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/*
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 * Lagarith lossless decoder
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 * Copyright (c) 2009 Nathan Caldwell <saintdev (at) gmail.com>
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 *
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 * This file is part of FFmpeg.
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 *
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 * FFmpeg is free software; you can redistribute it and/or
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 * modify it under the terms of the GNU Lesser General Public
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 * 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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 * FFmpeg is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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 * Lesser General Public License for more details.
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 *
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 * You should have received a copy of the GNU Lesser General Public
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 * License along with FFmpeg; 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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/**
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 * @file libavcodec/lagarith.c
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 * Lagarith lossless decoder
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 * @author Nathan Caldwell
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 */
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#include "avcodec.h"
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#include "get_bits.h"
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#include "mathops.h"
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#include "dsputil.h"
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#include "lagarithrac.h"
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enum LagarithFrameType {
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    FRAME_RAW           = 1,    /*!< uncompressed */
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    FRAME_U_RGB24       = 2,    /*!< unaligned RGB24 */
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    FRAME_ARITH_YUY2    = 3,    /*!< arithmetic coded YUY2 */
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    FRAME_ARITH_RGB24   = 4,    /*!< arithmetic coded RGB24 */
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    FRAME_SOLID_GRAY    = 5,    /*!< solid grayscale color frame */
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    FRAME_SOLID_COLOR   = 6,    /*!< solid non-grayscale color frame */
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    FRAME_OLD_ARITH_RGB = 7,    /*!< obsolete arithmetic coded RGB (no longer encoded by upstream since version 1.1.0) */
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    FRAME_ARITH_RGBA    = 8,    /*!< arithmetic coded RGBA */
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    FRAME_SOLID_RGBA    = 9,    /*!< solid RGBA color frame */
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    FRAME_ARITH_YV12    = 10,   /*!< arithmetic coded YV12 */
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    FRAME_REDUCED_RES   = 11,   /*!< reduced resolution YV12 frame */
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};
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typedef struct LagarithContext {
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    AVCodecContext *avctx;
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    AVFrame picture;
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    DSPContext dsp;
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    int zeros;                  /*!< number of consecutive zero bytes encountered */
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    int zeros_rem;              /*!< number of zero bytes remaining to output */
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} LagarithContext;
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/**
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 * Compute the 52bit mantissa of 1/(double)denom.
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 * This crazy format uses floats in an entropy coder and we have to match x86
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 * rounding exactly, thus ordinary floats aren't portable enough.
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 * @param denom denominator
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 * @return 52bit mantissa
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 * @see softfloat_mul
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 */
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static uint64_t softfloat_reciprocal(uint32_t denom)
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{
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    int shift = av_log2(denom - 1) + 1;
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    uint64_t ret = (1ULL << 52) / denom;
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    uint64_t err = (1ULL << 52) - ret * denom;
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    ret <<= shift;
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    err <<= shift;
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    err +=  denom / 2;
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    return ret + err / denom;
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}
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/**
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 * (uint32_t)(x*f), where f has the given mantissa, and exponent 0
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 * Used in combination with softfloat_reciprocal computes x/(double)denom.
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 * @param x 32bit integer factor
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 * @param mantissa mantissa of f with exponent 0
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 * @return 32bit integer value (x*f)
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 * @see softfloat_reciprocal
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 */
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static uint32_t softfloat_mul(uint32_t x, uint64_t mantissa)
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{
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    uint64_t l = x * (mantissa & 0xffffffff);
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    uint64_t h = x * (mantissa >> 32);
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    h += l >> 32;
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    l &= 0xffffffff;
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    l += 1 << av_log2(h >> 21);
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    h += l >> 32;
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    return h >> 20;
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}
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static uint8_t lag_calc_zero_run(int8_t x)
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{
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    return (x << 1) ^ (x >> 7);
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}
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static int lag_decode_prob(GetBitContext *gb, uint32_t *value)
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{
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    static const uint8_t series[] = { 1, 2, 3, 5, 8, 13, 21 };
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    int i;
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    int bit     = 0;
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    int bits    = 0;
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    int prevbit = 0;
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    unsigned val;
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    for (i = 0; i < 7; i++) {
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        if (prevbit && bit)
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            break;
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        prevbit = bit;
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        bit = get_bits1(gb);
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        if (bit && !prevbit)
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            bits += series[i];
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    }
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    bits--;
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    if (bits < 0 || bits > 31) {
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        *value = 0;
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        return -1;
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    } else if (bits == 0) {
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        *value = 0;
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        return 0;
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    }
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    val  = get_bits_long(gb, bits);
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    val |= 1 << bits;
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    *value = val - 1;
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    return 0;
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}
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static int lag_read_prob_header(lag_rac *rac, GetBitContext *gb)
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{
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    int i, j, scale_factor;
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    unsigned prob, cumulative_target;
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    unsigned cumul_prob = 0;
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    unsigned scaled_cumul_prob = 0;
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    rac->prob[0] = 0;
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    rac->prob[257] = UINT_MAX;
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    /* Read probabilities from bitstream */
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    for (i = 1; i < 257; i++) {
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        if (lag_decode_prob(gb, &rac->prob[i]) < 0) {
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            av_log(rac->avctx, AV_LOG_ERROR, "Invalid probability encountered.\n");
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            return -1;
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        }
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        if ((uint64_t)cumul_prob + rac->prob[i] > UINT_MAX) {
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            av_log(rac->avctx, AV_LOG_ERROR, "Integer overflow encountered in cumulative probability calculation.\n");
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            return -1;
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        }
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        cumul_prob += rac->prob[i];
153
        if (!rac->prob[i]) {
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            if (lag_decode_prob(gb, &prob)) {
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                av_log(rac->avctx, AV_LOG_ERROR, "Invalid probability run encountered.\n");
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                return -1;
157
            }
158
            if (prob > 257 - i)
159
                prob = 257 - i;
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            for (j = 0; j < prob; j++)
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                rac->prob[++i] = 0;
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        }
163
    }
164

    
165
    if (!cumul_prob) {
166
        av_log(rac->avctx, AV_LOG_ERROR, "All probabilities are 0!\n");
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        return -1;
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    }
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    /* Scale probabilities so cumulative probability is an even power of 2. */
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    scale_factor = av_log2(cumul_prob);
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173
    if (cumul_prob & (cumul_prob - 1)) {
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        uint64_t mul = softfloat_reciprocal(cumul_prob);
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        for (i = 1; i < 257; i++) {
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            rac->prob[i] = softfloat_mul(rac->prob[i], mul);
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            scaled_cumul_prob += rac->prob[i];
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        }
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        scale_factor++;
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        cumulative_target = 1 << scale_factor;
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        if (scaled_cumul_prob > cumulative_target) {
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            av_log(rac->avctx, AV_LOG_ERROR,
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                   "Scaled probabilities are larger than target!\n");
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            return -1;
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        }
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        scaled_cumul_prob = cumulative_target - scaled_cumul_prob;
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        for (i = 1; scaled_cumul_prob; i = (i & 0x7f) + 1) {
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            if (rac->prob[i]) {
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                rac->prob[i]++;
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                scaled_cumul_prob--;
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            }
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            /* Comment from reference source:
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             * if (b & 0x80 == 0) {     // order of operations is 'wrong'; it has been left this way
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             *                          // since the compression change is negligable and fixing it
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             *                          // breaks backwards compatibilty
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             *      b =- (signed int)b;
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             *      b &= 0xFF;
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             * } else {
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             *      b++;
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             *      b &= 0x7f;
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             * }
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             */
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        }
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    }
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    rac->scale = scale_factor;
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    /* Fill probability array with cumulative probability for each symbol. */
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    for (i = 1; i < 257; i++)
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        rac->prob[i] += rac->prob[i - 1];
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    return 0;
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}
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static void add_lag_median_prediction(uint8_t *dst, uint8_t *src1,
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                                      uint8_t *diff, int w, int *left,
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                                      int *left_top)
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{
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    /* This is almost identical to add_hfyu_median_prediction in dsputil.h.
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     * However the &0xFF on the gradient predictor yealds incorrect output
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     * for lagarith.
226
     */
227
    int i;
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    uint8_t l, lt;
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    l  = *left;
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    lt = *left_top;
232

    
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    for (i = 0; i < w; i++) {
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        l = mid_pred(l, src1[i], l + src1[i] - lt) + diff[i];
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        lt = src1[i];
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        dst[i] = l;
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    }
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    *left     = l;
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    *left_top = lt;
241
}
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static void lag_pred_line(LagarithContext *l, uint8_t *buf,
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                          int width, int stride, int line)
245
{
246
    int L, TL;
247

    
248
    if (!line) {
249
        /* Left prediction only for first line */
250
        L = l->dsp.add_hfyu_left_prediction(buf + 1, buf + 1,
251
                                            width - 1, buf[0]);
252
        return;
253
    } else if (line == 1) {
254
        /* Second line, left predict first pixel, the rest of the line is median predicted */
255
        /* FIXME: In the case of RGB this pixel is top predicted */
256
        TL = buf[-stride];
257
    } else {
258
        /* Top left is 2 rows back, last pixel */
259
        TL = buf[width - (2 * stride) - 1];
260
    }
261
    /* Left pixel is actually prev_row[width] */
262
    L = buf[width - stride - 1];
263

    
264
    add_lag_median_prediction(buf, buf - stride, buf,
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                              width, &L, &TL);
266
}
267

    
268
static int lag_decode_line(LagarithContext *l, lag_rac *rac,
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                           uint8_t *dst, int width, int stride,
270
                           int esc_count)
271
{
272
    int i = 0;
273
    int ret = 0;
274

    
275
    if (!esc_count)
276
        esc_count = -1;
277

    
278
    /* Output any zeros remaining from the previous run */
279
handle_zeros:
280
    if (l->zeros_rem) {
281
        int count = FFMIN(l->zeros_rem, width - i);
282
        memset(dst + i, 0, count);
283
        i += count;
284
        l->zeros_rem -= count;
285
    }
286

    
287
    while (i < width) {
288
        dst[i] = lag_get_rac(rac);
289
        ret++;
290

    
291
        if (dst[i])
292
            l->zeros = 0;
293
        else
294
            l->zeros++;
295

    
296
        i++;
297
        if (l->zeros == esc_count) {
298
            int index = lag_get_rac(rac);
299
            ret++;
300

    
301
            l->zeros = 0;
302

    
303
            l->zeros_rem = lag_calc_zero_run(index);
304
            goto handle_zeros;
305
        }
306
    }
307
    return ret;
308
}
309

    
310
static int lag_decode_zero_run_line(LagarithContext *l, uint8_t *dst,
311
                                    const uint8_t *src, int width,
312
                                    int esc_count)
313
{
314
    int i = 0;
315
    int count;
316
    uint8_t zero_run = 0;
317
    const uint8_t *start = src;
318
    uint8_t mask1 = -(esc_count < 2);
319
    uint8_t mask2 = -(esc_count < 3);
320
    uint8_t *end = dst + (width - 2);
321

    
322
output_zeros:
323
    if (l->zeros_rem) {
324
        count = FFMIN(l->zeros_rem, width - i);
325
        memset(dst, 0, count);
326
        l->zeros_rem -= count;
327
        dst += count;
328
    }
329

    
330
    while (dst < end) {
331
        i = 0;
332
        while (!zero_run && dst + i < end) {
333
            i++;
334
            zero_run =
335
                !(src[i] | (src[i + 1] & mask1) | (src[i + 2] & mask2));
336
        }
337
        if (zero_run) {
338
            zero_run = 0;
339
            i += esc_count;
340
            memcpy(dst, src, i);
341
            dst += i;
342
            l->zeros_rem = lag_calc_zero_run(src[i]);
343

    
344
            src += i + 1;
345
            goto output_zeros;
346
        } else {
347
            memcpy(dst, src, i);
348
            src += i;
349
        }
350
    }
351
    return start - src;
352
}
353

    
354

    
355

    
356
static int lag_decode_arith_plane(LagarithContext *l, uint8_t *dst,
357
                                  int width, int height, int stride,
358
                                  const uint8_t *src, int src_size)
359
{
360
    int i = 0;
361
    int read = 0;
362
    uint32_t length;
363
    uint32_t offset = 1;
364
    int esc_count = src[0];
365
    GetBitContext gb;
366
    lag_rac rac;
367

    
368
    rac.avctx = l->avctx;
369
    l->zeros = 0;
370

    
371
    if (esc_count < 4) {
372
        length = width * height;
373
        if (esc_count && AV_RL32(src + 1) < length) {
374
            length = AV_RL32(src + 1);
375
            offset += 4;
376
        }
377

    
378
        init_get_bits(&gb, src + offset, src_size * 8);
379

    
380
        if (lag_read_prob_header(&rac, &gb) < 0)
381
            return -1;
382

    
383
        lag_rac_init(&rac, &gb, length - stride);
384

    
385
        for (i = 0; i < height; i++)
386
            read += lag_decode_line(l, &rac, dst + (i * stride), width,
387
                                    stride, esc_count);
388

    
389
        if (read > length)
390
            av_log(l->avctx, AV_LOG_WARNING,
391
                   "Output more bytes than length (%d of %d)\n", read,
392
                   length);
393
    } else if (esc_count < 8) {
394
        esc_count -= 4;
395
        if (esc_count > 0) {
396
            /* Zero run coding only, no range coding. */
397
            for (i = 0; i < height; i++)
398
                src += lag_decode_zero_run_line(l, dst + (i * stride), src,
399
                                                width, esc_count);
400
        } else {
401
            /* Plane is stored uncompressed */
402
            for (i = 0; i < height; i++) {
403
                memcpy(dst + (i * stride), src, width);
404
                src += width;
405
            }
406
        }
407
    } else if (esc_count == 0xff) {
408
        /* Plane is a solid run of given value */
409
        for (i = 0; i < height; i++)
410
            memset(dst + i * stride, src[1], width);
411
        /* Do not apply prediction.
412
           Note: memset to 0 above, setting first value to src[1]
413
           and applying prediction gives the same result. */
414
        return 0;
415
    } else {
416
        av_log(l->avctx, AV_LOG_ERROR,
417
               "Invalid zero run escape code! (%#x)\n", esc_count);
418
        return -1;
419
    }
420

    
421
    for (i = 0; i < height; i++) {
422
        lag_pred_line(l, dst, width, stride, i);
423
        dst += stride;
424
    }
425

    
426
    return 0;
427
}
428

    
429
/**
430
 * Decode a frame.
431
 * @param avctx codec context
432
 * @param data output AVFrame
433
 * @param data_size size of output data or 0 if no picture is returned
434
 * @param avpkt input packet
435
 * @return number of consumed bytes on success or negative if decode fails
436
 */
437
static int lag_decode_frame(AVCodecContext *avctx,
438
                            void *data, int *data_size, AVPacket *avpkt)
439
{
440
    const uint8_t *buf = avpkt->data;
441
    int buf_size = avpkt->size;
442
    LagarithContext *l = avctx->priv_data;
443
    AVFrame *const p = &l->picture;
444
    uint8_t frametype = 0;
445
    uint32_t offset_gu = 0, offset_bv = 0, offset_ry = 9;
446

    
447
    AVFrame *picture = data;
448

    
449
    if (p->data[0])
450
        avctx->release_buffer(avctx, p);
451

    
452
    p->reference = 0;
453
    p->key_frame = 1;
454

    
455
    frametype = buf[0];
456

    
457
    offset_gu = AV_RL32(buf + 1);
458
    offset_bv = AV_RL32(buf + 5);
459

    
460
    switch (frametype) {
461
    case FRAME_ARITH_YV12:
462
        avctx->pix_fmt = PIX_FMT_YUV420P;
463

    
464
        if (avctx->get_buffer(avctx, p) < 0) {
465
            av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
466
            return -1;
467
        }
468

    
469
        lag_decode_arith_plane(l, p->data[0], avctx->width, avctx->height,
470
                               p->linesize[0], buf + offset_ry,
471
                               buf_size);
472
        lag_decode_arith_plane(l, p->data[2], avctx->width / 2,
473
                               avctx->height / 2, p->linesize[2],
474
                               buf + offset_gu, buf_size);
475
        lag_decode_arith_plane(l, p->data[1], avctx->width / 2,
476
                               avctx->height / 2, p->linesize[1],
477
                               buf + offset_bv, buf_size);
478
        break;
479
    default:
480
        av_log(avctx, AV_LOG_ERROR,
481
               "Unsupported Lagarith frame type: %#x\n", frametype);
482
        return -1;
483
    }
484

    
485
    *picture = *p;
486
    *data_size = sizeof(AVFrame);
487

    
488
    return buf_size;
489
}
490

    
491
static av_cold int lag_decode_init(AVCodecContext *avctx)
492
{
493
    LagarithContext *l = avctx->priv_data;
494
    l->avctx = avctx;
495

    
496
    dsputil_init(&l->dsp, avctx);
497

    
498
    return 0;
499
}
500

    
501
static av_cold int lag_decode_end(AVCodecContext *avctx)
502
{
503
    LagarithContext *l = avctx->priv_data;
504

    
505
    if (l->picture.data[0])
506
        avctx->release_buffer(avctx, &l->picture);
507

    
508
    return 0;
509
}
510

    
511
AVCodec ff_lagarith_decoder = {
512
    "lagarith",
513
    AVMEDIA_TYPE_VIDEO,
514
    CODEC_ID_LAGARITH,
515
    sizeof(LagarithContext),
516
    lag_decode_init,
517
    NULL,
518
    lag_decode_end,
519
    lag_decode_frame,
520
    CODEC_CAP_DR1,
521
    .long_name = NULL_IF_CONFIG_SMALL("Lagarith lossless"),
522
};