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docs/reference: describe out-of-bounds behavior of bit_select/word_select.

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Catherine 2024-02-13 05:40:05 +00:00
parent 2dea83cffd
commit 3867623727
1 changed files with 12 additions and 4 deletions
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amaranth/hdl/_ast.py
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@ -1056,8 +1056,12 @@ class Value(metaclass=ABCMeta):
"""Part-select with bit granularity. """Part-select with bit granularity.
Selects a constant width, variable offset part of :pc:`self`, where parts with successive Selects a constant width, variable offset part of :pc:`self`, where parts with successive
offsets overlap by :pc:`width - 1` bits. When :pc:`offset` is a constant integer, this offsets overlap by :pc:`width - 1` bits. Bits above the most significant bit of :pc:`self`
operation is equivalent to :pc:`self[offset:offset + width]`. may be selected; they are equal to zero if :pc:`self` is unsigned, to :pc:`self[-1]` if
:pc:`self` is signed, and assigning to them does nothing.
When :pc:`offset` is a constant integer and :pc:`offset + width <= len(self)`,
this operation is equivalent to :pc:`self[offset:offset + width]`.
Parameters Parameters
---------- ----------
@ -1086,8 +1090,12 @@ class Value(metaclass=ABCMeta):
"""Part-select with word granularity. """Part-select with word granularity.
Selects a constant width, variable offset part of :pc:`self`, where parts with successive Selects a constant width, variable offset part of :pc:`self`, where parts with successive
offsets are adjacent but do not overlap. When :pc:`offset` is a constant integer, this offsets are adjacent but do not overlap. Bits above the most significant bit of :pc:`self`
operation is equivalent to :pc:`self[offset * width:(offset + 1) * width]`. may be selected; they are equal to zero if :pc:`self` is unsigned, to :pc:`self[-1]` if
:pc:`self` is signed, and assigning to them does nothing.
When :pc:`offset` is a constant integer and :pc:`width:(offset + 1) * width <= len(self)`,
this operation is equivalent to :pc:`self[offset * width:(offset + 1) * width]`.
Parameters Parameters
---------- ----------