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hdl.ast: add const-shift operations.

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Also, clean up the rotate code a bit.

Fixes #378.
This commit is contained in:
whitequark 2020-05-20 03:18:33 +00:00
parent 72ef4303a9
commit 7ea81f5f06
3 changed files with 145 additions and 22 deletions
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72
nmigen/hdl/ast.py
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@ -423,41 +423,85 @@ class Value(metaclass=ABCMeta):
else:
return Cat(*matches).any()
def rotate_left(self, offset):
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
----------
offset : int
amount : int
Amount to rotate by.
Returns
-------
Value, out
If the offset is positive, the input rotated left. Otherwise, the input rotated right.
If the amount is positive, the input rotated left. Otherwise, the input rotated right.
"""
if not isinstance(offset, int):
raise TypeError("Rotate amount must be an integer, not {!r}".format(offset))
offset %= len(self)
return Cat(self[-offset:], self[:-offset]) # meow :3
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, offset):
def rotate_right(self, amount):
"""Rotate right by constant amount.
Parameters
----------
offset : int
amount : int
Amount to rotate by.
Returns
-------
Value, out
If the offset is positive, the input rotated right. Otherwise, the input rotated right.
If the amount is positive, the input rotated right. Otherwise, the input rotated right.
"""
if not isinstance(offset, int):
raise TypeError("Rotate amount must be an integer, not {!r}".format(offset))
offset %= len(self)
return Cat(self[offset:], self[:offset])
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.