from migen.fhdl.std import *
from migen.genlib.fsm import *
from migen.actorlib.fifo import *
from migen.flow.actor import EndpointDescription

user_layout = EndpointDescription(
	[	("dst", 8),
	 	("length", 4*8),
	 	("error", 1),
		("d", 8)
	],
	packetized=True
)

phy_layout = [
	("d", 8)
]

class LiteUSBPipe:
	def __init__(self, layout):
		self.sink = Sink(layout)
		self.source = Source(layout)

class LiteUSBTimeout(Module):
	def __init__(self, clk_freq, length):
		cnt_max = int(clk_freq*length)
		width = bits_for(cnt_max)

		self.clear = Signal()
		self.done = Signal()

		cnt = Signal(width)
		self.sync += \
			If(self.clear,
				cnt.eq(0)
			).Elif(~self.done,
				cnt.eq(cnt+1)
			)
		self.comb += self.done.eq(cnt == cnt_max)

#
# TB
#
import random

def randn(max_n):
	return random.randint(0, max_n-1)

class RandRun:
	def __init__(self, level=0):
		self.run = True
		self.level = level

	def do_simulation(self, selfp):
		self.run = True
		n = randn(100)
		if n < self.level:
			self.run = False