This was an especially insidious bug because the minus character is
valid in case values but has a completely different meaning (wildcard
rather than sign).
Fixes#559.
Before this commit, ArrayProxy would add sign padding (an extra bit)
a homogeneous array of signed values, or an array where all unsigned
values are smaller than the largest signed one. After this commit,
ArrayProxy would only add padding in arrays with mixed signedness
where all signed values are smaller or equal in size to the largest
unsigned value.
Fixes#476.
Co-authored-by: Pepijn de Vos <pepijndevos@gmail.com>
The default __repr__() from typing.NamedTuple does not include
the module name, so the replacement (which uses the preferred syntax
for specifying these shapes) doesn't either.
Before this commit, there was no way to do so besides creating and
assigning an intermediate signal, which could not be extracted into
a helper function due to Module statefulness.
Fixes#292.
These are not desirable in a HDL, and currently elaborate to broken
RTLIL (after YosysHQ/yosys#1551); prohibit them completely, like
we already do for division and modulo.
Fixes#302.
A property statement that is created but not added to a module is
virtually always a serious bug, since it can make formal verification
pass when it should not. Therefore, add a warning to it, similar to
UnusedElaboratable.
Doing this to all statements is possible, but many temporary ones are
created internally by nMigen, and the extensive changes required to
remove false positives are likely not worth the true positives.
We can revisit this in the future.
Fixes#303.
To properly represent a negation of a signed X-bit quantity we may, in
general, need a signed (X+1)-bit signal — for example, negation of
3-bit -4 is 4, which is not representable in signed 3 bits.
We don't have any other convenient shortcut for x[off*w:(off+1)*w],
but using word_select to extract a single static range would result
in severe bloat of emitted code through expansion to dead branches.
Recognize and simplify this pattern.
Although constructor methods can improve clarity, there are many
contexts in which it is useful to use range() as a shape: notably
Layout, but also Const and AnyConst/AnyValue. Instead of duplicating
these constructor methods everywhere (which is not even easily
possible for Layout), use casting to Shape, introduced in 6aabdc0a.
Fixes#225.
Shapes have long been a part of nMigen, but represented using tuples.
This commit adds a Shape class (using namedtuple for backwards
compatibility), and accepts anything castable to Shape (including
enums, ranges, etc) anywhere a tuple was accepted previously.
In addition, `signed(n)` and `unsigned(n)` are added as aliases for
`Shape(n, signed=True)` and `Shape(n, signed=False)`, transforming
code such as `Signal((8, True))` to `Signal(signed(8))`.
These aliases are also included in prelude.
Preparation for #225.
This can cause confusion:
* If the erroneous object is None, it is printed as 'None', which
appears as a string (and could be the result of converting None
to a string.)
* If the erroneous object is a string, it is printed as ''<val>'',
which is a rather strange combination of quotes.
Almost no code would specify Signal(_, name) as a positional argument
on purpose, but forgetting parens and accidentally placing signedness
into the name position is so common that we had a test for it.
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.
