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/*
* Copyright (C) 2004-2012 Geometer Plus <[email protected]>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*/
#include "LZXDecompressor.h"
void LZXDecompressor::E8Decoder::reset(unsigned int fileSize) {
myFileSize = fileSize;
myFramesCounter = 0;
myPosition = 0;
}
void LZXDecompressor::E8Decoder::decode(unsigned char *buffer, const std::size_t size) {
if (myFramesCounter >= 32768) {
return;
}
++myFramesCounter;
if (myFileSize == 0) {
return;
}
myPosition += size;
if (size <= 10) {
return;
}
const unsigned char *end = buffer + size - 10;
for (unsigned char *ptr = buffer; ptr < end; ) {
if (*ptr == 0xE8) {
int absoluteOffset =
ptr[1] + (ptr[2] << 8) + (ptr[3] << 16) + (ptr[4] << 24);
int relativeOffset =
(absoluteOffset >= 0) ?
absoluteOffset - (ptr - buffer) : absoluteOffset + myFileSize;
ptr[1] = (unsigned char)relativeOffset;
ptr[2] = (unsigned char)(relativeOffset >> 8);
ptr[3] = (unsigned char)(relativeOffset >> 16);
ptr[4] = (unsigned char)(relativeOffset >> 24);
ptr += 5;
} else {
++ptr;
}
}
}
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