/*
* LZG extraction
*
* ----------------------------------------------------------------------------
*
* Authors:
* Enrique Calot <ecalot.cod@princed.com.ar>
*
* Research: Tammo Jan Dijkemma, Anke Balderer, Enrique Calot
*
* ----------------------------------------------------------------------------
*
* Copyright (C) 2004, 2005 the Princed Team
*
* This file is part of the Princed project.
*
* Princed 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.
*
* Princed 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 Library 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#include <stdio.h>
#include <stdlib.h>
#include "compress.h"
/* modulus to be used in the 10 bits of the algorithm */
#define LZG_WINDOW_SIZE 0x400 /* =1024=1<<10 */
/* LZG expansion algorithm sub function */
unsigned char popBit(unsigned char *byte) {
register unsigned char bit=(*byte)&1;
(*byte)>>=1;
return bit;
}
/* Expands LZ Groody algorithm. This is the core of PR */
int expandLzg(tBinary input, unsigned char** output2, int *outputSize) {
int oCursor=0, iCursor=0;
unsigned char maskbyte=0;
unsigned char output[65000];
register int loc;
register unsigned char rep, k;
if (*outputSize) (*outputSize)+=LZG_WINDOW_SIZE; else *outputSize=65000;
/* initialize the first 1024 bytes of the window with zeros */
for(oCursor=0;oCursor<LZG_WINDOW_SIZE;output[oCursor++]=0);
/* main loop */
while (iCursor<input.size&&oCursor<(*outputSize)) {
maskbyte=input.data[iCursor++];
for (k=8;k&&(iCursor<input.size);k--) {
if (popBit(&maskbyte)) {
output[oCursor++]=input.data[iCursor++]; /* copy input.data to output */
} else {
/*
* loc:
* 10 bits for the slide iCursorition (S). Add 66 to this number,
* substract the result to the current oCursor and take the last 10 bits.
* rep:
* 6 bits for the repetition number (R). Add 3 to this number.
*/
loc= 66 + ((input.data[iCursor] & 0x03 /*00000011*/) <<8) + input.data[iCursor+1];
rep= 3 + ((input.data[iCursor] & 0xfc /*11111100*/) >>2);
iCursor+=2; /* move the cursor 2 bytes ahead */
loc=(oCursor-loc)&0x3ff; /* this is the real loc number (allways positive!) */
while (rep--) { /* repeat pattern in output */
output[oCursor]=output[oCursor-loc];
oCursor++;
}
}
}
}
input.size-=iCursor;
/* ignore the first 1024 bytes */
*outputSize=oCursor-LZG_WINDOW_SIZE;
*output2=(unsigned char*)malloc(*outputSize);
for(iCursor=LZG_WINDOW_SIZE;iCursor<oCursor;iCursor++)
(*output2)[iCursor-LZG_WINDOW_SIZE]=output[iCursor];
if (oCursor>=(*outputSize)) return input.size; /* TODO: check if this case never happens !!! */
return (!maskbyte)-1;
/*return rep?COMPRESS_RESULT_WARNING:COMPRESS_RESULT_SUCCESS;*/
}