BoxedUint: impl BitAnd* (#314)

Author: tarcieri

src/boxed/uint.rs

@@ -1,6 +1,7 @@
 //! Heap-allocated big unsigned integers.
 
 mod add;
+mod bit_and;
 mod cmp;
 pub(crate) mod encoding;
 mod mul;

src/boxed/uint/bit_and.rs

@@ -0,0 +1,138 @@
+//! [`BoxedUint`] bitwise AND operations.
+
+use super::BoxedUint;
+use crate::{Limb, Wrapping};
+use core::ops::{BitAnd, BitAndAssign};
+use subtle::{Choice, CtOption};
+
+impl BoxedUint {
+    /// Computes bitwise `a & b`.
+    #[inline(always)]
+    pub fn bitand(&self, rhs: &Self) -> Self {
+        Self::chain(self, rhs, Limb::ZERO, |a, b, z| (a.bitand(b), z)).0
+    }
+
+    /// Perform wrapping bitwise `AND`.
+    ///
+    /// There's no way wrapping could ever happen.
+    /// This function exists so that all operations are accounted for in the wrapping operations
+    pub fn wrapping_and(&self, rhs: &Self) -> Self {
+        self.bitand(rhs)
+    }
+
+    /// Perform checked bitwise `AND`, returning a [`CtOption`] which `is_some` always
+    pub fn checked_and(&self, rhs: &Self) -> CtOption<Self> {
+        let result = self.bitand(rhs);
+        CtOption::new(result, Choice::from(1))
+    }
+}
+
+impl BitAnd for BoxedUint {
+    type Output = Self;
+
+    fn bitand(self, rhs: Self) -> BoxedUint {
+        self.bitand(&rhs)
+    }
+}
+
+impl BitAnd<&BoxedUint> for BoxedUint {
+    type Output = BoxedUint;
+
+    #[allow(clippy::needless_borrow)]
+    fn bitand(self, rhs: &BoxedUint) -> BoxedUint {
+        (&self).bitand(rhs)
+    }
+}
+
+impl BitAnd<BoxedUint> for &BoxedUint {
+    type Output = BoxedUint;
+
+    fn bitand(self, rhs: BoxedUint) -> BoxedUint {
+        self.bitand(&rhs)
+    }
+}
+
+impl BitAnd<&BoxedUint> for &BoxedUint {
+    type Output = BoxedUint;
+
+    fn bitand(self, rhs: &BoxedUint) -> BoxedUint {
+        self.bitand(rhs)
+    }
+}
+
+impl BitAndAssign for BoxedUint {
+    #[allow(clippy::assign_op_pattern)]
+    fn bitand_assign(&mut self, other: Self) {
+        *self = BoxedUint::bitand(self, &other);
+    }
+}
+
+impl BitAndAssign<&BoxedUint> for BoxedUint {
+    #[allow(clippy::assign_op_pattern)]
+    fn bitand_assign(&mut self, other: &Self) {
+        *self = BoxedUint::bitand(self, other);
+    }
+}
+
+impl BitAnd for Wrapping<BoxedUint> {
+    type Output = Self;
+
+    fn bitand(self, rhs: Self) -> Wrapping<BoxedUint> {
+        Wrapping(self.0.bitand(&rhs.0))
+    }
+}
+
+impl BitAnd<&Wrapping<BoxedUint>> for Wrapping<BoxedUint> {
+    type Output = Wrapping<BoxedUint>;
+
+    fn bitand(self, rhs: &Wrapping<BoxedUint>) -> Wrapping<BoxedUint> {
+        Wrapping(self.0.bitand(&rhs.0))
+    }
+}
+
+impl BitAnd<Wrapping<BoxedUint>> for &Wrapping<BoxedUint> {
+    type Output = Wrapping<BoxedUint>;
+
+    fn bitand(self, rhs: Wrapping<BoxedUint>) -> Wrapping<BoxedUint> {
+        Wrapping(BoxedUint::bitand(&self.0, &rhs.0))
+    }
+}
+
+impl BitAnd<&Wrapping<BoxedUint>> for &Wrapping<BoxedUint> {
+    type Output = Wrapping<BoxedUint>;
+
+    fn bitand(self, rhs: &Wrapping<BoxedUint>) -> Wrapping<BoxedUint> {
+        Wrapping(BoxedUint::bitand(&self.0, &rhs.0))
+    }
+}
+
+impl BitAndAssign for Wrapping<BoxedUint> {
+    #[allow(clippy::assign_op_pattern)]
+    fn bitand_assign(&mut self, other: Self) {
+        *self = Wrapping(BoxedUint::bitand(&self.0, &other.0))
+    }
+}
+
+impl BitAndAssign<&Wrapping<BoxedUint>> for Wrapping<BoxedUint> {
+    #[allow(clippy::assign_op_pattern)]
+    fn bitand_assign(&mut self, other: &Self) {
+        *self = Wrapping(BoxedUint::bitand(&self.0, &other.0))
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::BoxedUint;
+
+    #[test]
+    fn checked_and_ok() {
+        let result = BoxedUint::zero().checked_and(&BoxedUint::one());
+        assert_eq!(result.unwrap(), BoxedUint::zero());
+    }
+
+    #[test]
+    fn overlapping_and_ok() {
+        let result = BoxedUint::max(128).unwrap().wrapping_and(&BoxedUint::one());
+        assert_eq!(result, BoxedUint::one());
+    }
+}

src/uint/bit_and.rs

@@ -1,4 +1,4 @@
-//! [`Uint`] bitwise and operations.
+//! [`Uint`] bitwise AND operations.
 
 use super::Uint;
 use crate::{Limb, Wrapping};

src/uint/bit_not.rs

@@ -1,4 +1,4 @@
-//! [`Uint`] bitwise not operations.
+//! [`Uint`] bitwise NOT operations.
 
 use super::Uint;
 use crate::{Limb, Wrapping};

src/uint/bit_or.rs

@@ -1,4 +1,4 @@
-//! [`Uint`] bitwise or operations.
+//! [`Uint`] bitwise OR operations.
 
 use super::Uint;
 use crate::{Limb, Wrapping};

src/uint/bit_xor.rs

@@ -1,4 +1,4 @@
-//! [`Uint`] bitwise xor operations.
+//! [`Uint`] bitwise XOR operations.
 
 use super::Uint;
 use crate::{Limb, Wrapping};