Adding upstream version 0.70.1+ds1.upstream/0.70.1+ds1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 182 insertions, 0 deletions

diff --git a/vendor/crypto-bigint/src/limb/sub.rs b/vendor/crypto-bigint/src/limb/sub.rs
new file mode 100644
index 0000000..0fc7a4a
--- /dev/null
+++ b/vendor/crypto-bigint/src/limb/sub.rs
@@ -0,0 +1,182 @@
+//! Limb subtraction
+
+use crate::{Checked, CheckedSub, Limb, WideWord, Word, Wrapping, Zero};
+use core::ops::{Sub, SubAssign};
+use subtle::CtOption;
+
+impl Limb {
+    /// Computes `self - (rhs + borrow)`, returning the result along with the new borrow.
+    #[inline(always)]
+    pub const fn sbb(self, rhs: Limb, borrow: Limb) -> (Limb, Limb) {
+        let a = self.0 as WideWord;
+        let b = rhs.0 as WideWord;
+        let borrow = (borrow.0 >> (Self::BITS - 1)) as WideWord;
+        let ret = a.wrapping_sub(b + borrow);
+        (Limb(ret as Word), Limb((ret >> Self::BITS) as Word))
+    }
+
+    /// Perform saturating subtraction.
+    #[inline]
+    pub const fn saturating_sub(&self, rhs: Self) -> Self {
+        Limb(self.0.saturating_sub(rhs.0))
+    }
+
+    /// Perform wrapping subtraction, discarding underflow and wrapping around
+    /// the boundary of the type.
+    #[inline(always)]
+    pub const fn wrapping_sub(&self, rhs: Self) -> Self {
+        Limb(self.0.wrapping_sub(rhs.0))
+    }
+}
+
+impl CheckedSub for Limb {
+    type Output = Self;
+
+    #[inline]
+    fn checked_sub(&self, rhs: Self) -> CtOption<Self> {
+        let (result, underflow) = self.sbb(rhs, Limb::ZERO);
+        CtOption::new(result, underflow.is_zero())
+    }
+}
+
+impl Sub for Wrapping<Limb> {
+    type Output = Self;
+
+    fn sub(self, rhs: Self) -> Wrapping<Limb> {
+        Wrapping(self.0.wrapping_sub(rhs.0))
+    }
+}
+
+impl Sub<&Wrapping<Limb>> for Wrapping<Limb> {
+    type Output = Wrapping<Limb>;
+
+    fn sub(self, rhs: &Wrapping<Limb>) -> Wrapping<Limb> {
+        Wrapping(self.0.wrapping_sub(rhs.0))
+    }
+}
+
+impl Sub<Wrapping<Limb>> for &Wrapping<Limb> {
+    type Output = Wrapping<Limb>;
+
+    fn sub(self, rhs: Wrapping<Limb>) -> Wrapping<Limb> {
+        Wrapping(self.0.wrapping_sub(rhs.0))
+    }
+}
+
+impl Sub<&Wrapping<Limb>> for &Wrapping<Limb> {
+    type Output = Wrapping<Limb>;
+
+    fn sub(self, rhs: &Wrapping<Limb>) -> Wrapping<Limb> {
+        Wrapping(self.0.wrapping_sub(rhs.0))
+    }
+}
+
+impl SubAssign for Wrapping<Limb> {
+    fn sub_assign(&mut self, other: Self) {
+        *self = *self - other;
+    }
+}
+
+impl SubAssign<&Wrapping<Limb>> for Wrapping<Limb> {
+    fn sub_assign(&mut self, other: &Self) {
+        *self = *self - other;
+    }
+}
+
+impl Sub for Checked<Limb> {
+    type Output = Self;
+
+    fn sub(self, rhs: Self) -> Checked<Limb> {
+        Checked(
+            self.0
+                .and_then(|lhs| rhs.0.and_then(|rhs| lhs.checked_sub(rhs))),
+        )
+    }
+}
+
+impl Sub<&Checked<Limb>> for Checked<Limb> {
+    type Output = Checked<Limb>;
+
+    fn sub(self, rhs: &Checked<Limb>) -> Checked<Limb> {
+        Checked(
+            self.0
+                .and_then(|lhs| rhs.0.and_then(|rhs| lhs.checked_sub(rhs))),
+        )
+    }
+}
+
+impl Sub<Checked<Limb>> for &Checked<Limb> {
+    type Output = Checked<Limb>;
+
+    fn sub(self, rhs: Checked<Limb>) -> Checked<Limb> {
+        Checked(
+            self.0
+                .and_then(|lhs| rhs.0.and_then(|rhs| lhs.checked_sub(rhs))),
+        )
+    }
+}
+
+impl Sub<&Checked<Limb>> for &Checked<Limb> {
+    type Output = Checked<Limb>;
+
+    fn sub(self, rhs: &Checked<Limb>) -> Checked<Limb> {
+        Checked(
+            self.0
+                .and_then(|lhs| rhs.0.and_then(|rhs| lhs.checked_sub(rhs))),
+        )
+    }
+}
+
+impl SubAssign for Checked<Limb> {
+    fn sub_assign(&mut self, other: Self) {
+        *self = *self - other;
+    }
+}
+
+impl SubAssign<&Checked<Limb>> for Checked<Limb> {
+    fn sub_assign(&mut self, other: &Self) {
+        *self = *self - other;
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::{CheckedSub, Limb};
+
+    #[test]
+    fn sbb_no_borrow() {
+        let (res, borrow) = Limb::ONE.sbb(Limb::ONE, Limb::ZERO);
+        assert_eq!(res, Limb::ZERO);
+        assert_eq!(borrow, Limb::ZERO);
+    }
+
+    #[test]
+    fn sbb_with_borrow() {
+        let (res, borrow) = Limb::ZERO.sbb(Limb::ONE, Limb::ZERO);
+
+        assert_eq!(res, Limb::MAX);
+        assert_eq!(borrow, Limb::MAX);
+    }
+
+    #[test]
+    fn wrapping_sub_no_borrow() {
+        assert_eq!(Limb::ONE.wrapping_sub(Limb::ONE), Limb::ZERO);
+    }
+
+    #[test]
+    fn wrapping_sub_with_borrow() {
+        assert_eq!(Limb::ZERO.wrapping_sub(Limb::ONE), Limb::MAX);
+    }
+
+    #[test]
+    fn checked_sub_ok() {
+        let result = Limb::ONE.checked_sub(Limb::ONE);
+        assert_eq!(result.unwrap(), Limb::ZERO);
+    }
+
+    #[test]
+    fn checked_sub_overflow() {
+        let result = Limb::ZERO.checked_sub(Limb::ONE);
+        assert!(!bool::from(result.is_some()));
+    }
+}