In mathematics, the greatest common divisor (gcd), also known as the greatest common factor (gcf), or highest common factor (hcf), of two or more integers(at least one of which is not zero), is the largest positive integer that divides the numbers without a remainder. For example, the GCD of 8 and 12 is 4. here GCD algorithm of int16 bit is implemented in vhdl. This has module like fsm(finite state machine),datapath which are used to compute greatest common divisor of two numbers.