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ffmpeg / libavcodec / msrledec.c @ ce60c2d1

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/*
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 * Micrsoft RLE Decoder
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 * Copyright (C) 2008 Konstantin Shishkov
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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 msrledec.c
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 * MS RLE Decoder based on decoder by Mike Melanson and my own for TSCC
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 * For more information about the MS RLE format, visit:
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 *   http://www.multimedia.cx/msrle.txt
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 */
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#include "avcodec.h"
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#define FETCH_NEXT_STREAM_BYTE() \
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    if (stream_ptr >= data_size) \
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    { \
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      av_log(avctx, AV_LOG_ERROR, " MS RLE: stream ptr just went out of bounds (1)\n"); \
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      return -1; \
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    } \
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    stream_byte = data[stream_ptr++];
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static int msrle_decode_pal4(AVCodecContext *avctx, AVPicture *pic,
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                              const uint8_t *data, int data_size)
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{
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    int stream_ptr = 0;
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    unsigned char rle_code;
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    unsigned char extra_byte, odd_pixel;
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    unsigned char stream_byte;
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    int pixel_ptr = 0;
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    int row_dec = pic->linesize[0];
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    int row_ptr = (avctx->height - 1) * row_dec;
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    int frame_size = row_dec * avctx->height;
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    int i;
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    while (row_ptr >= 0) {
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        FETCH_NEXT_STREAM_BYTE();
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        rle_code = stream_byte;
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        if (rle_code == 0) {
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            /* fetch the next byte to see how to handle escape code */
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            FETCH_NEXT_STREAM_BYTE();
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            if (stream_byte == 0) {
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                /* line is done, goto the next one */
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                row_ptr -= row_dec;
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                pixel_ptr = 0;
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            } else if (stream_byte == 1) {
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                /* decode is done */
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                return 0;
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            } else if (stream_byte == 2) {
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                /* reposition frame decode coordinates */
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                FETCH_NEXT_STREAM_BYTE();
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                pixel_ptr += stream_byte;
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                FETCH_NEXT_STREAM_BYTE();
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                row_ptr -= stream_byte * row_dec;
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        } else {
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            // copy pixels from encoded stream
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            odd_pixel =  stream_byte & 1;
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            rle_code = (stream_byte + 1) / 2;
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            extra_byte = rle_code & 0x01;
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            if ((row_ptr + pixel_ptr + stream_byte > frame_size) ||
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                (row_ptr < 0)) {
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                av_log(avctx, AV_LOG_ERROR, " MS RLE: frame ptr just went out of bounds (1)\n");
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                return -1;
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            }
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            for (i = 0; i < rle_code; i++) {
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                if (pixel_ptr >= avctx->width)
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                    break;
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                FETCH_NEXT_STREAM_BYTE();
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                pic->data[0][row_ptr + pixel_ptr] = stream_byte >> 4;
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                pixel_ptr++;
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                if (i + 1 == rle_code && odd_pixel)
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                    break;
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                if (pixel_ptr >= avctx->width)
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                    break;
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                pic->data[0][row_ptr + pixel_ptr] = stream_byte & 0x0F;
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                pixel_ptr++;
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            }
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            // if the RLE code is odd, skip a byte in the stream
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            if (extra_byte)
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              stream_ptr++;
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            }
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        } else {
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            // decode a run of data
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            if ((row_ptr + pixel_ptr + stream_byte > frame_size) ||
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                (row_ptr < 0)) {
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                av_log(avctx, AV_LOG_ERROR, " MS RLE: frame ptr just went out of bounds (1)\n");
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                return -1;
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            }
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            FETCH_NEXT_STREAM_BYTE();
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            for (i = 0; i < rle_code; i++) {
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                if (pixel_ptr >= avctx->width)
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                    break;
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                if ((i & 1) == 0)
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                    pic->data[0][row_ptr + pixel_ptr] = stream_byte >> 4;
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                else
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                    pic->data[0][row_ptr + pixel_ptr] = stream_byte & 0x0F;
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                pixel_ptr++;
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            }
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        }
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    }
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    /* one last sanity check on the way out */
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    if (stream_ptr < data_size) {
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        av_log(avctx, AV_LOG_ERROR, " MS RLE: ended frame decode with bytes left over (%d < %d)\n",
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            stream_ptr, data_size);
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        return -1;
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    }
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    return 0;
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}
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static int msrle_decode_8_16_24_32(AVCodecContext *avctx, AVPicture *pic, int depth,
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                                    const uint8_t *data, int srcsize)
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{
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    uint8_t *output, *output_end;
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    const uint8_t* src = data;
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    int p1, p2, line=avctx->height, pos=0, i;
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    uint16_t pix16;
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    uint32_t pix32;
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    output = pic->data[0] + (avctx->height - 1) * pic->linesize[0];
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    output_end = pic->data[0] + (avctx->height) * pic->linesize[0];
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    while(src < data + srcsize) {
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        p1 = *src++;
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        if(p1 == 0) { //Escape code
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            p2 = *src++;
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            if(p2 == 0) { //End-of-line
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                output = pic->data[0] + (--line) * pic->linesize[0];
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                if (line < 0){
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                    av_log(avctx, AV_LOG_ERROR, "Next line is beyond picture bounds\n");
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                    return -1;
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                }
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                pos = 0;
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                continue;
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            } else if(p2 == 1) { //End-of-picture
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                return 0;
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            } else if(p2 == 2) { //Skip
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                p1 = *src++;
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                p2 = *src++;
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                line -= p2;
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                if (line < 0){
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                    av_log(avctx, AV_LOG_ERROR, "Skip beyond picture bounds\n");
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                    return -1;
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                }
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                pos += p1;
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                output = pic->data[0] + line * pic->linesize[0] + pos * (depth >> 3);
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                continue;
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            }
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            // Copy data
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            if (output + p2 * (depth >> 3) > output_end) {
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                src += p2 * (depth >> 3);
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                continue;
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            }
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            if ((depth == 8) || (depth == 24)) {
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                for(i = 0; i < p2 * (depth >> 3); i++) {
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                    *output++ = *src++;
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                }
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                // RLE8 copy is actually padded - and runs are not!
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                if(depth == 8 && (p2 & 1)) {
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                    src++;
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                }
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            } else if (depth == 16) {
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                for(i = 0; i < p2; i++) {
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                    pix16 = AV_RL16(src);
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                    src += 2;
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                    *(uint16_t*)output = pix16;
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                    output += 2;
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                }
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            } else if (depth == 32) {
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                for(i = 0; i < p2; i++) {
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                    pix32 = AV_RL32(src);
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                    src += 4;
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                    *(uint32_t*)output = pix32;
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                    output += 4;
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                }
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            }
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            pos += p2;
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        } else { //Run of pixels
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            int pix[4]; //original pixel
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            switch(depth){
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            case  8: pix[0] = *src++;
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                     break;
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            case 16: pix16 = AV_RL16(src);
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                     src += 2;
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                     *(uint16_t*)pix = pix16;
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                     break;
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            case 24: pix[0] = *src++;
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                     pix[1] = *src++;
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                     pix[2] = *src++;
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                     break;
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            case 32: pix32 = AV_RL32(src);
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                     src += 4;
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                     *(uint32_t*)pix = pix32;
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                     break;
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            }
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            if (output + p1 * (depth >> 3) > output_end)
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                continue;
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            for(i = 0; i < p1; i++) {
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                switch(depth){
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                case  8: *output++ = pix[0];
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                         break;
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                case 16: *(uint16_t*)output = pix16;
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                         output += 2;
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                         break;
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                case 24: *output++ = pix[0];
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                         *output++ = pix[1];
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                         *output++ = pix[2];
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                         break;
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                case 32: *(uint32_t*)output = pix32;
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                         output += 4;
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                         break;
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                }
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            }
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            pos += p1;
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        }
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    }
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    av_log(avctx, AV_LOG_WARNING, "MS RLE warning: no End-of-picture code\n");
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    return 0;
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}
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int ff_msrle_decode(AVCodecContext *avctx, AVPicture *pic, int depth,
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                    const uint8_t* data, int data_size)
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{
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    switch(depth){
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    case  4:
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        return msrle_decode_pal4(avctx, pic, data, data_size);
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    case  8:
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    case 16:
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    case 24:
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    case 32:
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        return msrle_decode_8_16_24_32(avctx, pic, depth, data, data_size);
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    default:
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        av_log(avctx, AV_LOG_ERROR, "Unknown depth %d\n", depth);
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        return -1;
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    }
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}
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