#include <fcntl.h>
#include "mystdlib.h"
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include <unistd.h>

int main( int args, char **argv )
{
  int      filenum = 0;
  size_t   offset = 0, oldoffset = -1;
  uint8_t *mappedfile;
  MAP      map;

  uint8_t mantra0 = 0x1b, mantra1 = 0x35, mantra2 = 0x2d, mantra3 = 0x6c; /* clean*/
//  unsigned char mantra0 = 0x08, mantra1 = 0x57, mantra2 = 0x64, mantra3 = 0x69; /* 98 H */
//  unsigned char mantra0 = 0x13, mantra1 = 0xe4, mantra2 = 0x55, mantra3 = 0x05; /* 99 F */
//  unsigned char mantra0 = 0x12, mantra1 = 0x08, mantra2 = 0x23, mantra3 = 0x01; /* 99 H */

  if( args != 2 )
    { fputs( "Missing filenames.", stderr ); exit( 1 ); }

  map = map_file( argv[1], 1 );
  mappedfile = map->addr;

  mantra0 ^= mappedfile[0];
  mantra1 ^= mappedfile[5];
  mantra2 ^= mappedfile[2];
  mantra3 ^= mappedfile[3];

  while( 1 )
  {
    while( ( offset < map->size ) && (
           ( mappedfile[ offset + 0 ] != ( 0x1b^ mantra0 )) ||
           ( mappedfile[ offset + 2 ] != ( '-' ^ mantra2 )) ||
           ( mappedfile[ offset + 3 ] != ( 'l' ^ mantra3 )) ||
           ( mappedfile[ offset + 4 ] != ( 'h' ^ mantra0 )) ||
           ( mappedfile[ offset + 5 ] != ( '5' ^ mantra1 )) ||
           ( mappedfile[ offset + 6 ] != ( '-' ^ mantra2 ))
          ) ) offset++;

    printf( "Found an appropriate offset at: %zd\n", oldoffset );

    if( offset == map->size )
    {
        unmap_file( &map );
        exit(0);
    }

    if( oldoffset != -1 )
    {
        uint8_t cs = 0, *mf = mappedfile + oldoffset, df[32];
        char filename[20];
        int i;

        for( i=0; i<8; ++i)
        {
           df[4*i+0] = mf[4*i+0] ^ mantra0;
           df[4*i+1] = mf[4*i+1] ^ mantra1;
           df[4*i+2] = mf[4*i+2] ^ mantra2;
           df[4*i+3] = mf[4*i+3] ^ mantra3;
        }

        snprintf( filename, sizeof( filename ), "%05d.lha", filenum++ );
        memcpy( ((uint8_t*)df) + 22, filename, 5);

        for( i=2; i<29; ++i) cs += ((uint8_t*)df)[i];
        ((uint8_t*)df)[1] = cs;

        i = open( filename, O_CREAT | O_TRUNC | O_WRONLY, 0644 );
        write( i, df, 32 );
        write( i, mf + 32, offset - oldoffset - 32 );
        close( i );
    }
    oldoffset = offset;
    offset++;
  }

  return 0;
}