Its a university project for "Logic Circuits" course. We had to design a circuit that measures frequency of an input signal by Verilog language to be implemented on FPGA board.
First take a look at project manual on /Manual directory. Its a list of projects to choose and we choose project #11.
Note: Manual is in Persian language not English (sorry!)
Then check out my suggested circuit freqMeter.v . I tried to document the code in itself by comments, hope its more readable.
There is also a pins.ucf file that is written for our FPGA board and you should change it for yours if you want to implement it on a board.