/*
* 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, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
* email: dact@rkeene.org
*/
/*
Example block compression routine for interfacing with DACT.
Uses zlib.
*/
#include "dact.h"
#include "comp_zlib.h"
#ifdef HAVE_LIBZ
#include <stdio.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#ifdef HAVE_STDLIB_H
#include <stdlib.h>
#endif
#ifdef HAVE_STRING_H
#include <string.h>
#endif
#ifdef HAVE_ZLIB_H
#include <zlib.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(USE_MODULES) && defined(AS_MODULE)
#include "module.h"
uint32_t DC_NUM=4;
uint32_t DC_TYPE=DACT_MOD_TYPE_COMP;
void *DC_ALGO=comp_zlib_algo;
char *DC_NAME="Zlib Compression (MOD)";
#endif
int comp_zlib_algo(int mode, unsigned char *prev_block, unsigned char *curr_block, char *out_block, int blk_size) {
switch(mode) {
case DACT_MODE_COMPR:
return(comp_zlib_compress(prev_block,curr_block,out_block,blk_size));
break; /* Heh */
case DACT_MODE_DECMP:
return(comp_zlib_decompress(prev_block,curr_block,out_block,blk_size));
break;
default:
printf("Unsupported mode: %i\n", mode);
return(-1);
}
}
int comp_zlib_compress(unsigned char *prev_block, unsigned char *curr_block, unsigned char *out_block, int blk_size) {
unsigned long dest_size;
int retval;
dest_size=(int) ((float) (blk_size*1.01)+13);
#ifdef HAVE_COMPRESS2
retval=compress2(out_block, &dest_size, curr_block, blk_size, Z_BEST_COMPRESSION);
#else
retval=compress(out_block, &dest_size, curr_block, blk_size);
#endif
if (retval!=Z_OK) return(-1);
/* Remove the 120,218 header */
dest_size-=2;
memmove(out_block, out_block+2, dest_size);
return(dest_size);
}
int comp_zlib_decompress(unsigned char *prev_block, unsigned char *curr_block, char *out_block, int blk_size) {
unsigned long dest_size;
unsigned char *tmpbuf;
int retval;
/* Replant the header. */
tmpbuf=malloc(blk_size+2);
tmpbuf[0]=120;
tmpbuf[1]=218;
memcpy(tmpbuf+2, curr_block, blk_size);
dest_size=(DACT_BLK_SIZE*2);
retval=uncompress(out_block,&dest_size,tmpbuf,blk_size+2);
free(tmpbuf);
if (retval!=Z_OK) return(0);
return(dest_size);
}
#endif