/*
 * @(#) arcoder.c - Arithmetic byte compressor/decompressor.
 * (c) 1998 Ivan Maidanski <ivmai@chat.ru> http://ivmai.chat.ru
 * Freeware program source. All rights reserved.
 **
 * Language: ANSI C
 * Tested with: Microsoft Visual C++ (R) v4.2, Borland C/C++ v3.1
 * Last modified: 1998-08-04 13:20:00 GMT+04:00
 */

/*
 Notes:
  declare own ARITHPCK_VALUE_TYPE macro
   to override predefined encoded/decoded value type,
  declare own ARITHPCK_SYM_TYPE macro
   to override predefined symbol/index type,
  declare own ARITHPCK_FREQ_TYPE macro
   to override predefined frequence type,
  declare own ARITHPCK_FREQ_MAX macro
   to override predefined maximum frequence constant,
  declare own SYMSCALE macro
   to override predefined char update scale constant.
*/


#include "arithpck.h" /* ARITHPCK_SYM_TYPE, ARITHPCK_FREQ_TYPE */
                      /* ARITHPCK_VALUE_TYPE, ARITHSTART() */
                      /* arithinitinput(), arithpacksym(), arithunpacksym() */
                      /* arithoutput(), ARITHOUTFINISH(), arithflushfinish() */
                      /* FREQMODELALLOC(), freqmodelstart(), FREQMODELFREE() */

#include <stdlib.h> /* NULL, malloc(), free() */
#include <stdio.h> /* FILE, SEEK_SET, SEEK_END */
                   /* puts(), fopen(), fclose(), fseek(), ftell() */
                   /* getc(), putc() */

#ifndef SYMSCALE
#define SYMSCALE 4 /* frequence model char (symbol) update scale */
#endif

void packfile(FILE *destfile, FILE *srcfile, long srclen,
              ARITHPCK_SYM_TYPE symtbl[], ARITHPCK_FREQ_TYPE freqtbl[],
              ARITHPCK_VALUE_TYPE maxcum)
{
 unsigned char outcode=0;
 ARITHPCK_VALUE_TYPE low,high;
 ARITHSTART(low,high);
 while ((srclen--)>0)
  for (arithpacksym(&low,&high,(ARITHPCK_SYM_TYPE)getc(srcfile),
                    symtbl,freqtbl,SYMSCALE,&maxcum);
       arithoutput(&outcode,NULL,NULL,&low,&high,maxcum);outcode=0)
   putc(outcode,destfile);
 for (;ARITHOUTFINISH(&outcode,NULL,NULL,&low,&high);outcode=0)
  putc(outcode,destfile);
 if (arithflushfinish(&outcode,NULL,NULL))
  putc(outcode,destfile);
}

void unpackfile(FILE *destfile, FILE *srcfile, long destlen,
                ARITHPCK_SYM_TYPE symtbl[], ARITHPCK_FREQ_TYPE freqtbl[],
                ARITHPCK_VALUE_TYPE maxcum)
{
 ARITHPCK_VALUE_TYPE low,high,input=0;
 unsigned char incode,outcode=0;
 while (arithinitinput(&input,(unsigned char)getc(srcfile)));
 incode=(unsigned char)getc(srcfile);
 ARITHSTART(low,high);
 while ((destlen--)>0)
  for (putc(arithunpacksym(&low,&high,input,
                           symtbl,freqtbl,SYMSCALE,&maxcum),destfile);
       arithoutput(&outcode,&input,&incode,&low,&high,maxcum);outcode=0)
   incode=(unsigned char)getc(srcfile);
/*
 for (;ARITHOUTFINISH(&outcode,&input,&incode,&low,&high);outcode=0)
  incode=(unsigned char)getc(srcfile);
 if (arithflushfinish(&outcode,&input,&incode))
  incode=(unsigned char)getc(srcfile);
*/
}

void fputlong(long value, FILE *f)
{
 int cnt=sizeof(long);
 unsigned char *p=(unsigned char *)&value+cnt;
 while ((cnt--)>0)
  putc(*--p,f);
}

long fgetlong(FILE *f)
{
 long value=0;
 unsigned char *p=(unsigned char *)&value;
 *p=(unsigned char)1;
 p+=sizeof(long);
 while (!*--p)
  *p=(unsigned char)getc(f);
 *p=(unsigned char)getc(f);
 return value;
}

int packunpackfile(char *destfname, char *srcfname, int compression)
{
 long srclen;
 FILE *srcfile,*destfile;
 ARITHPCK_SYM_TYPE *symtbl;
 ARITHPCK_FREQ_TYPE *freqtbl;
 ARITHPCK_VALUE_TYPE maxcum;
 if ((srcfile=fopen(srcfname,"rb"))==NULL)
  return 2;
 if (FREQMODELALLOC(symtbl,freqtbl,(unsigned char)~0)<0)
 {
  fclose(srcfile);
  return 1;
 }
 if ((destfile=fopen(destfname,"wb"))==NULL)
 {
  FREQMODELFREE(symtbl,freqtbl);
  fclose(srcfile);
  return 3;
 }
 freqmodelstart(symtbl,freqtbl,&maxcum,(unsigned char)~0);
 if (compression)
 {
  fseek(srcfile,0L,SEEK_END);
  srclen=ftell(srcfile);
  fseek(srcfile,0L,SEEK_SET);
  fputlong(srclen,destfile);
  packfile(destfile,srcfile,srclen,symtbl,freqtbl,maxcum);
 }
  else unpackfile(destfile,srcfile,fgetlong(srcfile),symtbl,freqtbl,maxcum);
 fclose(destfile);
 FREQMODELFREE(symtbl,freqtbl);
 fclose(srcfile);
 return 0;
}

int main(int argc, char *argv[])
{
 if (argc!=4 || !(argc=argv[1][0]=='E' || argv[1][0]=='e') &&
                !(argv[1][0]=='D' || argv[1][0]=='d'))
 {
  puts("Arithmetic byte compressor/decompressor\n"
       "Usage parameters: E|D <source_file> <destination_file>\n");
  return -1;
 }
 argc=packunpackfile(argv[3],argv[2],argc);
 switch (argc)
 {
  case 1:
   puts("Error: not enough memory.");
   break;
  case 2:
   puts("Error: cannot open source file.");
   break;
  case 3:
   puts("Error: cannot open destination file.");
 }
 return argc;
}