amaranth/tests/test_lib_cdc.py
whitequark 67b957d4f4 tests: move out of the main package.
Compared to tests in the repository root, tests in the package have
many downsides:
  * Unless explicitly excluded in find_packages(), tests and their
    support code effectively become a part of public API.
    This, unfortunately, happened with FHDLTestCase, which was never
    intended for downstream use.
  * Even if explicitly excluded from the setuptools package, using
    an editable install, or setting PYTHONPATH still allows accessing
    the tests.
  * Having a sub-package that is present in the source tree but not
    exported (or, worse, exported only sometimes) is confusing.
  * The name `nmigen.test` cannot be used for anything else, such as
    testing utilities that *are* intended for downstream use.
2020-08-27 00:33:31 +00:00

232 lines
7.8 KiB
Python

# nmigen: UnusedElaboratable=no
from nmigen.hdl import *
from nmigen.back.pysim import *
from nmigen.lib.cdc import *
from .utils import *
class FFSynchronizerTestCase(FHDLTestCase):
def test_stages_wrong(self):
with self.assertRaisesRegex(TypeError,
r"^Synchronization stage count must be a positive integer, not 0$"):
FFSynchronizer(Signal(), Signal(), stages=0)
with self.assertRaisesRegex(ValueError,
r"^Synchronization stage count may not safely be less than 2$"):
FFSynchronizer(Signal(), Signal(), stages=1)
def test_basic(self):
i = Signal()
o = Signal()
frag = FFSynchronizer(i, o)
sim = Simulator(frag)
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)
sim = Simulator(frag)
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 AsyncFFSynchronizerTestCase(FHDLTestCase):
def test_stages_wrong(self):
with self.assertRaisesRegex(TypeError,
r"^Synchronization stage count must be a positive integer, not 0$"):
ResetSynchronizer(Signal(), stages=0)
with self.assertRaisesRegex(ValueError,
r"^Synchronization stage count may not safely be less than 2$"):
ResetSynchronizer(Signal(), stages=1)
def test_edge_wrong(self):
with self.assertRaisesRegex(ValueError,
r"^AsyncFFSynchronizer async edge must be one of 'pos' or 'neg', not 'xxx'$"):
AsyncFFSynchronizer(Signal(), Signal(), o_domain="sync", async_edge="xxx")
def test_pos_edge(self):
i = Signal()
o = Signal()
m = Module()
m.domains += ClockDomain("sync")
m.submodules += AsyncFFSynchronizer(i, o)
sim = Simulator(m)
sim.add_clock(1e-6)
def process():
# initial reset
self.assertEqual((yield i), 0)
self.assertEqual((yield o), 1)
yield Tick(); yield Delay(1e-8)
self.assertEqual((yield o), 1)
yield Tick(); yield Delay(1e-8)
self.assertEqual((yield o), 0)
yield Tick(); yield Delay(1e-8)
self.assertEqual((yield o), 0)
yield Tick(); yield Delay(1e-8)
yield i.eq(1)
yield Delay(1e-8)
self.assertEqual((yield o), 1)
yield Tick(); yield Delay(1e-8)
self.assertEqual((yield o), 1)
yield i.eq(0)
yield Tick(); yield Delay(1e-8)
self.assertEqual((yield o), 1)
yield Tick(); yield Delay(1e-8)
self.assertEqual((yield o), 0)
yield Tick(); yield Delay(1e-8)
self.assertEqual((yield o), 0)
yield Tick(); yield Delay(1e-8)
sim.add_process(process)
with sim.write_vcd("test.vcd"):
sim.run()
def test_neg_edge(self):
i = Signal(reset=1)
o = Signal()
m = Module()
m.domains += ClockDomain("sync")
m.submodules += AsyncFFSynchronizer(i, o, async_edge="neg")
sim = Simulator(m)
sim.add_clock(1e-6)
def process():
# initial reset
self.assertEqual((yield i), 1)
self.assertEqual((yield o), 1)
yield Tick(); yield Delay(1e-8)
self.assertEqual((yield o), 1)
yield Tick(); yield Delay(1e-8)
self.assertEqual((yield o), 0)
yield Tick(); yield Delay(1e-8)
self.assertEqual((yield o), 0)
yield Tick(); yield Delay(1e-8)
yield i.eq(0)
yield Delay(1e-8)
self.assertEqual((yield o), 1)
yield Tick(); yield Delay(1e-8)
self.assertEqual((yield o), 1)
yield i.eq(1)
yield Tick(); yield Delay(1e-8)
self.assertEqual((yield o), 1)
yield Tick(); yield Delay(1e-8)
self.assertEqual((yield o), 0)
yield Tick(); yield Delay(1e-8)
self.assertEqual((yield o), 0)
yield Tick(); yield Delay(1e-8)
sim.add_process(process)
with sim.write_vcd("test.vcd"):
sim.run()
class ResetSynchronizerTestCase(FHDLTestCase):
def test_stages_wrong(self):
with self.assertRaisesRegex(TypeError,
r"^Synchronization stage count must be a positive integer, not 0$"):
ResetSynchronizer(Signal(), stages=0)
with self.assertRaisesRegex(ValueError,
r"^Synchronization stage count may not safely be less than 2$"):
ResetSynchronizer(Signal(), stages=1)
def test_basic(self):
arst = Signal()
m = Module()
m.domains += ClockDomain("sync")
m.submodules += ResetSynchronizer(arst)
s = Signal(reset=1)
m.d.sync += s.eq(0)
sim = Simulator(m)
sim.add_clock(1e-6)
def process():
# initial reset
self.assertEqual((yield s), 1)
yield Tick(); yield Delay(1e-8)
self.assertEqual((yield s), 1)
yield Tick(); yield Delay(1e-8)
self.assertEqual((yield s), 1)
yield Tick(); yield Delay(1e-8)
self.assertEqual((yield s), 0)
yield Tick(); yield Delay(1e-8)
yield arst.eq(1)
yield Delay(1e-8)
self.assertEqual((yield s), 0)
yield Tick(); yield Delay(1e-8)
self.assertEqual((yield s), 1)
yield arst.eq(0)
yield Tick(); yield Delay(1e-8)
self.assertEqual((yield s), 1)
yield Tick(); yield Delay(1e-8)
self.assertEqual((yield s), 1)
yield Tick(); yield Delay(1e-8)
self.assertEqual((yield s), 0)
yield Tick(); yield Delay(1e-8)
sim.add_process(process)
with sim.write_vcd("test.vcd"):
sim.run()
# TODO: test with distinct clocks
class PulseSynchronizerTestCase(FHDLTestCase):
def test_stages_wrong(self):
with self.assertRaisesRegex(TypeError,
r"^Synchronization stage count must be a positive integer, not 0$"):
PulseSynchronizer("w", "r", stages=0)
with self.assertRaisesRegex(ValueError,
r"^Synchronization stage count may not safely be less than 2$"):
PulseSynchronizer("w", "r", stages=1)
def test_smoke(self):
m = Module()
m.domains += ClockDomain("sync")
ps = m.submodules.dut = PulseSynchronizer("sync", "sync")
sim = Simulator(m)
sim.add_clock(1e-6)
def process():
yield ps.i.eq(0)
# TODO: think about reset
for n in range(5):
yield Tick()
# Make sure no pulses are generated in quiescent state
for n in range(3):
yield Tick()
self.assertEqual((yield ps.o), 0)
# Check conservation of pulses
accum = 0
for n in range(10):
yield ps.i.eq(1 if n < 4 else 0)
yield Tick()
accum += yield ps.o
self.assertEqual(accum, 4)
sim.add_process(process)
sim.run()