SixtyPical/eg/c64/joystick.60p

word screen @ 1024
byte joy2 @ $dc00

word delta

routine read_stick
  inputs joy2
  outputs delta
  trashes a, x, z, n
{
    ld x, joy2
    ld a, x
    and a, 1                   // up
    if z {
        copy $ffd8, delta      // -40
    } else {
        ld a, x
        and a, 2               // down
        if z {
            copy word 40, delta
        } else {
            ld a, x
            and a, 4               // left
            if z {
                copy $ffff, delta  // -1
            } else {
                ld a, x
                and a, 8           // right
                if z {
                    copy word 1, delta
                } else {
                    copy word 0, delta
                }
            }
        }
    }
}

routine main
  inputs joy2
  outputs delta
  trashes a, x, z, n, screen
{
    repeat {
        call read_stick
        copy delta, screen
        ld a, 1
    } until z
}