huffyuvdec.c

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/*
 * huffyuv decoder
 *
 * 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
 *
 * yuva, gray, 4:4:4, 4:1:1, 4:1:0 and >8 bit per sample support sponsored by NOA
 */
 
/**
 * @file
 * huffyuv decoder
 */
 
#define UNCHECKED_BITSTREAM_READER 1
 
#include "config_components.h"
 
#include "avcodec.h"
#include "bswapdsp.h"
#include "bytestream.h"
#include "codec_internal.h"
#include "get_bits.h"
#include "huffyuv.h"
#include "huffyuvdsp.h"
#include "lossless_videodsp.h"
#include "thread.h"
#include "libavutil/imgutils.h"
#include "libavutil/mem.h"
#include "libavutil/pixdesc.h"
 
#define VLC_BITS 12
 
typedef struct HYuvDecContext {
    GetBitContext gb;
    Predictor predictor;
    int interlaced;
    int decorrelate;
    int bitstream_bpp;
    int version;
    int yuy2;                               //use yuy2 instead of 422P
    int bgr32;                              //use bgr32 instead of bgr24
    int bps;
    int n;                                  // 1<<bps
    int vlc_n;                              // number of vlc codes (FFMIN(1<<bps, MAX_VLC_N))
    int alpha;
    int chroma;
    int yuv;
    int chroma_h_shift;
    int chroma_v_shift;
    int flags;
    int context;
    int last_slice_end;
 
    union {
        uint8_t  *temp[3];
        uint16_t *temp16[3];
    };
    uint8_t len[4][MAX_VLC_N];
    uint32_t bits[4][MAX_VLC_N];
    uint32_t pix_bgr_map[1<<VLC_BITS];
    VLC vlc[8];                             //Y,U,V,A,YY,YU,YV,AA
    uint8_t *bitstream_buffer;
    unsigned int bitstream_buffer_size;
    BswapDSPContext bdsp;
    HuffYUVDSPContext hdsp;
    LLVidDSPContext llviddsp;
} HYuvDecContext;
 
 
static const uint8_t classic_shift_luma[] = {
    34, 36, 35, 69, 135, 232,   9, 16, 10, 24,  11,  23,  12,  16, 13, 10,
    14,  8, 15,  8,  16,   8,  17, 20, 16, 10, 207, 206, 205, 236, 11,  8,
    10, 21,  9, 23,   8,   8, 199, 70, 69, 68,
};
 
static const uint8_t classic_shift_chroma[] = {
    66, 36,  37,  38, 39, 40,  41,  75,  76,  77, 110, 239, 144, 81, 82,  83,
    84, 85, 118, 183, 56, 57,  88,  89,  56,  89, 154,  57,  58, 57, 26, 141,
    57, 56,  58,  57, 58, 57, 184, 119, 214, 245, 116,  83,  82, 49, 80,  79,
    78, 77,  44,  75, 41, 40,  39,  38,  37,  36,  34,
};
 
static const unsigned char classic_add_luma[256] = {
     3,  9,  5, 12, 10, 35, 32, 29, 27, 50, 48, 45, 44, 41, 39, 37,
    73, 70, 68, 65, 64, 61, 58, 56, 53, 50, 49, 46, 44, 41, 38, 36,
    68, 65, 63, 61, 58, 55, 53, 51, 48, 46, 45, 43, 41, 39, 38, 36,
    35, 33, 32, 30, 29, 27, 26, 25, 48, 47, 46, 44, 43, 41, 40, 39,
    37, 36, 35, 34, 32, 31, 30, 28, 27, 26, 24, 23, 22, 20, 19, 37,
    35, 34, 33, 31, 30, 29, 27, 26, 24, 23, 21, 20, 18, 17, 15, 29,
    27, 26, 24, 22, 21, 19, 17, 16, 14, 26, 25, 23, 21, 19, 18, 16,
    15, 27, 25, 23, 21, 19, 17, 16, 14, 26, 25, 23, 21, 18, 17, 14,
    12, 17, 19, 13,  4,  9,  2, 11,  1,  7,  8,  0, 16,  3, 14,  6,
    12, 10,  5, 15, 18, 11, 10, 13, 15, 16, 19, 20, 22, 24, 27, 15,
    18, 20, 22, 24, 26, 14, 17, 20, 22, 24, 27, 15, 18, 20, 23, 25,
    28, 16, 19, 22, 25, 28, 32, 36, 21, 25, 29, 33, 38, 42, 45, 49,
    28, 31, 34, 37, 40, 42, 44, 47, 49, 50, 52, 54, 56, 57, 59, 60,
    62, 64, 66, 67, 69, 35, 37, 39, 40, 42, 43, 45, 47, 48, 51, 52,
    54, 55, 57, 59, 60, 62, 63, 66, 67, 69, 71, 72, 38, 40, 42, 43,
    46, 47, 49, 51, 26, 28, 30, 31, 33, 34, 18, 19, 11, 13,  7,  8,
};
 
static const unsigned char classic_add_chroma[256] = {
     3,    1,   2,   2,   2,   2,   3,   3,   7,   5,   7,   5,   8,   6,  11,   9,
     7,   13,  11,  10,   9,   8,   7,   5,   9,   7,   6,   4,   7,   5,   8,   7,
     11,   8,  13,  11,  19,  15,  22,  23,  20,  33,  32,  28,  27,  29,  51,  77,
     43,  45,  76,  81,  46,  82,  75,  55,  56, 144,  58,  80,  60,  74, 147,  63,
    143,  65,  66,  67,  68,  69,  70,  71,  72,  73,  74,  75,  76,  77,  78,  79,
     80,  81,  82,  83,  84,  85,  86,  87,  88,  89,  90,  91,  27,  30,  21,  22,
     17,  14,   5,   6, 100,  54,  47,  50,  51,  53, 106, 107, 108, 109, 110, 111,
    112, 113, 114, 115,   4, 117, 118,  92,  94, 121, 122,   3, 124, 103,   2,   1,
      0, 129, 130, 131, 120, 119, 126, 125, 136, 137, 138, 139, 140, 141, 142, 134,
    135, 132, 133, 104,  64, 101,  62,  57, 102,  95,  93,  59,  61,  28,  97,  96,
     52,  49,  48,  29,  32,  25,  24,  46,  23,  98,  45,  44,  43,  20,  42,  41,
     19,  18,  99,  40,  15,  39,  38,  16,  13,  12,  11,  37,  10,   9,   8,  36,
      7, 128, 127, 105, 123, 116,  35,  34,  33, 145,  31,  79,  42, 146,  78,  26,
     83,  48,  49,  50,  44,  47,  26,  31,  30,  18,  17,  19,  21,  24,  25,  13,
     14,  16,  17,  18,  20,  21,  12,  14,  15,   9,  10,   6,   9,   6,   5,   8,
      6,  12,   8,  10,   7,   9,   6,   4,   6,   2,   2,   3,   3,   3,   3,   2,
};
 
static int read_len_table(uint8_t *dst, GetByteContext *gb, int n)
{
    int i, val, repeat;
 
    for (i = 0; i < n;) {
        if (bytestream2_get_bytes_left(gb) <= 0)
            goto error;
        repeat = bytestream2_peek_byteu(gb) >> 5;
        val    = bytestream2_get_byteu(gb) & 0x1F;
        if (repeat == 0) {
            if (bytestream2_get_bytes_left(gb) <= 0)
                goto error;
            repeat = bytestream2_get_byteu(gb);
        }
        if (i + repeat > n)
            goto error;
        while (repeat--)
            dst[i++] = val;
    }
    return 0;
 
error:
    av_log(NULL, AV_LOG_ERROR, "Error reading huffman table\n");
    return AVERROR_INVALIDDATA;
}
 
static int generate_joint_tables(HYuvDecContext *s)
{
    int ret;
    uint16_t *symbols = av_mallocz(5 << VLC_BITS);
    uint16_t *bits;
    uint8_t *len;
    if (!symbols)
        return AVERROR(ENOMEM);
    bits = symbols + (1 << VLC_BITS);
    len = (uint8_t *)(bits + (1 << VLC_BITS));
 
    if (s->bitstream_bpp < 24 || s->version > 2) {
        int count = 1 + s->alpha + 2 * s->chroma;
        int p, i, y, u;
        for (p = 0; p < count; p++) {
            int p0 = s->version > 2 ? p : 0;
            for (i = y = 0; y < s->vlc_n; y++) {
                int len0  = s->len[p0][y];
                int limit = VLC_BITS - len0;
                if (limit <= 0 || !len0)
                    continue;
                if ((sign_extend(y, 8) & (s->vlc_n-1)) != y)
                    continue;
                for (u = 0; u < s->vlc_n; u++) {
                    int len1 = s->len[p][u];
                    if (len1 > limit || !len1)
                        continue;
                    if ((sign_extend(u, 8) & (s->vlc_n-1)) != u)
                        continue;
                    av_assert0(i < (1 << VLC_BITS));
                    len[i]     = len0 + len1;
                    bits[i]    = (s->bits[p0][y] << len1) + s->bits[p][u];
                    symbols[i] = (y << 8) + (u & 0xFF);
                        i++;
                }
            }
            ff_vlc_free(&s->vlc[4 + p]);
            if ((ret = ff_vlc_init_sparse(&s->vlc[4 + p], VLC_BITS, i, len, 1, 1,
                                          bits, 2, 2, symbols, 2, 2, 0)) < 0)
                goto out;
        }
    } else {
        uint8_t (*map)[4] = (uint8_t(*)[4]) s->pix_bgr_map;
        int i, b, g, r, code;
        int p0 = s->decorrelate;
        int p1 = !s->decorrelate;
        /* Restrict the range to +/-16 because that's pretty much guaranteed
         * to cover all the combinations that fit in 11 bits total, and it
         *  does not matter if we miss a few rare codes. */
        for (i = 0, g = -16; g < 16; g++) {
            int len0   = s->len[p0][g & 255];
            int limit0 = VLC_BITS - len0;
            if (limit0 < 2 || !len0)
                continue;
            for (b = -16; b < 16; b++) {
                int len1   = s->len[p1][b & 255];
                int limit1 = limit0 - len1;
                if (limit1 < 1 || !len1)
                    continue;
                code = (s->bits[p0][g & 255] << len1) + s->bits[p1][b & 255];
                for (r = -16; r < 16; r++) {
                    int len2 = s->len[2][r & 255];
                    if (len2 > limit1 || !len2)
                        continue;
                    av_assert0(i < (1 << VLC_BITS));
                    len[i]  = len0 + len1 + len2;
                    bits[i] = (code << len2) + s->bits[2][r & 255];
                    if (s->decorrelate) {
                        map[i][G] = g;
                        map[i][B] = g + b;
                        map[i][R] = g + r;
                    } else {
                        map[i][B] = g;
                        map[i][G] = b;
                        map[i][R] = r;
                    }
                    i++;
                }
            }
        }
        ff_vlc_free(&s->vlc[4]);
        if ((ret = vlc_init(&s->vlc[4], VLC_BITS, i, len, 1, 1,
                            bits, 2, 2, 0)) < 0)
            goto out;
    }
    ret = 0;
out:
    av_freep(&symbols);
    return ret;
}
 
static int read_huffman_tables(HYuvDecContext *s, const uint8_t *src, int length)
{
    GetByteContext gb;
    int i, ret;
    int count = 3;
 
    bytestream2_init(&gb, src, length);
 
    if (s->version > 2)
        count = 1 + s->alpha + 2*s->chroma;
 
    for (i = 0; i < count; i++) {
        if ((ret = read_len_table(s->len[i], &gb, s->vlc_n)) < 0)
            return ret;
        if ((ret = ff_huffyuv_generate_bits_table(s->bits[i], s->len[i], s->vlc_n)) < 0)
            return ret;
        ff_vlc_free(&s->vlc[i]);
        if ((ret = vlc_init(&s->vlc[i], VLC_BITS, s->vlc_n, s->len[i], 1, 1,
                           s->bits[i], 4, 4, 0)) < 0)
            return ret;
    }
 
    if ((ret = generate_joint_tables(s)) < 0)
        return ret;
 
    return bytestream2_tell(&gb);
}
 
static int read_old_huffman_tables(HYuvDecContext *s)
{
    GetByteContext gb;
    int i, ret;
 
    bytestream2_init(&gb, classic_shift_luma,
                     sizeof(classic_shift_luma));
    ret = read_len_table(s->len[0], &gb, 256);
    av_assert1(ret >= 0);
 
    bytestream2_init(&gb, classic_shift_chroma,
                     sizeof(classic_shift_chroma));
    ret = read_len_table(s->len[1], &gb, 256);
    av_assert1(ret >= 0);
 
    for (i = 0; i < 256; i++)
        s->bits[0][i] = classic_add_luma[i];
    for (i = 0; i < 256; i++)
        s->bits[1][i] = classic_add_chroma[i];
 
    if (s->bitstream_bpp >= 24) {
        memcpy(s->bits[1], s->bits[0], 256 * sizeof(uint32_t));
        memcpy(s->len[1], s->len[0], 256 * sizeof(uint8_t));
    }
    memcpy(s->bits[2], s->bits[1], 256 * sizeof(uint32_t));
    memcpy(s->len[2], s->len[1], 256 * sizeof(uint8_t));
 
    for (i = 0; i < 4; i++) {
        ff_vlc_free(&s->vlc[i]);
        if ((ret = vlc_init(&s->vlc[i], VLC_BITS, 256, s->len[i], 1, 1,
                            s->bits[i], 4, 4, 0)) < 0)
            return ret;
    }
 
    if ((ret = generate_joint_tables(s)) < 0)
        return ret;
 
    return 0;
}
 
static av_cold int decode_end(AVCodecContext *avctx)
{
    HYuvDecContext *s = avctx->priv_data;
    int i;
 
    for (int i = 0; i < 3; i++)
        av_freep(&s->temp[i]);
 
    av_freep(&s->bitstream_buffer);
 
    for (i = 0; i < 8; i++)
        ff_vlc_free(&s->vlc[i]);
 
    return 0;
}
 
static av_cold int decode_init(AVCodecContext *avctx)
{
    HYuvDecContext *s = avctx->priv_data;
    int ret;
 
    ret = av_image_check_size(avctx->width, avctx->height, 0, avctx);
    if (ret < 0)
        return ret;
 
    s->flags = avctx->flags;
 
    ff_bswapdsp_init(&s->bdsp);
    ff_huffyuvdsp_init(&s->hdsp);
    ff_llviddsp_init(&s->llviddsp);
 
    s->interlaced = avctx->height > 288;
    s->bgr32      = 1;
 
    if (avctx->extradata_size) {
        if ((avctx->bits_per_coded_sample & 7) &&
            avctx->bits_per_coded_sample != 12)
            s->version = 1; // do such files exist at all?
        else if (avctx->extradata_size > 3 && avctx->extradata[3] == 0)
            s->version = 2;
        else
            s->version = 3;
    } else
        s->version = 0;
 
    s->bps = 8;
    s->n = 1<<s->bps;
    s->vlc_n = FFMIN(s->n, MAX_VLC_N);
    s->chroma = 1;
    if (s->version >= 2) {
        int method, interlace;
 
        if (avctx->extradata_size < 4)
            return AVERROR_INVALIDDATA;
 
        method           = avctx->extradata[0];
        s->decorrelate   = method & 64 ? 1 : 0;
        s->predictor     = method & 63;
        if (s->version == 2) {
            s->bitstream_bpp = avctx->extradata[1];
            if (s->bitstream_bpp == 0)
                s->bitstream_bpp = avctx->bits_per_coded_sample & ~7;
        } else {
            s->bps = (avctx->extradata[1] >> 4) + 1;
            s->n = 1<<s->bps;
            s->vlc_n = FFMIN(s->n, MAX_VLC_N);
            s->chroma_h_shift = avctx->extradata[1] & 3;
            s->chroma_v_shift = (avctx->extradata[1] >> 2) & 3;
            s->yuv   = !!(avctx->extradata[2] & 1);
            s->chroma= !!(avctx->extradata[2] & 3);
            s->alpha = !!(avctx->extradata[2] & 4);
        }
        interlace     = (avctx->extradata[2] & 0x30) >> 4;
        s->interlaced = (interlace == 1) ? 1 : (interlace == 2) ? 0 : s->interlaced;
        s->context    = avctx->extradata[2] & 0x40 ? 1 : 0;
 
        if ((ret = read_huffman_tables(s, avctx->extradata + 4,
                                       avctx->extradata_size - 4)) < 0)
            return ret;
    } else {
        switch (avctx->bits_per_coded_sample & 7) {
        case 1:
            s->predictor   = LEFT;
            s->decorrelate = 0;
            break;
        case 2:
            s->predictor   = LEFT;
            s->decorrelate = 1;
            break;
        case 3:
            s->predictor   = PLANE;
            s->decorrelate = avctx->bits_per_coded_sample >= 24;
            break;
        case 4:
            s->predictor   = MEDIAN;
            s->decorrelate = 0;
            break;
        default:
            s->predictor   = LEFT; // OLD
            s->decorrelate = 0;
            break;
        }
        s->bitstream_bpp = avctx->bits_per_coded_sample & ~7;
        s->context       = 0;
 
        if ((ret = read_old_huffman_tables(s)) < 0)
            return ret;
    }
 
    if (s->version <= 2) {
        switch (s->bitstream_bpp) {
        case 12:
            avctx->pix_fmt = AV_PIX_FMT_YUV420P;
            s->yuv = 1;
            break;
        case 16:
            if (s->yuy2)
                avctx->pix_fmt = AV_PIX_FMT_YUYV422;
            else
                avctx->pix_fmt = AV_PIX_FMT_YUV422P;
            s->yuv = 1;
            break;
        case 24:
            if (s->bgr32)
                avctx->pix_fmt = AV_PIX_FMT_0RGB32;
            else
                avctx->pix_fmt = AV_PIX_FMT_BGR24;
            break;
        case 32:
            av_assert0(s->bgr32);
            avctx->pix_fmt = AV_PIX_FMT_RGB32;
            s->alpha = 1;
            break;
        default:
            return AVERROR_INVALIDDATA;
        }
        av_pix_fmt_get_chroma_sub_sample(avctx->pix_fmt,
                                         &s->chroma_h_shift,
                                         &s->chroma_v_shift);
    } else {
        switch ( (s->chroma<<10) | (s->yuv<<9) | (s->alpha<<8) | ((s->bps-1)<<4) | s->chroma_h_shift | (s->chroma_v_shift<<2)) {
        case 0x070:
            avctx->pix_fmt = AV_PIX_FMT_GRAY8;
            break;
        case 0x0F0:
            avctx->pix_fmt = AV_PIX_FMT_GRAY16;
            break;
        case 0x470:
            avctx->pix_fmt = AV_PIX_FMT_GBRP;
            break;
        case 0x480:
            avctx->pix_fmt = AV_PIX_FMT_GBRP9;
            break;
        case 0x490:
            avctx->pix_fmt = AV_PIX_FMT_GBRP10;
            break;
        case 0x4B0:
            avctx->pix_fmt = AV_PIX_FMT_GBRP12;
            break;
        case 0x4D0:
            avctx->pix_fmt = AV_PIX_FMT_GBRP14;
            break;
        case 0x4F0:
            avctx->pix_fmt = AV_PIX_FMT_GBRP16;
            break;
        case 0x570:
            avctx->pix_fmt = AV_PIX_FMT_GBRAP;
            break;
        case 0x670:
            avctx->pix_fmt = AV_PIX_FMT_YUV444P;
            break;
        case 0x680:
            avctx->pix_fmt = AV_PIX_FMT_YUV444P9;
            break;
        case 0x690:
            avctx->pix_fmt = AV_PIX_FMT_YUV444P10;
            break;
        case 0x6B0:
            avctx->pix_fmt = AV_PIX_FMT_YUV444P12;
            break;
        case 0x6D0:
            avctx->pix_fmt = AV_PIX_FMT_YUV444P14;
            break;
        case 0x6F0:
            avctx->pix_fmt = AV_PIX_FMT_YUV444P16;
            break;
        case 0x671:
            avctx->pix_fmt = AV_PIX_FMT_YUV422P;
            break;
        case 0x681:
            avctx->pix_fmt = AV_PIX_FMT_YUV422P9;
            break;
        case 0x691:
            avctx->pix_fmt = AV_PIX_FMT_YUV422P10;
            break;
        case 0x6B1:
            avctx->pix_fmt = AV_PIX_FMT_YUV422P12;
            break;
        case 0x6D1:
            avctx->pix_fmt = AV_PIX_FMT_YUV422P14;
            break;
        case 0x6F1:
            avctx->pix_fmt = AV_PIX_FMT_YUV422P16;
            break;
        case 0x672:
            avctx->pix_fmt = AV_PIX_FMT_YUV411P;
            break;
        case 0x674:
            avctx->pix_fmt = AV_PIX_FMT_YUV440P;
            break;
        case 0x675:
            avctx->pix_fmt = AV_PIX_FMT_YUV420P;
            break;
        case 0x685:
            avctx->pix_fmt = AV_PIX_FMT_YUV420P9;
            break;
        case 0x695:
            avctx->pix_fmt = AV_PIX_FMT_YUV420P10;
            break;
        case 0x6B5:
            avctx->pix_fmt = AV_PIX_FMT_YUV420P12;
            break;
        case 0x6D5:
            avctx->pix_fmt = AV_PIX_FMT_YUV420P14;
            break;
        case 0x6F5:
            avctx->pix_fmt = AV_PIX_FMT_YUV420P16;
            break;
        case 0x67A:
            avctx->pix_fmt = AV_PIX_FMT_YUV410P;
            break;
        case 0x770:
            avctx->pix_fmt = AV_PIX_FMT_YUVA444P;
            break;
        case 0x780:
            avctx->pix_fmt = AV_PIX_FMT_YUVA444P9;
            break;
        case 0x790:
            avctx->pix_fmt = AV_PIX_FMT_YUVA444P10;
            break;
        case 0x7F0:
            avctx->pix_fmt = AV_PIX_FMT_YUVA444P16;
            break;
        case 0x771:
            avctx->pix_fmt = AV_PIX_FMT_YUVA422P;
            break;
        case 0x781:
            avctx->pix_fmt = AV_PIX_FMT_YUVA422P9;
            break;
        case 0x791:
            avctx->pix_fmt = AV_PIX_FMT_YUVA422P10;
            break;
        case 0x7F1:
            avctx->pix_fmt = AV_PIX_FMT_YUVA422P16;
            break;
        case 0x775:
            avctx->pix_fmt = AV_PIX_FMT_YUVA420P;
            break;
        case 0x785:
            avctx->pix_fmt = AV_PIX_FMT_YUVA420P9;
            break;
        case 0x795:
            avctx->pix_fmt = AV_PIX_FMT_YUVA420P10;
            break;
        case 0x7F5:
            avctx->pix_fmt = AV_PIX_FMT_YUVA420P16;
            break;
        default:
            return AVERROR_INVALIDDATA;
        }
    }
 
    if ((avctx->pix_fmt == AV_PIX_FMT_YUV422P || avctx->pix_fmt == AV_PIX_FMT_YUV420P) && avctx->width & 1) {
        av_log(avctx, AV_LOG_ERROR, "width must be even for this colorspace\n");
        return AVERROR_INVALIDDATA;
    }
    if (s->predictor == MEDIAN && avctx->pix_fmt == AV_PIX_FMT_YUV422P &&
        avctx->width % 4) {
        av_log(avctx, AV_LOG_ERROR, "width must be a multiple of 4 "
               "for this combination of colorspace and predictor type.\n");
        return AVERROR_INVALIDDATA;
    }
 
    for (int i = 0; i < 3; i++) {
        s->temp[i] = av_malloc(4 * avctx->width + 16);
        if (!s->temp[i])
            return AVERROR(ENOMEM);
    }
 
    return 0;
}
 
/** Subset of GET_VLC for use in hand-roller VLC code */
#define VLC_INTERN(dst, table, gb, name, bits, max_depth)   \
    code = table[index].sym;                                \
    n    = table[index].len;                                \
    if (max_depth > 1 && n < 0) {                           \
        LAST_SKIP_BITS(name, gb, bits);                     \
        UPDATE_CACHE(name, gb);                             \
                                                            \
        nb_bits = -n;                                       \
        index   = SHOW_UBITS(name, gb, nb_bits) + code;     \
        code    = table[index].sym;                         \
        n       = table[index].len;                         \
        if (max_depth > 2 && n < 0) {                       \
            LAST_SKIP_BITS(name, gb, nb_bits);              \
            UPDATE_CACHE(name, gb);                         \
                                                            \
            nb_bits = -n;                                   \
            index   = SHOW_UBITS(name, gb, nb_bits) + code; \
            code    = table[index].sym;                     \
            n       = table[index].len;                     \
        }                                                   \
    }                                                       \
    dst = code;                                             \
    LAST_SKIP_BITS(name, gb, n)
 
 
#define GET_VLC_DUAL(dst0, dst1, name, gb, dtable, table1, table2,  \
                     bits, max_depth, OP)                           \
    do {                                                            \
        unsigned int index = SHOW_UBITS(name, gb, bits);            \
        int          code, n = dtable[index].len;                   \
                                                                    \
        if (n<=0) {                                                 \
            int nb_bits;                                            \
            VLC_INTERN(dst0, table1, gb, name, bits, max_depth);    \
                                                                    \
            UPDATE_CACHE(re, gb);                                   \
            index = SHOW_UBITS(name, gb, bits);                     \
            VLC_INTERN(dst1, table2, gb, name, bits, max_depth);    \
        } else {                                                    \
            code = dtable[index].sym;                               \
            OP(dst0, dst1, code);                                   \
            LAST_SKIP_BITS(name, gb, n);                            \
        }                                                           \
    } while (0)
 
#define OP8bits(dst0, dst1, code) dst0 = code>>8; dst1 = code
 
#define READ_2PIX(dst0, dst1, plane1)                                   \
    UPDATE_CACHE(re, &s->gb);                                           \
    GET_VLC_DUAL(dst0, dst1, re, &s->gb, s->vlc[4+plane1].table,        \
                 s->vlc[0].table, s->vlc[plane1].table, VLC_BITS, 3, OP8bits)
 
static void decode_422_bitstream(HYuvDecContext *s, int count)
{
    int i, icount;
    OPEN_READER(re, &s->gb);
    count /= 2;
 
    icount = get_bits_left(&s->gb) / (32 * 4);
    if (count >= icount) {
        for (i = 0; i < icount; i++) {
            READ_2PIX(s->temp[0][2 * i],     s->temp[1][i], 1);
            READ_2PIX(s->temp[0][2 * i + 1], s->temp[2][i], 2);
        }
        for (; i < count && BITS_LEFT(re, &s->gb) > 0; i++) {
            READ_2PIX(s->temp[0][2 * i    ], s->temp[1][i], 1);
            if (BITS_LEFT(re, &s->gb) <= 0) break;
            READ_2PIX(s->temp[0][2 * i + 1], s->temp[2][i], 2);
        }
        for (; i < count; i++)
            s->temp[0][2 * i    ] = s->temp[1][i] =
            s->temp[0][2 * i + 1] = s->temp[2][i] = 0;
    } else {
        for (i = 0; i < count; i++) {
            READ_2PIX(s->temp[0][2 * i],     s->temp[1][i], 1);
            READ_2PIX(s->temp[0][2 * i + 1], s->temp[2][i], 2);
        }
    }
    CLOSE_READER(re, &s->gb);
}
 
#define READ_2PIX_PLANE(dst0, dst1, plane, OP) \
    UPDATE_CACHE(re, &s->gb); \
    GET_VLC_DUAL(dst0, dst1, re, &s->gb, s->vlc[4+plane].table, \
                 s->vlc[plane].table, s->vlc[plane].table, VLC_BITS, 3, OP)
 
#define OP14bits(dst0, dst1, code) dst0 = code>>8; dst1 = sign_extend(code, 8)
 
/* TODO instead of restarting the read when the code isn't in the first level
 * of the joint table, jump into the 2nd level of the individual table. */
#define READ_2PIX_PLANE16(dst0, dst1, plane){\
    dst0 = get_vlc2(&s->gb, s->vlc[plane].table, VLC_BITS, 3)*4;\
    dst0 += get_bits(&s->gb, 2);\
    dst1 = get_vlc2(&s->gb, s->vlc[plane].table, VLC_BITS, 3)*4;\
    dst1 += get_bits(&s->gb, 2);\
}
static void decode_plane_bitstream(HYuvDecContext *s, int width, int plane)
{
    int i, count = width/2;
 
    if (s->bps <= 8) {
        OPEN_READER(re, &s->gb);
        if (count >= (get_bits_left(&s->gb)) / (32 * 2)) {
            for (i = 0; i < count && BITS_LEFT(re, &s->gb) > 0; i++) {
                READ_2PIX_PLANE(s->temp[0][2 * i], s->temp[0][2 * i + 1], plane, OP8bits);
            }
        } else {
            for(i=0; i<count; i++){
                READ_2PIX_PLANE(s->temp[0][2 * i], s->temp[0][2 * i + 1], plane, OP8bits);
            }
        }
        if( width&1 && BITS_LEFT(re, &s->gb)>0 ) {
            unsigned int index;
            int nb_bits, code, n;
            UPDATE_CACHE(re, &s->gb);
            index = SHOW_UBITS(re, &s->gb, VLC_BITS);
            VLC_INTERN(s->temp[0][width-1], s->vlc[plane].table,
                       &s->gb, re, VLC_BITS, 3);
        }
        CLOSE_READER(re, &s->gb);
    } else if (s->bps <= 14) {
        OPEN_READER(re, &s->gb);
        if (count >= (get_bits_left(&s->gb)) / (32 * 2)) {
            for (i = 0; i < count && BITS_LEFT(re, &s->gb) > 0; i++) {
                READ_2PIX_PLANE(s->temp16[0][2 * i], s->temp16[0][2 * i + 1], plane, OP14bits);
            }
        } else {
            for(i=0; i<count; i++){
                READ_2PIX_PLANE(s->temp16[0][2 * i], s->temp16[0][2 * i + 1], plane, OP14bits);
            }
        }
        if( width&1 && BITS_LEFT(re, &s->gb)>0 ) {
            unsigned int index;
            int nb_bits, code, n;
            UPDATE_CACHE(re, &s->gb);
            index = SHOW_UBITS(re, &s->gb, VLC_BITS);
            VLC_INTERN(s->temp16[0][width-1], s->vlc[plane].table,
                       &s->gb, re, VLC_BITS, 3);
        }
        CLOSE_READER(re, &s->gb);
    } else {
        if (count >= (get_bits_left(&s->gb)) / (32 * 2)) {
            for (i = 0; i < count && get_bits_left(&s->gb) > 0; i++) {
                READ_2PIX_PLANE16(s->temp16[0][2 * i], s->temp16[0][2 * i + 1], plane);
            }
        } else {
            for(i=0; i<count; i++){
                READ_2PIX_PLANE16(s->temp16[0][2 * i], s->temp16[0][2 * i + 1], plane);
            }
        }
        if( width&1 && get_bits_left(&s->gb)>0 ) {
            int dst = (unsigned)get_vlc2(&s->gb, s->vlc[plane].table, VLC_BITS, 3)<<2;
            s->temp16[0][width-1] = dst + get_bits(&s->gb, 2);
        }
    }
}
 
static void decode_gray_bitstream(HYuvDecContext *s, int count)
{
    int i;
    OPEN_READER(re, &s->gb);
    count /= 2;
 
    if (count >= (get_bits_left(&s->gb)) / (32 * 2)) {
        for (i = 0; i < count && BITS_LEFT(re, &s->gb) > 0; i++) {
            READ_2PIX(s->temp[0][2 * i], s->temp[0][2 * i + 1], 0);
        }
        for (; i < count; i++)
            s->temp[0][2 * i] = s->temp[0][2 * i + 1] = 0;
    } else {
        for (i = 0; i < count; i++) {
            READ_2PIX(s->temp[0][2 * i], s->temp[0][2 * i + 1], 0);
        }
    }
    CLOSE_READER(re, &s->gb);
}
 
static av_always_inline void decode_bgr_1(HYuvDecContext *s, int count,
                                          int decorrelate, int alpha)
{
    int i;
    OPEN_READER(re, &s->gb);
 
    for (i = 0; i < count && BITS_LEFT(re, &s->gb) > 0; i++) {
        unsigned int index;
        int code, n, nb_bits;
 
        UPDATE_CACHE(re, &s->gb);
        index = SHOW_UBITS(re, &s->gb, VLC_BITS);
        n     = s->vlc[4].table[index].len;
 
        if (n>0) {
            code  = s->vlc[4].table[index].sym;
            *(uint32_t *) &s->temp[0][4 * i] = s->pix_bgr_map[code];
            LAST_SKIP_BITS(re, &s->gb, n);
        } else {
            if (decorrelate) {
                VLC_INTERN(s->temp[0][4 * i + G], s->vlc[1].table,
                           &s->gb, re, VLC_BITS, 3);
 
                UPDATE_CACHE(re, &s->gb);
                index = SHOW_UBITS(re, &s->gb, VLC_BITS);
                VLC_INTERN(code, s->vlc[0].table, &s->gb, re, VLC_BITS, 3);
                s->temp[0][4 * i + B] = code + s->temp[0][4 * i + G];
 
                UPDATE_CACHE(re, &s->gb);
                index = SHOW_UBITS(re, &s->gb, VLC_BITS);
                VLC_INTERN(code, s->vlc[2].table, &s->gb, re, VLC_BITS, 3);
                s->temp[0][4 * i + R] = code + s->temp[0][4 * i + G];
            } else {
                VLC_INTERN(s->temp[0][4 * i + B], s->vlc[0].table,
                           &s->gb, re, VLC_BITS, 3);
 
                UPDATE_CACHE(re, &s->gb);
                index = SHOW_UBITS(re, &s->gb, VLC_BITS);
                VLC_INTERN(s->temp[0][4 * i + G], s->vlc[1].table,
                           &s->gb, re, VLC_BITS, 3);
 
                UPDATE_CACHE(re, &s->gb);
                index = SHOW_UBITS(re, &s->gb, VLC_BITS);
                VLC_INTERN(s->temp[0][4 * i + R], s->vlc[2].table,
                           &s->gb, re, VLC_BITS, 3);
            }
        }
        if (alpha) {
            UPDATE_CACHE(re, &s->gb);
            index = SHOW_UBITS(re, &s->gb, VLC_BITS);
            VLC_INTERN(s->temp[0][4 * i + A], s->vlc[2].table,
                       &s->gb, re, VLC_BITS, 3);
        } else
            s->temp[0][4 * i + A] = 0;
    }
    CLOSE_READER(re, &s->gb);
}
 
static void decode_bgr_bitstream(HYuvDecContext *s, int count)
{
    if (s->decorrelate) {
        if (s->bitstream_bpp == 24)
            decode_bgr_1(s, count, 1, 0);
        else
            decode_bgr_1(s, count, 1, 1);
    } else {
        if (s->bitstream_bpp == 24)
            decode_bgr_1(s, count, 0, 0);
        else
            decode_bgr_1(s, count, 0, 1);
    }
}
 
static void draw_slice(HYuvDecContext *s, AVCodecContext *avctx, AVFrame *frame, int y)
{
    int h, cy, i;
    int offset[AV_NUM_DATA_POINTERS];
 
    if (!avctx->draw_horiz_band)
        return;
 
    h  = y - s->last_slice_end;
    y -= h;
 
    if (s->bitstream_bpp == 12)
        cy = y >> 1;
    else
        cy = y;
 
    offset[0] = frame->linesize[0] * y;
    offset[1] = frame->linesize[1] * cy;
    offset[2] = frame->linesize[2] * cy;
    for (i = 3; i < AV_NUM_DATA_POINTERS; i++)
        offset[i] = 0;
 
    avctx->draw_horiz_band(avctx, frame, offset, y, 3, h);
 
    s->last_slice_end = y + h;
}
 
static int left_prediction(HYuvDecContext *s, uint8_t *dst, const uint8_t *src, int w, int acc)
{
    if (s->bps <= 8) {
        return s->llviddsp.add_left_pred(dst, src, w, acc);
    } else {
        return s->llviddsp.add_left_pred_int16((      uint16_t *)dst, (const uint16_t *)src, s->n-1, w, acc);
    }
}
 
static void add_bytes(HYuvDecContext *s, uint8_t *dst, uint8_t *src, int w)
{
    if (s->bps <= 8) {
        s->llviddsp.add_bytes(dst, src, w);
    } else {
        s->hdsp.add_int16((uint16_t*)dst, (const uint16_t*)src, s->n - 1, w);
    }
}
 
static void add_median_prediction(HYuvDecContext *s, uint8_t *dst, const uint8_t *src, const uint8_t *diff, int w, int *left, int *left_top)
{
    if (s->bps <= 8) {
        s->llviddsp.add_median_pred(dst, src, diff, w, left, left_top);
    } else {
        s->hdsp.add_hfyu_median_pred_int16((uint16_t *)dst, (const uint16_t *)src, (const uint16_t *)diff, s->n-1, w, left, left_top);
    }
}
 
static int decode_slice(AVCodecContext *avctx, AVFrame *p, int height,
                        int buf_size, int y_offset, int table_size)
{
    HYuvDecContext *s = avctx->priv_data;
    int fake_ystride, fake_ustride, fake_vstride;
    const int width  = avctx->width;
    const int width2 = avctx->width >> 1;
    int ret;
 
    if ((ret = init_get_bits8(&s->gb, s->bitstream_buffer + table_size, buf_size - table_size)) < 0)
        return ret;
 
    fake_ystride = s->interlaced ? p->linesize[0] * 2 : p->linesize[0];
    fake_ustride = s->interlaced ? p->linesize[1] * 2 : p->linesize[1];
    fake_vstride = s->interlaced ? p->linesize[2] * 2 : p->linesize[2];
 
    if (s->version > 2) {
        int plane;
        for(plane = 0; plane < 1 + 2*s->chroma + s->alpha; plane++) {
            int left, lefttop, y;
            int w = width;
            int h = height;
            int fake_stride = fake_ystride;
 
            if (s->chroma && (plane == 1 || plane == 2)) {
                w >>= s->chroma_h_shift;
                h >>= s->chroma_v_shift;
                fake_stride = plane == 1 ? fake_ustride : fake_vstride;
            }
 
            switch (s->predictor) {
            case LEFT:
            case PLANE:
                decode_plane_bitstream(s, w, plane);
                left = left_prediction(s, p->data[plane], s->temp[0], w, 0);
 
                for (y = 1; y < h; y++) {
                    uint8_t *dst = p->data[plane] + p->linesize[plane]*y;
 
                    decode_plane_bitstream(s, w, plane);
                    left = left_prediction(s, dst, s->temp[0], w, left);
                    if (s->predictor == PLANE) {
                        if (y > s->interlaced) {
                            add_bytes(s, dst, dst - fake_stride, w);
                        }
                    }
                }
 
                break;
            case MEDIAN:
                decode_plane_bitstream(s, w, plane);
                left= left_prediction(s, p->data[plane], s->temp[0], w, 0);
 
                y = 1;
                if (y >= h)
                    break;
 
                /* second line is left predicted for interlaced case */
                if (s->interlaced) {
                    decode_plane_bitstream(s, w, plane);
                    left = left_prediction(s, p->data[plane] + p->linesize[plane], s->temp[0], w, left);
                    y++;
                    if (y >= h)
                        break;
                }
 
                lefttop = p->data[plane][0];
                decode_plane_bitstream(s, w, plane);
                add_median_prediction(s, p->data[plane] + fake_stride, p->data[plane], s->temp[0], w, &left, &lefttop);
                y++;
 
                for (; y<h; y++) {
                    uint8_t *dst;
 
                    decode_plane_bitstream(s, w, plane);
 
                    dst = p->data[plane] + p->linesize[plane] * y;
 
                    add_median_prediction(s, dst, dst - fake_stride, s->temp[0], w, &left, &lefttop);
                }
 
                break;
            }
        }
        draw_slice(s, avctx, p, height);
    } else if (s->bitstream_bpp < 24) {
        int y, cy;
        int lefty, leftu, leftv;
        int lefttopy, lefttopu, lefttopv;
 
        if (s->yuy2) {
            p->data[0][3] = get_bits(&s->gb, 8);
            p->data[0][2] = get_bits(&s->gb, 8);
            p->data[0][1] = get_bits(&s->gb, 8);
            p->data[0][0] = get_bits(&s->gb, 8);
 
            av_log(avctx, AV_LOG_ERROR,
                   "YUY2 output is not implemented yet\n");
            return AVERROR_PATCHWELCOME;
        } else {
            leftv         =
            p->data[2][0 + y_offset * p->linesize[2]] = get_bits(&s->gb, 8);
            lefty         =
            p->data[0][1 + y_offset * p->linesize[0]] = get_bits(&s->gb, 8);
            leftu         =
            p->data[1][0 + y_offset * p->linesize[1]] = get_bits(&s->gb, 8);
            p->data[0][0 + y_offset * p->linesize[0]] = get_bits(&s->gb, 8);
 
            switch (s->predictor) {
            case LEFT:
            case PLANE:
                decode_422_bitstream(s, width - 2);
                lefty = s->llviddsp.add_left_pred(p->data[0] + p->linesize[0] * y_offset + 2, s->temp[0],
                                                   width - 2, lefty);
                if (!(s->flags & AV_CODEC_FLAG_GRAY)) {
                    leftu = s->llviddsp.add_left_pred(p->data[1] + p->linesize[1] * y_offset + 1, s->temp[1], width2 - 1, leftu);
                    leftv = s->llviddsp.add_left_pred(p->data[2] + p->linesize[2] * y_offset + 1, s->temp[2], width2 - 1, leftv);
                }
 
                for (cy = y = 1; y < height; y++, cy++) {
                    uint8_t *ydst, *udst, *vdst;
 
                    if (s->bitstream_bpp == 12) {
                        decode_gray_bitstream(s, width);
 
                        ydst = p->data[0] + p->linesize[0] * (y + y_offset);
 
                        lefty = s->llviddsp.add_left_pred(ydst, s->temp[0],
                                                           width, lefty);
                        if (s->predictor == PLANE) {
                            if (y > s->interlaced)
                                s->llviddsp.add_bytes(ydst, ydst - fake_ystride, width);
                        }
                        y++;
                        if (y >= height)
                            break;
                    }
 
                    draw_slice(s, avctx, p, y);
 
                    ydst = p->data[0] + p->linesize[0] * (y  + y_offset);
                    udst = p->data[1] + p->linesize[1] * (cy + y_offset);
                    vdst = p->data[2] + p->linesize[2] * (cy + y_offset);
 
                    decode_422_bitstream(s, width);
                    lefty = s->llviddsp.add_left_pred(ydst, s->temp[0],
                                                       width, lefty);
                    if (!(s->flags & AV_CODEC_FLAG_GRAY)) {
                        leftu = s->llviddsp.add_left_pred(udst, s->temp[1], width2, leftu);
                        leftv = s->llviddsp.add_left_pred(vdst, s->temp[2], width2, leftv);
                    }
                    if (s->predictor == PLANE) {
                        if (cy > s->interlaced) {
                            s->llviddsp.add_bytes(ydst, ydst - fake_ystride, width);
                            if (!(s->flags & AV_CODEC_FLAG_GRAY)) {
                                s->llviddsp.add_bytes(udst, udst - fake_ustride, width2);
                                s->llviddsp.add_bytes(vdst, vdst - fake_vstride, width2);
                            }
                        }
                    }
                }
                draw_slice(s, avctx, p, height);
 
                break;
            case MEDIAN:
                /* first line except first 2 pixels is left predicted */
                decode_422_bitstream(s, width - 2);
                lefty = s->llviddsp.add_left_pred(p->data[0] + 2, s->temp[0],
                                                   width - 2, lefty);
                if (!(s->flags & AV_CODEC_FLAG_GRAY)) {
                    leftu = s->llviddsp.add_left_pred(p->data[1] + 1, s->temp[1], width2 - 1, leftu);
                    leftv = s->llviddsp.add_left_pred(p->data[2] + 1, s->temp[2], width2 - 1, leftv);
                }
 
                cy = y = 1;
                if (y >= height)
                    break;
 
                /* second line is left predicted for interlaced case */
                if (s->interlaced) {
                    decode_422_bitstream(s, width);
                    lefty = s->llviddsp.add_left_pred(p->data[0] + p->linesize[0],
                                                       s->temp[0], width, lefty);
                    if (!(s->flags & AV_CODEC_FLAG_GRAY)) {
                        leftu = s->llviddsp.add_left_pred(p->data[1] + p->linesize[2], s->temp[1], width2, leftu);
                        leftv = s->llviddsp.add_left_pred(p->data[2] + p->linesize[1], s->temp[2], width2, leftv);
                    }
                    y++;
                    cy++;
                    if (y >= height)
                        break;
                }
 
                /* next 4 pixels are left predicted too */
                decode_422_bitstream(s, 4);
                lefty = s->llviddsp.add_left_pred(p->data[0] + fake_ystride,
                                                   s->temp[0], 4, lefty);
                if (!(s->flags & AV_CODEC_FLAG_GRAY)) {
                    leftu = s->llviddsp.add_left_pred(p->data[1] + fake_ustride, s->temp[1], 2, leftu);
                    leftv = s->llviddsp.add_left_pred(p->data[2] + fake_vstride, s->temp[2], 2, leftv);
                }
 
                /* next line except the first 4 pixels is median predicted */
                lefttopy = p->data[0][3];
                decode_422_bitstream(s, width - 4);
                s->llviddsp.add_median_pred(p->data[0] + fake_ystride + 4,
                                             p->data[0] + 4, s->temp[0],
                                             width - 4, &lefty, &lefttopy);
                if (!(s->flags & AV_CODEC_FLAG_GRAY)) {
                    lefttopu = p->data[1][1];
                    lefttopv = p->data[2][1];
                    s->llviddsp.add_median_pred(p->data[1] + fake_ustride + 2, p->data[1] + 2, s->temp[1], width2 - 2, &leftu, &lefttopu);
                    s->llviddsp.add_median_pred(p->data[2] + fake_vstride + 2, p->data[2] + 2, s->temp[2], width2 - 2, &leftv, &lefttopv);
                }
                y++;
                cy++;
 
                for (; y < height; y++, cy++) {
                    uint8_t *ydst, *udst, *vdst;
 
                    if (s->bitstream_bpp == 12) {
                        while (2 * cy > y) {
                            decode_gray_bitstream(s, width);
                            ydst = p->data[0] + p->linesize[0] * y;
                            s->llviddsp.add_median_pred(ydst, ydst - fake_ystride,
                                                         s->temp[0], width,
                                                         &lefty, &lefttopy);
                            y++;
                        }
                        if (y >= height)
                            break;
                    }
                    draw_slice(s, avctx, p, y);
 
                    decode_422_bitstream(s, width);
 
                    ydst = p->data[0] + p->linesize[0] * y;
                    udst = p->data[1] + p->linesize[1] * cy;
                    vdst = p->data[2] + p->linesize[2] * cy;
 
                    s->llviddsp.add_median_pred(ydst, ydst - fake_ystride,
                                                 s->temp[0], width,
                                                 &lefty, &lefttopy);
                    if (!(s->flags & AV_CODEC_FLAG_GRAY)) {
                        s->llviddsp.add_median_pred(udst, udst - fake_ustride, s->temp[1], width2, &leftu, &lefttopu);
                        s->llviddsp.add_median_pred(vdst, vdst - fake_vstride, s->temp[2], width2, &leftv, &lefttopv);
                    }
                }
 
                draw_slice(s, avctx, p, height);
                break;
            }
        }
    } else {
        int y;
        uint8_t left[4];
        const int last_line = (y_offset + height - 1) * p->linesize[0];
 
        if (s->bitstream_bpp == 32) {
            left[A] = p->data[0][last_line + A] = get_bits(&s->gb, 8);
            left[R] = p->data[0][last_line + R] = get_bits(&s->gb, 8);
            left[G] = p->data[0][last_line + G] = get_bits(&s->gb, 8);
            left[B] = p->data[0][last_line + B] = get_bits(&s->gb, 8);
        } else {
            left[R] = p->data[0][last_line + R] = get_bits(&s->gb, 8);
            left[G] = p->data[0][last_line + G] = get_bits(&s->gb, 8);
            left[B] = p->data[0][last_line + B] = get_bits(&s->gb, 8);
            left[A] = p->data[0][last_line + A] = 255;
            skip_bits(&s->gb, 8);
        }
 
        if (s->bgr32) {
            switch (s->predictor) {
            case LEFT:
            case PLANE:
                decode_bgr_bitstream(s, width - 1);
                s->hdsp.add_hfyu_left_pred_bgr32(p->data[0] + last_line + 4,
                                                 s->temp[0], width - 1, left);
 
                for (y = height - 2; y >= 0; y--) { // Yes it is stored upside down.
                    decode_bgr_bitstream(s, width);
 
                    s->hdsp.add_hfyu_left_pred_bgr32(p->data[0] + p->linesize[0] * (y + y_offset),
                                                     s->temp[0], width, left);
                    if (s->predictor == PLANE) {
                        if (s->bitstream_bpp != 32)
                            left[A] = 0;
                        if (y < height - 1 - s->interlaced) {
                            s->llviddsp.add_bytes(p->data[0] + p->linesize[0] * (y + y_offset),
                                              p->data[0] + p->linesize[0] * (y + y_offset) +
                                              fake_ystride, 4 * width);
                        }
                    }
                }
                // just 1 large slice as this is not possible in reverse order
                draw_slice(s, avctx, p, height);
                break;
            default:
                av_log(avctx, AV_LOG_ERROR,
                       "prediction type not supported!\n");
            }
        } else {
            av_log(avctx, AV_LOG_ERROR,
                   "BGR24 output is not implemented yet\n");
            return AVERROR_PATCHWELCOME;
        }
    }
 
    return 0;
}
 
static int decode_frame(AVCodecContext *avctx, AVFrame *p,
                        int *got_frame, AVPacket *avpkt)
{
    const uint8_t *buf = avpkt->data;
    int buf_size       = avpkt->size;
    HYuvDecContext *s = avctx->priv_data;
    const int width  = avctx->width;
    const int height = avctx->height;
    int slice, table_size = 0, ret, nb_slices;
    unsigned slices_info_offset;
    int slice_height;
 
    if (buf_size < (width * height + 7)/8)
        return AVERROR_INVALIDDATA;
 
    av_fast_padded_malloc(&s->bitstream_buffer,
                   &s->bitstream_buffer_size,
                   buf_size);
    if (!s->bitstream_buffer)
        return AVERROR(ENOMEM);
 
    s->bdsp.bswap_buf((uint32_t *) s->bitstream_buffer,
                      (const uint32_t *) buf, buf_size / 4);
 
    if ((ret = ff_thread_get_buffer(avctx, p, 0)) < 0)
        return ret;
 
    if (s->context) {
        table_size = read_huffman_tables(s, s->bitstream_buffer, buf_size);
        if (table_size < 0)
            return table_size;
    }
 
    if ((unsigned) (buf_size - table_size) >= INT_MAX / 8)
        return AVERROR_INVALIDDATA;
 
    s->last_slice_end = 0;
 
    if (avctx->codec_id == AV_CODEC_ID_HYMT &&
        (buf_size > 32 && AV_RL32(avpkt->data + buf_size - 16) == 0)) {
        slices_info_offset = AV_RL32(avpkt->data + buf_size - 4);
        slice_height = AV_RL32(avpkt->data + buf_size - 8);
        nb_slices = AV_RL32(avpkt->data + buf_size - 12);
        if (nb_slices * 8LL + slices_info_offset > buf_size - 16 ||
            s->chroma_v_shift ||
            slice_height <= 0 || nb_slices * (uint64_t)slice_height > height)
            return AVERROR_INVALIDDATA;
    } else {
        slice_height = height;
        nb_slices = 1;
    }
 
    for (slice = 0; slice < nb_slices; slice++) {
        int y_offset, slice_offset, slice_size;
 
        if (nb_slices > 1) {
            slice_offset = AV_RL32(avpkt->data + slices_info_offset + slice * 8);
            slice_size = AV_RL32(avpkt->data + slices_info_offset + slice * 8 + 4);
 
            if (slice_offset < 0 || slice_size <= 0 || (slice_offset&3) ||
                slice_offset + (int64_t)slice_size > buf_size)
                return AVERROR_INVALIDDATA;
 
            y_offset = height - (slice + 1) * slice_height;
            s->bdsp.bswap_buf((uint32_t *)s->bitstream_buffer,
                              (const uint32_t *)(buf + slice_offset), slice_size / 4);
        } else {
            y_offset = 0;
            slice_offset = 0;
            slice_size = buf_size;
        }
 
        ret = decode_slice(avctx, p, slice_height, slice_size, y_offset, table_size);
        if (ret < 0)
            return ret;
    }
 
    *got_frame = 1;
 
    return (get_bits_count(&s->gb) + 31) / 32 * 4 + table_size;
}
 
const FFCodec ff_huffyuv_decoder = {
    .p.name           = "huffyuv",
    CODEC_LONG_NAME("Huffyuv / HuffYUV"),
    .p.type           = AVMEDIA_TYPE_VIDEO,
    .p.id             = AV_CODEC_ID_HUFFYUV,
    .priv_data_size   = sizeof(HYuvDecContext),
    .init             = decode_init,
    .close            = decode_end,
    FF_CODEC_DECODE_CB(decode_frame),
    .p.capabilities   = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_DRAW_HORIZ_BAND |
                        AV_CODEC_CAP_FRAME_THREADS,
    .caps_internal    = FF_CODEC_CAP_INIT_CLEANUP,
};
 
#if CONFIG_FFVHUFF_DECODER
const FFCodec ff_ffvhuff_decoder = {
    .p.name           = "ffvhuff",
    CODEC_LONG_NAME("Huffyuv FFmpeg variant"),
    .p.type           = AVMEDIA_TYPE_VIDEO,
    .p.id             = AV_CODEC_ID_FFVHUFF,
    .priv_data_size   = sizeof(HYuvDecContext),
    .init             = decode_init,
    .close            = decode_end,
    FF_CODEC_DECODE_CB(decode_frame),
    .p.capabilities   = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_DRAW_HORIZ_BAND |
                        AV_CODEC_CAP_FRAME_THREADS,
    .caps_internal    = FF_CODEC_CAP_INIT_CLEANUP,
};
#endif /* CONFIG_FFVHUFF_DECODER */
 
#if CONFIG_HYMT_DECODER
const FFCodec ff_hymt_decoder = {
    .p.name           = "hymt",
    CODEC_LONG_NAME("HuffYUV MT"),
    .p.type           = AVMEDIA_TYPE_VIDEO,
    .p.id             = AV_CODEC_ID_HYMT,
    .priv_data_size   = sizeof(HYuvDecContext),
    .init             = decode_init,
    .close            = decode_end,
    FF_CODEC_DECODE_CB(decode_frame),
    .p.capabilities   = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_DRAW_HORIZ_BAND |
                        AV_CODEC_CAP_FRAME_THREADS,
    .caps_internal    = FF_CODEC_CAP_INIT_CLEANUP,
};
#endif /* CONFIG_HYMT_DECODER */