Livt.Collections

tests/fifo/StoppedFifoStorage.lvt

namespace Livt.Collections.Tests

using Livt.Collections

/**
 * Stops the write clock immediately after its first non-reset edge.
 * The asynchronous read tap remains observable from the live test clock.
 */
component StoppedFifoStorage
{
	// Test-only clock gate and single-edge payload store.
	base: IContext
	clockLine: clock
	resetLine: reset
	stopped: bool
	storage: AsyncFifoArray<byte, 4>
	public data: out byte
	public edges: out uint
	count: uint

	/**
	 * Owns storage in the gated context; the supplied timebase stays running.
	 */
	new(base: IContext)
	{
		this.base = base
		this.context.clk = clockLine
		this.context.rst = resetLine
		this.storage = new AsyncFifoArray<byte, 4>()
	}

	/**
	 * Drives a stable write before the only edge and keeps the read tap live.
	 */
	process Connect[]()
	{
		this.clockLine = base.clk
		this.resetLine = base.rst
		if (stopped) {
			this.clockLine = 0b0
		}

		this.storage.writeEnable = true
		this.storage.writeAddress = 0
		this.storage.writeData = 0xA5
		this.storage.readAddress = 0
		this.data = storage.readData
		this.edges = count
	}

	/**
	 * Allows no additional write edge to hide a delayed storage write.
	 */
	process StopClock()
	{
		state Tick {
			this.count = count + 1
			this.stopped = true
			goto Tick
		}
	}
}