huffyuv.c

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/*
 * huffyuv codec for libavcodec
 *
 * Copyright (c) 2002-2014 Michael Niedermayer <michaelni@gmx.at>
 *
 * see https://multimedia.cx/huffyuv.txt for a description of
 * the algorithm used
 *
 * 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
 */
 
/**
 * @file
 * huffyuv codec for libavcodec.
 */
 
#include <stddef.h>
#include <stdint.h>
 
#include "libavutil/error.h"
#include "libavutil/log.h"
#include "libavutil/macros.h"
 
#include "huffyuv.h"
 
int ff_huffyuv_generate_bits_table(uint32_t *dst, const uint8_t *len_table, int n)
{
    int lens[33] = { 0 };
    uint32_t codes[33];
 
    for (int i = 0; i < n; i++)
        lens[len_table[i]]++;
 
    codes[32] = 0;
    for (int i = FF_ARRAY_ELEMS(lens) - 1; i > 0; i--) {
        if ((lens[i] + codes[i]) & 1) {
            av_log(NULL, AV_LOG_ERROR, "Error generating huffman table\n");
            return AVERROR_INVALIDDATA;
        }
        codes[i - 1] = (lens[i] + codes[i]) >> 1;
    }
    for (int i = 0; i < n; i++) {
        if (len_table[i])
            dst[i] = codes[len_table[i]]++;
    }
    return 0;
}