Add bit accessor methods #122
Merged
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
tarcieri
reviewed
Sep 20, 2022
tarcieri
reviewed
Sep 20, 2022
andrewwhitehead
commented
Sep 20, 2022
Signed-off-by: Andrew Whitehead <[email protected]>
Signed-off-by: Andrew Whitehead <[email protected]>
andrewwhitehead
force-pushed
the
get-bit
branch
from
893a472 to
3b74461
Compare
|
I've updated this PR to only add |
andrewwhitehead
commented
Oct 6, 2022
| @@ -25,7 +25,7 @@ impl<const LIMBS: usize> UInt<LIMBS> { | |||
| // Sometimes an increase is too far, especially with large | |||
| // powers, and then takes a long time to walk back. The upper | |||
| // bound is based on bit size, so saturate on that. | |||
| let res = Limb::ct_cmp(Limb(xn.bits() as Word), Limb(max_bits as Word)) - 1; | |||
| let res = Limb::ct_cmp(Limb(xn.bits_vartime() as Word), Limb(max_bits as Word)) - 1; | |||
There was a problem hiding this comment.
This use of bits_vartime seems a little concerning after the renaming? @tarcieri
There was a problem hiding this comment.
Seems okay for now. Not a clear direction yet going forward
There was a problem hiding this comment.
It seems like this method should probably use a prospective constant-time implementation of bits?
I can open a tracking issue
tarcieri
reviewed
Oct 7, 2022
Signed-off-by: Andrew Whitehead <[email protected]>
andrewwhitehead
force-pushed
the
get-bit
branch
from
fb04760 to
b78a6fc
Compare
|
Looks good now, thanks! |
Merged
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
This adds
UInt::bit_vartime(index)for accessing the value of the bit at a given index. It's trivial to cast the result to u8 or bool so I leave that up to the caller, to avoid casting the value twice.For consistency and accuracy,
bitsis renamed tobits_vartime.