migen/test/test_signed: add a (currently failing) signed comparison testcase

diff --git a/migen/test/test_signed.py b/migen/test/test_signed.py
new file mode 100644 (file)
index 0000000..d84691e
--- /dev/null
+++ b/migen/test/test_signed.py
@@ -0,0 +1,45 @@
+import unittest
+
+from migen.fhdl.std import *
+from migen.test.support import SimCase, SimBench
+
+class SignedCase(SimCase, unittest.TestCase):
+       class TestBench(SimBench):
+               def __init__(self):
+                       self.a = Signal((3, True))
+                       self.b = Signal((4, True))
+                       comps = [
+                                       lambda p, q: p > q,
+                                       lambda p, q: p >= q,
+                                       lambda p, q: p < q,
+                                       lambda p, q: p <= q,
+                                       lambda p, q: p == q,
+                                       lambda p, q: p != q,
+                                       ]
+                       self.vals = []
+                       for asign in 1, -1:
+                               for bsign in 1, -1:
+                                       for f in comps:
+                                               r = Signal()
+                                               r0 = f(asign*self.a, bsign*self.b)
+                                               self.comb += r.eq(r0)
+                                               self.vals.append((asign, bsign, f, r, r0.op))
+
+       def test_comparisons(self):
+               values = range(-4, 4)
+               agen = iter(values)
+               bgen = iter(values)
+               def cb(tb, s):
+                       try:
+                               s.wr(self.tb.a, next(agen))
+                               s.wr(self.tb.b, next(bgen))
+                       except StopIteration:
+                               s.interrupt = True
+                       a = s.rd(self.tb.a)
+                       b = s.rd(self.tb.b)
+                       for asign, bsign, f, r, op in self.tb.vals:
+                               r, r0 = s.rd(r), f(asign*a, bsign*b)
+                               self.assertEqual(r, int(r0),
+                                               "got {}, want {}*{} {} {}*{} = {}".format(
+                                                       r, asign, a, op, bsign, b, r0))
+               self.run_with(cb)