amaranth/nmigen/test/test_lib_cdc.py
2019-09-23 14:18:45 +00:00

82 lines
2.7 KiB
Python

from .tools import *
from ..hdl import *
from ..back.pysim import *
from ..lib.cdc import *
class FFSynchronizerTestCase(FHDLTestCase):
def test_basic(self):
i = Signal()
o = Signal()
frag = FFSynchronizer(i, o)
with Simulator(frag) as sim:
sim.add_clock(1e-6)
def process():
self.assertEqual((yield o), 0)
yield i.eq(1)
yield Tick()
self.assertEqual((yield o), 0)
yield Tick()
self.assertEqual((yield o), 0)
yield Tick()
self.assertEqual((yield o), 1)
sim.add_process(process)
sim.run()
def test_reset_value(self):
i = Signal(reset=1)
o = Signal()
frag = FFSynchronizer(i, o, reset=1)
with Simulator(frag) as sim:
sim.add_clock(1e-6)
def process():
self.assertEqual((yield o), 1)
yield i.eq(0)
yield Tick()
self.assertEqual((yield o), 1)
yield Tick()
self.assertEqual((yield o), 1)
yield Tick()
self.assertEqual((yield o), 0)
sim.add_process(process)
sim.run()
class ResetSynchronizerTestCase(FHDLTestCase):
def test_basic(self):
arst = Signal()
m = Module()
m.domains += ClockDomain("sync")
m.submodules += ResetSynchronizer(arst)
s = Signal(reset=1)
m.d.sync += s.eq(0)
with Simulator(m, vcd_file=open("test.vcd", "w")) as sim:
sim.add_clock(1e-6)
def process():
# initial reset
self.assertEqual((yield s), 1)
yield Tick(); yield Delay(1e-8)
self.assertEqual((yield s), 1)
yield Tick(); yield Delay(1e-8)
self.assertEqual((yield s), 1)
yield Tick(); yield Delay(1e-8)
self.assertEqual((yield s), 0)
yield Tick(); yield Delay(1e-8)
yield arst.eq(1)
yield Delay(1e-8)
self.assertEqual((yield s), 1)
yield Tick(); yield Delay(1e-8)
self.assertEqual((yield s), 1)
yield arst.eq(0)
yield Tick(); yield Delay(1e-8)
self.assertEqual((yield s), 1)
yield Tick(); yield Delay(1e-8)
self.assertEqual((yield s), 1)
yield Tick(); yield Delay(1e-8)
self.assertEqual((yield s), 0)
yield Tick(); yield Delay(1e-8)
sim.add_process(process)
sim.run()