test/test_bitslip.py

   1 import unittest
   2 import random
   3
   4 from migen import *
   5 from migen.genlib.misc import BitSlip
   6
   7
   8 class BitSlipModel:
   9     def __init__(self, data_width, latency):
  10         self.data_width = data_width
  11         self.latency = latency
  12
  13     def simulate(self, bitslip, sequence):
  14         # prepare sequence for simulation
  15         s = [0]*self.latency
  16         for d in sequence:
  17             s.append(d)
  18         # simulate bitslip
  19         r = []
  20         for i in range(len(s)-1):
  21             v = (s[i+1] << self.data_width) | s[i]
  22             v = v >> bitslip
  23             v &= 2**self.data_width-1
  24             r.append(v)
  25         return r
  26
  27
  28 def main_generator(dut):
  29     dut.o_sequence = []
  30     yield dut.value.eq(dut.bitslip)
  31     for i, data in enumerate(dut.i_sequence):
  32         yield dut.i.eq(data)
  33         dut.o_sequence.append((yield dut.o))
  34         yield
  35
  36
  37 class TestBitSlip(unittest.TestCase):
  38     def bitslip_test(self, data_width, length=128):
  39         prng = random.Random(42)
  40         sequence = [prng.randrange(2**data_width) for i in range(length)]
  41
  42         for i in range(data_width):
  43             dut = BitSlip(data_width)
  44             dut.bitslip = i
  45             dut.i_sequence = sequence
  46             run_simulation(dut, main_generator(dut))
  47
  48             model = BitSlipModel(data_width, 4)
  49             m_sequence = model.simulate(i, sequence)
  50
  51             self.assertEqual(dut.o_sequence, m_sequence[:len(dut.o_sequence)])
  52
  53     def test_bitslip_4b(self):
  54         self.bitslip_test(4)
  55
  56     def test_bitslip_8b(self):
  57         self.bitslip_test(8)
  58
  59     def test_bitslip_16b(self):
  60         self.bitslip_test(16)
  61
  62     def test_bitslip_32b(self):
  63         self.bitslip_test(32)
  64
  65     def test_bitslip_64b(self):
  66         self.bitslip_test(64)
  67
  68     def test_bitslip_128b(self):
  69         self.bitslip_test(128)