XADMaster/LZSS.c
2018-03-21 14:24:50 +02:00

63 lines
1.7 KiB
C

/*
* LZSS.c
*
* Copyright (c) 2017-present, MacPaw Inc. All rights reserved.
*
* This library 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.
*
* This library 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 this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA 02110-1301 USA
*/
#include "LZSS.h"
#include <stdlib.h>
#include <string.h>
bool InitializeLZSS(LZSS *self,size_t windowsize)
{
self->window=malloc(windowsize);
if(!self->window) return false;
self->mask=windowsize-1; // Assume windows are power-of-two sized!
RestartLZSS(self);
return true;
}
void CleanupLZSS(LZSS *self)
{
free(self->window);
}
void RestartLZSS(LZSS *self)
{
memset(self->window,0,LZSSWindowSize(self));
self->position=0;
}
void CopyBytesFromLZSSWindow(LZSS *self,uint8_t *buffer,int64_t startpos,int length)
{
size_t windowoffs=LZSSWindowOffsetForPosition(self,startpos);
if(windowoffs+length<=LZSSWindowSize(self)) // Request fits inside window
{
memcpy(buffer,&self->window[windowoffs],length);
}
else // Request wraps around window
{
size_t firstpart=LZSSWindowSize(self)-windowoffs;
memcpy(&buffer[0],&self->window[windowoffs],firstpart);
memcpy(&buffer[firstpart],&self->window[0],length-firstpart);
}
}