riscv-formal-nmigen/nmigen/hdl/ast.py

1602 lines
54 KiB
Python

from abc import ABCMeta, abstractmethod
import traceback
import warnings
import typing
from collections import OrderedDict
from collections.abc import Iterable, MutableMapping, MutableSet, MutableSequence
from enum import Enum
from .. import tracer
from .._utils import *
from .._unused import *
__all__ = [
"Shape", "signed", "unsigned",
"Value", "Const", "C", "AnyConst", "AnySeq", "Operator", "Mux", "Part", "Slice", "Cat", "Repl",
"Array", "ArrayProxy",
"Signal", "ClockSignal", "ResetSignal",
"UserValue",
"Sample", "Past", "Stable", "Rose", "Fell", "Initial",
"Statement", "Switch",
"Property", "Assign", "Assert", "Assume", "Cover",
"ValueKey", "ValueDict", "ValueSet", "SignalKey", "SignalDict", "SignalSet",
]
class DUID:
"""Deterministic Unique IDentifier."""
__next_uid = 0
def __init__(self):
self.duid = DUID.__next_uid
DUID.__next_uid += 1
class Shape(typing.NamedTuple):
"""Bit width and signedness of a value.
A ``Shape`` can be constructed using:
* explicit bit width and signedness;
* aliases :func:`signed` and :func:`unsigned`;
* casting from a variety of objects.
A ``Shape`` can be cast from:
* an integer, where the integer specifies the bit width;
* a range, where the result is wide enough to represent any element of the range, and is
signed if any element of the range is signed;
* an :class:`Enum` with all integer members or :class:`IntEnum`, where the result is wide
enough to represent any member of the enumeration, and is signed if any member of
the enumeration is signed.
Parameters
----------
width : int
The number of bits in the representation, including the sign bit (if any).
signed : bool
If ``False``, the value is unsigned. If ``True``, the value is signed two's complement.
"""
width: int = 1
signed: bool = False
@staticmethod
def cast(obj, *, src_loc_at=0):
if isinstance(obj, Shape):
return obj
if isinstance(obj, int):
return Shape(obj)
if isinstance(obj, tuple):
width, signed = obj
warnings.warn("instead of `{tuple}`, use `{constructor}({width})`"
.format(constructor="signed" if signed else "unsigned", width=width,
tuple=obj),
DeprecationWarning, stacklevel=2 + src_loc_at)
return Shape(width, signed)
if isinstance(obj, range):
if len(obj) == 0:
return Shape(0, obj.start < 0)
signed = obj.start < 0 or (obj.stop - obj.step) < 0
width = max(bits_for(obj.start, signed),
bits_for(obj.stop - obj.step, signed))
return Shape(width, signed)
if isinstance(obj, type) and issubclass(obj, Enum):
min_value = min(member.value for member in obj)
max_value = max(member.value for member in obj)
if not isinstance(min_value, int) or not isinstance(max_value, int):
raise TypeError("Only enumerations with integer values can be used "
"as value shapes")
signed = min_value < 0 or max_value < 0
width = max(bits_for(min_value, signed), bits_for(max_value, signed))
return Shape(width, signed)
raise TypeError("Object {!r} cannot be used as value shape".format(obj))
# TODO: use dataclasses instead of this hack
def _Shape___init__(self, width=1, signed=False):
if not isinstance(width, int) or width < 0:
raise TypeError("Width must be a non-negative integer, not {!r}"
.format(width))
Shape.__init__ = _Shape___init__
def unsigned(width):
"""Shorthand for ``Shape(width, signed=False)``."""
return Shape(width, signed=False)
def signed(width):
"""Shorthand for ``Shape(width, signed=True)``."""
return Shape(width, signed=True)
class Value(metaclass=ABCMeta):
@staticmethod
def cast(obj):
"""Converts ``obj`` to an nMigen value.
Booleans and integers are wrapped into a :class:`Const`. Enumerations whose members are
all integers are converted to a :class:`Const` with a shape that fits every member.
"""
if isinstance(obj, Value):
return obj
if isinstance(obj, int):
return Const(obj)
if isinstance(obj, Enum):
return Const(obj.value, Shape.cast(type(obj)))
raise TypeError("Object {!r} cannot be converted to an nMigen value".format(obj))
def __init__(self, *, src_loc_at=0):
super().__init__()
self.src_loc = tracer.get_src_loc(1 + src_loc_at)
def __bool__(self):
raise TypeError("Attempted to convert nMigen value to boolean")
def __invert__(self):
return Operator("~", [self])
def __neg__(self):
return Operator("-", [self])
def __add__(self, other):
return Operator("+", [self, other])
def __radd__(self, other):
return Operator("+", [other, self])
def __sub__(self, other):
return Operator("-", [self, other])
def __rsub__(self, other):
return Operator("-", [other, self])
def __mul__(self, other):
return Operator("*", [self, other])
def __rmul__(self, other):
return Operator("*", [other, self])
def __check_divisor(self):
width, signed = self.shape()
if signed:
# Python's division semantics and Verilog's division semantics differ for negative
# divisors (Python uses div/mod, Verilog uses quo/rem); for now, avoid the issue
# completely by prohibiting such division operations.
raise NotImplementedError("Division by a signed value is not supported")
def __mod__(self, other):
other = Value.cast(other)
other.__check_divisor()
return Operator("%", [self, other])
def __rmod__(self, other):
self.__check_divisor()
return Operator("%", [other, self])
def __floordiv__(self, other):
other = Value.cast(other)
other.__check_divisor()
return Operator("//", [self, other])
def __rfloordiv__(self, other):
self.__check_divisor()
return Operator("//", [other, self])
def __check_shamt(self):
width, signed = self.shape()
if signed:
# Neither Python nor HDLs implement shifts by negative values; prohibit any shifts
# by a signed value to make sure the shift amount can always be interpreted as
# an unsigned value.
raise NotImplementedError("Shift by a signed value is not supported")
def __lshift__(self, other):
other = Value.cast(other)
other.__check_shamt()
return Operator("<<", [self, other])
def __rlshift__(self, other):
self.__check_shamt()
return Operator("<<", [other, self])
def __rshift__(self, other):
other = Value.cast(other)
other.__check_shamt()
return Operator(">>", [self, other])
def __rrshift__(self, other):
self.__check_shamt()
return Operator(">>", [other, self])
def __and__(self, other):
return Operator("&", [self, other])
def __rand__(self, other):
return Operator("&", [other, self])
def __xor__(self, other):
return Operator("^", [self, other])
def __rxor__(self, other):
return Operator("^", [other, self])
def __or__(self, other):
return Operator("|", [self, other])
def __ror__(self, other):
return Operator("|", [other, self])
def __eq__(self, other):
return Operator("==", [self, other])
def __ne__(self, other):
return Operator("!=", [self, other])
def __lt__(self, other):
return Operator("<", [self, other])
def __le__(self, other):
return Operator("<=", [self, other])
def __gt__(self, other):
return Operator(">", [self, other])
def __ge__(self, other):
return Operator(">=", [self, other])
def __len__(self):
return self.shape().width
def __getitem__(self, key):
n = len(self)
if isinstance(key, int):
if key not in range(-n, n):
raise IndexError("Cannot index {} bits into {}-bit value".format(key, n))
if key < 0:
key += n
return Slice(self, key, key + 1)
elif isinstance(key, slice):
start, stop, step = key.indices(n)
if step != 1:
return Cat(self[i] for i in range(start, stop, step))
return Slice(self, start, stop)
else:
raise TypeError("Cannot index value with {}".format(repr(key)))
def as_unsigned(self):
"""Conversion to unsigned.
Returns
-------
Value, out
This ``Value`` reinterpreted as a unsigned integer.
"""
return Operator("u", [self])
def as_signed(self):
"""Conversion to signed.
Returns
-------
Value, out
This ``Value`` reinterpreted as a signed integer.
"""
return Operator("s", [self])
def bool(self):
"""Conversion to boolean.
Returns
-------
Value, out
``1`` if any bits are set, ``0`` otherwise.
"""
return Operator("b", [self])
def any(self):
"""Check if any bits are ``1``.
Returns
-------
Value, out
``1`` if any bits are set, ``0`` otherwise.
"""
return Operator("r|", [self])
def all(self):
"""Check if all bits are ``1``.
Returns
-------
Value, out
``1`` if all bits are set, ``0`` otherwise.
"""
return Operator("r&", [self])
def xor(self):
"""Compute pairwise exclusive-or of every bit.
Returns
-------
Value, out
``1`` if an odd number of bits are set, ``0`` if an even number of bits are set.
"""
return Operator("r^", [self])
def implies(premise, conclusion):
"""Implication.
Returns
-------
Value, out
``0`` if ``premise`` is true and ``conclusion`` is not, ``1`` otherwise.
"""
return ~premise | conclusion
def bit_select(self, offset, width):
"""Part-select with bit granularity.
Selects a constant width but variable offset part of a ``Value``, such that successive
parts overlap by all but 1 bit.
Parameters
----------
offset : Value, in
Index of first selected bit.
width : int
Number of selected bits.
Returns
-------
Part, out
Selected part of the ``Value``
"""
offset = Value.cast(offset)
if type(offset) is Const and isinstance(width, int):
return self[offset.value:offset.value + width]
return Part(self, offset, width, stride=1, src_loc_at=1)
def word_select(self, offset, width):
"""Part-select with word granularity.
Selects a constant width but variable offset part of a ``Value``, such that successive
parts do not overlap.
Parameters
----------
offset : Value, in
Index of first selected word.
width : int
Number of selected bits.
Returns
-------
Part, out
Selected part of the ``Value``
"""
offset = Value.cast(offset)
if type(offset) is Const and isinstance(width, int):
return self[offset.value * width:(offset.value + 1) * width]
return Part(self, offset, width, stride=width, src_loc_at=1)
def matches(self, *patterns):
"""Pattern matching.
Matches against a set of patterns, which may be integers or bit strings, recognizing
the same grammar as ``Case()``.
Parameters
----------
patterns : int or str
Patterns to match against.
Returns
-------
Value, out
``1`` if any pattern matches the value, ``0`` otherwise.
"""
matches = []
for pattern in patterns:
if not isinstance(pattern, (int, str, Enum)):
raise SyntaxError("Match pattern must be an integer, a string, or an enumeration, "
"not {!r}"
.format(pattern))
if isinstance(pattern, str) and any(bit not in "01- \t" for bit in pattern):
raise SyntaxError("Match pattern '{}' must consist of 0, 1, and - (don't care) "
"bits, and may include whitespace"
.format(pattern))
if (isinstance(pattern, str) and
len("".join(pattern.split())) != len(self)):
raise SyntaxError("Match pattern '{}' must have the same width as match value "
"(which is {})"
.format(pattern, len(self)))
if isinstance(pattern, int) and bits_for(pattern) > len(self):
warnings.warn("Match pattern '{:b}' is wider than match value "
"(which has width {}); comparison will never be true"
.format(pattern, len(self)),
SyntaxWarning, stacklevel=3)
continue
if isinstance(pattern, str):
pattern = "".join(pattern.split()) # remove whitespace
mask = int(pattern.replace("0", "1").replace("-", "0"), 2)
pattern = int(pattern.replace("-", "0"), 2)
matches.append((self & mask) == pattern)
elif isinstance(pattern, int):
matches.append(self == pattern)
elif isinstance(pattern, Enum):
matches.append(self == pattern.value)
else:
assert False
if not matches:
return Const(0)
elif len(matches) == 1:
return matches[0]
else:
return Cat(*matches).any()
def eq(self, value):
"""Assignment.
Parameters
----------
value : Value, in
Value to be assigned.
Returns
-------
Assign
Assignment statement that can be used in combinatorial or synchronous context.
"""
return Assign(self, value, src_loc_at=1)
@abstractmethod
def shape(self):
"""Bit width and signedness of a value.
Returns
-------
Shape
See :class:`Shape`.
Examples
--------
>>> Signal(8).shape()
Shape(width=8, signed=False)
>>> Const(0xaa).shape()
Shape(width=8, signed=False)
"""
pass # :nocov:
def _lhs_signals(self):
raise TypeError("Value {!r} cannot be used in assignments".format(self))
@abstractmethod
def _rhs_signals(self):
pass # :nocov:
def _as_const(self):
raise TypeError("Value {!r} cannot be evaluated as constant".format(self))
__hash__ = None
@final
class Const(Value):
"""A constant, literal integer value.
Parameters
----------
value : int
shape : int or tuple or None
Either an integer ``width`` or a tuple ``(width, signed)`` specifying the number of bits
in this constant and whether it is signed (can represent negative values).
``shape`` defaults to the minimum possible width and signedness of ``value``.
Attributes
----------
width : int
signed : bool
"""
src_loc = None
@staticmethod
def normalize(value, shape):
width, signed = shape
mask = (1 << width) - 1
value &= mask
if signed and value >> (width - 1):
value |= ~mask
return value
def __init__(self, value, shape=None, *, src_loc_at=0):
# We deliberately do not call Value.__init__ here.
self.value = int(value)
if shape is None:
shape = Shape(bits_for(self.value), signed=self.value < 0)
elif isinstance(shape, int):
shape = Shape(shape, signed=self.value < 0)
else:
shape = Shape.cast(shape, src_loc_at=1 + src_loc_at)
self.width, self.signed = shape
self.value = self.normalize(self.value, shape)
def shape(self):
return Shape(self.width, self.signed)
def _rhs_signals(self):
return ValueSet()
def _as_const(self):
return self.value
def __repr__(self):
return "(const {}'{}d{})".format(self.width, "s" if self.signed else "", self.value)
C = Const # shorthand
class AnyValue(Value, DUID):
def __init__(self, shape, *, src_loc_at=0):
super().__init__(src_loc_at=src_loc_at)
self.width, self.signed = Shape.cast(shape, src_loc_at=1 + src_loc_at)
if not isinstance(self.width, int) or self.width < 0:
raise TypeError("Width must be a non-negative integer, not {!r}"
.format(self.width))
def shape(self):
return Shape(self.width, self.signed)
def _rhs_signals(self):
return ValueSet()
@final
class AnyConst(AnyValue):
def __repr__(self):
return "(anyconst {}'{})".format(self.width, "s" if self.signed else "")
@final
class AnySeq(AnyValue):
def __repr__(self):
return "(anyseq {}'{})".format(self.width, "s" if self.signed else "")
@final
class Operator(Value):
def __init__(self, operator, operands, *, src_loc_at=0):
super().__init__(src_loc_at=1 + src_loc_at)
self.operator = operator
self.operands = [Value.cast(op) for op in operands]
def shape(self):
def _bitwise_binary_shape(a_shape, b_shape):
a_bits, a_sign = a_shape
b_bits, b_sign = b_shape
if not a_sign and not b_sign:
# both operands unsigned
return Shape(max(a_bits, b_bits), False)
elif a_sign and b_sign:
# both operands signed
return Shape(max(a_bits, b_bits), True)
elif not a_sign and b_sign:
# first operand unsigned (add sign bit), second operand signed
return Shape(max(a_bits + 1, b_bits), True)
else:
# first signed, second operand unsigned (add sign bit)
return Shape(max(a_bits, b_bits + 1), True)
op_shapes = list(map(lambda x: x.shape(), self.operands))
if len(op_shapes) == 1:
(a_width, a_signed), = op_shapes
if self.operator in ("+", "~"):
return Shape(a_width, a_signed)
if self.operator == "-":
return Shape(a_width + 1, True)
if self.operator in ("b", "r|", "r&", "r^"):
return Shape(1, False)
if self.operator == "u":
return Shape(a_width, False)
if self.operator == "s":
return Shape(a_width, True)
elif len(op_shapes) == 2:
(a_width, a_signed), (b_width, b_signed) = op_shapes
if self.operator in ("+", "-"):
width, signed = _bitwise_binary_shape(*op_shapes)
return Shape(width + 1, signed)
if self.operator == "*":
return Shape(a_width + b_width, a_signed or b_signed)
if self.operator in ("//", "%"):
assert not b_signed
return Shape(a_width, a_signed)
if self.operator in ("<", "<=", "==", "!=", ">", ">="):
return Shape(1, False)
if self.operator in ("&", "^", "|"):
return _bitwise_binary_shape(*op_shapes)
if self.operator == "<<":
if b_signed:
extra = 2 ** (b_width - 1) - 1
else:
extra = 2 ** (b_width) - 1
return Shape(a_width + extra, a_signed)
if self.operator == ">>":
if b_signed:
extra = 2 ** (b_width - 1)
else:
extra = 0
return Shape(a_width + extra, a_signed)
elif len(op_shapes) == 3:
if self.operator == "m":
s_shape, a_shape, b_shape = op_shapes
return _bitwise_binary_shape(a_shape, b_shape)
raise NotImplementedError("Operator {}/{} not implemented"
.format(self.operator, len(op_shapes))) # :nocov:
def _rhs_signals(self):
return union(op._rhs_signals() for op in self.operands)
def __repr__(self):
return "({} {})".format(self.operator, " ".join(map(repr, self.operands)))
def Mux(sel, val1, val0):
"""Choose between two values.
Parameters
----------
sel : Value, in
Selector.
val1 : Value, in
val0 : Value, in
Input values.
Returns
-------
Value, out
Output ``Value``. If ``sel`` is asserted, the Mux returns ``val1``, else ``val0``.
"""
sel = Value.cast(sel)
if len(sel) != 1:
sel = sel.bool()
return Operator("m", [sel, val1, val0])
@final
class Slice(Value):
def __init__(self, value, start, stop, *, src_loc_at=0):
if not isinstance(start, int):
raise TypeError("Slice start must be an integer, not {!r}".format(start))
if not isinstance(stop, int):
raise TypeError("Slice stop must be an integer, not {!r}".format(stop))
n = len(value)
if start not in range(-(n+1), n+1):
raise IndexError("Cannot start slice {} bits into {}-bit value".format(start, n))
if start < 0:
start += n
if stop not in range(-(n+1), n+1):
raise IndexError("Cannot stop slice {} bits into {}-bit value".format(stop, n))
if stop < 0:
stop += n
if start > stop:
raise IndexError("Slice start {} must be less than slice stop {}".format(start, stop))
super().__init__(src_loc_at=src_loc_at)
self.value = Value.cast(value)
self.start = start
self.stop = stop
def shape(self):
return Shape(self.stop - self.start)
def _lhs_signals(self):
return self.value._lhs_signals()
def _rhs_signals(self):
return self.value._rhs_signals()
def __repr__(self):
return "(slice {} {}:{})".format(repr(self.value), self.start, self.stop)
@final
class Part(Value):
def __init__(self, value, offset, width, stride=1, *, src_loc_at=0):
if not isinstance(width, int) or width < 0:
raise TypeError("Part width must be a non-negative integer, not {!r}".format(width))
if not isinstance(stride, int) or stride <= 0:
raise TypeError("Part stride must be a positive integer, not {!r}".format(stride))
super().__init__(src_loc_at=src_loc_at)
self.value = value
self.offset = Value.cast(offset)
self.width = width
self.stride = stride
def shape(self):
return Shape(self.width)
def _lhs_signals(self):
return self.value._lhs_signals()
def _rhs_signals(self):
return self.value._rhs_signals() | self.offset._rhs_signals()
def __repr__(self):
return "(part {} {} {} {})".format(repr(self.value), repr(self.offset),
self.width, self.stride)
@final
class Cat(Value):
"""Concatenate values.
Form a compound ``Value`` from several smaller ones by concatenation.
The first argument occupies the lower bits of the result.
The return value can be used on either side of an assignment, that
is, the concatenated value can be used as an argument on the RHS or
as a target on the LHS. If it is used on the LHS, it must solely
consist of ``Signal`` s, slices of ``Signal`` s, and other concatenations
meeting these properties. The bit length of the return value is the sum of
the bit lengths of the arguments::
len(Cat(args)) == sum(len(arg) for arg in args)
Parameters
----------
*args : Values or iterables of Values, inout
``Value`` s to be concatenated.
Returns
-------
Value, inout
Resulting ``Value`` obtained by concatentation.
"""
def __init__(self, *args, src_loc_at=0):
super().__init__(src_loc_at=src_loc_at)
self.parts = [Value.cast(v) for v in flatten(args)]
def shape(self):
return Shape(sum(len(part) for part in self.parts))
def _lhs_signals(self):
return union((part._lhs_signals() for part in self.parts), start=ValueSet())
def _rhs_signals(self):
return union((part._rhs_signals() for part in self.parts), start=ValueSet())
def _as_const(self):
value = 0
for part in reversed(self.parts):
value <<= len(part)
value |= part._as_const()
return value
def __repr__(self):
return "(cat {})".format(" ".join(map(repr, self.parts)))
@final
class Repl(Value):
"""Replicate a value
An input value is replicated (repeated) several times
to be used on the RHS of assignments::
len(Repl(s, n)) == len(s) * n
Parameters
----------
value : Value, in
Input value to be replicated.
count : int
Number of replications.
Returns
-------
Repl, out
Replicated value.
"""
def __init__(self, value, count, *, src_loc_at=0):
if not isinstance(count, int) or count < 0:
raise TypeError("Replication count must be a non-negative integer, not {!r}"
.format(count))
super().__init__(src_loc_at=src_loc_at)
self.value = Value.cast(value)
self.count = count
def shape(self):
return Shape(len(self.value) * self.count)
def _rhs_signals(self):
return self.value._rhs_signals()
def __repr__(self):
return "(repl {!r} {})".format(self.value, self.count)
# @final
class Signal(Value, DUID):
"""A varying integer value.
Parameters
----------
shape : ``Shape``-castable object or None
Specification for the number of bits in this ``Signal`` and its signedness (whether it
can represent negative values). See ``Shape.cast`` for details.
If not specified, ``shape`` defaults to 1-bit and non-signed.
name : str
Name hint for this signal. If ``None`` (default) the name is inferred from the variable
name this ``Signal`` is assigned to.
reset : int or integral Enum
Reset (synchronous) or default (combinatorial) value.
When this ``Signal`` is assigned to in synchronous context and the corresponding clock
domain is reset, the ``Signal`` assumes the given value. When this ``Signal`` is unassigned
in combinatorial context (due to conditional assignments not being taken), the ``Signal``
assumes its ``reset`` value. Defaults to 0.
reset_less : bool
If ``True``, do not generate reset logic for this ``Signal`` in synchronous statements.
The ``reset`` value is only used as a combinatorial default or as the initial value.
Defaults to ``False``.
attrs : dict
Dictionary of synthesis attributes.
decoder : function or Enum
A function converting integer signal values to human-readable strings (e.g. FSM state
names). If an ``Enum`` subclass is passed, it is concisely decoded using format string
``"{0.name:}/{0.value:}"``, or a number if the signal value is not a member of
the enumeration.
Attributes
----------
width : int
signed : bool
name : str
reset : int
reset_less : bool
attrs : dict
decoder : function
"""
def __init__(self, shape=None, *, name=None, reset=0, reset_less=False,
attrs=None, decoder=None, src_loc_at=0):
super().__init__(src_loc_at=src_loc_at)
if name is not None and not isinstance(name, str):
raise TypeError("Name must be a string, not {!r}".format(name))
self.name = name or tracer.get_var_name(depth=2 + src_loc_at, default="$signal")
if shape is None:
shape = unsigned(1)
self.width, self.signed = Shape.cast(shape, src_loc_at=1 + src_loc_at)
if isinstance(reset, Enum):
reset = reset.value
if not isinstance(reset, int):
raise TypeError("Reset value has to be an int or an integral Enum")
reset_width = bits_for(reset, self.signed)
if reset != 0 and reset_width > self.width:
warnings.warn("Reset value {!r} requires {} bits to represent, but the signal "
"only has {} bits"
.format(reset, reset_width, self.width),
SyntaxWarning, stacklevel=2 + src_loc_at)
self.reset = reset
self.reset_less = bool(reset_less)
self.attrs = OrderedDict(() if attrs is None else attrs)
if decoder is None and isinstance(shape, type) and issubclass(shape, Enum):
decoder = shape
if isinstance(decoder, type) and issubclass(decoder, Enum):
def enum_decoder(value):
try:
return "{0.name:}/{0.value:}".format(decoder(value))
except ValueError:
return str(value)
self.decoder = enum_decoder
else:
self.decoder = decoder
# Not a @classmethod because nmigen.compat requires it.
@staticmethod
def like(other, *, name=None, name_suffix=None, src_loc_at=0, **kwargs):
"""Create Signal based on another.
Parameters
----------
other : Value
Object to base this Signal on.
"""
if name is not None:
new_name = str(name)
elif name_suffix is not None:
new_name = other.name + str(name_suffix)
else:
new_name = tracer.get_var_name(depth=2 + src_loc_at, default="$like")
kw = dict(shape=Value.cast(other).shape(), name=new_name)
if isinstance(other, Signal):
kw.update(reset=other.reset, reset_less=other.reset_less,
attrs=other.attrs, decoder=other.decoder)
kw.update(kwargs)
return Signal(**kw, src_loc_at=1 + src_loc_at)
def shape(self):
return Shape(self.width, self.signed)
def _lhs_signals(self):
return ValueSet((self,))
def _rhs_signals(self):
return ValueSet((self,))
def __repr__(self):
return "(sig {})".format(self.name)
@final
class ClockSignal(Value):
"""Clock signal for a clock domain.
Any ``ClockSignal`` is equivalent to ``cd.clk`` for a clock domain with the corresponding name.
All of these signals ultimately refer to the same signal, but they can be manipulated
independently of the clock domain, even before the clock domain is created.
Parameters
----------
domain : str
Clock domain to obtain a clock signal for. Defaults to ``"sync"``.
"""
def __init__(self, domain="sync", *, src_loc_at=0):
super().__init__(src_loc_at=src_loc_at)
if not isinstance(domain, str):
raise TypeError("Clock domain name must be a string, not {!r}".format(domain))
if domain == "comb":
raise ValueError("Domain '{}' does not have a clock".format(domain))
self.domain = domain
def shape(self):
return Shape(1)
def _lhs_signals(self):
return ValueSet((self,))
def _rhs_signals(self):
raise NotImplementedError("ClockSignal must be lowered to a concrete signal") # :nocov:
def __repr__(self):
return "(clk {})".format(self.domain)
@final
class ResetSignal(Value):
"""Reset signal for a clock domain.
Any ``ResetSignal`` is equivalent to ``cd.rst`` for a clock domain with the corresponding name.
All of these signals ultimately refer to the same signal, but they can be manipulated
independently of the clock domain, even before the clock domain is created.
Parameters
----------
domain : str
Clock domain to obtain a reset signal for. Defaults to ``"sync"``.
allow_reset_less : bool
If the clock domain is reset-less, act as a constant ``0`` instead of reporting an error.
"""
def __init__(self, domain="sync", allow_reset_less=False, *, src_loc_at=0):
super().__init__(src_loc_at=src_loc_at)
if not isinstance(domain, str):
raise TypeError("Clock domain name must be a string, not {!r}".format(domain))
if domain == "comb":
raise ValueError("Domain '{}' does not have a reset".format(domain))
self.domain = domain
self.allow_reset_less = allow_reset_less
def shape(self):
return Shape(1)
def _lhs_signals(self):
return ValueSet((self,))
def _rhs_signals(self):
raise NotImplementedError("ResetSignal must be lowered to a concrete signal") # :nocov:
def __repr__(self):
return "(rst {})".format(self.domain)
class Array(MutableSequence):
"""Addressable multiplexer.
An array is similar to a ``list`` that can also be indexed by ``Value``s; indexing by an integer or a slice works the same as for Python lists, but indexing by a ``Value`` results
in a proxy.
The array proxy can be used as an ordinary ``Value``, i.e. participate in calculations and
assignments, provided that all elements of the array are values. The array proxy also supports
attribute access and further indexing, each returning another array proxy; this means that
the results of indexing into arrays, arrays of records, and arrays of arrays can all
be used as first-class values.
It is an error to change an array or any of its elements after an array proxy was created.
Changing the array directly will raise an exception. However, it is not possible to detect
the elements being modified; if an element's attribute or element is modified after the proxy
for it has been created, the proxy will refer to stale data.
Examples
--------
Simple array::
gpios = Array(Signal() for _ in range(10))
with m.If(bus.we):
m.d.sync += gpios[bus.addr].eq(bus.w_data)
with m.Else():
m.d.sync += bus.r_data.eq(gpios[bus.addr])
Multidimensional array::
mult = Array(Array(x * y for y in range(10)) for x in range(10))
a = Signal.range(10)
b = Signal.range(10)
r = Signal(8)
m.d.comb += r.eq(mult[a][b])
Array of records::
layout = [
("r_data", 16),
("r_en", 1),
]
buses = Array(Record(layout) for busno in range(4))
master = Record(layout)
m.d.comb += [
buses[sel].r_en.eq(master.r_en),
master.r_data.eq(buses[sel].r_data),
]
"""
def __init__(self, iterable=()):
self._inner = list(iterable)
self._proxy_at = None
self._mutable = True
def __getitem__(self, index):
if isinstance(index, Value):
if self._mutable:
self._proxy_at = tracer.get_src_loc()
self._mutable = False
return ArrayProxy(self, index)
else:
return self._inner[index]
def __len__(self):
return len(self._inner)
def _check_mutability(self):
if not self._mutable:
raise ValueError("Array can no longer be mutated after it was indexed with a value "
"at {}:{}".format(*self._proxy_at))
def __setitem__(self, index, value):
self._check_mutability()
self._inner[index] = value
def __delitem__(self, index):
self._check_mutability()
del self._inner[index]
def insert(self, index, value):
self._check_mutability()
self._inner.insert(index, value)
def __repr__(self):
return "(array{} [{}])".format(" mutable" if self._mutable else "",
", ".join(map(repr, self._inner)))
@final
class ArrayProxy(Value):
def __init__(self, elems, index, *, src_loc_at=0):
super().__init__(src_loc_at=1 + src_loc_at)
self.elems = elems
self.index = Value.cast(index)
def __getattr__(self, attr):
return ArrayProxy([getattr(elem, attr) for elem in self.elems], self.index)
def __getitem__(self, index):
return ArrayProxy([ elem[index] for elem in self.elems], self.index)
def _iter_as_values(self):
return (Value.cast(elem) for elem in self.elems)
def shape(self):
width, signed = 0, False
for elem_width, elem_signed in (elem.shape() for elem in self._iter_as_values()):
width = max(width, elem_width + elem_signed)
signed = max(signed, elem_signed)
return Shape(width, signed)
def _lhs_signals(self):
signals = union((elem._lhs_signals() for elem in self._iter_as_values()), start=ValueSet())
return signals
def _rhs_signals(self):
signals = union((elem._rhs_signals() for elem in self._iter_as_values()), start=ValueSet())
return self.index._rhs_signals() | signals
def __repr__(self):
return "(proxy (array [{}]) {!r})".format(", ".join(map(repr, self.elems)), self.index)
class UserValue(Value):
"""Value with custom lowering.
A ``UserValue`` is a value whose precise representation does not have to be immediately known,
which is useful in certain metaprogramming scenarios. Instead of providing fixed semantics
upfront, it is kept abstract for as long as possible, only being lowered to a concrete nMigen
value when required.
Note that the ``lower`` method will only be called once; this is necessary to ensure that
nMigen's view of representation of all values stays internally consistent. If the class
deriving from ``UserValue`` is mutable, then it must ensure that after ``lower`` is called,
it is not mutated in a way that changes its representation.
The following is an incomplete list of actions that, when applied to an ``UserValue`` directly
or indirectly, will cause it to be lowered, provided as an illustrative reference:
* Querying the shape using ``.shape()`` or ``len()``;
* Creating a similarly shaped signal using ``Signal.like``;
* Indexing or iterating through individual bits;
* Adding an assignment to the value to a ``Module`` using ``m.d.<domain> +=``.
"""
def __init__(self, *, src_loc_at=0):
super().__init__(src_loc_at=1 + src_loc_at)
self.__lowered = None
@abstractmethod
def lower(self):
"""Conversion to a concrete representation."""
pass # :nocov:
def _lazy_lower(self):
if self.__lowered is None:
self.__lowered = Value.cast(self.lower())
return self.__lowered
def shape(self):
return self._lazy_lower().shape()
def _lhs_signals(self):
return self._lazy_lower()._lhs_signals()
def _rhs_signals(self):
return self._lazy_lower()._rhs_signals()
@final
class Sample(Value):
"""Value from the past.
A ``Sample`` of an expression is equal to the value of the expression ``clocks`` clock edges
of the ``domain`` clock back. If that moment is before the beginning of time, it is equal
to the value of the expression calculated as if each signal had its reset value.
"""
def __init__(self, expr, clocks, domain, *, src_loc_at=0):
super().__init__(src_loc_at=1 + src_loc_at)
self.value = Value.cast(expr)
self.clocks = int(clocks)
self.domain = domain
if not isinstance(self.value, (Const, Signal, ClockSignal, ResetSignal, Initial)):
raise TypeError("Sampled value must be a signal or a constant, not {!r}"
.format(self.value))
if self.clocks < 0:
raise ValueError("Cannot sample a value {} cycles in the future"
.format(-self.clocks))
if not (self.domain is None or isinstance(self.domain, str)):
raise TypeError("Domain name must be a string or None, not {!r}"
.format(self.domain))
def shape(self):
return self.value.shape()
def _rhs_signals(self):
return ValueSet((self,))
def __repr__(self):
return "(sample {!r} @ {}[{}])".format(
self.value, "<default>" if self.domain is None else self.domain, self.clocks)
def Past(expr, clocks=1, domain=None):
return Sample(expr, clocks, domain)
def Stable(expr, clocks=0, domain=None):
return Sample(expr, clocks + 1, domain) == Sample(expr, clocks, domain)
def Rose(expr, clocks=0, domain=None):
return ~Sample(expr, clocks + 1, domain) & Sample(expr, clocks, domain)
def Fell(expr, clocks=0, domain=None):
return Sample(expr, clocks + 1, domain) & ~Sample(expr, clocks, domain)
@final
class Initial(Value):
"""Start indicator, for model checking.
An ``Initial`` signal is ``1`` at the first cycle of model checking, and ``0`` at any other.
"""
def __init__(self, *, src_loc_at=0):
super().__init__(src_loc_at=src_loc_at)
def shape(self):
return Shape(1)
def _rhs_signals(self):
return ValueSet((self,))
def __repr__(self):
return "(initial)"
class _StatementList(list):
def __repr__(self):
return "({})".format(" ".join(map(repr, self)))
class Statement:
def __init__(self, *, src_loc_at=0):
self.src_loc = tracer.get_src_loc(1 + src_loc_at)
@staticmethod
def cast(obj):
if isinstance(obj, Iterable):
return _StatementList(sum((Statement.cast(e) for e in obj), []))
else:
if isinstance(obj, Statement):
return _StatementList([obj])
else:
raise TypeError("Object {!r} is not an nMigen statement".format(obj))
@final
class Assign(Statement):
def __init__(self, lhs, rhs, *, src_loc_at=0):
super().__init__(src_loc_at=src_loc_at)
self.lhs = Value.cast(lhs)
self.rhs = Value.cast(rhs)
def _lhs_signals(self):
return self.lhs._lhs_signals()
def _rhs_signals(self):
return self.lhs._rhs_signals() | self.rhs._rhs_signals()
def __repr__(self):
return "(eq {!r} {!r})".format(self.lhs, self.rhs)
class UnusedProperty(UnusedMustUse):
pass
class Property(Statement, MustUse):
_MustUse__warning = UnusedProperty
def __init__(self, test, *, _check=None, _en=None, src_loc_at=0):
super().__init__(src_loc_at=src_loc_at)
self.test = Value.cast(test)
self._check = _check
self._en = _en
if self._check is None:
self._check = Signal(reset_less=True, name="${}$check".format(self._kind))
self._check.src_loc = self.src_loc
if _en is None:
self._en = Signal(reset_less=True, name="${}$en".format(self._kind))
self._en.src_loc = self.src_loc
def _lhs_signals(self):
return ValueSet((self._en, self._check))
def _rhs_signals(self):
return self.test._rhs_signals()
def __repr__(self):
return "({} {!r})".format(self._kind, self.test)
@final
class Assert(Property):
_kind = "assert"
@final
class Assume(Property):
_kind = "assume"
@final
class Cover(Property):
_kind = "cover"
# @final
class Switch(Statement):
def __init__(self, test, cases, *, src_loc=None, src_loc_at=0, case_src_locs={}):
if src_loc is None:
super().__init__(src_loc_at=src_loc_at)
else:
# Switch is a bit special in terms of location tracking because it is usually created
# long after the control has left the statement that directly caused its creation.
self.src_loc = src_loc
# Switch is also a bit special in that its parts also have location information. It can't
# be automatically traced, so whatever constructs a Switch may optionally provide it.
self.case_src_locs = {}
self.test = Value.cast(test)
self.cases = OrderedDict()
for orig_keys, stmts in cases.items():
# Map: None -> (); key -> (key,); (key...) -> (key...)
keys = orig_keys
if keys is None:
keys = ()
if not isinstance(keys, tuple):
keys = (keys,)
# Map: 2 -> "0010"; "0010" -> "0010"
new_keys = ()
for key in keys:
if isinstance(key, str):
key = "".join(key.split()) # remove whitespace
elif isinstance(key, int):
key = format(key, "b").rjust(len(self.test), "0")
elif isinstance(key, Enum):
key = format(key.value, "b").rjust(len(self.test), "0")
else:
raise TypeError("Object {!r} cannot be used as a switch key"
.format(key))
assert len(key) == len(self.test)
new_keys = (*new_keys, key)
if not isinstance(stmts, Iterable):
stmts = [stmts]
self.cases[new_keys] = Statement.cast(stmts)
if orig_keys in case_src_locs:
self.case_src_locs[new_keys] = case_src_locs[orig_keys]
def _lhs_signals(self):
signals = union((s._lhs_signals() for ss in self.cases.values() for s in ss),
start=ValueSet())
return signals
def _rhs_signals(self):
signals = union((s._rhs_signals() for ss in self.cases.values() for s in ss),
start=ValueSet())
return self.test._rhs_signals() | signals
def __repr__(self):
def case_repr(keys, stmts):
stmts_repr = " ".join(map(repr, stmts))
if keys == ():
return "(default {})".format(stmts_repr)
elif len(keys) == 1:
return "(case {} {})".format(keys[0], stmts_repr)
else:
return "(case ({}) {})".format(" ".join(keys), stmts_repr)
case_reprs = [case_repr(keys, stmts) for keys, stmts in self.cases.items()]
return "(switch {!r} {})".format(self.test, " ".join(case_reprs))
class _MappedKeyCollection(metaclass=ABCMeta):
@abstractmethod
def _map_key(self, key):
pass # :nocov:
@abstractmethod
def _unmap_key(self, key):
pass # :nocov:
class _MappedKeyDict(MutableMapping, _MappedKeyCollection):
def __init__(self, pairs=()):
self._storage = OrderedDict()
for key, value in pairs:
self[key] = value
def __getitem__(self, key):
key = None if key is None else self._map_key(key)
return self._storage[key]
def __setitem__(self, key, value):
key = None if key is None else self._map_key(key)
self._storage[key] = value
def __delitem__(self, key):
key = None if key is None else self._map_key(key)
del self._storage[key]
def __iter__(self):
for key in self._storage:
if key is None:
yield None
else:
yield self._unmap_key(key)
def __eq__(self, other):
if not isinstance(other, type(self)):
return False
if len(self) != len(other):
return False
for ak, bk in zip(sorted(self._storage), sorted(other._storage)):
if ak != bk:
return False
if self._storage[ak] != other._storage[bk]:
return False
return True
def __len__(self):
return len(self._storage)
def __repr__(self):
pairs = ["({!r}, {!r})".format(k, v) for k, v in self.items()]
return "{}.{}([{}])".format(type(self).__module__, type(self).__name__,
", ".join(pairs))
class _MappedKeySet(MutableSet, _MappedKeyCollection):
def __init__(self, elements=()):
self._storage = OrderedDict()
for elem in elements:
self.add(elem)
def add(self, value):
self._storage[self._map_key(value)] = None
def update(self, values):
for value in values:
self.add(value)
def discard(self, value):
if value in self:
del self._storage[self._map_key(value)]
def __contains__(self, value):
return self._map_key(value) in self._storage
def __iter__(self):
for key in [k for k in self._storage]:
yield self._unmap_key(key)
def __len__(self):
return len(self._storage)
def __repr__(self):
return "{}.{}({})".format(type(self).__module__, type(self).__name__,
", ".join(repr(x) for x in self))
class ValueKey:
def __init__(self, value):
self.value = Value.cast(value)
if isinstance(self.value, Const):
self._hash = hash(self.value.value)
elif isinstance(self.value, (Signal, AnyValue)):
self._hash = hash(self.value.duid)
elif isinstance(self.value, (ClockSignal, ResetSignal)):
self._hash = hash(self.value.domain)
elif isinstance(self.value, Operator):
self._hash = hash((self.value.operator,
tuple(ValueKey(o) for o in self.value.operands)))
elif isinstance(self.value, Slice):
self._hash = hash((ValueKey(self.value.value), self.value.start, self.value.stop))
elif isinstance(self.value, Part):
self._hash = hash((ValueKey(self.value.value), ValueKey(self.value.offset),
self.value.width, self.value.stride))
elif isinstance(self.value, Cat):
self._hash = hash(tuple(ValueKey(o) for o in self.value.parts))
elif isinstance(self.value, ArrayProxy):
self._hash = hash((ValueKey(self.value.index),
tuple(ValueKey(e) for e in self.value._iter_as_values())))
elif isinstance(self.value, Sample):
self._hash = hash((ValueKey(self.value.value), self.value.clocks, self.value.domain))
elif isinstance(self.value, Initial):
self._hash = 0
else: # :nocov:
raise TypeError("Object {!r} cannot be used as a key in value collections"
.format(self.value))
def __hash__(self):
return self._hash
def __eq__(self, other):
if type(other) is not ValueKey:
return False
if type(self.value) is not type(other.value):
return False
if isinstance(self.value, Const):
return self.value.value == other.value.value
elif isinstance(self.value, (Signal, AnyValue)):
return self.value is other.value
elif isinstance(self.value, (ClockSignal, ResetSignal)):
return self.value.domain == other.value.domain
elif isinstance(self.value, Operator):
return (self.value.operator == other.value.operator and
len(self.value.operands) == len(other.value.operands) and
all(ValueKey(a) == ValueKey(b)
for a, b in zip(self.value.operands, other.value.operands)))
elif isinstance(self.value, Slice):
return (ValueKey(self.value.value) == ValueKey(other.value.value) and
self.value.start == other.value.start and
self.value.stop == other.value.stop)
elif isinstance(self.value, Part):
return (ValueKey(self.value.value) == ValueKey(other.value.value) and
ValueKey(self.value.offset) == ValueKey(other.value.offset) and
self.value.width == other.value.width and
self.value.stride == other.value.stride)
elif isinstance(self.value, Cat):
return all(ValueKey(a) == ValueKey(b)
for a, b in zip(self.value.parts, other.value.parts))
elif isinstance(self.value, ArrayProxy):
return (ValueKey(self.value.index) == ValueKey(other.value.index) and
len(self.value.elems) == len(other.value.elems) and
all(ValueKey(a) == ValueKey(b)
for a, b in zip(self.value._iter_as_values(),
other.value._iter_as_values())))
elif isinstance(self.value, Sample):
return (ValueKey(self.value.value) == ValueKey(other.value.value) and
self.value.clocks == other.value.clocks and
self.value.domain == self.value.domain)
elif isinstance(self.value, Initial):
return True
else: # :nocov:
raise TypeError("Object {!r} cannot be used as a key in value collections"
.format(self.value))
def __lt__(self, other):
if not isinstance(other, ValueKey):
return False
if type(self.value) != type(other.value):
return False
if isinstance(self.value, Const):
return self.value < other.value
elif isinstance(self.value, (Signal, AnyValue)):
return self.value.duid < other.value.duid
elif isinstance(self.value, Slice):
return (ValueKey(self.value.value) < ValueKey(other.value.value) and
self.value.start < other.value.start and
self.value.end < other.value.end)
else: # :nocov:
raise TypeError("Object {!r} cannot be used as a key in value collections")
def __repr__(self):
return "<{}.ValueKey {!r}>".format(__name__, self.value)
class ValueDict(_MappedKeyDict):
_map_key = ValueKey
_unmap_key = lambda self, key: key.value
class ValueSet(_MappedKeySet):
_map_key = ValueKey
_unmap_key = lambda self, key: key.value
class SignalKey:
def __init__(self, signal):
self.signal = signal
if isinstance(signal, Signal):
self._intern = (0, signal.duid)
elif type(signal) is ClockSignal:
self._intern = (1, signal.domain)
elif type(signal) is ResetSignal:
self._intern = (2, signal.domain)
else:
raise TypeError("Object {!r} is not an nMigen signal".format(signal))
def __hash__(self):
return hash(self._intern)
def __eq__(self, other):
if type(other) is not SignalKey:
return False
return self._intern == other._intern
def __lt__(self, other):
if type(other) is not SignalKey:
raise TypeError("Object {!r} cannot be compared to a SignalKey".format(signal))
return self._intern < other._intern
def __repr__(self):
return "<{}.SignalKey {!r}>".format(__name__, self.signal)
class SignalDict(_MappedKeyDict):
_map_key = SignalKey
_unmap_key = lambda self, key: key.signal
class SignalSet(_MappedKeySet):
_map_key = SignalKey
_unmap_key = lambda self, key: key.signal