);

    f->end    = f->buffer + size;

    av_fifo_reset(f);

    if (!f->buffer)

        av_freep(&f);

    return f;

}

void av_fifo_free(AVFifoBuffer *f)

{

    if (f) {

        av_freep(&f->buffer);

        av_free(f);

    }

}

void av_fifo_reset(AVFifoBuffer *f)

{

    f->wptr = f->rptr = f->buffer;

    f->wndx = f->rndx = 0;

}

int av_fifo_size(AVFifoBuffer *f)

{

    return (uint32_t)(f->wndx - f->rndx);

}

int av_fifo_space(AVFifoBuffer *f)

{

    return f->end - f->buffer - av_fifo_size(f);

}

int av_fifo_realloc2(AVFifoBuffer *f, unsigned int new_size)

{

    unsigned int old_size = f->end - f->buffer;

    if (old_size < new_size) {

        int len          = av_fifo_size(f);

        AVFifoBuffer *f2 = av_fifo_alloc(new_size);

        if (!f2)

            return AVERROR(ENOMEM);

        av_fifo_generic_read(f, f2->buffer, len, NULL);

        f2->wptr += len;

        f2->wndx += len;

        av_free(f->buffer);

        *f = *f2;

        av_free(f2);

    }

    return 0;

}

int av_fifo_grow(AVFifoBuffer *f, unsigned int size)

{

    unsigned int old_size = f->end - f->buffer;

    if(size + (unsigned)av_fifo_size(f) < size)

        return AVERROR(EINVAL);

    size += av_fifo_size(f);

    if (old_size < size)

        return av_fifo_realloc2(f, FFMAX(size, 2*size));

    return 0;

}

/* src must NOT be const as it can be a context for func that may need

 * updating (like a pointer or byte counter) */

int av_fifo_generic_write(AVFifoBuffer *f, void *src, int size,

                          int (*func)(void *, void *, int))

{

    int total = size;

    uint32_t wndx= f->wndx;

    uint8_t *wptr= f->wptr;

    do {

        int len = FFMIN(f->end - wptr, size);

        if (func) {

            if (func(src, wptr, len) <= 0)

                break;

        } else {

            memcpy(wptr, src, len);

            src = (uint8_t *)src + len;

        }

// Write memory barrier needed for SMP here in theory

        wptr += len;

        if (wptr >= f->end)

            wptr = f->buffer;

        wndx    += len;

        size    -= len;

    } while (size > 0);

    f->wndx= wndx;

    f->wptr= wptr;

    return total - size;

}

int av_fifo_generic_read(AVFifoBuffer *f, void *dest, int buf_size,

                         void (*func)(void *, void *, int))

{

// Read memory barrier needed for SMP here in theory

    do {

        int len = FFMIN(f->end - f->rptr, buf_size);

        if (func)

            func(dest, f->rptr, len);

        else {

            memcpy(dest, f->rptr, len);

            dest = (uint8_t *)dest + len;

        }

// memory barrier needed for SMP here in theory

        av_fifo_drain(f, len);

        buf_size -= len;

    } while (buf_size > 0);

    return 0;

}

/** Discard data from the FIFO. */

void av_fifo_drain(AVFifoBuffer *f, int size)

{

    av_assert2(av_fifo_size(f) >= size);

    f->rptr += size;

    if (f->rptr >= f->end)

        f->rptr -= f->end - f->buffer;

    f->rndx += size;

}

#ifdef TEST

int main(void)

{

    /* create a FIFO buffer */

    AVFifoBuffer *fifo = av_fifo_alloc(13 * sizeof(int));

    int i, j, n;

    /* fill data */

    for (i = 0; av_fifo_space(fifo) >= sizeof(int); i++)

        av_fifo_generic_write(fifo, &i, sizeof(int), NULL);

    /* peek at FIFO */

    n = av_fifo_size(fifo) / sizeof(int);

    for (i = -n + 1; i < n; i++) {

        int *v = (int *)av_fifo_peek2(fifo, i * sizeof(int));

        printf("%d: %d\n", i, *v);

    }

    printf("\n");

    /* read data */

    for (i = 0; av_fifo_size(fifo) >= sizeof(int); i++) {

        av_fifo_generic_read(fifo, &j, sizeof(int), NULL);

        printf("%d ", j);

    }

    printf("\n");

    av_fifo_free(fifo);

    return 0;

}

#endif