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comp_mzlib2.c

/*
 * 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
 */


/*
      Compress by gathering bytes that are most often placed near each other
      and rearranging the ASCII Charectar Set to make those bytes have
      similar values.

*/


#include "dact.h"
#include "comp_mzlib2.h"
#ifndef comp_mzlib2_algo

#ifdef HAVE_LIBZ
#ifdef HAVE_ZLIB_H
#include <zlib.h>
#endif
#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
#include "sort.h"
#define SQRD_256 65536


/*
      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=8;
uint32_t DC_TYPE=DACT_MOD_TYPE_COMP;
void *DC_ALGO=comp_mzlib2_algo;
char *DC_NAME="Second Modified Zlib Compression (MOD)";
#endif

#ifdef DEBUG
#if DEBUG>=2
#define MAKE_MZLIB2 1
#endif
#endif

#ifdef MAKE_MZLIB2
int comp_mzlib2_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_mzlib2_compress(prev_block, curr_block, out_block, blk_size, bufsize));
                  break; /* Heh */
            case DACT_MODE_DECMP:
                  return(comp_mzlib2_decompress(prev_block, curr_block, out_block, blk_size, bufsize));
                  break;
            default:
                  printf("Unsupported mode: %i\n", mode);
                  return(-1);
      }
}
#else
int comp_mzlib2_algo(int mode, unsigned char *prev_block, unsigned char *curr_block, char *out_block, int blk_size, int bufsize) {
      return(-1);
}
#endif

int comp_mzlib2_compress(unsigned char *prev_block, unsigned char *curr_block, char *out_block, int blk_size, int bufsize) {
      unsigned long dest_size;
      unsigned char *tmp_block;
      uint32_t freq[SQRD_256];
      uint16_t lookup_table[SQRD_256], curr_val, repl_val;
      int i, cnt, m=2, retval, low_byte=0, x;

      memset(freq,0,sizeof(freq));

      for (i=0;i<blk_size;i+=2) {
            x=(curr_block[i]<<8)|(curr_block[i+1]);
            freq[x]++;
            if (freq[x]==0xffff) return(-1);
      }


      int_sort_fast(freq, SQRD_256, 0);

      for (i=0;i<(SQRD_256);i++) {
            if ((freq[i]&0xffff)!=0) {
                  out_block[m++]=freq[i]>>24;
                  out_block[m++]=(freq[i]>>16)&0xff;
                  if (m>=(blk_size*2)) {
                        return(-1);
                  }
                  lookup_table[freq[i]>>16]=i;
                  PRINT_LINE; fprintf(stderr, "%04x: 0x%02x and 0x%02x are near each other %i times\n",i,(freq[i]>>24),(freq[i]>>16)&0xff,freq[i]&0xffff);
            } else {
                  break;
            }
      }

      cnt=(m-2);
      out_block[0]=((m-2)>>8);
      out_block[1]=((m-2)&0xff);
      if ((m-2)<0x200) low_byte=1;

      for (i=0;i<blk_size;i+=2) {
            curr_val=((curr_block[i]<<8)| curr_block[i+1]);
            repl_val=lookup_table[curr_val];
            if (!low_byte) 
                  out_block[m++]=repl_val>>8;
            out_block[m++]=repl_val&0xff;
SPOTVAR_NUM(m);
            if (m>=(blk_size*2)) return(-1);
      }

      dest_size=(int) ((float) ((m*1.02)+15));
SPOTVAR_NUM(dest_size);
      if ((tmp_block=malloc(dest_size))==NULL) {
            return(-1);
      }
        memcpy(tmp_block,out_block,m);
/*
      for (i=0;i<m;i++) {
            printf("%02x ", tmp_block[i]);
            if (i==(cnt+2)) printf("-- ");
            if (((i+1)%25)==0) printf("\n");
      }
      printf("\n\n");
*/

/*
      for (i=0;i<blk_size;i++) printf("%02x ", curr_block[i]);
      printf("\n");
*/

      retval=compress(out_block, &dest_size, tmp_block, m);
      if (retval!=Z_OK) {
            return(blk_size*2);
      }

      free(tmp_block);
      return(dest_size);
}

int comp_mzlib2_decompress(unsigned char *prev_block, unsigned char *curr_block, unsigned char *out_block, int blk_size, int bufsize) {
      uint16_t lookup_table[SQRD_256], curr_val, repl_val;
      unsigned long dest_size=(blk_size*2);
      unsigned char *tmp_block;
      unsigned int m=0, hdrsize;
      int retval, i, low_byte=0;

      tmp_block=malloc(dest_size);
      retval=uncompress(tmp_block,&dest_size,curr_block,blk_size);

      if (retval!=Z_OK) return(0);

      hdrsize=((unsigned int) (((tmp_block[0]<<8)|tmp_block[1])))+2;

      if ((hdrsize-2)<0x200) low_byte=1;

      for (i=2;i<hdrsize;i+=2) {
            lookup_table[(i-2)/2]=((tmp_block[i]<<8)|tmp_block[i+1]);
      }

      for (i=hdrsize;i<(dest_size);i+=(2-low_byte)) {
            if (low_byte) {
                  curr_val=tmp_block[i];
            } else {
                  curr_val=((tmp_block[i]<<8)|tmp_block[i+1]);
            }
            repl_val=lookup_table[curr_val];
            out_block[m++]=repl_val>>8;
            out_block[m++]=repl_val&0xff;
      }

/*
      for (i=0;i<m;i++) printf("%02x ", out_block[i]);
      printf("\n");
*/

      free(tmp_block);
      return(m);
}
#endif

#endif

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