[otbn] Change how we describe valid ranges for PC-relative operands
It used to look something like this:
Valid range: .-1048576 to .+1048574 in steps of 2
And is now expanded quite a lot to be super-explicit:
Valid range: -1048576 to 1048574 in steps of 2. This is encoded
PC-relative but appears as an absolute value in assembly. To write a
raw value in an assembly file, write something in the range
.-1048576 to .+1048574.
Signed-off-by: Rupert Swarbrick <rswarbrick@lowrisc.org>
diff --git a/hw/ip/otbn/util/shared/operand.py b/hw/ip/otbn/util/shared/operand.py
index 033bf96..97109a1 100644
--- a/hw/ip/otbn/util/shared/operand.py
+++ b/hw/ip/otbn/util/shared/operand.py
@@ -295,10 +295,9 @@
return ImmOperandType(width, enc_offset, shift, signed, pc_rel)
- def doc_rel_to_abs(self, value: int) -> str:
- if not self.pc_rel:
- return str(value)
-
+ @staticmethod
+ def _doc_rel_to_abs(value: int) -> str:
+ '''Turn X to . + X or . - X, as appropriate.'''
if value < 0:
return '.-{}'.format(-value)
elif value == 0:
@@ -308,21 +307,27 @@
def markdown_doc(self) -> Optional[str]:
# Override from OperandType base class
- rel_rng = self.get_doc_range()
- if rel_rng is None:
+ rng = self.get_doc_range()
+ if rng is None:
return None
- rel_lo, rel_hi = rel_rng
+ lo, hi = rng
if self.shift == 0:
stp_msg = ''
else:
stp_msg = ' in steps of `{}`'.format(1 << self.shift)
- abs_lo = self.doc_rel_to_abs(rel_lo)
- abs_hi = self.doc_rel_to_abs(rel_hi)
+ rel_suffix = ''
+ if self.pc_rel:
+ rel_suffix = (' This is encoded PC-relative but appears '
+ 'as an absolute value in assembly. To write a raw '
+ 'value in an assembly file, write something in the '
+ 'range `{}` to `{}`.'
+ .format(ImmOperandType._doc_rel_to_abs(lo),
+ ImmOperandType._doc_rel_to_abs(hi)))
- return ('Valid range: `{} to {}`{}'
- .format(abs_lo, abs_hi, stp_msg))
+ return ('Valid range: `{}` to `{}`{}.{}'
+ .format(lo, hi, stp_msg, rel_suffix))
def describe_decode(self, bits_lst: List[str]) -> str:
# The "most general" result is something like this:
