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crypto-bigint fields: do addition, subtraction and negation in-place #29

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Merged
frozenspider merged 2 commits into from
Feb 5, 2026
Merged

crypto-bigint fields: do addition, subtraction and negation in-place #29

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dbd22fa
Do addition and subtraction in-place without cloning parameters
frozenspider Feb 5, 2026
91faf6a
Do the same with negation
frozenspider Feb 5, 2026
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18 changes: 14 additions & 4 deletions src/field/crypto_bigint_const_monty.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -187,8 +187,12 @@ impl<Mod: Params<LIMBS>, const LIMBS: usize> Neg for ConstMontyField<Mod, LIMBS>
type Output = Self;

#[inline(always)]
fn neg(self) -> Self::Output {
Self(self.0.neg())
fn neg(mut self) -> Self::Output {
*self.0.as_montgomery_mut() = self
.0
.as_montgomery()
.neg_mod(Mod::PARAMS.modulus().as_nz_ref());
self
}
}

Expand Down Expand Up @@ -291,14 +295,20 @@ impl_op_assign_boilerplate!(DivAssign, div_assign);
impl<Mod: Params<LIMBS>, const LIMBS: usize> AddAssign<&Self> for ConstMontyField<Mod, LIMBS> {
#[inline(always)]
fn add_assign(&mut self, rhs: &Self) {
self.0.add_assign(&rhs.0);
*self.0.as_montgomery_mut() = self
.0
.as_montgomery()
.add_mod(rhs.0.as_montgomery(), Mod::PARAMS.modulus().as_nz_ref());
}
}

impl<Mod: Params<LIMBS>, const LIMBS: usize> SubAssign<&Self> for ConstMontyField<Mod, LIMBS> {
#[inline(always)]
fn sub_assign(&mut self, rhs: &Self) {
self.0.sub_assign(&rhs.0);
*self.0.as_montgomery_mut() = self
.0
.as_montgomery()
.sub_mod(rhs.0.as_montgomery(), Mod::PARAMS.modulus().as_nz_ref());
}
}

Expand Down
18 changes: 14 additions & 4 deletions src/field/crypto_bigint_monty.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -133,8 +133,12 @@ impl<const LIMBS: usize> Hash for MontyField<LIMBS> {
impl<const LIMBS: usize> Neg for MontyField<LIMBS> {
type Output = Self;

fn neg(self) -> Self::Output {
Self(self.0.neg())
fn neg(mut self) -> Self::Output {
*self.0.as_montgomery_mut() = self
.0
.as_montgomery()
.neg_mod(self.0.params().modulus().as_nz_ref());
self
}
}

Expand Down Expand Up @@ -243,14 +247,20 @@ impl_op_assign_boilerplate!(DivAssign, div_assign);
impl<const LIMBS: usize> AddAssign<&Self> for MontyField<LIMBS> {
#[inline(always)]
fn add_assign(&mut self, rhs: &Self) {
self.0.add_assign(&rhs.0);
*self.0.as_montgomery_mut() = self
.0
.as_montgomery()
.add_mod(rhs.0.as_montgomery(), self.0.params().modulus().as_nz_ref());
}
}

impl<const LIMBS: usize> SubAssign<&Self> for MontyField<LIMBS> {
#[inline(always)]
fn sub_assign(&mut self, rhs: &Self) {
self.0.sub_assign(&rhs.0);
*self.0.as_montgomery_mut() = self
.0
.as_montgomery()
.sub_mod(rhs.0.as_montgomery(), self.0.params().modulus().as_nz_ref());
}
}

Expand Down