libavcodec/vpx_rac.c

/*
 * VP5/6/8 decoder
 * Copyright (c) 2010 Fiona Glaser <fiona@x264.com>
 *
 * 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 <stdint.h>
#include "libavutil/error.h"
#include "bytestream.h"
#include "vpx_rac.h"

const uint8_t ff_vpx_norm_shift[256]= {
 8,7,6,6,5,5,5,5,4,4,4,4,4,4,4,4,
 3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,
 2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
 2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
};

int ff_vpx_init_range_decoder(VPXRangeCoder *c, const uint8_t *buf, int buf_size)
{
    c->high = 255;
    c->bits = -16;
    c->buffer = buf;
    c->end = buf + buf_size;
    c->end_reached = 0;
    if (buf_size < 1)
        return AVERROR_INVALIDDATA;
    c->code_word = bytestream_get_be24(&c->buffer);
    return 0;
}