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/*
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 * Wing Commander/Xan Video Decoder
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 * Copyright (C) 2003 the ffmpeg project
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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/xan.c
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 * Xan video decoder for Wing Commander III computer game
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 * by Mario Brito (mbrito@student.dei.uc.pt)
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 * and Mike Melanson (melanson@pcisys.net)
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 *
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 * The xan_wc3 decoder outputs PAL8 data.
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 */
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include "libavutil/intreadwrite.h"
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#include "avcodec.h"
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// for av_memcpy_backptr
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#include "libavutil/lzo.h"
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typedef struct XanContext {
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    AVCodecContext *avctx;
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    AVFrame last_frame;
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    AVFrame current_frame;
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    const unsigned char *buf;
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    int size;
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    /* scratch space */
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    unsigned char *buffer1;
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    int buffer1_size;
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    unsigned char *buffer2;
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    int buffer2_size;
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    int frame_size;
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} XanContext;
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static av_cold int xan_decode_init(AVCodecContext *avctx)
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{
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    XanContext *s = avctx->priv_data;
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    s->avctx = avctx;
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    s->frame_size = 0;
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    if ((avctx->codec->id == CODEC_ID_XAN_WC3) &&
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        (s->avctx->palctrl == NULL)) {
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        av_log(avctx, AV_LOG_ERROR, " WC3 Xan video: palette expected.\n");
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        return -1;
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    }
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    avctx->pix_fmt = PIX_FMT_PAL8;
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    if(avcodec_check_dimensions(avctx, avctx->width, avctx->height))
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        return -1;
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    s->buffer1_size = avctx->width * avctx->height;
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    s->buffer1 = av_malloc(s->buffer1_size);
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    s->buffer2_size = avctx->width * avctx->height;
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    s->buffer2 = av_malloc(s->buffer2_size + 12);
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    if (!s->buffer1 || !s->buffer2)
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        return -1;
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    return 0;
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}
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static int xan_huffman_decode(unsigned char *dest, const unsigned char *src,
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    int dest_len)
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{
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    unsigned char byte = *src++;
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    unsigned char ival = byte + 0x16;
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    const unsigned char * ptr = src + byte*2;
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    unsigned char val = ival;
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    int counter = 0;
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    unsigned char *dest_end = dest + dest_len;
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    unsigned char bits = *ptr++;
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    while ( val != 0x16 ) {
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        if ( (1 << counter) & bits )
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            val = src[byte + val - 0x17];
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        else
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            val = src[val - 0x17];
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        if ( val < 0x16 ) {
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            if (dest + 1 > dest_end)
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                return 0;
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            *dest++ = val;
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            val = ival;
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        }
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        if (counter++ == 7) {
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            counter = 0;
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            bits = *ptr++;
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        }
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    }
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    return 0;
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}
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/**
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 * unpack simple compression
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 *
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 * @param dest destination buffer of dest_len, must be sufficiently padded for av_memcpy_backptr
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 */
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static void xan_unpack(unsigned char *dest, const unsigned char *src, int dest_len)
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{
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    unsigned char opcode;
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    int size;
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    int offset;
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    int byte1, byte2, byte3;
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    unsigned char *dest_end = dest + dest_len;
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    for (;;) {
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        opcode = *src++;
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        if ( (opcode & 0x80) == 0 ) {
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            offset = *src++;
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            size = opcode & 3;
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            if (size > dest_end - dest)
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                return;
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            memcpy(dest, src, size);  dest += size;  src += size;
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            size = ((opcode & 0x1c) >> 2) + 3;
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            if (size > dest_end - dest)
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                return;
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            av_memcpy_backptr(dest, ((opcode & 0x60) << 3) + offset + 1, size);
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            dest += size;
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        } else if ( (opcode & 0x40) == 0 ) {
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            byte1 = *src++;
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            byte2 = *src++;
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            size = byte1 >> 6;
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            if (size > dest_end - dest)
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                return;
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            memcpy(dest, src, size);  dest += size;  src += size;
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            size = (opcode & 0x3f) + 4;
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            if (size > dest_end - dest)
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                return;
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            av_memcpy_backptr(dest, ((byte1 & 0x3f) << 8) + byte2 + 1, size);
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            dest += size;
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        } else if ( (opcode & 0x20) == 0 ) {
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            byte1 = *src++;
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            byte2 = *src++;
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            byte3 = *src++;
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            size = opcode & 3;
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            if (size > dest_end - dest)
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                return;
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            memcpy(dest, src, size);  dest += size;  src += size;
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            size = byte3 + 5 + ((opcode & 0xc) << 6);
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            if (size > dest_end - dest)
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                return;
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            av_memcpy_backptr(dest,
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                ((opcode & 0x10) << 12) + 1 + (byte1 << 8) + byte2,
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                size);
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            dest += size;
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        } else {
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            size = ((opcode & 0x1f) << 2) + 4;
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            if (size > 0x70)
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                break;
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            if (size > dest_end - dest)
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                return;
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            memcpy(dest, src, size);  dest += size;  src += size;
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        }
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    }
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    size = opcode & 3;
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    memcpy(dest, src, size);  dest += size;  src += size;
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}
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static inline void xan_wc3_output_pixel_run(XanContext *s,
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    const unsigned char *pixel_buffer, int x, int y, int pixel_count)
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{
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    int stride;
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    int line_inc;
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    int index;
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    int current_x;
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    int width = s->avctx->width;
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    unsigned char *palette_plane;
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    palette_plane = s->current_frame.data[0];
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    stride = s->current_frame.linesize[0];
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    line_inc = stride - width;
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    index = y * stride + x;
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    current_x = x;
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    while((pixel_count--) && (index < s->frame_size)) {
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        /* don't do a memcpy() here; keyframes generally copy an entire
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         * frame of data and the stride needs to be accounted for */
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        palette_plane[index++] = *pixel_buffer++;
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        current_x++;
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        if (current_x >= width) {
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            index += line_inc;
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            current_x = 0;
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        }
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    }
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}
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static inline void xan_wc3_copy_pixel_run(XanContext *s,
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    int x, int y, int pixel_count, int motion_x, int motion_y)
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{
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    int stride;
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    int line_inc;
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    int curframe_index, prevframe_index;
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    int curframe_x, prevframe_x;
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    int width = s->avctx->width;
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    unsigned char *palette_plane, *prev_palette_plane;
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    palette_plane = s->current_frame.data[0];
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    prev_palette_plane = s->last_frame.data[0];
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    stride = s->current_frame.linesize[0];
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    line_inc = stride - width;
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    curframe_index = y * stride + x;
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    curframe_x = x;
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    prevframe_index = (y + motion_y) * stride + x + motion_x;
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    prevframe_x = x + motion_x;
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    while((pixel_count--) && (curframe_index < s->frame_size)) {
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        palette_plane[curframe_index++] =
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            prev_palette_plane[prevframe_index++];
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        curframe_x++;
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        if (curframe_x >= width) {
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            curframe_index += line_inc;
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            curframe_x = 0;
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        }
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        prevframe_x++;
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        if (prevframe_x >= width) {
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            prevframe_index += line_inc;
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            prevframe_x = 0;
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        }
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    }
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}
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static void xan_wc3_decode_frame(XanContext *s) {
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    int width = s->avctx->width;
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    int height = s->avctx->height;
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    int total_pixels = width * height;
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    unsigned char opcode;
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    unsigned char flag = 0;
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    int size = 0;
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    int motion_x, motion_y;
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    int x, y;
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    unsigned char *opcode_buffer = s->buffer1;
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    int opcode_buffer_size = s->buffer1_size;
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    const unsigned char *imagedata_buffer = s->buffer2;
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    /* pointers to segments inside the compressed chunk */
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    const unsigned char *huffman_segment;
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    const unsigned char *size_segment;
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    const unsigned char *vector_segment;
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    const unsigned char *imagedata_segment;
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    huffman_segment =   s->buf + AV_RL16(&s->buf[0]);
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    size_segment =      s->buf + AV_RL16(&s->buf[2]);
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    vector_segment =    s->buf + AV_RL16(&s->buf[4]);
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    imagedata_segment = s->buf + AV_RL16(&s->buf[6]);
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    xan_huffman_decode(opcode_buffer, huffman_segment, opcode_buffer_size);
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    if (imagedata_segment[0] == 2)
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        xan_unpack(s->buffer2, &imagedata_segment[1], s->buffer2_size);
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    else
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        imagedata_buffer = &imagedata_segment[1];
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    /* use the decoded data segments to build the frame */
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    x = y = 0;
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    while (total_pixels) {
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        opcode = *opcode_buffer++;
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        size = 0;
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        switch (opcode) {
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        case 0:
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            flag ^= 1;
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            continue;
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        case 1:
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        case 2:
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        case 3:
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        case 4:
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        case 5:
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        case 6:
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        case 7:
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        case 8:
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            size = opcode;
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            break;
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        case 12:
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        case 13:
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        case 14:
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        case 15:
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        case 16:
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        case 17:
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        case 18:
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            size += (opcode - 10);
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            break;
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        case 9:
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        case 19:
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            size = *size_segment++;
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            break;
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        case 10:
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        case 20:
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            size = AV_RB16(&size_segment[0]);
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            size_segment += 2;
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            break;
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        case 11:
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        case 21:
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            size = AV_RB24(size_segment);
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            size_segment += 3;
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            break;
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        }
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        if (opcode < 12) {
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            flag ^= 1;
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            if (flag) {
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                /* run of (size) pixels is unchanged from last frame */
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                xan_wc3_copy_pixel_run(s, x, y, size, 0, 0);
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            } else {
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                /* output a run of pixels from imagedata_buffer */
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                xan_wc3_output_pixel_run(s, imagedata_buffer, x, y, size);
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                imagedata_buffer += size;
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            }
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        } else {
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            /* run-based motion compensation from last frame */
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            motion_x = (*vector_segment >> 4) & 0xF;
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            motion_y = *vector_segment & 0xF;
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            vector_segment++;
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            /* sign extension */
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            if (motion_x & 0x8)
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                motion_x |= 0xFFFFFFF0;
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            if (motion_y & 0x8)
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                motion_y |= 0xFFFFFFF0;
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            /* copy a run of pixels from the previous frame */
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            xan_wc3_copy_pixel_run(s, x, y, size, motion_x, motion_y);
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            flag = 0;
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        }
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        /* coordinate accounting */
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        total_pixels -= size;
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        while (size) {
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            if (x + size >= width) {
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                y++;
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                size -= (width - x);
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                x = 0;
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            } else {
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                x += size;
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                size = 0;
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            }
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        }
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    }
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}
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static void xan_wc4_decode_frame(XanContext *s) {
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}
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static int xan_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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    const uint8_t *buf = avpkt->data;
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    int buf_size = avpkt->size;
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    XanContext *s = avctx->priv_data;
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    AVPaletteControl *palette_control = avctx->palctrl;
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    if (avctx->get_buffer(avctx, &s->current_frame)) {
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        av_log(s->avctx, AV_LOG_ERROR, "  Xan Video: get_buffer() failed\n");
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        return -1;
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    }
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    s->current_frame.reference = 3;
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    if (!s->frame_size)
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        s->frame_size = s->current_frame.linesize[0] * s->avctx->height;
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    palette_control->palette_changed = 0;
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    memcpy(s->current_frame.data[1], palette_control->palette,
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        AVPALETTE_SIZE);
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    s->current_frame.palette_has_changed = 1;
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    s->buf = buf;
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    s->size = buf_size;
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    if (avctx->codec->id == CODEC_ID_XAN_WC3)
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        xan_wc3_decode_frame(s);
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    else if (avctx->codec->id == CODEC_ID_XAN_WC4)
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        xan_wc4_decode_frame(s);
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    /* release the last frame if it is allocated */
432
    if (s->last_frame.data[0])
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        avctx->release_buffer(avctx, &s->last_frame);
434

    
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    *data_size = sizeof(AVFrame);
436
    *(AVFrame*)data = s->current_frame;
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    /* shuffle frames */
439
    FFSWAP(AVFrame, s->current_frame, s->last_frame);
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    /* always report that the buffer was completely consumed */
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    return buf_size;
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}
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static av_cold int xan_decode_end(AVCodecContext *avctx)
446
{
447
    XanContext *s = avctx->priv_data;
448

    
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    /* release the frames */
450
    if (s->last_frame.data[0])
451
        avctx->release_buffer(avctx, &s->last_frame);
452
    if (s->current_frame.data[0])
453
        avctx->release_buffer(avctx, &s->current_frame);
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455
    av_free(s->buffer1);
456
    av_free(s->buffer2);
457

    
458
    return 0;
459
}
460

    
461
AVCodec xan_wc3_decoder = {
462
    "xan_wc3",
463
    CODEC_TYPE_VIDEO,
464
    CODEC_ID_XAN_WC3,
465
    sizeof(XanContext),
466
    xan_decode_init,
467
    NULL,
468
    xan_decode_end,
469
    xan_decode_frame,
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    CODEC_CAP_DR1,
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    .long_name = NULL_IF_CONFIG_SMALL("Wing Commander III / Xan"),
472
};
473

    
474
/*
475
AVCodec xan_wc4_decoder = {
476
    "xan_wc4",
477
    CODEC_TYPE_VIDEO,
478
    CODEC_ID_XAN_WC4,
479
    sizeof(XanContext),
480
    xan_decode_init,
481
    NULL,
482
    xan_decode_end,
483
    xan_decode_frame,
484
    CODEC_CAP_DR1,
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};
486
*/