from migen.fhdl.std import *
from migen.bank.description import *
from migen.bank.eventmanager import *
from migen.genlib.fifo import SyncFIFOBuffered

from misoclib.com.liteusb.common import *

class LiteUSBUART(Module, AutoCSR):
	def __init__(self, tag, fifo_depth=64):
		self.tag = tag

		self._rxtx = CSR(8)

		self.submodules.ev = EventManager()
		self.ev.tx = EventSourcePulse()
		self.ev.rx = EventSourceLevel()
		self.ev.finalize()

		self.source = source = Source(user_layout)
		self.sink = sink = Sink(user_layout)

		###

		# TX
		tx_start = self._rxtx.re
		tx_done  = self.ev.tx.trigger

		self.sync += \
			If(tx_start,
				source.stb.eq(1),
				source.d.eq(self._rxtx.r),
			).Elif(tx_done,
				source.stb.eq(0)
			)

		self.comb += [
			source.sop.eq(1),
			source.eop.eq(1),
			source.length.eq(1),
			source.dst.eq(self.tag),
			tx_done.eq(source.stb & source.ack),
		]

		# RX
		rx_available = self.ev.rx.trigger

		rx_fifo = SyncFIFOBuffered(8, fifo_depth)
		self.submodules += rx_fifo
		self.comb += [
			rx_fifo.we.eq(sink.stb),
			sink.ack.eq(sink.stb & rx_fifo.writable),
			rx_fifo.din.eq(sink.d),

			rx_available.eq(rx_fifo.readable),
			rx_fifo.re.eq(self.ev.rx.clear),
			self._rxtx.w.eq(rx_fifo.dout)
		]