Rename sh(r/l)1_with_overflow to *_with_carry

Author: fjarri

src/modular/div_by_2.rs

@@ -18,7 +18,7 @@ pub(crate) fn div_by_2<const LIMBS: usize>(a: &Uint<LIMBS>, modulus: &Uint<LIMBS
     // ("+1" because both `a` and `modulus` are odd, we lose 0.5 in each integer division).
     // This will not overflow, so we can just use wrapping operations.
 
-    let (half, is_odd) = a.shr1_with_overflow();
+    let (half, is_odd) = a.shr1_with_carry();
     let half_modulus = modulus.shr1();
 
     let if_even = half;

src/uint/boxed/inv_mod.rs

@@ -126,9 +126,9 @@ impl BoxedUint {
             let cyy = new_u.conditional_adc_assign(modulus, cy);
             debug_assert!(bool::from(cy.ct_eq(&cyy)));
 
-            let (new_a, overflow) = a.shr1_with_overflow();
-            debug_assert!(bool::from(!modulus_is_odd | !overflow));
-            let (mut new_u, cy) = new_u.shr1_with_overflow();
+            let (new_a, carry) = a.shr1_with_carry();
+            debug_assert!(bool::from(!modulus_is_odd | !carry));
+            let (mut new_u, cy) = new_u.shr1_with_carry();
             let cy = new_u.conditional_adc_assign(&m1hp, cy);
             debug_assert!(bool::from(!modulus_is_odd | !cy));
 

src/uint/boxed/shr.rs

@@ -85,9 +85,9 @@ impl BoxedUint {
         success.map(|_| result)
     }
 
-    /// Computes `self >> 1` in constant-time, returning a true [`Choice`] if the overflowing bit
-    /// was set, and a false [`Choice::FALSE`] otherwise.
-    pub(crate) fn shr1_with_overflow(&self) -> (Self, Choice) {
+    /// Computes `self >> 1` in constant-time, returning a true [`Choice`]
+    /// if the least significant bit was set, and a false [`Choice::FALSE`] otherwise.
+    pub(crate) fn shr1_with_carry(&self) -> (Self, Choice) {
         let carry = self.limbs[0].0 & 1;
         (self.shr1(), Choice::from(carry as u8))
     }

src/uint/inv_mod.rs

@@ -128,9 +128,9 @@ impl<const LIMBS: usize> Uint<LIMBS> {
             let (new_u, cyy) = new_u.conditional_wrapping_add(modulus, cy);
             debug_assert!(cy.is_true_vartime() == cyy.is_true_vartime());
 
-            let (new_a, overflow) = a.shr1_with_overflow();
-            debug_assert!(modulus_is_odd.not().or(overflow.not()).is_true_vartime());
-            let (new_u, cy) = new_u.shr1_with_overflow();
+            let (new_a, carry) = a.shr1_with_carry();
+            debug_assert!(modulus_is_odd.not().or(carry.not()).is_true_vartime());
+            let (new_u, cy) = new_u.shr1_with_carry();
             let (new_u, cy) = new_u.conditional_wrapping_add(&m1hp, cy);
             debug_assert!(modulus_is_odd.not().or(cy.not()).is_true_vartime());
 

src/uint/shl.rs

@@ -118,10 +118,10 @@ impl<const LIMBS: usize> Uint<LIMBS> {
         (Uint::<LIMBS>::new(limbs), Limb(carry))
     }
 
-    /// Computes `self << 1` in constant-time, returning [`CtChoice::TRUE`] if the overflowing bit
-    /// was set, and [`CtChoice::FALSE`] otherwise.
+    /// Computes `self << 1` in constant-time, returning [`CtChoice::TRUE`]
+    /// if the most significant bit was set, and [`CtChoice::FALSE`] otherwise.
     #[inline(always)]
-    pub(crate) const fn shl1_with_overflow(&self) -> (Self, CtChoice) {
+    pub(crate) const fn shl1_with_carry(&self) -> (Self, CtChoice) {
         let mut ret = Self::ZERO;
         let mut i = 0;
         let mut carry = Limb::ZERO;
@@ -138,7 +138,7 @@ impl<const LIMBS: usize> Uint<LIMBS> {
     /// Computes `self << 1` in constant-time.
     pub(crate) const fn shl1(&self) -> Self {
         // TODO(tarcieri): optimized implementation
-        self.shl1_with_overflow().0
+        self.shl1_with_carry().0
     }
 }
 

src/uint/shr.rs

@@ -93,10 +93,10 @@ impl<const LIMBS: usize> Uint<LIMBS> {
         }
     }
 
-    /// Computes `self >> 1` in constant-time, returning [`CtChoice::TRUE`] if the overflowing bit
-    /// was set, and [`CtChoice::FALSE`] otherwise.
+    /// Computes `self >> 1` in constant-time, returning [`CtChoice::TRUE`]
+    /// if the least significant bit was set, and [`CtChoice::FALSE`] otherwise.
     #[inline(always)]
-    pub(crate) const fn shr1_with_overflow(&self) -> (Self, CtChoice) {
+    pub(crate) const fn shr1_with_carry(&self) -> (Self, CtChoice) {
         let mut ret = Self::ZERO;
         let mut i = LIMBS;
         let mut carry = Limb::ZERO;
@@ -113,7 +113,7 @@ impl<const LIMBS: usize> Uint<LIMBS> {
     /// Computes `self >> 1` in constant-time.
     pub(crate) const fn shr1(&self) -> Self {
         // TODO(tarcieri): optimized implementation
-        self.shr1_with_overflow().0
+        self.shr1_with_carry().0
     }
 }