delay_timer_test.8o

# CHIP-8 Delay Timer Test
# Copyright 2015 Matthew Mikolay
# See github.com/mattmikolay/chip-8 or mattmik.com for more info.

# Note: Don't use v0, v1, or v2, as they are needed for printing digits
:alias x v3                     # x coordinate of current digit
:alias y v4                     # y coordinate of current digit
:alias current_key v5           # Key pressed by user
:alias duration v6              # Duration of time entered by user

: main

    y := 0

    loop

        loop

            print_time

            current_key := key

            # If user pressed 2 key, increment duration
            if current_key == 0x02 then
                duration += 0x01

            # If user pressed 8 key, decrement duration
            if current_key == 0x08 then
                duration += 0xFF

            # Continue accepting user input until the 5 key is pressed
            if current_key != 0x05 then
        again

        # Begin a countdown from the time entered by the user
        delay := duration
        loop
            duration := delay
            print_time
            if duration != 0x00 then
        again

    again

: print_time

    clear

    # Store BCD of current time in program memory
    i := program_end
    bcd duration
    load v2

    x := 0

    # Print hundreds digit
    i := hex v0
    sprite x y 0x05

    x += 5

    # Print tens digit
    i := hex v1
    sprite x y 0x05

    x += 5

    # Print ones digit
    i := hex v2
    sprite x y 0x05

    return

: program_end