Binary Counter 4 LEDs 4 Switches (16F877)

MairtinH2

I am currently programming a microcontroller and need to make a switching interface which has the following functions:

Switch1 - LEDs will count in binary and add 1 each time
Switch2 - 1 will be subtracted from binary total
Switch3 - 2 will be added onto binary total
Switch4 - 2 will be subtracted from binary total

If anyone could give me a few tips on how to write the functionality of adding and subtracting binary numbers as well as showing them onto LEDs would be much appreciated