litex/test/test_prbs.py

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#
# This file is part of LiteX.
#
# Copyright (c) 2019 Florent Kermarrec <florent@enjoy-digital.fr>
# SPDX-License-Identifier: BSD-2-Clause
2019-06-23 17:31:11 -04:00
import unittest
from migen import *
from litex.soc.cores.prbs import *
class PRBSModel:
def __init__(self, n_state=23, taps=[17, 22]):
self.n_state = n_state
self.taps = taps
self.state = 1
def getbit(self):
feedback = 0
for tap in self.taps:
feedback = feedback ^ (self.state >> tap) & 0x1
self.state = (self.state << 1) & (2**self.n_state-1) | feedback
return feedback
def getbits(self, n):
v = 0
for i in range(n):
v <<= 1
v |= self.getbit()
return v
class PRBS7Model(PRBSModel):
def __init__(self):
PRBSModel.__init__(self, n_state=7, taps=[5, 6])
class PRBS15Model(PRBSModel):
def __init__(self):
PRBSModel.__init__(self, n_state=15, taps=[13, 14])
class PRBS31Model(PRBSModel):
def __init__(self):
PRBSModel.__init__(self, n_state=31, taps=[27, 30])
class TestPRBS(unittest.TestCase):
def test_prbs_generator(self):
duts = {
"prbs7": PRBS7Generator(8),
"prbs15": PRBS15Generator(16),
"prbs31": PRBS31Generator(32),
}
models = {
"prbs7": PRBS7Model(),
"prbs15": PRBS15Model(),
"prbs31": PRBS31Model(),
}
errors = 0
for test in ["prbs7", "prbs15", "prbs31"]:
dut = duts[test]
dut._errors = 0
model = models[test]
def checker(dut, cycles):
yield
# Let the generator run and check values against model.
for i in range(cycles):
if (yield dut.o) != model.getbits(len(dut.o)):
dut._errors += 1
yield
run_simulation(dut, checker(dut, 1024))
self.assertEqual(dut._errors, 0)
def test_prbs_checker(self):
duts = {
"prbs7": PRBS7Checker(8),
"prbs15": PRBS15Checker(16),
"prbs31": PRBS31Checker(32),
}
models = {
"prbs7": PRBS7Model(),
"prbs15": PRBS15Model(),
"prbs31": PRBS31Model(),
}
errors = 0
for test in ["prbs7", "prbs15", "prbs31"]:
dut = duts[test]
dut._errors = 0
model = models[test]
@passive
def generator(dut):
# Inject PRBS values from model.
while True:
yield dut.i.eq(model.getbits(len(dut.i)))
yield
def checker(dut, cycles):
# Wait PRBS synchronization.
for i in range(8):
yield
# Check that no errors are reported.
for i in range(cycles):
if (yield dut.errors) != 0:
dut._errors += 1
yield
run_simulation(dut, [generator(dut), checker(dut, 1024)])
self.assertEqual(dut._errors, 0)