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hdl._ast: fix using 0-width Switch with integer keys. #1134

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Merged
merged 1 commit into from
Feb 14, 2024
Merged

hdl._ast: fix using 0-width Switch with integer keys. #1134

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6 changes: 6 additions & 0 deletions amaranth/hdl/_ast.py
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Original file line number Diff line number Diff line change
Expand Up @@ -2294,8 +2294,14 @@ def __init__(self, test, cases, *, src_loc=None, src_loc_at=0, case_src_locs={})
key = "".join(key.split()) # remove whitespace
elif isinstance(key, int):
key = format(key & key_mask, "b").rjust(len(self.test), "0")
# fixup for 0-width test
if key_mask == 0:
key = ""
elif isinstance(key, Enum):
key = format(key.value & key_mask, "b").rjust(len(self.test), "0")
# fixup for 0-width test
if key_mask == 0:
key = ""
else:
raise TypeError("Object {!r} cannot be used as a switch key"
.format(key))
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10 changes: 10 additions & 0 deletions tests/test_hdl_ast.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1473,6 +1473,16 @@ def test_int_neg_case(self):
s = Switch(Const(0, 8), {-10: []})
self.assertEqual(s.cases, {("11110110",): []})

def test_int_zero_width(self):
s = Switch(Const(0, 0), {0: []})
self.assertEqual(s.cases, {("",): []})

def test_int_zero_width_enum(self):
class ZeroEnum(Enum):
A = 0
s = Switch(Const(0, 0), {ZeroEnum.A: []})
self.assertEqual(s.cases, {("",): []})

def test_enum_case(self):
s = Switch(Const(0, UnsignedEnum), {UnsignedEnum.FOO: []})
self.assertEqual(s.cases, {("01",): []})
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