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Support for more backends #797

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Description

closes: #XXXX


Before we can merge this PR, please make sure that all the following items have been
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  • Targeted PR against correct branch (master)
  • Linked to GitHub issue with discussion and accepted design OR have an explanation in the PR that describes this work.
  • Wrote unit tests
  • Updated relevant documentation in the code
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@Pratyush Pratyush requested review from a team as code owners February 27, 2024 15:50
@Pratyush Pratyush requested review from z-tech, mmagician and weikengchen and removed request for a team February 27, 2024 15:50
}

pub(super) const fn mul_without_cond_subtract(mut self, other: &Self) -> (bool, Self) {
let (mut lo, mut hi) = ([0u64; N], [0u64; N]);
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Why not using the MulBuffer helper here for an easier manipulation?

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Good question, it's been a while since I looked at this code =)

ff/src/fields/models/fp/montgomery/backend.rs Show resolved Hide resolved
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mmagician commented Mar 6, 2024

This is the basically tackling #769 (comment) right?

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Looks good, just some minor comments

Comment on lines +295 to +298
// We compute this as follows.
// First, MODULUS mod 2^64 is just the lower 64 bits of MODULUS.
// Hence MODULUS mod 2^64 = MODULUS.0[0] mod 2^64.
//
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As a follow-up to this PR, the next step would be to rename this existing BigInt to BigInt64, and then also add a BigInt32, correct?

Comment on lines +68 to 71
/// Does the modulus have a spare unused bit (i.e., the MSB is 0)
///
/// This condition applies if
/// (a) `Self::MODULUS[N-1] >> 63 == 0`
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The comment Self::MODULUS[N-1] >> 63 == 0 would (later) need to be changed to reflect that the underlying representation might be other than an array of u64s.


/// (MODULUS + 1) / 4 when MODULUS % 4 == 3. Used for square root precomputations.
///
/// Can be computed if the `BigInt` type has a `plus_one_div_four` method.
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And otherwise?
Do you mean if plus_one_div_four returns Some(...)?

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3 participants