107 lines
3.0 KiB
Python
107 lines
3.0 KiB
Python
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import unittest
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import random
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from collections import namedtuple
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from litex.gen import *
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from litex.soc.cores import code_8b10b
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Control = namedtuple("Control", "value")
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def encode_sequence(seq):
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output = []
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dut = code_8b10b.Encoder()
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def pump():
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for w in seq:
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if isinstance(w, Control):
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yield dut.k[0].eq(1)
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yield dut.d[0].eq(w.value)
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else:
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yield dut.k[0].eq(0)
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yield dut.d[0].eq(w)
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yield
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output.append((yield dut.output[0]))
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for _ in range(2):
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yield
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output.append((yield dut.output[0]))
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run_simulation(dut, pump())
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return output[2:]
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def decode_sequence(seq):
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output = []
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dut = code_8b10b.Decoder()
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def pump():
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for w in seq:
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yield dut.input.eq(w)
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yield
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if (yield dut.k):
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output.append(Control((yield dut.d)))
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else:
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output.append((yield dut.d))
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yield
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if (yield dut.k):
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output.append(Control((yield dut.d)))
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else:
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output.append((yield dut.d))
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run_simulation(dut, pump())
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return output[1:]
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class TestLineCoding(unittest.TestCase):
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@classmethod
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def setUpClass(cls):
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prng = random.Random(42)
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cls.input_sequence = []
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for i in 23, 27, 29, 30:
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cls.input_sequence += [Control((7 << 5) | i)]*2
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for i in range(8):
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cls.input_sequence += [Control((i << 5) | 28)]*2
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cls.input_sequence += [prng.randrange(256) for _ in range(10000)]
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cls.output_sequence = encode_sequence(cls.input_sequence)
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def test_comma(self):
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control_chars = [
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0b1110101000,
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0b1101101000,
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0b1011101000,
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0b0111101000,
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0b0011110100,
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0b0011111001,
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0b0011110101,
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0b0011110011,
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0b0011110010,
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0b0011111010,
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0b0011110110,
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0b0011111000,
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]
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for i, c in enumerate(control_chars):
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ok = {c, ~c & 0b1111111111}
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with self.subTest(i=i):
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self.assertIn(self.output_sequence[2*i], ok)
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self.assertIn(self.output_sequence[2*i+1], ok)
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def test_running_disparity(self):
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rd = -1
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for w in self.output_sequence:
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rd += code_8b10b.disparity(w, 10)
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self.assertIn(rd, {-1, 1})
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def test_no_spurious_commas(self):
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for w1, w2 in zip(self.output_sequence[16+8:], self.output_sequence[16+8+1:]):
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for shift in range(10):
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cw = (w1 << shift) | (w2 >> (10-shift))
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self.assertNotIn(cw, {0b0011111001, 0b1100000110, # K28.1
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0b0011111010, 0b1100000101, # K28.5
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0b0011111000, 0b1100000111}) # K28.7
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def test_roundtrip(self):
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self.assertEqual(self.input_sequence,
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decode_sequence(self.output_sequence))
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