6fae06aea9
Although a dir="oe" pin is generally equivalent to dir="io" pin with the i* signal(s) disconnected, they are not equivalent, because some pins may not be able to support input buffers at all, either because there are no input buffers, or because the input buffers are consumed by some other resource. E.g. this can happen on iCE40 when the input buffer is consumed by a PLL.
108 lines
4 KiB
Python
108 lines
4 KiB
Python
__all__ = ["Pins", "DiffPairs", "Subsignal", "Resource"]
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class Pins:
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def __init__(self, names, dir="io"):
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if not isinstance(names, str):
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raise TypeError("Names must be a whitespace-separated string, not {!r}"
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.format(names))
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self.names = names.split()
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if dir not in ("i", "o", "io"):
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raise TypeError("Direction must be one of \"i\", \"o\", \"oe\", or \"io\", not {!r}"
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.format(dir))
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self.dir = dir
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def __len__(self):
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return len(self.names)
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def __iter__(self):
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return iter(self.names)
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def __repr__(self):
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return "(pins {} {})".format(self.dir, " ".join(self.names))
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class DiffPairs:
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def __init__(self, p, n, dir="io"):
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self.p = Pins(p, dir=dir)
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self.n = Pins(n, dir=dir)
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if len(self.p.names) != len(self.n.names):
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raise TypeError("Positive and negative pins must have the same width, but {!r} "
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"and {!r} do not"
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.format(self.p, self.n))
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self.dir = dir
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def __len__(self):
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return len(self.p.names)
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def __iter__(self):
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return zip(self.p.names, self.n.names)
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def __repr__(self):
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return "(diffpairs {} (p {}) (n {}))".format(
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self.dir, " ".join(self.p.names), " ".join(self.n.names))
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class Subsignal:
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def __init__(self, name, *io, extras=None):
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self.name = name
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if not io:
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raise TypeError("Missing I/O constraints")
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for c in io:
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if not isinstance(c, (Pins, DiffPairs, Subsignal)):
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raise TypeError("I/O constraint must be one of Pins, DiffPairs or Subsignal, "
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"not {!r}"
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.format(c))
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if isinstance(io[0], (Pins, DiffPairs)) and len(io) > 1:
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raise TypeError("Pins and DiffPairs cannot be followed by more I/O constraints, but "
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"{!r} is followed by {!r}"
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.format(io[0], io[1]))
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if isinstance(io[0], Subsignal):
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for c in io[1:]:
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if not isinstance(c, Subsignal):
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raise TypeError("A Subsignal can only be followed by more Subsignals, but "
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"{!r} is followed by {!r}"
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.format(io[0], c))
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self.io = io
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self.extras = {}
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if extras is not None:
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if not isinstance(extras, dict):
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raise TypeError("Extra constraints must be a dict, not {!r}"
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.format(extras))
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for extra_key, extra_value in extras.items():
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if not isinstance(extra_key, str):
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raise TypeError("Extra constraint key must be a string, not {!r}"
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.format(extra_key))
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if not isinstance(extra_value, str):
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raise TypeError("Extra constraint value must be a string, not {!r}"
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.format(extra_value))
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self.extras[extra_key] = extra_value
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if isinstance(self.io[0], Subsignal):
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for sub in self.io:
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sub.extras.update(self.extras)
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def __repr__(self):
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return "(subsignal {} {} {})".format(self.name,
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" ".join(map(repr, self.io)),
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" ".join("{}={}".format(k, v)
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for k, v in self.extras.items()))
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class Resource(Subsignal):
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def __init__(self, name, number, *io, extras=None):
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super().__init__(name, *io, extras=extras)
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self.number = number
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def __repr__(self):
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return "(resource {} {} {} {})".format(self.name, self.number,
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" ".join(map(repr, self.io)),
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" ".join("{}={}".format(k, v)
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for k, v in self.extras.items()))
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