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//! Wrapping arithmetic.

use crate::Zero;
use core::fmt;
use subtle::{Choice, ConditionallySelectable, ConstantTimeEq};

/// Provides intentionally-wrapped arithmetic on `T`.
///
/// This is analogous to [`core::num::Wrapping`] but allows this crate to
/// define trait impls for this type.
#[derive(Copy, Clone, Debug, Default, Eq, PartialEq, PartialOrd, Ord)]
pub struct Wrapping<T>(pub T);

impl<T: Zero> Zero for Wrapping<T> {
    const ZERO: Self = Self(T::ZERO);
}

impl<T: fmt::Display> fmt::Display for Wrapping<T> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        self.0.fmt(f)
    }
}

impl<T: fmt::Binary> fmt::Binary for Wrapping<T> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        self.0.fmt(f)
    }
}

impl<T: fmt::Octal> fmt::Octal for Wrapping<T> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        self.0.fmt(f)
    }
}

impl<T: fmt::LowerHex> fmt::LowerHex for Wrapping<T> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        self.0.fmt(f)
    }
}

impl<T: fmt::UpperHex> fmt::UpperHex for Wrapping<T> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        self.0.fmt(f)
    }
}

impl<T: ConditionallySelectable> ConditionallySelectable for Wrapping<T> {
    fn conditional_select(a: &Self, b: &Self, choice: Choice) -> Self {
        Wrapping(T::conditional_select(&a.0, &b.0, choice))
    }
}

impl<T: ConstantTimeEq> ConstantTimeEq for Wrapping<T> {
    fn ct_eq(&self, other: &Self) -> Choice {
        self.0.ct_eq(&other.0)
    }
}