class StepperMotor
	var pins: Sequence[RPiPin]
	var delay: Int

	init (delay: Int, a, b, c, d: RPiPin)
	do
		pins = [a, b, c, d]
		self.delay = delay

		for p in pins do p.fsel = new FunctionSelect.outp
	end

	fun forward(steps: Int)
	do
		for s in [0..steps[ do
			set(true, false, false, false)
			delay.bcm2835_delay
			set(true, true, false, false)
			delay.bcm2835_delay
			set(false, true, false, false)
			delay.bcm2835_delay
			set(false, true, true, false)
			delay.bcm2835_delay
			set(false, false, true, false)
			delay.bcm2835_delay
			set(false, false, true, true)
			delay.bcm2835_delay
			set(false, false, false, true)
			delay.bcm2835_delay
			set(true, false, false, true)
			delay.bcm2835_delay
		end
	end

	fun backwards(steps: Int)
	do
		for s in [0..steps[ do
			set(true, false, false, true)
			delay.bcm2835_delay
			set(false, false, false, true)
			delay.bcm2835_delay
			set(false, false, true, true)
			delay.bcm2835_delay
			set(false, false, true, false)
			delay.bcm2835_delay
			set(false, true, true, false)
			delay.bcm2835_delay
			set(false, true, false, false)
			delay.bcm2835_delay
			set(true, true, false, false)
			delay.bcm2835_delay
			set(true, false, false, false)
			delay.bcm2835_delay
		end
	end

	fun release do set(false, false, false, false)

	protected fun set(a, b, c, d: Bool)
	do
		var bits = new Array[Bool].with_items(a, b, c, d)

		for i in [0..4[ do pins[i].write(bits[i])
	end
end