> int myMulti(unsigned long *a,int len_a,unsigned long *b, int len_b,unsigned long *c)
> {
> 	int i=0, j=0;
> 	unsigned long step=0;
> 	__int64 h=0;
> 	unsigned long *p_h =(unsigned long *)&h;
> 	memset(c, 0, sizeof(unsigned long)*(len_a+len_b));
> 	for(i=0; i<len_b; i++)
> 	{
> 		step=0;
> 		for(j=0; j<len_a; j++)
> 		{
> 			h=(__int64)a[j]*b[i]+c[i+j]+step;
> 			c[i+j]=p_h[0];   
> 			step=p_h[1];     
> 		}
> 		c[(j++)+i]=step;
> 	}
> 	return i+j-1;
> }