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build.res: always return a Pin record.

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In the simple cases, a Pin record consisting of exactly one field
is equivalent in every way to this single field. In the more complex
case however, it can be used as a record, making the code more robust
such that it works with both bidirectional and unidirectional pins.
This commit is contained in:
whitequark 2019-06-01 16:41:30 +00:00
parent 8c1b5a26b3
commit 53ddff9f33
2 changed files with 26 additions and 23 deletions
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31
nmigen/build/res.py
View file

@ -21,8 +21,8 @@ class ConstraintManager:
self.clocks = OrderedDict()
self._ports = []
self._tristates = []
self._diffpairs = []
self._se_pins = []
self._dp_pins = []
self.add_resources(resources)
for name_number, frequency in clocks:
@ -133,19 +133,16 @@ class ConstraintManager:
yield (value, subsignal.io[0], subsignal.extras)
for (pin, io, extras) in match_constraints(value, resource):
if isinstance(io, DiffPairs):
p = Signal(pin.width, name="{}_p".format(pin.name))
n = Signal(pin.width, name="{}_n".format(pin.name))
self._diffpairs.append((pin, p, n))
self._ports.append((p, io.p.names, extras))
self._ports.append((n, io.n.names, extras))
elif isinstance(io, Pins):
if pin.dir == "io":
port = Signal(pin.width, name="{}_io".format(pin.name))
self._tristates.append((pin, port))
else:
port = getattr(pin, pin.dir)
if isinstance(io, Pins):
port = Signal(pin.width, name="{}_io".format(pin.name))
self._se_pins.append((pin, port))
self._ports.append((port, io.names, extras))
elif isinstance(io, DiffPairs):
p_port = Signal(pin.width, name="{}_p".format(pin.name))
n_port = Signal(pin.width, name="{}_n".format(pin.name))
self._dp_pins.append((pin, p_port, n_port))
self._ports.append((p_port, io.p.names, extras))
self._ports.append((n_port, io.n.names, extras))
else:
assert False # :nocov:
@ -169,8 +166,10 @@ class ConstraintManager:
raise ConstraintError("Cannot constrain frequency of resource {}#{} because "
"it has been requested as a tristate buffer"
.format(name, number))
if isinstance(resource.io[0], DiffPairs):
if isinstance(resource.io[0], Pins):
port_name = "{}_io".format(pin.name)
elif isinstance(resource.io[0], DiffPairs):
port_name = "{}_p".format(pin.name)
else:
port_name = getattr(pin, pin.dir).name
assert False
yield (port_name, period)