Eccelerators.RiscV

tests/Rv32CsrEngineTest.lvt

namespace Eccelerators.RiscV.Tests

using Eccelerators.RiscV.Sequential
using Eccelerators.RiscV.Storage
using Eccelerators.RiscV.Presets
using Eccelerators.RiscV.Machine

/**
 * Instruction-level checks observe committed writes independently of CPU storage.
 * Every wait is bounded so a stalled bus or controller fails the test.
 */
@Test
component Rv32CsrEngineTest
{
	// Owned platform, explicit execution composition and architectural scoreboard.
	fetch: RvFetchRom<512, 9>
	loadStore: RvLoadStoreRam<256, 8>
	core: Rv32SequentialEngine<0>
	registers: Rv32RegisterBank
	baseDecoder: Rv32iZmmulDecoder
	decoder: Rv32ZicsrDecoder
	integer: Rv32iIntegerUnit
	multiplier: Rv32DspMultiplier
	csrs: Rv32MachineCsrs
	observed: uint[32]
	retireCount: uint
	clearObservation: bool
	cycles: uint
	csrCommits: uint
	lastCsrCycle: uint
	previousWasCsr: bool
	tracePc: uint[512]
	traceWord: uint[512]
	traceRd: uint[512]
	traceValue: uint[512]

	/**
	 * Creates distinct instruction and data providers in the test clock context.
	 */
	new()
	{
		fetch = new RvFetchRom<512, 9>()
		loadStore = new RvLoadStoreRam<256, 8>()
		registers = new Rv32RegisterBank()
		baseDecoder = new Rv32iZmmulDecoder()
		decoder = new Rv32ZicsrDecoder(baseDecoder)
		integer = new Rv32iIntegerUnit()
		multiplier = new Rv32DspMultiplier()
		csrs = new Rv32MachineCsrs()
		core = new Rv32SequentialEngine<0>(registers, fetch, loadStore, decoder, integer, multiplier, csrs)
	}

	/**
	 * Samples retirement every clock; tests never read a CPU-private register array.
	 */
	process Observe()
	{
		state {
			cycles++

			if (clearObservation) {
				csrCommits = 0
				previousWasCsr = false
			} elif (csrs.retire == 0b1) {
				if (csrs.commit == 0b1) {
					var word = core.retiredInstruction as uint
					var form = (word >> 12) & 7
					var source = (word >> 15) & 31
					var destination = (word >> 7) & 31
					assert (csrs.readEnable == 0b1) == ((form & 3) != 1 || destination != 0)
					assert (csrs.writeEnable == 0b1) == ((form & 3) == 1 || source != 0)

					if (form >= 4) {
						assert csrs.operand as uint == source
					}

					if (previousWasCsr && core.run == 0b1) {
						assert cycles - lastCsrCycle == 10
					}

					lastCsrCycle = cycles
					csrCommits++
					Simulation.Report("CSR commit")
				}

				previousWasCsr = csrs.commit == 0b1
			}

			assert csrs.commit == 0b0 || (csrs.retire == 0b1 && csrs.illegal == 0b0)

			if (clearObservation) {
				retireCount = 0
			} elif (core.retired == 0b1) {
				assert retireCount < 512
				tracePc[retireCount] = core.retiredPc as uint
				traceWord[retireCount] = core.retiredInstruction as uint
				traceRd[retireCount] = core.retiredRd as uint
				traceValue[retireCount] = core.retiredValue as uint
				retireCount++

				if (core.retiredRd != 0) {
					observed[core.retiredRd as uint] = core.retiredValue as uint
				}
			}
		}
	}

	/**
	 * Programs one word with the CPU paused; writes are sampled once.
	 */
	fn Load(index: uint, word: uint)
	{
		state {
			fetch.programWrite = 0b1
			fetch.programIndex = index as logic[9]
			fetch.programData = word as logic[32]
		}

		state {
			fetch.programWrite = 0b0
		}
	}

	/**
	 * Runs to a fault stop and bounds uninterrupted cycles per retired instruction.
	 */
	fn RunToStop(cause: uint)
	{
		var start = cycles
		core.run = 0b1

		while (core.halted == 0b0 && cycles - start < 20000) {
			state {
			}
		}

		core.run = 0b0
		assert core.halted == 0b1
		assert core.faultCause as uint == cause
		assert cycles - start < retireCount * 50 + 50
	}

	/**
	 * Initializes every data location that a vector can read before execution.
	 */
	fn Prepare()
	{
		core.run = 0b0
		Simulation.Wait(40)
		assert core.idle == 0b1
		var ticket = ~core.restartAck
		core.restartRequest = ticket
		var elapsed: uint = 0

		while (core.restartAck != ticket && elapsed < 100) {
			state {
				elapsed++
			}
		}

		assert core.restartAck == ticket
		clearObservation = true
		Simulation.Wait(4)
		clearObservation = false

		for (var index: uint = 0; index < 256; index++) {
			state {
				loadStore.programWrite = 0b1
				loadStore.programIndex = index as logic[8]
				loadStore.programData = 0
			}
		}

		state {
			loadStore.programWrite = 0b0
		}

		assert core.idle == 0b1
	}

	/**
	 * Compares one ordered committed event with independently computed constants.
	 */
	fn CheckRetirement(index: uint, pc: uint, word: uint, rd: uint, value: uint)
	{
		assert tracePc[index] == pc
		assert traceWord[index] == word
		assert traceRd[index] == rd
		assert traceValue[index] == value
	}

	/**
	 * Checks all CSR forms, encoded-zero suppression, aliases, WARL and counter commits.
	 */
	@Test
	fn CsrRetirement()
	{
		Prepare()

		for (var index: uint = 0; index < (Rv32CsrRetirement.WORDS.Length as uint); index++) {
			Load(index, Rv32CsrRetirement.WORDS[index])
		}

		RunToStop(3)
		assert retireCount == Rv32CsrRetirement.VALUES.Length as uint

		for (var index: uint = 0; index < (Rv32CsrRetirement.VALUES.Length as uint); index++) {
			CheckRetirement(index, index * 4, Rv32CsrRetirement.WORDS[index],
				Rv32CsrRetirement.DESTINATIONS[index], Rv32CsrRetirement.VALUES[index])
		}
	}

	/**
	 * Rejects UnknownCsr with no CSR access commit, retirement or destination write.
	 */
	@Test
	fn UnknownCsr()
	{
		Prepare()
		Load(0, 0x777020f3)
		RunToStop(2)
		assert retireCount == 0 && csrCommits == 0 && core.pc == 0
		assert core.faultValue == 0x777020f3
	}

	/**
	 * Rejects ReadOnlyWrite with no CSR access commit, retirement or destination write.
	 */
	@Test
	fn ReadOnlyWrite()
	{
		Prepare()
		Load(0, 0xf11110f3)
		RunToStop(2)
		assert retireCount == 0 && csrCommits == 0 && core.pc == 0
		assert core.faultValue == 0xf11110f3
	}

	/**
	 * Rejects ZeroRegisterValueStillWrites with no CSR access commit, retirement or destination write.
	 */
	@Test
	fn ZeroRegisterValueStillWrites()
	{
		Prepare()
		Load(0, 0xf11120f3)
		RunToStop(2)
		assert retireCount == 0 && csrCommits == 0 && core.pc == 0
		assert core.faultValue == 0xf11120f3
	}

	/**
	 * Rejects UnknownWithoutRead with no CSR access commit, retirement or destination write.
	 */
	@Test
	fn UnknownWithoutRead()
	{
		Prepare()
		Load(0, 0x77701073)
		RunToStop(2)
		assert retireCount == 0 && csrCommits == 0 && core.pc == 0
		assert core.faultValue == 0x77701073
	}

	/**
	 * Rejects MachineReturnUnavailable with no CSR access commit, retirement or destination write.
	 */
	@Test
	fn MachineReturnUnavailable()
	{
		Prepare()
		Load(0, 0x30200073)
		RunToStop(2)
		assert retireCount == 0 && csrCommits == 0 && core.pc == 0
		assert core.faultValue == 0x30200073
	}

	/**
	 * Rejects UserCounterUnavailable with no CSR access commit, retirement or destination write.
	 */
	@Test
	fn UserCounterUnavailable()
	{
		Prepare()
		Load(0, 0xc00020f3)
		RunToStop(2)
		assert retireCount == 0 && csrCommits == 0 && core.pc == 0
		assert core.faultValue == 0xc00020f3
	}

	/**
	 * Rejects SupervisorUnavailable with no CSR access commit, retirement or destination write.
	 */
	@Test
	fn SupervisorUnavailable()
	{
		Prepare()
		Load(0, 0x100020f3)
		RunToStop(2)
		assert retireCount == 0 && csrCommits == 0 && core.pc == 0
		assert core.faultValue == 0x100020f3
	}

	/**
	 * Toggles one instruction step and bounds the completion acknowledgement.
	 */
	fn Step()
	{
		core.stepRequest = ~core.stepRequest
		var elapsed: uint = 0

		while (core.stepAck != core.stepRequest && elapsed < 200) {
			state {
				elapsed++
			}
		}

		assert core.stepAck == core.stepRequest
	}

	/**
	 * A held step writes once; pause retains CSR state; restart clears it.
	 */
	@Test
	fn CsrStepPauseRestart()
	{
		Prepare()
		Load(0, 0x3403d0f3)
		Load(1, 0x34002173)
		Load(2, 0x00100073)
		Step()
		assert retireCount == 1 && csrCommits == 1 && traceValue[0] == 0
		Simulation.Wait(40)
		assert retireCount == 1 && csrCommits == 1 && core.pc == 4
		Step()
		assert retireCount == 2 && traceValue[1] == 7
		Step()
		assert core.halted == 0b1 && core.faultCause == 3
		var ticket = ~core.restartAck
		core.restartRequest = ticket
		Simulation.Wait(50)
		assert core.restartAck == ticket && core.pc == 0 && core.halted == 0b0
		Load(0, 0x340021f3)
		Load(1, 0xb0202273)
		Step()
		assert retireCount == 3 && traceValue[2] == 0
		Step()
		assert retireCount == 4 && traceValue[3] == 1
	}
}