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


int __stdcall myCRC(unsigned char * chBuf)
{
    int out = 0;
    for ( int i = 0; i < 8; ++i )
    {
        if ( isalpha(chBuf[i]) ) 
            out = (out<<4) + chBuf[i] - 55;
        else
            out = (out<<4) + chBuf[i] - 48;
    }
    return out;
}


unsigned char* __stdcall myValue(unsigned int ival, unsigned char* outbuf, int rann = 30)
{
    int out = 0, i = 0;
    int tival = ival;

    for (i=8; i>0; i--)
    {
        unsigned int tmpval = tival + 55;
        unsigned char tv = (tmpval&0xF);
        tmpval = tmpval>>4;
        tv = tv + (((tmpval&0xF)-rann)<<4);

        if (isalpha(tv))
        {
            outbuf[i-1] = tv;
        }
        else
        {
            outbuf[i-1] = tv - 7;
        }
        tival = (tival+55-outbuf[i-1])>>4;
    }
    if ( ival != myCRC(outbuf) )
    {
        // 如果不行，换一个key 
        return myValue(ival, outbuf, rann+1);
    }
    return outbuf;
}


int main(int argc, char* argv[])
{
    unsigned char buf[8] = {0};
    srand(time(NULL));
    
    for (int i=0; i<999999; i++)
    {
        for (int j=0; j<8; j++)
        {
            buf[j] = rand()&0xFF;
        }
        
        int vv = myCRC(buf);

        myValue(vv, buf);

        if (myCRC(buf) != vv)
        {
            printf("No OK!\n");
        }
    }
    
	return 0;
}