当除数或被除数的值较大，超过除法指令所允许的数据范围时，就不能用一条除法指令完成除法运算，必须通过一段程序实现。本程序实现了5字节除以4字节的运算.-When the divisor or dividend the value of a larger, more than the division instruction permit data range, a division instructions can not be used to complete computing divisi