Livt.IO

tests/uart/UartCapacityTest.lvt

namespace Livt.IO.Tests

using Livt.IO

/**
 * Checks partial sends, explicit status and RTS headroom on a small public UART.
 */
@Test
@Context(ClockFrequency = 100MHz)
component UartCapacityTest
{
	// Shared fixture instances, signals, and observation state.
	uart: RtsCtsBufferedUart<3, 3, UartDataBits.Eight, UartParity.None, UartStopBits.One, 1MHz>
	wire: logic
	ctsN: logic = 0b1
	rtsN: logic

	/**
	 * Uses non-power-of-two capacities and starts with transmission blocked.
	 */
	new()
	{
		this.uart = new RtsCtsBufferedUart<3, 3, UartDataBits.Eight, UartParity.None, UartStopBits.One, 1MHz>(wire, wire, ctsN, rtsN)
	}

	/**
	 * A full queue rejects the suffix without losing its accepted prefix.
	 */
	@Test
	fn TestPartialSendAndWatermarks()
	{
		var message: byte[5] = [0x00, 0x22, 0x33, 0x44, 0x55]
		assert this.uart.Send(message) == 3
		assert this.uart.GetTransmitSpace() == 0
		assert this.uart.TryTransmit(0xFF) == false
		assert this.uart.IsTransmitting() == false
		assert this.uart.HasPendingTransmit() == true
		assert this.uart.IsTransmitIdle() == false
		ctsN = 0b0
		Simulation.Wait(4000)
		assert this.uart.IsTransmitIdle() == true
		assert this.uart.GetReceiveCount() == 3
		assert rtsN == 0b1
		var value: byte = 0xFF
		assert this.uart.TryReceive(value) == true
		assert value == 0x00
		assert rtsN == 0b1
		assert this.uart.TryReceive(value) == true
		assert value == 0x22
		Simulation.Wait(10)
		assert rtsN == 0b0
		assert this.uart.TryReceive(value) == true
		assert value == 0x33
		assert this.uart.TryReceive(value) == false
		assert value == 0x00
		assert this.uart.GetReceiveOverflowCount() == 0
	}

	/**
	 * Clearing a blocked queue returns it to idle and retains full capacity.
	 */
	@Test
	fn TestClearBlockedQueue()
	{
		ctsN = 0b1
		Simulation.Wait(10)
		assert this.uart.TryTransmit(0x66) == true
		this.uart.ClearTransmitBuffer()
		assert this.uart.IsTransmitIdle() == true
		assert this.uart.GetTransmitSpace() == 3
		ctsN = 0b0
		Simulation.Wait(1200)
		assert this.uart.GetReceiveCount() == 0
	}
}