lib.io: Implement *Buffer from RFC 55.
This commit is contained in:
Wanda
Catherine
parent
81eae1dd35
commit
456dcaeb7b
3 changed files with 965 additions and 25 deletions
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@ -1,13 +1,19 @@
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import enum
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import operator
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from abc import ABCMeta, abstractmethod
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from collections.abc import Iterable
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from ..hdl import *
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from ..lib import wiring
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from ..lib import wiring, data
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from ..lib.wiring import In, Out
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from .. import tracer
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__all__ = ["Direction", "SingleEndedPort", "DifferentialPort", "Pin"]
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__all__ = [
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"Direction", "PortLike", "SingleEndedPort", "DifferentialPort",
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"Buffer", "FFBuffer", "DDRBuffer",
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"Pin",
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]
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class Direction(enum.Enum):
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@ -41,16 +47,52 @@ class Direction(enum.Enum):
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raise ValueError("Cannot combine input port with output port")
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class SingleEndedPort:
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class PortLike(metaclass=ABCMeta):
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"""Represents an abstract port that can be passed to a buffer.
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The port types supported by most platforms are :class:`SingleEndedPort` and
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:class:`DifferentialPort`. Platforms may define additional custom port types as appropriate.
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"""
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@property
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@abstractmethod
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def direction(self):
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"""The direction of this port, as :class:`Direction`."""
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raise NotImplementedError # :nocov:
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@abstractmethod
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def __len__(self):
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"""Returns the width of this port in bits."""
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raise NotImplementedError # :nocov:
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@abstractmethod
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def __getitem__(self, index):
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"""Slices the port, returning another :class:`PortLike` with a subset
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of its bits.
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The index can be a :class:`slice` or :class:`int`. If the index is
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an :class:`int`, the result is a single-bit :class:`PortLike`."""
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raise NotImplementedError # :nocov:
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@abstractmethod
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def __invert__(self):
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"""Returns a new :class:`PortLike` object like this one, but with inverted polarity.
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The result should be such that using :class:`Buffer` on it is equivalent to using
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:class:`Buffer` on the original, with added inverters on the :py:`i` and :py:`o` ports."""
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raise NotImplementedError # :nocov:
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class SingleEndedPort(PortLike):
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"""Represents a single-ended I/O port with optional inversion.
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Parameters
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----------
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io : IOValue
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io : :class:`IOValue`
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The raw I/O value being wrapped.
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invert : bool or iterable of bool
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invert : :class:`bool` or iterable of :class:`bool`
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If true, the electrical state of the physical pin will be opposite from the Amaranth value
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(the ``*Buffer`` classes will insert inverters on ``o`` and ``i`` pins, as appropriate).
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(the ``*Buffer`` classes will insert inverters on :py:`o` and :py:`i` pins, as appropriate).
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This can be used for various purposes:
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@ -59,9 +101,9 @@ class SingleEndedPort:
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on the pin
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If the value is a simple :class:`bool`, it is used for all bits of this port. If the value
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is an iterable of :class:`bool`, the iterable must have the same length as ``io``, and
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is an iterable of :class:`bool`, the iterable must have the same length as :py:`io`, and
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the inversion is specified per-bit.
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direction : Direction or str
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direction : :class:`Direction` or :class:`str`
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Represents the allowed directions of this port. If equal to :attr:`Direction.Input` or
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:attr:`Direction.Output`, this port can only be used with buffers of matching direction.
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If equal to :attr:`Direction.Bidir`, this port can be used with buffers of any direction.
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@ -84,18 +126,18 @@ class SingleEndedPort:
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@property
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def io(self):
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"""The ``io`` argument passed to the constructor."""
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"""The :py:`io` argument passed to the constructor."""
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return self._io
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@property
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def invert(self):
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"""The ``invert`` argument passed to the constructor, normalized to a :class:`tuple`
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"""The :py:`invert` argument passed to the constructor, normalized to a :class:`tuple`
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of :class:`bool`."""
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return self._invert
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@property
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def direction(self):
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"""The ``direction`` argument passed to the constructor, normalized to :class:`Direction`."""
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"""The :py:`direction` argument passed to the constructor, normalized to :class:`Direction`."""
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return self._direction
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def __len__(self):
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@ -103,7 +145,7 @@ class SingleEndedPort:
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return len(self._io)
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def __invert__(self):
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"""Returns a new :class:`SingleEndedPort` with the opposite value of ``invert``."""
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"""Returns a new :class:`SingleEndedPort` with the opposite value of :py:`invert`."""
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return SingleEndedPort(self._io, invert=tuple(not inv for inv in self._invert),
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direction=self._direction)
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@ -141,19 +183,19 @@ class SingleEndedPort:
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return f"SingleEndedPort({self._io!r}, invert={invert!r}, direction={self._direction})"
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class DifferentialPort:
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class DifferentialPort(PortLike):
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"""Represents a differential I/O port with optional inversion.
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Parameters
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----------
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p : IOValue
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p : :class:`IOValue`
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The raw I/O value used as positive (true) half of the port.
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n : IOValue
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n : :class:`IOValue`
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The raw I/O value used as negative (complemented) half of the port. Must have the same
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length as ``p``.
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invert : bool or iterable of bool
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length as :py:`p`.
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invert : :class:`bool` or iterable of :class`bool`
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If true, the electrical state of the physical pin will be opposite from the Amaranth value
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(the ``*Buffer`` classes will insert inverters on ``o`` and ``i`` pins, as appropriate).
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(the ``*Buffer`` classes will insert inverters on :py:`o` and :py:`i` pins, as appropriate).
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This can be used for various purposes:
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@ -161,9 +203,9 @@ class DifferentialPort:
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- Compensating for boards where the P and N pins are swapped (e.g. for easier routing)
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If the value is a simple :class:`bool`, it is used for all bits of this port. If the value
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is an iterable of :class:`bool`, the iterable must have the same length as ``io``, and
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is an iterable of :class:`bool`, the iterable must have the same length as :py:`io`, and
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the inversion is specified per-bit.
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direction : Direction or str
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direction : :class:`Direction` or :class:`str`
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Represents the allowed directions of this port. If equal to :attr:`Direction.Input` or
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:attr:`Direction.Output`, this port can only be used with buffers of matching direction.
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If equal to :attr:`Direction.Bidir`, this port can be used with buffers of any direction.
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@ -190,23 +232,23 @@ class DifferentialPort:
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@property
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def p(self):
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"""The ``p`` argument passed to the constructor."""
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"""The :py:`p` argument passed to the constructor."""
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return self._p
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@property
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def n(self):
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"""The ``n`` argument passed to the constructor."""
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"""The :py:`n` argument passed to the constructor."""
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return self._n
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@property
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def invert(self):
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"""The ``invert`` argument passed to the constructor, normalized to a :class:`tuple`
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"""The :py:`invert` argument passed to the constructor, normalized to a :class:`tuple`
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of :class:`bool`."""
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return self._invert
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@property
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def direction(self):
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"""The ``direction`` argument passed to the constructor, normalized to :class:`Direction`."""
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"""The :py:`direction` argument passed to the constructor, normalized to :class:`Direction`."""
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return self._direction
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def __len__(self):
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@ -214,7 +256,7 @@ class DifferentialPort:
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return len(self._p)
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def __invert__(self):
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"""Returns a new :class:`DifferentialPort` with the opposite value of ``invert``."""
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"""Returns a new :class:`DifferentialPort` with the opposite value of :py:`invert`."""
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return DifferentialPort(self._p, self._n, invert=tuple(not inv for inv in self._invert),
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direction=self._direction)
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@ -253,6 +295,357 @@ class DifferentialPort:
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return f"DifferentialPort({self._p!r}, {self._n!r}, invert={invert!r}, direction={self._direction})"
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class Buffer(wiring.Component):
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"""A combinatorial I/O buffer.
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Parameters
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----------
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direction : :class:`Direction`
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port : :class:`PortLike`
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Attributes
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----------
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signature : :class:`Buffer.Signature`
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Created based on constructor arguments.
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"""
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class Signature(wiring.Signature):
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"""A signature of a combinatorial I/O buffer.
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Parameters
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----------
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direction : :class:`Direction`
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width : :class:`int`
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Attributes
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----------
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i: :py:`unsigned(width)` (if :py:`direction in (Direction.Input, Direction.Bidir)`)
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o: :py:`unsigned(width)` (if :py:`direction in (Direction.Output, Direction.Bidir)`)
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oe: :py:`unsigned(1, init=0)` (if :py:`direction is Direction.Bidir`)
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oe: :py:`unsigned(1, init=1)` (if :py:`direction is Direction.Output`)
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"""
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def __init__(self, direction, width):
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self._direction = Direction(direction)
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self._width = operator.index(width)
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members = {}
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if self._direction is not Direction.Output:
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members["i"] = wiring.In(self._width)
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if self._direction is not Direction.Input:
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members["o"] = wiring.Out(self._width)
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members["oe"] = wiring.Out(1, init=int(self._direction is Direction.Output))
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super().__init__(members)
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@property
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def direction(self):
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return self._direction
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@property
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def width(self):
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return self._width
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def __eq__(self, other):
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return type(self) is type(other) and self.direction == other.direction and self.width == other.width
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def __repr__(self):
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return f"Buffer.Signature({self.direction}, {self.width})"
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def __init__(self, direction, port):
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if not isinstance(port, PortLike):
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raise TypeError(f"'port' must be a 'PortLike', not {port!r}")
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self._port = port
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super().__init__(Buffer.Signature(direction, len(port)).flip())
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if port.direction is Direction.Input and self.direction is not Direction.Input:
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raise ValueError(f"Input port cannot be used with {self.direction.name} buffer")
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if port.direction is Direction.Output and self.direction is not Direction.Output:
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raise ValueError(f"Output port cannot be used with {self.direction.name} buffer")
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@property
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def port(self):
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return self._port
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@property
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def direction(self):
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return self.signature.direction
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def elaborate(self, platform):
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if hasattr(platform, "get_io_buffer"):
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return platform.get_io_buffer(self)
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m = Module()
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invert = sum(bit << idx for idx, bit in enumerate(self._port.invert))
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if self.direction is not Direction.Input:
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if invert != 0:
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o_inv = Signal.like(self.o)
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m.d.comb += o_inv.eq(self.o ^ invert)
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else:
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o_inv = self.o
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if self.direction is not Direction.Output:
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if invert:
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i_inv = Signal.like(self.i)
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m.d.comb += self.i.eq(i_inv ^ invert)
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else:
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i_inv = self.i
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if isinstance(self._port, SingleEndedPort):
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if self.direction is Direction.Input:
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m.submodules += IOBufferInstance(self._port.io, i=i_inv)
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elif self.direction is Direction.Output:
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m.submodules += IOBufferInstance(self._port.io, o=o_inv, oe=self.oe)
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else:
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m.submodules += IOBufferInstance(self._port.io, o=o_inv, oe=self.oe, i=i_inv)
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elif isinstance(self._port, DifferentialPort):
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if self.direction is Direction.Input:
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m.submodules += IOBufferInstance(self._port.p, i=i_inv)
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elif self.direction is Direction.Output:
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m.submodules += IOBufferInstance(self._port.p, o=o_inv, oe=self.oe)
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m.submodules += IOBufferInstance(self._port.n, o=~o_inv, oe=self.oe)
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else:
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m.submodules += IOBufferInstance(self._port.p, o=o_inv, oe=self.oe, i=i_inv)
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m.submodules += IOBufferInstance(self._port.n, o=~o_inv, oe=self.oe)
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else:
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raise TypeError("Cannot elaborate generic 'Buffer' with port {self._port!r}")
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return m
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class FFBuffer(wiring.Component):
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"""A registered I/O buffer.
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Equivalent to a plain :class:`Buffer` combined with reset-less registers on :py:`i`, :py:`o`,
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:py:`oe`.
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Parameters
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----------
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direction : :class:`Direction`
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port : :class:`PortLike`
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i_domain : :class:`str`
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Domain for input register. Only used when :py:`direction in (Direction.Input, Direction.Bidir)`.
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Defaults to :py:`"sync"`
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o_domain : :class:`str`
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Domain for output and output enable registers. Only used when
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:py:`direction in (Direction.Output, Direction.Bidir)`. Defaults to :py:`"sync"`
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Attributes
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----------
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signature : FFBuffer.Signature
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Created based on constructor arguments.
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"""
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class Signature(wiring.Signature):
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"""A signature of a registered I/O buffer.
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Parameters
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----------
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direction : :class:`Direction`
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width : :class:`int`
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Attributes
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----------
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i: :py:`unsigned(width)` (if :py:`direction in (Direction.Input, Direction.Bidir)`)
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o: :py:`unsigned(width)` (if :py:`direction in (Direction.Output, Direction.Bidir)`)
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oe: :py:`unsigned(1, init=0)` (if :py:`direction is Direction.Bidir`)
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oe: :py:`unsigned(1, init=1)` (if :py:`direction is Direction.Output`)
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"""
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def __init__(self, direction, width):
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self._direction = Direction(direction)
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self._width = operator.index(width)
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members = {}
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if self._direction is not Direction.Output:
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members["i"] = wiring.In(self._width)
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if self._direction is not Direction.Input:
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members["o"] = wiring.Out(self._width)
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members["oe"] = wiring.Out(1, init=int(self._direction is Direction.Output))
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super().__init__(members)
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@property
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def direction(self):
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return self._direction
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@property
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def width(self):
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return self._width
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def __eq__(self, other):
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return type(self) is type(other) and self.direction == other.direction and self.width == other.width
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def __repr__(self):
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return f"FFBuffer.Signature({self.direction}, {self.width})"
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def __init__(self, direction, port, *, i_domain=None, o_domain=None):
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if not isinstance(port, PortLike):
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raise TypeError(f"'port' must be a 'PortLike', not {port!r}")
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self._port = port
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super().__init__(FFBuffer.Signature(direction, len(port)).flip())
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if self.signature.direction is not Direction.Output:
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self._i_domain = i_domain or "sync"
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elif i_domain is not None:
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raise ValueError("Output buffer doesn't have an input domain")
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if self.signature.direction is not Direction.Input:
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self._o_domain = o_domain or "sync"
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elif o_domain is not None:
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raise ValueError("Input buffer doesn't have an output domain")
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if port.direction is Direction.Input and self.direction is not Direction.Input:
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raise ValueError(f"Input port cannot be used with {self.direction.name} buffer")
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if port.direction is Direction.Output and self.direction is not Direction.Output:
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raise ValueError(f"Output port cannot be used with {self.direction.name} buffer")
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@property
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def port(self):
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return self._port
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@property
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def direction(self):
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return self.signature.direction
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@property
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def i_domain(self):
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if self.direction is Direction.Output:
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raise AttributeError("Output buffer doesn't have an input domain")
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return self._i_domain
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@property
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def o_domain(self):
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if self.direction is Direction.Input:
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raise AttributeError("Input buffer doesn't have an output domain")
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return self._o_domain
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def elaborate(self, platform):
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if hasattr(platform, "get_io_buffer"):
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return platform.get_io_buffer(self)
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m = Module()
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m.submodules.io_buffer = io_buffer = Buffer(self.direction, self.port)
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if self.direction is not Direction.Output:
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i_ff = Signal(len(self.port), reset_less=True)
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m.d[self.i_domain] += i_ff.eq(io_buffer.i)
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m.d.comb += self.i.eq(i_ff)
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if self.direction is not Direction.Input:
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o_ff = Signal(len(self.port), reset_less=True)
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oe_ff = Signal(reset_less=True)
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m.d[self.o_domain] += o_ff.eq(self.o)
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m.d[self.o_domain] += oe_ff.eq(self.oe)
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m.d.comb += io_buffer.o.eq(o_ff)
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m.d.comb += io_buffer.oe.eq(oe_ff)
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return m
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class DDRBuffer(wiring.Component):
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"""A double data rate registered I/O buffer.
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In the input direction, the port is sampled at both edges of the input clock domain.
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The data sampled on the active clock edge of the domain appears on :py:`i[0]` with a delay
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of 1 clock cycle. The data sampled on the opposite clock edge appears on :py:`i[1]` with a delay
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of 0.5 clock cycle. Both :py:`i[0]` and :py:`i[1]` thus change on the active clock edge of the domain.
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In the output direction, both :py:`o[0]` and :py:`o[1]` are sampled on the active clock edge
|
||||
of the domain. The value of :py:`o[0]` immediately appears on the output port. The value
|
||||
of :py:`o[1]` then appears on the output port on the opposite edge, with a delay of 0.5 clock cycle.
|
||||
|
||||
Support for this compoment is platform-specific, and may be missing on some platforms.
|
||||
|
||||
Parameters
|
||||
----------
|
||||
direction : :class:`Direction`
|
||||
port : :class:`PortLike`
|
||||
i_domain : :class:`str`
|
||||
Domain for input register. Only used when :py:`direction in (Direction.Input, Direction.Bidir)`.
|
||||
o_domain : :class:`str`
|
||||
Domain for output and output enable registers. Only used when
|
||||
:py:`direction in (Direction.Output, Direction.Bidir)`.
|
||||
|
||||
Attributes
|
||||
----------
|
||||
signature : DDRBuffer.Signature
|
||||
Created based on constructor arguments.
|
||||
"""
|
||||
class Signature(wiring.Signature):
|
||||
"""A signature of a double data rate registered I/O buffer.
|
||||
|
||||
Parameters
|
||||
----------
|
||||
direction : :class:`Direction`
|
||||
width : :class:`int`
|
||||
|
||||
Attributes
|
||||
----------
|
||||
i: :py:`unsigned(ArrayLayout(width, 2))` (if :py:`direction in (Direction.Input, Direction.Bidir)`)
|
||||
o: :py:`unsigned(ArrayLayout(width, 2))` (if :py:`direction in (Direction.Output, Direction.Bidir)`)
|
||||
oe: :py:`unsigned(1, init=0)` (if :py:`direction is Direction.Bidir`)
|
||||
oe: :py:`unsigned(1, init=1)` (if :py:`direction is Direction.Output`)
|
||||
"""
|
||||
def __init__(self, direction, width):
|
||||
self._direction = Direction(direction)
|
||||
self._width = operator.index(width)
|
||||
members = {}
|
||||
if self._direction is not Direction.Output:
|
||||
members["i"] = wiring.In(data.ArrayLayout(self._width, 2))
|
||||
if self._direction is not Direction.Input:
|
||||
members["o"] = wiring.Out(data.ArrayLayout(self._width, 2))
|
||||
members["oe"] = wiring.Out(1, init=int(self._direction is Direction.Output))
|
||||
super().__init__(members)
|
||||
|
||||
@property
|
||||
def direction(self):
|
||||
return self._direction
|
||||
|
||||
@property
|
||||
def width(self):
|
||||
return self._width
|
||||
|
||||
def __eq__(self, other):
|
||||
return type(self) is type(other) and self.direction == other.direction and self.width == other.width
|
||||
|
||||
def __repr__(self):
|
||||
return f"DDRBuffer.Signature({self.direction}, {self.width})"
|
||||
|
||||
def __init__(self, direction, port, *, i_domain=None, o_domain=None):
|
||||
if not isinstance(port, PortLike):
|
||||
raise TypeError(f"'port' must be a 'PortLike', not {port!r}")
|
||||
self._port = port
|
||||
super().__init__(DDRBuffer.Signature(direction, len(port)).flip())
|
||||
if self.signature.direction is not Direction.Output:
|
||||
self._i_domain = i_domain or "sync"
|
||||
elif i_domain is not None:
|
||||
raise ValueError("Output buffer doesn't have an input domain")
|
||||
if self.signature.direction is not Direction.Input:
|
||||
self._o_domain = o_domain or "sync"
|
||||
elif o_domain is not None:
|
||||
raise ValueError("Input buffer doesn't have an output domain")
|
||||
if port.direction is Direction.Input and self.direction is not Direction.Input:
|
||||
raise ValueError(f"Input port cannot be used with {self.direction.name} buffer")
|
||||
if port.direction is Direction.Output and self.direction is not Direction.Output:
|
||||
raise ValueError(f"Output port cannot be used with {self.direction.name} buffer")
|
||||
|
||||
@property
|
||||
def port(self):
|
||||
return self._port
|
||||
|
||||
@property
|
||||
def direction(self):
|
||||
return self.signature.direction
|
||||
|
||||
@property
|
||||
def i_domain(self):
|
||||
if self.direction is Direction.Output:
|
||||
raise AttributeError("Output buffer doesn't have an input domain")
|
||||
return self._i_domain
|
||||
|
||||
@property
|
||||
def o_domain(self):
|
||||
if self.direction is Direction.Input:
|
||||
raise AttributeError("Input buffer doesn't have an output domain")
|
||||
return self._o_domain
|
||||
|
||||
def elaborate(self, platform):
|
||||
if hasattr(platform, "get_io_buffer"):
|
||||
return platform.get_io_buffer(self)
|
||||
|
||||
raise NotImplementedError("DDR buffers cannot be elaborated without a supported platform")
|
||||
|
||||
|
||||
class Pin(wiring.PureInterface):
|
||||
"""
|
||||
An interface to an I/O buffer or a group of them that provides uniform access to input, output,
|
||||
|
|
|
|||
Loading…
Add table
Add a link
Reference in a new issue