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/*
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 * Chronomaster DFA Video Decoder
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 * Copyright (c) 2011 Konstantin Shishkov
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 * based on work by Vladimir "VAG" Gneushev
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 *
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 * This file is part of Libav.
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 *
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 * Libav 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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 * Libav 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 Libav; 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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#include "avcodec.h"
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#include "libavutil/intreadwrite.h"
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#include "bytestream.h"
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#include "libavutil/lzo.h" // for av_memcpy_backptr
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typedef struct DfaContext {
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    AVFrame pic;
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    uint32_t pal[256];
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    uint8_t *frame_buf;
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} DfaContext;
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static av_cold int dfa_decode_init(AVCodecContext *avctx)
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{
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    DfaContext *s = avctx->priv_data;
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    avctx->pix_fmt = PIX_FMT_PAL8;
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    s->frame_buf = av_mallocz(avctx->width * avctx->height + AV_LZO_OUTPUT_PADDING);
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    if (!s->frame_buf)
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        return AVERROR(ENOMEM);
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    return 0;
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}
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static int decode_copy(uint8_t *frame, int width, int height,
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                       const uint8_t *src, const uint8_t *src_end)
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{
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    const int size = width * height;
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    if (src_end - src < size)
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        return -1;
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    bytestream_get_buffer(&src, frame, size);
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    return 0;
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}
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static int decode_tsw1(uint8_t *frame, int width, int height,
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                       const uint8_t *src, const uint8_t *src_end)
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{
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    const uint8_t *frame_start = frame;
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    const uint8_t *frame_end   = frame + width * height;
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    int mask = 0x10000, bitbuf = 0;
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    int v, offset, count, segments;
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    segments = bytestream_get_le32(&src);
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    frame   += bytestream_get_le32(&src);
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    if (frame < frame_start || frame > frame_end)
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        return -1;
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    while (segments--) {
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        if (mask == 0x10000) {
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            if (src >= src_end)
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                return -1;
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            bitbuf = bytestream_get_le16(&src);
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            mask = 1;
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        }
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        if (src_end - src < 2 || frame_end - frame < 2)
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            return -1;
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        if (bitbuf & mask) {
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            v = bytestream_get_le16(&src);
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            offset = (v & 0x1FFF) << 1;
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            count = ((v >> 13) + 2) << 1;
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            if (frame - frame_start < offset || frame_end - frame < count)
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                return -1;
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            av_memcpy_backptr(frame, offset, count);
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            frame += count;
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        } else {
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            *frame++ = *src++;
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            *frame++ = *src++;
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        }
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        mask <<= 1;
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    }
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    return 0;
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}
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static int decode_dsw1(uint8_t *frame, int width, int height,
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                       const uint8_t *src, const uint8_t *src_end)
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{
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    const uint8_t *frame_start = frame;
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    const uint8_t *frame_end   = frame + width * height;
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    int mask = 0x10000, bitbuf = 0;
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    int v, offset, count, segments;
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    segments = bytestream_get_le16(&src);
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    while (segments--) {
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        if (mask == 0x10000) {
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            if (src >= src_end)
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                return -1;
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            bitbuf = bytestream_get_le16(&src);
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            mask = 1;
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        }
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        if (src_end - src < 2 || frame_end - frame < 2)
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            return -1;
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        if (bitbuf & mask) {
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            v = bytestream_get_le16(&src);
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            offset = (v & 0x1FFF) << 1;
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            count = ((v >> 13) + 2) << 1;
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            if (frame - frame_start < offset || frame_end - frame < count)
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                return -1;
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            // can't use av_memcpy_backptr() since it can overwrite following pixels
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            for (v = 0; v < count; v++)
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                frame[v] = frame[v - offset];
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            frame += count;
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        } else if (bitbuf & (mask << 1)) {
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            frame += bytestream_get_le16(&src);
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        } else {
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            *frame++ = *src++;
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            *frame++ = *src++;
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        }
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        mask <<= 2;
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    }
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    return 0;
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}
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static int decode_dds1(uint8_t *frame, int width, int height,
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                       const uint8_t *src, const uint8_t *src_end)
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{
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    const uint8_t *frame_start = frame;
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    const uint8_t *frame_end   = frame + width * height;
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    int mask = 0x10000, bitbuf = 0;
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    int i, v, offset, count, segments;
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    segments = bytestream_get_le16(&src);
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    while (segments--) {
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        if (mask == 0x10000) {
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            if (src >= src_end)
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                return -1;
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            bitbuf = bytestream_get_le16(&src);
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            mask = 1;
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        }
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        if (src_end - src < 2 || frame_end - frame < 2)
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            return -1;
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        if (bitbuf & mask) {
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            v = bytestream_get_le16(&src);
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            offset = (v & 0x1FFF) << 2;
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            count = ((v >> 13) + 2) << 1;
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            if (frame - frame_start < offset || frame_end - frame < count*2 + width)
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                return -1;
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            for (i = 0; i < count; i++) {
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                frame[0] = frame[1] =
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                frame[width] = frame[width + 1] = frame[-offset];
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                frame += 2;
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            }
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        } else if (bitbuf & (mask << 1)) {
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            frame += bytestream_get_le16(&src) * 2;
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        } else {
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            frame[0] = frame[1] =
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            frame[width] = frame[width + 1] =  *src++;
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            frame += 2;
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            frame[0] = frame[1] =
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            frame[width] = frame[width + 1] =  *src++;
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            frame += 2;
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        }
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        mask <<= 2;
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    }
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    return 0;
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}
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static int decode_bdlt(uint8_t *frame, int width, int height,
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                       const uint8_t *src, const uint8_t *src_end)
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{
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    const uint8_t *frame_end = frame + width * height;
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    uint8_t *line_ptr;
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    int count, lines, segments;
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    count = bytestream_get_le16(&src);
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    if (count >= height || width * count < 0)
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        return -1;
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    frame += width * count;
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    lines = bytestream_get_le16(&src);
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    if (frame + lines * width > frame_end || src >= src_end)
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        return -1;
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    while (lines--) {
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        line_ptr = frame;
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        frame += width;
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        segments = *src++;
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        while (segments--) {
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            if (src_end - src < 3)
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                return -1;
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            line_ptr += *src++;
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            if (line_ptr >= frame)
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                return -1;
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            count = (int8_t)*src++;
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            if (count >= 0) {
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                if (line_ptr + count > frame || src_end - src < count)
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                    return -1;
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                bytestream_get_buffer(&src, line_ptr, count);
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            } else {
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                count = -count;
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                if (line_ptr + count > frame || src >= src_end)
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                    return -1;
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                memset(line_ptr, *src++, count);
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            }
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            line_ptr += count;
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        }
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    }
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    return 0;
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}
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static int decode_wdlt(uint8_t *frame, int width, int height,
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                       const uint8_t *src, const uint8_t *src_end)
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{
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    const uint8_t *frame_end   = frame + width * height;
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    uint8_t *line_ptr;
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    int count, i, v, lines, segments;
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    lines = bytestream_get_le16(&src);
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    if (frame + lines * width > frame_end || src >= src_end)
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        return -1;
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    while (lines--) {
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        segments = bytestream_get_le16(&src);
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        while ((segments & 0xC000) == 0xC000) {
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            frame    -= (int16_t)segments * width;
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            if (frame >= frame_end)
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                return -1;
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            segments = bytestream_get_le16(&src);
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        }
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        if (segments & 0x8000) {
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            frame[width - 1] = segments & 0xFF;
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            segments = bytestream_get_le16(&src);
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        }
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        line_ptr = frame;
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        frame += width;
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        while (segments--) {
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            if (src_end - src < 2)
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                return -1;
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            line_ptr += *src++;
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            if (line_ptr >= frame)
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                return -1;
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            count = (int8_t)*src++;
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            if (count >= 0) {
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                if (line_ptr + count*2 > frame || src_end - src < count*2)
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                    return -1;
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                bytestream_get_buffer(&src, line_ptr, count*2);
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                line_ptr += count * 2;
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            } else {
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                count = -count;
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                if (line_ptr + count*2 > frame || src_end - src < 2)
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                    return -1;
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                v = bytestream_get_le16(&src);
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                for (i = 0; i < count; i++)
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                    bytestream_put_le16(&line_ptr, v);
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            }
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        }
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    }
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    return 0;
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}
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static int decode_unk6(uint8_t *frame, int width, int height,
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                       const uint8_t *src, const uint8_t *src_end)
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{
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    return -1;
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}
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static int decode_blck(uint8_t *frame, int width, int height,
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                       const uint8_t *src, const uint8_t *src_end)
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{
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    memset(frame, 0, width * height);
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    return 0;
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}
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typedef int (*chunk_decoder)(uint8_t *frame, int width, int height,
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                             const uint8_t *src, const uint8_t *src_end);
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static const chunk_decoder decoder[8] = {
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    decode_copy, decode_tsw1, decode_bdlt, decode_wdlt,
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    decode_unk6, decode_dsw1, decode_blck, decode_dds1,
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};
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static const char* chunk_name[8] = {
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    "COPY", "TSW1", "BDLT", "WDLT", "????", "DSW1", "BLCK", "DDS1"
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};
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static int dfa_decode_frame(AVCodecContext *avctx,
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                            void *data, int *data_size,
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                            AVPacket *avpkt)
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{
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    DfaContext *s = avctx->priv_data;
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    const uint8_t *buf = avpkt->data;
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    const uint8_t *buf_end = avpkt->data + avpkt->size;
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    const uint8_t *tmp_buf;
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    uint32_t chunk_type, chunk_size;
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    uint8_t *dst;
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    int ret;
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    int i, pal_elems;
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    if (s->pic.data[0])
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        avctx->release_buffer(avctx, &s->pic);
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    if ((ret = avctx->get_buffer(avctx, &s->pic))) {
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        av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
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        return ret;
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    }
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    while (buf < buf_end) {
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        chunk_size = AV_RL32(buf + 4);
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        chunk_type = AV_RL32(buf + 8);
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        buf += 12;
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        if (buf_end - buf < chunk_size) {
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            av_log(avctx, AV_LOG_ERROR, "Chunk size is too big (%d bytes)\n", chunk_size);
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            return -1;
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        }
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        if (!chunk_type)
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            break;
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        if (chunk_type == 1) {
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            pal_elems = FFMIN(chunk_size / 3, 256);
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            tmp_buf = buf;
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            for (i = 0; i < pal_elems; i++) {
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                s->pal[i] = bytestream_get_be24(&tmp_buf) << 2;
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                s->pal[i] |= (s->pal[i] >> 6) & 0x333;
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            }
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            s->pic.palette_has_changed = 1;
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        } else if (chunk_type <= 9) {
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            if (decoder[chunk_type - 2](s->frame_buf, avctx->width, avctx->height,
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                                        buf, buf + chunk_size)) {
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                av_log(avctx, AV_LOG_ERROR, "Error decoding %s chunk\n",
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                       chunk_name[chunk_type - 2]);
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                return -1;
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            }
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        } else {
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            av_log(avctx, AV_LOG_WARNING, "Ignoring unknown chunk type %d\n",
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                   chunk_type);
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        }
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        buf += chunk_size;
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    }
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    buf = s->frame_buf;
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    dst = s->pic.data[0];
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    for (i = 0; i < avctx->height; i++) {
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        memcpy(dst, buf, avctx->width);
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        dst += s->pic.linesize[0];
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        buf += avctx->width;
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    }
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    memcpy(s->pic.data[1], s->pal, sizeof(s->pal));
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    *data_size = sizeof(AVFrame);
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    *(AVFrame*)data = s->pic;
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    return avpkt->size;
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}
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static av_cold int dfa_decode_end(AVCodecContext *avctx)
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{
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    DfaContext *s = avctx->priv_data;
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    if (s->pic.data[0])
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        avctx->release_buffer(avctx, &s->pic);
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    av_freep(&s->frame_buf);
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    return 0;
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}
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AVCodec ff_dfa_decoder = {
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    "dfa",
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    AVMEDIA_TYPE_VIDEO,
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    CODEC_ID_DFA,
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    sizeof(DfaContext),
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    dfa_decode_init,
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    NULL,
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    dfa_decode_end,
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    dfa_decode_frame,
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    CODEC_CAP_DR1,
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    .long_name = NULL_IF_CONFIG_SMALL("Chronomaster DFA"),
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};