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hdl.ast: rename nbits to width.

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Also, replace `bits, sign = x.shape()` with more idiomatic
`width, signed = x.shape()`.

This unifies all properties corresponding to `len(x)` to `x.width`.
(Not all values have a `width` property.)

Fixes #210.
This commit is contained in:
whitequark 2019-09-20 15:35:55 +00:00
parent af7224de5d
commit 378e924280
9 changed files with 106 additions and 90 deletions
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134
nmigen/hdl/ast.py
View file

@ -35,14 +35,14 @@ def _enum_shape(enum_type):
max_value = max(member.value for member in enum_type)
if not isinstance(min_value, int) or not isinstance(max_value, int):
raise TypeError("Only enumerations with integer values can be converted to nMigen values")
sign = min_value < 0 or max_value < 0
bits = max(bits_for(min_value, sign), bits_for(max_value, sign))
return (bits, sign)
signed = min_value < 0 or max_value < 0
width = max(bits_for(min_value, signed), bits_for(max_value, signed))
return (width, signed)
def _enum_to_bits(enum_value):
bits, sign = _enum_shape(type(enum_value))
return format(enum_value.value & ((1 << bits) - 1), "b").rjust(bits, "0")
width, signed = _enum_shape(type(enum_value))
return format(enum_value.value & ((1 << width) - 1), "b").rjust(width, "0")
class Value(metaclass=ABCMeta):
@ -347,24 +347,23 @@ class Const(Value):
----------
value : int
shape : int or tuple or None
Either an integer `bits` or a tuple `(bits, signed)`
specifying the number of bits in this `Const` and whether it is
signed (can represent negative values). `shape` defaults
to the minimum width and signedness of `value`.
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
----------
nbits : int
width : int
signed : bool
"""
src_loc = None
@staticmethod
def normalize(value, shape):
nbits, signed = shape
mask = (1 << nbits) - 1
width, signed = shape
mask = (1 << width) - 1
value &= mask
if signed and value >> (nbits - 1):
if signed and value >> (width - 1):
value |= ~mask
return value
@ -375,14 +374,20 @@ class Const(Value):
shape = bits_for(self.value), self.value < 0
if isinstance(shape, int):
shape = shape, self.value < 0
self.nbits, self.signed = shape
if not isinstance(self.nbits, int) or self.nbits < 0:
self.width, self.signed = shape
if not isinstance(self.width, int) or self.width < 0:
raise TypeError("Width must be a non-negative integer, not '{!r}'"
.format(self.nbits))
.format(self.width))
self.value = self.normalize(self.value, shape)
# TODO(nmigen-0.2): move this to nmigen.compat and make it a deprecated extension
@property
@deprecated("instead of `const.nbits`, use `const.width`")
def nbits(self):
return self.width
def shape(self):
return self.nbits, self.signed
return self.width, self.signed
def _rhs_signals(self):
return ValueSet()
@ -391,7 +396,7 @@ class Const(Value):
return self.value
def __repr__(self):
return "(const {}'{}d{})".format(self.nbits, "s" if self.signed else "", self.value)
return "(const {}'{}d{})".format(self.width, "s" if self.signed else "", self.value)
C = Const # shorthand
@ -402,13 +407,13 @@ class AnyValue(Value, DUID):
super().__init__(src_loc_at=src_loc_at)
if isinstance(shape, int):
shape = shape, False
self.nbits, self.signed = shape
if not isinstance(self.nbits, int) or self.nbits < 0:
self.width, self.signed = shape
if not isinstance(self.width, int) or self.width < 0:
raise TypeError("Width must be a non-negative integer, not '{!r}'"
.format(self.nbits))
.format(self.width))
def shape(self):
return self.nbits, self.signed
return self.width, self.signed
def _rhs_signals(self):
return ValueSet()
@ -453,41 +458,41 @@ class Operator(Value):
def shape(self):
op_shapes = list(map(lambda x: x.shape(), self.operands))
if len(op_shapes) == 1:
(a_bits, a_sign), = op_shapes
(a_width, a_signed), = op_shapes
if self.op in ("+", "~"):
return a_bits, a_sign
return a_width, a_signed
if self.op == "-":
if not a_sign:
return a_bits + 1, True
if not a_signed:
return a_width + 1, True
else:
return a_bits, a_sign
return a_width, a_signed
if self.op in ("b", "r|", "r&", "r^"):
return 1, False
elif len(op_shapes) == 2:
(a_bits, a_sign), (b_bits, b_sign) = op_shapes
(a_width, a_signed), (b_width, b_signed) = op_shapes
if self.op == "+" or self.op == "-":
bits, sign = self._bitwise_binary_shape(*op_shapes)
return bits + 1, sign
width, signed = self._bitwise_binary_shape(*op_shapes)
return width + 1, signed
if self.op == "*":
return a_bits + b_bits, a_sign or b_sign
return a_width + b_width, a_signed or b_signed
if self.op == "%":
return a_bits, a_sign
return a_width, a_signed
if self.op in ("<", "<=", "==", "!=", ">", ">="):
return 1, False
if self.op in ("&", "^", "|"):
return self._bitwise_binary_shape(*op_shapes)
if self.op == "<<":
if b_sign:
extra = 2 ** (b_bits - 1) - 1
if b_signed:
extra = 2 ** (b_width - 1) - 1
else:
extra = 2 ** (b_bits) - 1
return a_bits + extra, a_sign
extra = 2 ** (b_width) - 1
return a_width + extra, a_signed
if self.op == ">>":
if b_sign:
extra = 2 ** (b_bits - 1)
if b_signed:
extra = 2 ** (b_width - 1)
else:
extra = 0
return a_bits + extra, a_sign
return a_width + extra, a_signed
elif len(op_shapes) == 3:
if self.op == "m":
s_shape, a_shape, b_shape = op_shapes
@ -683,7 +688,7 @@ class Signal(Value, DUID):
Parameters
----------
shape : int or tuple or None
Either an integer ``bits`` or a tuple ``(bits, signed)`` specifying the number of bits
Either an integer ``width`` or a tuple ``(width, signed)`` specifying the number of bits
in this ``Signal`` and whether it is signed (can represent negative values).
``shape`` defaults to 1-bit and non-signed.
name : str
@ -716,7 +721,7 @@ class Signal(Value, DUID):
Attributes
----------
nbits : int
width : int
signed : bool
name : str
reset : int
@ -750,27 +755,27 @@ class Signal(Value, DUID):
.format(min, max + 1))
self.signed = min < 0 or max < 0
if min == max:
self.nbits = 0
self.width = 0
else:
self.nbits = builtins.max(bits_for(min, self.signed),
self.width = builtins.max(bits_for(min, self.signed),
bits_for(max, self.signed))
else:
if not (min is None and max is None):
raise ValueError("Only one of bits/signedness or bounds may be specified")
if isinstance(shape, int):
self.nbits, self.signed = shape, False
self.width, self.signed = shape, False
else:
self.nbits, self.signed = shape
self.width, self.signed = shape
if not isinstance(self.nbits, int) or self.nbits < 0:
raise TypeError("Width must be a non-negative integer, not '{!r}'".format(self.nbits))
if not isinstance(self.width, int) or self.width < 0:
raise TypeError("Width must be a non-negative integer, not '{!r}'".format(self.width))
reset_nbits = bits_for(reset, self.signed)
if reset != 0 and reset_nbits > self.nbits:
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_nbits, self.nbits),
.format(reset, reset_width, self.width),
SyntaxWarning, stacklevel=2 + src_loc_at)
self.reset = int(reset)
@ -800,9 +805,9 @@ class Signal(Value, DUID):
signed = value_range.start < 0 or (value_range.stop - value_range.step) < 0
else:
signed = value_range.start < 0
nbits = max(bits_for(value_range.start, signed),
bits_for(value_range.stop - value_range.step, signed))
return cls((nbits, signed), src_loc_at=1 + src_loc_at, **kwargs)
width = max(bits_for(value_range.start, signed),
bits_for(value_range.stop - value_range.step, signed))
return cls((width, signed), src_loc_at=1 + src_loc_at, **kwargs)
@classmethod
def enum(cls, enum_type, *, src_loc_at=0, **kwargs):
@ -839,8 +844,19 @@ class Signal(Value, DUID):
kw.update(kwargs)
return cls(**kw, src_loc_at=1 + src_loc_at)
# TODO(nmigen-0.2): move this to nmigen.compat and make it a deprecated extension
@property
@deprecated("instead of `signal.nbits`, use `signal.width`")
def nbits(self):
return self.width
@nbits.setter
@deprecated("instead of `signal.nbits = x`, use `signal.width = x`")
def nbits(self, value):
self.width = value
def shape(self):
return self.nbits, self.signed
return self.width, self.signed
def _lhs_signals(self):
return ValueSet((self,))
@ -1028,11 +1044,11 @@ class ArrayProxy(Value):
return (Value.wrap(elem) for elem in self.elems)
def shape(self):
bits, sign = 0, False
for elem_bits, elem_sign in (elem.shape() for elem in self._iter_as_values()):
bits = max(bits, elem_bits + elem_sign)
sign = max(sign, elem_sign)
return bits, sign
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 width, signed
def _lhs_signals(self):
signals = union((elem._lhs_signals() for elem in self._iter_as_values()), start=ValueSet())

6
nmigen/hdl/dsl.py
View file

@ -168,8 +168,8 @@ class Module(_ModuleBuilderRoot, Elaboratable):
def _check_signed_cond(self, cond):
cond = Value.wrap(cond)
bits, sign = cond.shape()
if sign:
width, signed = cond.shape()
if signed:
warnings.warn("Signed values in If/Elif conditions usually result from inverting "
"Python booleans with ~, which leads to unexpected results: ~True is "
"-2, which is truthful. Replace `~flag` with `not flag`. (If this is "
@ -405,7 +405,7 @@ class Module(_ModuleBuilderRoot, Elaboratable):
fsm_state_src_locs = data["state_src_locs"]
if not fsm_states:
return
fsm_signal.nbits = bits_for(len(fsm_encoding) - 1)
fsm_signal.width = bits_for(len(fsm_encoding) - 1)
if fsm_reset is None:
fsm_signal.reset = fsm_encoding[next(iter(fsm_states))]
else:

8
nmigen/hdl/mem.py
View file

@ -95,8 +95,8 @@ class ReadPort(Elaboratable):
def elaborate(self, platform):
f = Instance("$memrd",
p_MEMID=self.memory,
p_ABITS=self.addr.nbits,
p_WIDTH=self.data.nbits,
p_ABITS=self.addr.width,
p_WIDTH=self.data.width,
p_CLK_ENABLE=self.domain != "comb",
p_CLK_POLARITY=1,
p_TRANSPARENT=self.transparent,
@ -158,8 +158,8 @@ class WritePort(Elaboratable):
def elaborate(self, platform):
f = Instance("$memwr",
p_MEMID=self.memory,
p_ABITS=self.addr.nbits,
p_WIDTH=self.data.nbits,
p_ABITS=self.addr.width,
p_WIDTH=self.data.width,
p_CLK_ENABLE=1,
p_CLK_POLARITY=1,
p_PRIORITY=self.priority,

4
nmigen/hdl/xfrm.py
View file

@ -523,7 +523,7 @@ class DomainLowerer(FragmentTransformer, ValueTransformer, StatementTransformer)
domain = fragment.domains[domain_name]
if domain.rst is None:
continue
stmts = [signal.eq(Const(signal.reset, signal.nbits))
stmts = [signal.eq(Const(signal.reset, signal.width))
for signal in signals if not signal.reset_less]
fragment.add_statements(Switch(domain.rst, {1: stmts}))
@ -732,7 +732,7 @@ class _ControlInserter(FragmentTransformer):
class ResetInserter(_ControlInserter):
def _insert_control(self, fragment, domain, signals):
stmts = [s.eq(Const(s.reset, s.nbits)) for s in signals if not s.reset_less]
stmts = [s.eq(Const(s.reset, s.width)) for s in signals if not s.reset_less]
fragment.add_statements(Switch(self.controls[domain], {1: stmts}, src_loc=self.src_loc))