add test directory with test_code_8b10b.py (from misoc)

setup.py

@@ -18,6 +18,7 @@ setup(
     author_email="florent@enjoy-digital.fr",
     url="http://enjoy-digital.fr",
     download_url="https://github.com/enjoy-digital/litex",
+    test_suite="test",
     license="BSD",
     platforms=["Any"],
     keywords="HDL ASIC FPGA hardware design",

test/test_code_8b10b.py

@@ -0,0 +1,106 @@
+import unittest
+import random
+from collections import namedtuple
+
+from litex.gen import *
+
+from litex.soc.cores import code_8b10b
+
+
+Control = namedtuple("Control", "value")
+
+
+def encode_sequence(seq):
+    output = []
+
+    dut = code_8b10b.Encoder()
+    def pump():
+        for w in seq:
+            if isinstance(w, Control):
+                yield dut.k[0].eq(1)
+                yield dut.d[0].eq(w.value)
+            else:
+                yield dut.k[0].eq(0)
+                yield dut.d[0].eq(w)
+            yield
+            output.append((yield dut.output[0]))
+        for _ in range(2):
+            yield
+            output.append((yield dut.output[0]))
+    run_simulation(dut, pump())
+
+    return output[2:]
+
+
+def decode_sequence(seq):
+    output = []
+
+    dut = code_8b10b.Decoder()
+    def pump():
+        for w in seq:
+            yield dut.input.eq(w)
+            yield
+            if (yield dut.k):
+                output.append(Control((yield dut.d)))
+            else:
+                output.append((yield dut.d))
+        yield
+        if (yield dut.k):
+            output.append(Control((yield dut.d)))
+        else:
+            output.append((yield dut.d))
+    run_simulation(dut, pump())
+    return output[1:]
+
+
+class TestLineCoding(unittest.TestCase):
+    @classmethod
+    def setUpClass(cls):
+        prng = random.Random(42)
+        cls.input_sequence = []
+        for i in 23, 27, 29, 30:
+            cls.input_sequence += [Control((7 << 5) | i)]*2
+        for i in range(8):
+            cls.input_sequence += [Control((i << 5) | 28)]*2
+        cls.input_sequence += [prng.randrange(256) for _ in range(10000)]
+        cls.output_sequence = encode_sequence(cls.input_sequence)
+
+    def test_comma(self):
+        control_chars = [
+            0b1110101000,
+            0b1101101000,
+            0b1011101000,
+            0b0111101000,
+
+            0b0011110100,
+            0b0011111001,
+            0b0011110101,
+            0b0011110011,
+            0b0011110010,
+            0b0011111010,
+            0b0011110110,
+            0b0011111000,
+        ]
+        for i, c in enumerate(control_chars):
+            ok = {c, ~c & 0b1111111111}
+            with self.subTest(i=i):
+                self.assertIn(self.output_sequence[2*i], ok)
+                self.assertIn(self.output_sequence[2*i+1], ok)
+
+    def test_running_disparity(self):
+        rd = -1
+        for w in self.output_sequence:
+            rd += code_8b10b.disparity(w, 10)
+            self.assertIn(rd, {-1, 1})
+
+    def test_no_spurious_commas(self):
+        for w1, w2 in zip(self.output_sequence[16+8:], self.output_sequence[16+8+1:]):
+            for shift in range(10):
+                cw = (w1 << shift) | (w2 >> (10-shift))
+                self.assertNotIn(cw, {0b0011111001, 0b1100000110,   # K28.1
+                                      0b0011111010, 0b1100000101,   # K28.5
+                                      0b0011111000, 0b1100000111})  # K28.7
+
+    def test_roundtrip(self):
+        self.assertEqual(self.input_sequence,
+                         decode_sequence(self.output_sequence))