from abc import ABCMeta, abstractmethod import warnings import functools from collections import OrderedDict from collections.abc import Iterable, MutableMapping, MutableSet, MutableSequence from enum import Enum from itertools import chain from .. import tracer from .._utils import * from .._unused import * __all__ = [ "Shape", "signed", "unsigned", "ShapeCastable", "Value", "Const", "C", "AnyConst", "AnySeq", "Operator", "Mux", "Part", "Slice", "Cat", "Repl", "Array", "ArrayProxy", "Signal", "ClockSignal", "ResetSignal", "ValueCastable", "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 ShapeCastable: """Interface of user-defined objects that can be cast to :class:`Shape` s. An object deriving from :class:`ShapeCastable` is automatically converted to a :class:`Shape` when it is used in a context where a :class:`Shape` is expected. Such objects can contain a richer description of the shape than what is supported by the core Amaranth language, yet still be transparently used with it. """ def __new__(cls, *args, **kwargs): self = super().__new__(cls) if not hasattr(self, "as_shape"): raise TypeError(f"Class '{cls.__name__}' deriving from `ShapeCastable` must override " f"the `as_shape` method") return self class Shape: """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. """ def __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)) self.width = width self.signed = signed @staticmethod def cast(obj, *, src_loc_at=0): while True: if isinstance(obj, Shape): return obj elif isinstance(obj, int): return Shape(obj) elif 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) elif isinstance(obj, type) and issubclass(obj, Enum): signed = False width = 0 for member in obj: try: member_shape = Const.cast(member.value).shape() except TypeError as e: raise TypeError("Only enumerations whose members have constant-castable " "values can be used in Amaranth code") if not signed and member_shape.signed: signed = True width = max(width + 1, member_shape.width) elif signed and not member_shape.signed: width = max(width, member_shape.width + 1) else: width = max(width, member_shape.width) return Shape(width, signed) elif isinstance(obj, ShapeCastable): new_obj = obj.as_shape() else: raise TypeError("Object {!r} cannot be converted to an Amaranth shape".format(obj)) if new_obj is obj: raise RecursionError("Shape-castable object {!r} casts to itself".format(obj)) obj = new_obj def __repr__(self): if self.signed: return "signed({})".format(self.width) else: return "unsigned({})".format(self.width) def __eq__(self, other): if not isinstance(other, Shape): try: other = self.__class__.cast(other) except TypeError as e: raise TypeError("Shapes may be compared with shape-castable objects, not {!r}" .format(other)) from e return self.width == other.width and self.signed == other.signed 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 Amaranth 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. :class:`ValueCastable` objects are recursively cast to an Amaranth value. """ while True: if isinstance(obj, Value): return obj elif isinstance(obj, ValueCastable): new_obj = obj.as_value() elif isinstance(obj, Enum): return Const(obj.value, Shape.cast(type(obj))) elif isinstance(obj, int): return Const(obj) else: raise TypeError("Object {!r} cannot be converted to an Amaranth value".format(obj)) if new_obj is obj: raise RecursionError("Value-castable object {!r} casts to itself".format(obj)) obj = new_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 Amaranth value to Python boolean") def __pos__(self): return self 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 __mod__(self, other): return Operator("%", [self, other]) def __rmod__(self, other): return Operator("%", [other, self]) def __floordiv__(self, other): return Operator("//", [self, other]) def __rfloordiv__(self, other): return Operator("//", [other, self]) def __check_shamt(self): if self.shape().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 TypeError("Shift amount must be unsigned") 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 __abs__(self): if self.shape().signed: return Mux(self >= 0, self, -self) else: return self 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(f"Index {key} is out of bounds for a {n}-bit value") 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, int 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, int 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 = [] # This code should accept exactly the same patterns as `with m.Case(...):`. for pattern in patterns: 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, 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) else: try: orig_pattern, pattern = pattern, Const.cast(pattern) except TypeError as e: raise SyntaxError("Match pattern must be a string or a constant-castable " "expression, not {!r}" .format(pattern)) from e pattern_len = bits_for(pattern.value) if pattern_len > len(self): warnings.warn("Match pattern '{!r}' ({}'{:b}) is wider than match value " "(which has width {}); comparison will never be true" .format(orig_pattern, pattern_len, pattern.value, len(self)), SyntaxWarning, stacklevel=2) continue matches.append(self == pattern) if not matches: return Const(0) elif len(matches) == 1: return matches[0] else: return Cat(*matches).any() def shift_left(self, amount): """Shift left by constant amount. Parameters ---------- amount : int Amount to shift by. Returns ------- Value, out If the amount is positive, the input shifted left. Otherwise, the input shifted right. """ if not isinstance(amount, int): raise TypeError("Shift amount must be an integer, not {!r}".format(amount)) if amount < 0: return self.shift_right(-amount) if self.shape().signed: return Cat(Const(0, amount), self).as_signed() else: return Cat(Const(0, amount), self) # unsigned def shift_right(self, amount): """Shift right by constant amount. Parameters ---------- amount : int Amount to shift by. Returns ------- Value, out If the amount is positive, the input shifted right. Otherwise, the input shifted left. """ if not isinstance(amount, int): raise TypeError("Shift amount must be an integer, not {!r}".format(amount)) if amount < 0: return self.shift_left(-amount) if self.shape().signed: return self[amount:].as_signed() else: return self[amount:] # unsigned def rotate_left(self, amount): """Rotate left by constant amount. Parameters ---------- amount : int Amount to rotate by. Returns ------- Value, out If the amount is positive, the input rotated left. Otherwise, the input rotated right. """ if not isinstance(amount, int): raise TypeError("Rotate amount must be an integer, not {!r}".format(amount)) amount %= len(self) return Cat(self[-amount:], self[:-amount]) # meow :3 def rotate_right(self, amount): """Rotate right by constant amount. Parameters ---------- amount : int Amount to rotate by. Returns ------- Value, out If the amount is positive, the input rotated right. Otherwise, the input rotated right. """ if not isinstance(amount, int): raise TypeError("Rotate amount must be an integer, not {!r}".format(amount)) amount %= len(self) return Cat(self[amount:], self[:amount]) 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: __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 # TODO(amaranth-0.5): remove @staticmethod @deprecated("instead of `Const.normalize(value, shape)`, use `Const(value, shape).value`") def normalize(value, shape): mask = (1 << shape.width) - 1 value &= mask if shape.signed and value >> (shape.width - 1): value |= ~mask return value @staticmethod def cast(obj): """Converts ``obj`` to an Amaranth constant. First, ``obj`` is converted to a value using :meth:`Value.cast`. If it is a constant, it is returned. If it is a constant-castable expression, it is evaluated and returned. Otherwise, :exn:`TypeError` is raised. """ obj = Value.cast(obj) if type(obj) is Const: return obj elif type(obj) is Cat: value = 0 width = 0 for part in obj.parts: const = Const.cast(part) value |= const.value << width width += len(const) return Const(value, width) else: raise TypeError("Value {!r} cannot be converted to an Amaranth constant".format(obj)) 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 = shape.width self.signed = shape.signed if self.signed and self.value >> (self.width - 1): self.value |= -(1 << self.width) else: self.value &= (1 << self.width) - 1 def shape(self): return Shape(self.width, self.signed) def _rhs_signals(self): return SignalSet() 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) shape = Shape.cast(shape, src_loc_at=1 + src_loc_at) self.width = shape.width self.signed = shape.signed def shape(self): return Shape(self.width, self.signed) def _rhs_signals(self): return SignalSet() @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): if not a_shape.signed and not b_shape.signed: # both operands unsigned return unsigned(max(a_shape.width, b_shape.width)) elif a_shape.signed and b_shape.signed: # both operands signed return signed(max(a_shape.width, b_shape.width)) elif not a_shape.signed and b_shape.signed: # first operand unsigned (add sign bit), second operand signed return signed(max(a_shape.width + 1, b_shape.width)) else: # first signed, second operand unsigned (add sign bit) return signed(max(a_shape.width, b_shape.width + 1)) op_shapes = list(map(lambda x: x.shape(), self.operands)) if len(op_shapes) == 1: a_shape, = op_shapes if self.operator in ("+", "~"): return Shape(a_shape.width, a_shape.signed) if self.operator == "-": return Shape(a_shape.width + 1, True) if self.operator in ("b", "r|", "r&", "r^"): return Shape(1, False) if self.operator == "u": return Shape(a_shape.width, False) if self.operator == "s": return Shape(a_shape.width, True) elif len(op_shapes) == 2: a_shape, b_shape = op_shapes if self.operator in ("+", "-"): o_shape = _bitwise_binary_shape(*op_shapes) return Shape(o_shape.width + 1, o_shape.signed) if self.operator == "*": return Shape(a_shape.width + b_shape.width, a_shape.signed or b_shape.signed) if self.operator == "//": return Shape(a_shape.width + b_shape.signed, a_shape.signed or b_shape.signed) if self.operator == "%": return Shape(b_shape.width, b_shape.signed) if self.operator in ("<", "<=", "==", "!=", ">", ">="): return Shape(1, False) if self.operator in ("&", "^", "|"): return _bitwise_binary_shape(*op_shapes) if self.operator == "<<": assert not b_shape.signed return Shape(a_shape.width + 2 ** b_shape.width - 1, a_shape.signed) if self.operator == ">>": assert not b_shape.signed return Shape(a_shape.width, a_shape.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 _lhs_signals(self): if self.operator in ("u", "s"): return union(op._lhs_signals() for op in self.operands) return super()._lhs_signals() 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``. """ 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 = int(start) self.stop = int(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 concatenation. """ def __init__(self, *args, src_loc_at=0): super().__init__(src_loc_at=src_loc_at) self.parts = [] for index, arg in enumerate(flatten(args)): if isinstance(arg, int) and not isinstance(arg, Enum) and arg not in [0, 1]: warnings.warn("Argument #{} of Cat() is a bare integer {} used in bit vector " "context; consider specifying explicit width using C({}, {}) instead" .format(index + 1, arg, arg, bits_for(arg)), SyntaxWarning, stacklevel=2 + src_loc_at) self.parts.append(Value.cast(arg)) 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=SignalSet()) def _rhs_signals(self): return union((part._rhs_signals() for part in self.parts), start=SignalSet()) 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) if isinstance(value, int) and value not in [0, 1]: warnings.warn("Value argument of Repl() is a bare integer {} used in bit vector " "context; consider specifying explicit width using C({}, {}) instead" .format(value, value, bits_for(value)), SyntaxWarning, stacklevel=2 + 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="$signal") orig_shape = shape if shape is None: shape = unsigned(1) else: shape = Shape.cast(shape, src_loc_at=1 + src_loc_at) self.width = shape.width self.signed = shape.signed if isinstance(reset, Enum): reset = reset.value if not isinstance(reset, int): raise TypeError("Reset value has to be an int or an integral Enum") reset_width = bits_for(reset, self.signed) if reset != 0 and reset_width > self.width: warnings.warn("Reset value {!r} requires {} bits to represent, but the signal " "only has {} bits" .format(reset, reset_width, self.width), SyntaxWarning, stacklevel=2 + src_loc_at) self.reset = reset self.reset_less = bool(reset_less) self.attrs = OrderedDict(() if attrs is None else attrs) if decoder is None and isinstance(orig_shape, type) and issubclass(orig_shape, Enum): decoder = orig_shape if isinstance(decoder, type) and issubclass(decoder, Enum): def enum_decoder(value): try: return "{0.name:}/{0.value:}".format(decoder(value)) except ValueError: return str(value) self.decoder = enum_decoder self._enum_class = decoder else: self.decoder = decoder self._enum_class = None # Not a @classmethod because amaranth.compat requires it. @staticmethod def like(other, *, name=None, name_suffix=None, src_loc_at=0, **kwargs): """Create Signal based on another. Parameters ---------- other : Value Object to base this Signal on. """ if name is not None: new_name = str(name) elif name_suffix is not None: new_name = other.name + str(name_suffix) else: new_name = tracer.get_var_name(depth=2 + src_loc_at, default="$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 SignalSet((self,)) def _rhs_signals(self): return SignalSet((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 SignalSet((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 SignalSet((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): unsigned_width = signed_width = 0 has_unsigned = has_signed = False for elem_shape in (elem.shape() for elem in self._iter_as_values()): if elem_shape.signed: has_signed = True signed_width = max(signed_width, elem_shape.width) else: has_unsigned = True unsigned_width = max(unsigned_width, elem_shape.width) # The shape of the proxy must be such that it preserves the mathematical value of the array # elements. I.e., shape-wise, an array proxy must be identical to an equivalent mux tree. # To ensure this holds, if the array contains both signed and unsigned values, make sure # that every unsigned value is zero-extended by at least one bit. if has_signed and has_unsigned and unsigned_width >= signed_width: # Array contains both signed and unsigned values, and at least one of the unsigned # values won't be zero-extended otherwise. return signed(unsigned_width + 1) else: # Array contains values of the same signedness, or else all of the unsigned values # are zero-extended. return Shape(max(unsigned_width, signed_width), has_signed) def _lhs_signals(self): signals = union((elem._lhs_signals() for elem in self._iter_as_values()), start=SignalSet()) return signals def _rhs_signals(self): signals = union((elem._rhs_signals() for elem in self._iter_as_values()), start=SignalSet()) return self.index._rhs_signals() | signals def __repr__(self): return "(proxy (array [{}]) {!r})".format(", ".join(map(repr, self.elems)), self.index) class ValueCastable: """Interface of user-defined objects that can be cast to :class:`Value` s. An object deriving from :class:`ValueCastable`` is automatically converted to a :class:`Value` when it is used in a context where a :class:`Value`` is expected. Such objects can implement different or richer semantics than what is supported by the core Amaranth language, yet still be transparently used with it as long as the final underlying representation is a single Amaranth :class:`Value`. These objects also need not commit to a specific representation until they are converted to a concrete Amaranth value. Note that it is necessary to ensure that Amaranth's view of representation of all values stays internally consistent. The class deriving from :class:`ValueCastable`` must decorate the :meth:`as_value` method with the :meth:`lowermethod` decorator, which ensures that all calls to :meth:`as_value` return the same :class:`Value` representation. If the class deriving from :class:`ValueCastable` is mutable, it is up to the user to ensure that it is not mutated in a way that changes its representation after the first call to :meth:`as_value`. """ def __new__(cls, *args, **kwargs): self = super().__new__(cls) if not hasattr(self, "as_value"): raise TypeError(f"Class '{cls.__name__}' deriving from `ValueCastable` must override " "the `as_value` method") if not hasattr(self.as_value, "_ValueCastable__memoized"): raise TypeError(f"Class '{cls.__name__}' deriving from `ValueCastable` must decorate " "the `as_value` method with the `ValueCastable.lowermethod` decorator") return self @staticmethod def lowermethod(func): """Decorator to memoize lowering methods. Ensures the decorated method is called only once, with subsequent method calls returning the object returned by the first first method call. This decorator is required to decorate the ``as_value`` method of ``ValueCastable`` subclasses. This is to ensure that Amaranth's view of representation of all values stays internally consistent. """ @functools.wraps(func) def wrapper_memoized(self, *args, **kwargs): # Use `in self.__dict__` instead of `hasattr` to avoid interfering with custom # `__getattr__` implementations. if not "_ValueCastable__lowered_to" in self.__dict__: self.__lowered_to = func(self, *args, **kwargs) return self.__lowered_to wrapper_memoized.__memoized = True return wrapper_memoized @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 SignalSet((self,)) def __repr__(self): return "(sample {!r} @ {}[{}])".format( self.value, "" 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 SignalSet((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(list(chain.from_iterable(map(Statement.cast, obj)))) else: if isinstance(obj, Statement): return _StatementList([obj]) else: raise TypeError("Object {!r} is not an Amaranth 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, name=None, src_loc_at=0): super().__init__(src_loc_at=src_loc_at) self.test = Value.cast(test) self._check = _check self._en = _en self.name = name if not isinstance(self.name, str) and self.name is not None: raise TypeError("Property name must be a string or None, not {!r}" .format(self.name)) 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 SignalSet((self._en, self._check)) def _rhs_signals(self): return self.test._rhs_signals() def __repr__(self): if self.name is not None: return "({}: {} {!r})".format(self.name, self._kind, self.test) 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 = () key_mask = (1 << len(self.test)) - 1 for key in keys: if isinstance(key, str): key = "".join(key.split()) # remove whitespace elif isinstance(key, int): key = format(key & key_mask, "b").rjust(len(self.test), "0") elif isinstance(key, Enum): key = format(key.value & key_mask, "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=SignalSet()) return signals def _rhs_signals(self): signals = union((s._rhs_signals() for ss in self.cases.values() for s in ss), start=SignalSet()) 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, Repl): self._hash = hash((ValueKey(self.value.value), self.value.count)) 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, Repl): return (ValueKey(self.value.value) == ValueKey(other.value.value) and self.value.count == other.value.count) 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 Amaranth 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(other)) 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