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Implement RFC 61: Minimal streams.
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‎amaranth/lib/stream.py

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from ..hdl import *
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from .._utils import final
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from . import wiring
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from .wiring import In, Out
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@final
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class Signature(wiring.Signature):
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def __init__(self, payload_shape: ShapeLike, *, always_valid=False, always_ready=False):
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Shape.cast(payload_shape)
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self._payload_shape = payload_shape
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self._always_valid = bool(always_valid)
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self._always_ready = bool(always_ready)
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super().__init__({
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"payload": Out(payload_shape),
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"valid": Out(1),
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"ready": In(1)
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})
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# payload_shape intentionally not introspectable (for now)
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@property
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def always_valid(self):
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return self._always_valid
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@property
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def always_ready(self):
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return self._always_ready
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def __eq__(self, other):
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return (type(other) is type(self) and
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other._payload_shape == self._payload_shape and
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other.always_valid == self.always_valid and
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other.always_ready == self.always_ready)
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def create(self, *, path=None, src_loc_at=0):
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return Interface(self, path=path, src_loc_at=1 + src_loc_at)
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def __repr__(self):
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always_valid_repr = "" if not self._always_valid else ", always_valid=True"
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always_ready_repr = "" if not self._always_ready else ", always_ready=True"
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return f"stream.Signature({self._payload_shape!r}{always_valid_repr}{always_ready_repr})"
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@final
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class Interface:
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payload: Signal
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valid: 'Signal | Const'
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ready: 'Signal | Const'
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def __init__(self, signature: Signature, *, path=None, src_loc_at=0):
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if not isinstance(signature, Signature):
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raise TypeError(f"Signature of stream.Interface must be a stream.Signature, not "
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f"{signature!r}")
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self._signature = signature
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self.__dict__.update(signature.members.create(path=path, src_loc_at=1 + src_loc_at))
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if signature.always_valid:
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self.valid = Const(1)
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if signature.always_ready:
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self.ready = Const(1)
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@property
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def signature(self):
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return self._signature
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@property
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def p(self):
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return self.payload
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def __repr__(self):
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return f"stream.Interface(payload={self.payload!r}, valid={self.valid!r}, ready={self.ready!r})"

‎docs/stdlib.rst

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@@ -4,7 +4,7 @@ Standard library
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The :mod:`amaranth.lib` module, also known as the standard library, provides modules that falls into one of the three categories:
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1. Modules that will used by essentially all idiomatic Amaranth code, and are necessary for interoperability. This includes :mod:`amaranth.lib.enum` (enumerations), :mod:`amaranth.lib.data` (data structures), and :mod:`amaranth.lib.wiring` (interfaces and components).
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2. Modules that abstract common functionality whose implementation differs between hardware platforms. This includes :mod:`amaranth.lib.cdc`, :mod:`amaranth.lib.memory`.
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2. Modules that abstract common functionality whose implementation differs between hardware platforms. This includes :mod:`amaranth.lib.memory`, :mod:`amaranth.lib.stream`, :mod:`amaranth.lib.cdc`.
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3. Modules that have essentially one correct implementation and are of broad utility in digital designs. This includes :mod:`amaranth.lib.coding`, :mod:`amaranth.lib.fifo`, and :mod:`amaranth.lib.crc`.
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As part of the Amaranth backwards compatibility guarantee, any behaviors described in these documents will not change from a version to another without at least one version including a warning about the impending change. Any nontrivial change to these behaviors must also go through the public review as a part of the `Amaranth Request for Comments process <https://amaranth-lang.org/rfcs/>`_.
@@ -18,6 +18,7 @@ The Amaranth standard library is separate from the Amaranth language: everything
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stdlib/data
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stdlib/wiring
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stdlib/memory
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stdlib/stream
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stdlib/cdc
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stdlib/coding
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stdlib/fifo

‎docs/stdlib/stream.rst

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Data streams
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------------
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.. py:module:: amaranth.lib.stream
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.. todo::
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Write this section.

‎tests/test_lib_stream.py

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from amaranth.hdl import *
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from amaranth.lib import stream, wiring
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from amaranth.lib.wiring import In, Out
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from .utils import *
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class StreamTestCase(FHDLTestCase):
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def test_nav_nar(self):
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sig = stream.Signature(2)
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self.assertRepr(sig, f"stream.Signature(2)")
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self.assertEqual(sig.always_valid, False)
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self.assertEqual(sig.always_ready, False)
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self.assertEqual(sig.members, wiring.SignatureMembers({
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"payload": Out(2),
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"valid": Out(1),
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"ready": In(1)
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}))
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intf = sig.create()
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self.assertRepr(intf, f"stream.Interface(payload=(sig intf__payload), valid=(sig intf__valid), ready=(sig intf__ready))")
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self.assertIs(intf.signature, sig)
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self.assertIsInstance(intf.payload, Signal)
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self.assertIs(intf.p, intf.payload)
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self.assertIsInstance(intf.valid, Signal)
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self.assertIsInstance(intf.ready, Signal)
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def test_av_nar(self):
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sig = stream.Signature(2, always_valid=True)
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self.assertRepr(sig, f"stream.Signature(2, always_valid=True)")
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self.assertEqual(sig.always_valid, True)
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self.assertEqual(sig.always_ready, False)
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self.assertEqual(sig.members, wiring.SignatureMembers({
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"payload": Out(2),
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"valid": Out(1),
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"ready": In(1)
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}))
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intf = sig.create()
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self.assertRepr(intf, f"stream.Interface(payload=(sig intf__payload), valid=(const 1'd1), ready=(sig intf__ready))")
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self.assertIs(intf.signature, sig)
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self.assertIsInstance(intf.payload, Signal)
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self.assertIs(intf.p, intf.payload)
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self.assertIsInstance(intf.valid, Const)
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self.assertEqual(intf.valid.value, 1)
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self.assertIsInstance(intf.ready, Signal)
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def test_nav_ar(self):
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sig = stream.Signature(2, always_ready=True)
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self.assertRepr(sig, f"stream.Signature(2, always_ready=True)")
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self.assertEqual(sig.always_valid, False)
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self.assertEqual(sig.always_ready, True)
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self.assertEqual(sig.members, wiring.SignatureMembers({
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"payload": Out(2),
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"valid": Out(1),
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"ready": In(1)
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}))
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intf = sig.create()
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self.assertRepr(intf, f"stream.Interface(payload=(sig intf__payload), valid=(sig intf__valid), ready=(const 1'd1))")
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self.assertIs(intf.signature, sig)
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self.assertIsInstance(intf.payload, Signal)
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self.assertIs(intf.p, intf.payload)
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self.assertIsInstance(intf.valid, Signal)
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self.assertIsInstance(intf.ready, Const)
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self.assertEqual(intf.ready.value, 1)
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def test_av_ar(self):
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sig = stream.Signature(2, always_valid=True, always_ready=True)
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self.assertRepr(sig, f"stream.Signature(2, always_valid=True, always_ready=True)")
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self.assertEqual(sig.always_valid, True)
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self.assertEqual(sig.always_ready, True)
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self.assertEqual(sig.members, wiring.SignatureMembers({
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"payload": Out(2),
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"valid": Out(1),
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"ready": In(1)
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}))
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intf = sig.create()
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self.assertRepr(intf, f"stream.Interface(payload=(sig intf__payload), valid=(const 1'd1), ready=(const 1'd1))")
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self.assertIs(intf.signature, sig)
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self.assertIsInstance(intf.payload, Signal)
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self.assertIs(intf.p, intf.payload)
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self.assertIsInstance(intf.valid, Const)
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self.assertEqual(intf.valid.value, 1)
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self.assertIsInstance(intf.ready, Const)
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self.assertEqual(intf.ready.value, 1)
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def test_eq(self):
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sig_nav_nar = stream.Signature(2)
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sig_av_nar = stream.Signature(2, always_valid=True)
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sig_nav_ar = stream.Signature(2, always_ready=True)
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sig_av_ar = stream.Signature(2, always_valid=True, always_ready=True)
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sig_av_ar2 = stream.Signature(3, always_valid=True, always_ready=True)
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self.assertNotEqual(sig_nav_nar, None)
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self.assertEqual(sig_nav_nar, sig_nav_nar)
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self.assertEqual(sig_av_nar, sig_av_nar)
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self.assertEqual(sig_nav_ar, sig_nav_ar)
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self.assertEqual(sig_av_ar, sig_av_ar)
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self.assertEqual(sig_av_ar2, sig_av_ar2)
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self.assertNotEqual(sig_nav_nar, sig_av_nar)
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self.assertNotEqual(sig_av_nar, sig_nav_ar)
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self.assertNotEqual(sig_nav_ar, sig_av_ar)
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self.assertNotEqual(sig_av_ar, sig_nav_nar)
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self.assertNotEqual(sig_av_ar, sig_av_ar2)
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def test_interface_create_bad(self):
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with self.assertRaisesRegex(TypeError,
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r"^Signature of stream\.Interface must be a stream\.Signature, not "
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r"Signature\(\{\}\)$"):
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stream.Interface(wiring.Signature({}))

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