Livt.IO

tests/spi/SPIFlashTestTransport.lvt

namespace Livt.IO.Tests

using Livt.IO

/**
 * Deterministic NOR transaction double. Captures complete addressed commands and
 * injects busy or rejected-write status. One test owner resets before each case.
 */
component SPIFlashTestTransport : ISPITransactions
{
	// Observed commands and address/payload bytes from the latest addressed command.
	public selections: int
	public selected: bool
	public lastCommand: byte
	captured: byte[260]
	public capturedLength: int

	// Injected status and per-transaction position.
	public busy: bool
	public rejectWrites: bool
	writeEnabled: bool
	command: byte
	position: int

	/**
	 * Reads one captured command byte; valid only below capturedLength.
	 */
	public fn GetCapturedByte(index: int) byte
	{
		return captured[index]
	}

	/**
	 * Clears observations and injected failures between test cases.
	 */
	public fn Reset()
	{
		selections = 0
		selected = false
		lastCommand = 0x00
		capturedLength = 0
		busy = false
		rejectWrites = false
		writeEnabled = false
		position = 0
	}

	/**
	 * Begins a transaction and counts its selection.
	 */
	override fn Select()
	{
		assert !selected
		selected = true
		selections++
		position = 0
	}

	/**
	 * Captures addressed commands and supplies deterministic status/read bytes.
	 */
	override fn Transfer(value: byte) byte
	{
		assert selected

		if (position == 0) {
			command = value

			if (command == 0x03 || command == 0x02 || command == 0x20) {
				lastCommand = command
				capturedLength = 0
			}
		}

		if (command == 0x03 || command == 0x02 || command == 0x20) {
			captured[capturedLength] = value
			capturedLength++
		}

		position++

		if (command == 0x9F) {
			if (position == 2) {
				return 0xEF
			}

			if (position == 3) {
				return 0x40
			}

			if (position == 4) {
				return 0x17
			}
		}

		if (command == 0x05) {
			if (busy) {
				return 0x01
			}

			if (writeEnabled) {
				return 0x02
			}
		}

		if (command == 0x03 && position > 4) {
			return (position - 5) as byte
		}

		return 0x00
	}

	/**
	 * Ends a command and models the write-enable latch.
	 */
	override fn Deselect()
	{
		assert selected
		selected = false

		if (command == 0x06 && !rejectWrites) {
			writeEnabled = true
		}

		if (command == 0x02 || command == 0x20) {
			assert writeEnabled
			writeEnabled = false
		}
	}
}