#include <stdio.h>
#include <stdlib.h>

#define CODE_LENGTH 8

typedef unsigned char u8;
typedef unsigned short int u16;
typedef unsigned long u32;
typedef unsigned long long int u64;

typedef signed char s8;
typedef signed short int s16;
typedef signed long s32;

u32     table[0x100];


//==========================================================================
//
//==========================================================================
void _Crc32Init( void )
{
u32     poly = 0xedba6320;  // DS‚Ì‚Æ‚« 0xedb88320;
u32     crc;

    for( u32 i = 0; i < 0x100; i++ )
    {
        crc = i;
        for( u32 j = 8; j > 0; j-- )
        {
            if( crc & 1 )
            {
                crc = (crc>>1)^poly;
            }
            else
            {
                crc >>= 1;
            }
        }
        table[i] = crc;
    }
}

//==========================================================================
//
//==========================================================================
u32 _CalcCrc32( const u8 *src, u32 len )
{
u32     crc = 0xffffffff;

    while( len )
    {
        crc = ((crc>>8)&0xffffffff)^table[(crc^(*src))&0xff];
        src++;
        len--;
    }
    return crc;
}

//==========================================================================
//
//==========================================================================
u32 _CalcMasterkey( const u8 *src )
{
u32     key;

    _Crc32Init();

    //key = ((_CalcCrc32( src, CODE_LENGTH )^0xaaaa)+5313)%100000;
    key = ((_CalcCrc32( src, CODE_LENGTH )^0xaaaa)+5719)%100000;
    return key;
}

//==========================================================================
//
//==========================================================================
int main( int argc, char *argv[] )
{
u32     masterKey;

    if ( ( argc != 2 ) || ( argv[1] == NULL ) )
    {
        printf( "usage: MakeMasterKeyForCtr [date+code]\n" );
        printf( "\n" );
        printf( "example: date = Sep 8. code = 1234\n" );
        printf( "         MakeMasterKeyForCtr 09081234\n" );
        return 1;
    }

    masterKey = _CalcMasterkey( (const u8*)argv[1] );

    printf( "Master Key = %05d\n", masterKey );

    return 0;
}