/*
* Copyright (C) 2001 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
*/
/*
Use "Range Encoding."
http://www.compressconsult.com/ or http://eiunix.tuwien.ac.at/~michael
michael@compressconsult.com michael@eiunix.tuwien.ac.at
*/
#include "dact.h"
#include "comp_range.h"
#include <stdio.h>
#include <stdlib.h>
#include "buffer.h"
#include "comp_range/rangecod.h"
#include "comp_range/port.h"
char *tmp_block;
int count_i=0;
/*
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=7;
uint32_t DC_TYPE=DACT_MOD_TYPE_COMP;
void *DC_ALGO=comp_range_algo;
char *DC_NAME="Range Encoding (MOD)";
#endif
int comp_range_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_range_compress(prev_block,curr_block,out_block,blk_size));
break; /* Heh */
case DACT_MODE_DECMP:
return(comp_range_decompress(prev_block,curr_block,out_block,blk_size));
break;
default:
printf("Unsupported mode: %i\n", mode);
return(-1);
}
}
int comp_range_compress(unsigned char *prev_block, unsigned char *curr_block, char *out_block, int blk_size) {
unsigned int ch;
freq counts[257];
rangecoder rc;
int i,x;
if ((tmp_block=malloc(DACT_BLK_SIZE))==NULL) {
return(-1);
}
count_i=0;
for (x=0;x<DACT_BLK_SIZE;x++) tmp_block[x]=0;
byte_buffer_purge();
byte_buffer_write(curr_block, blk_size);
start_encoding(&rc,0,0);
encode_freq(&rc,1,1,2);
for (x=0;x<257;x++) counts[x]=0;
for (x=0;x<blk_size;x++) counts[curr_block[x]]++;
for (x=0;x<256;x++) {
encode_short(&rc,counts[x]);
/* printf("={ 0x%02x, 0x%04x }\n",x,counts[x]); */
}
counts[256]=blk_size;
for (x=256; x; x--) counts[x-1]=counts[x]-counts[x-1];
for (i=0;i<blk_size;i++) {
ch=curr_block[i];
/* printf("i=%5i ch=0x%02x -- counts[ch+1]=0x%02x counts[ch]=0x%02x\n",i,ch,counts[ch+1],counts[ch]); */
encode_freq(&rc,counts[ch+1]-counts[ch],counts[ch],counts[256]);
}
encode_freq(&rc,1,0,2);
done_encoding(&rc);
if (count_i>blk_size) return(-1);
for (i=0;i<count_i;i++) {
out_block[i]=tmp_block[i];
}
free(tmp_block);
return(count_i);
}
int comp_range_decompress(unsigned char *prev_block, unsigned char *curr_block, char *out_block, int blk_size) {
int i,x;
int blocksize;
freq counts[257], tmp, cf, symbol;
rangecoder rc;
tmp_block=malloc(DACT_BLK_SIZE);
byte_buffer_purge();
byte_buffer_write(curr_block, blk_size);
count_i=0;
for (x=0;x<DACT_BLK_SIZE;x++) tmp_block[x]=0;
start_decoding(&rc);
cf = decode_culfreq(&rc,2);
decode_update(&rc,1,1,2);
for (x=0; x<256; x++) counts[x]=decode_short(&rc);
blocksize=0;
for (x=0; x<256; x++) {
tmp=counts[x];
counts[x]=blocksize;
blocksize+=tmp;
}
counts[256]=blocksize;
for (i=0; i<blocksize; i++) {
cf=decode_culfreq(&rc,counts[256]);
for (symbol=0; counts[symbol+1]<=cf; symbol++) { /**/; }
decode_update(&rc, counts[symbol+1]-counts[symbol],counts[symbol],counts[256]);
incoming_data(symbol);
}
done_decoding(&rc);
// Why am I not memcpy()'ing?
for (i=0;i<count_i;i++) out_block[i]=tmp_block[i];
free(tmp_block);
return(count_i);
}
void incoming_data(unsigned char value) {
if (count_i<=(BYTE_BUFF_SIZE))
tmp_block[count_i++]=value;
}