/*
* Copyright (C) 2001, 2002, and 2003 Roy Keene
*
* 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, see <http://www.gnu.org/licenses/>.
*
* email: dact@rkeene.org
*/
#include "dact.h"
#include "comp_textrle.h"
#include <stdio.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#ifdef HAVE_STDLIB_H
#include <stdlib.h>
#endif
/*
mode - DACT_MODE_COMPR or DACT_MODE_DECMP
Determine whether to compress or decompress.
prev_block - Previous (uncompressed) block.
curr_block - The data to be compressed.
out_block - Where to put data after compression.
blk_size - Size of prev_block and curr_block.
*/
#if defined(AS_MODULE) && defined(USE_MODULES)
#include "module.h"
uint32_t DACT_MOD_NUM=12;
uint32_t DACT_MOD_TYPE=DACT_MOD_TYPE_COMP;
void *DACT_MOD_ALGO=comp_textrle_algo;
char *DACT_MOD_NAME="Text RLE Compression (MOD)";
#endif
int comp_textrle_algo(int mode, unsigned char *prev_block, unsigned char *curr_block, char *out_block, int blk_size, int bufsize) {
switch(mode) {
case DACT_MODE_COMPR:
return(comp_textrle_compress(prev_block, curr_block, out_block, blk_size, bufsize));
break; /* Heh */
case DACT_MODE_DECMP:
return(comp_textrle_decompress(prev_block, curr_block, out_block, blk_size, bufsize));
break;
default:
printf("Unsupported mode: %i\n", mode);
return(-1);
}
}
int comp_textrle_compress(unsigned char *prev_block, unsigned char *curr_block, char *out_block, int blk_size, int bufsize) {
int i,x=0,m;
unsigned char sentinel=0xff;
unsigned char currchar=0, prevchar;
unsigned char charcnt=0;
unsigned int lowestcnt=0xffff;
unsigned int count[256];
for (i=0;i<256;i++) count[i]=0;
for (i=0;i<blk_size;i++) count[curr_block[i]]++;
for (i=0;i<256;i++) {
if (count[i]<lowestcnt) {
sentinel=i;
lowestcnt=count[i];
}
}
out_block[x++]=sentinel;
return(x);
}
int comp_textrle_decompress(unsigned char *prev_block, unsigned char *curr_block, char *out_block, int blk_size, int bufsize) {
int i,x=0,m;
unsigned char sentinel=curr_block[0];
unsigned char currchar;
unsigned char charcnt;
for (i=1;i<blk_size;i++) {
currchar=curr_block[i];
if (currchar==sentinel) {
currchar=curr_block[++i];
charcnt=curr_block[++i];
if ((x+charcnt)>bufsize) {
printf("Error in RLE compression!\n");
return(0);
}
for (m=0;m<charcnt;m++) out_block[x++]=currchar;
} else {
out_block[x++]=currchar;
}
}
return(x);
}