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//! Big integers are represented as an array of smaller CPU word-size integers
//! called "limbs".
#![allow(clippy::derive_hash_xor_eq)]
mod add;
mod bit_and;
mod bit_not;
mod bit_or;
mod bit_xor;
mod bits;
mod cmp;
mod encoding;
mod from;
mod mul;
mod shl;
mod shr;
mod sub;
#[cfg(feature = "rand_core")]
mod rand;
use crate::Zero;
use core::fmt;
use subtle::{Choice, ConditionallySelectable};
#[cfg(feature = "serde")]
use serdect::serde::{Deserialize, Deserializer, Serialize, Serializer};
#[cfg(not(any(target_pointer_width = "32", target_pointer_width = "64")))]
compile_error!("this crate builds on 32-bit and 64-bit platforms only");
//
// 32-bit definitions
//
/// Inner integer type that the [`Limb`] newtype wraps.
#[cfg(target_pointer_width = "32")]
pub type Word = u32;
/// Signed integer type that corresponds to [`Word`].
#[cfg(target_pointer_width = "32")]
pub(crate) type SignedWord = i32;
/// Unsigned wide integer type: double the width of [`Word`].
#[cfg(target_pointer_width = "32")]
pub type WideWord = u64;
/// Signed wide integer type: double the width of [`Limb`].
#[cfg(target_pointer_width = "32")]
pub(crate) type WideSignedWord = i64;
//
// 64-bit definitions
//
/// Unsigned integer type that the [`Limb`] newtype wraps.
#[cfg(target_pointer_width = "64")]
pub type Word = u64;
/// Signed integer type that corresponds to [`Word`].
#[cfg(target_pointer_width = "64")]
pub(crate) type SignedWord = i64;
/// Wide integer type: double the width of [`Word`].
#[cfg(target_pointer_width = "64")]
pub type WideWord = u128;
/// Signed wide integer type: double the width of [`SignedWord`].
#[cfg(target_pointer_width = "64")]
pub(crate) type WideSignedWord = i128;
//
// Deprecated legacy names
//
// TODO(tarcieri): remove these in the next breaking release
/// Deprecated: unsigned integer type that the [`Limb`] newtype wraps.
#[deprecated(since = "0.4.8", note = "please use `Word` instead")]
pub type LimbUInt = Word;
/// Deprecated: wide integer type which is double the width of [`Word`].
#[deprecated(since = "0.4.8", note = "please use `WideWord` instead")]
pub type WideLimbUInt = WideWord;
/// Highest bit in a [`Limb`].
pub(crate) const HI_BIT: usize = Limb::BIT_SIZE - 1;
/// Big integers are represented as an array of smaller CPU word-size integers
/// called "limbs".
#[derive(Copy, Clone, Debug, Default, Hash)]
#[repr(transparent)]
pub struct Limb(pub Word);
impl Limb {
/// The value `0`.
pub const ZERO: Self = Limb(0);
/// The value `1`.
pub const ONE: Self = Limb(1);
/// Maximum value this [`Limb`] can express.
pub const MAX: Self = Limb(Word::MAX);
// 32-bit
/// Size of the inner integer in bits.
#[cfg(target_pointer_width = "32")]
pub const BIT_SIZE: usize = 32;
/// Size of the inner integer in bytes.
#[cfg(target_pointer_width = "32")]
pub const BYTE_SIZE: usize = 4;
// 64-bit
/// Size of the inner integer in bits.
#[cfg(target_pointer_width = "64")]
pub const BIT_SIZE: usize = 64;
/// Size of the inner integer in bytes.
#[cfg(target_pointer_width = "64")]
pub const BYTE_SIZE: usize = 8;
/// Return `a` if `c`==0 or `b` if `c`==`Word::MAX`.
///
/// Const-friendly: we can't yet use `subtle` in `const fn` contexts.
#[inline]
pub(crate) const fn ct_select(a: Self, b: Self, c: Word) -> Self {
Self(a.0 ^ (c & (a.0 ^ b.0)))
}
}
impl ConditionallySelectable for Limb {
#[inline]
fn conditional_select(a: &Self, b: &Self, choice: Choice) -> Self {
Self(Word::conditional_select(&a.0, &b.0, choice))
}
}
impl Zero for Limb {
const ZERO: Self = Self::ZERO;
}
impl fmt::Display for Limb {
#[inline]
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
fmt::UpperHex::fmt(self, f)
}
}
impl fmt::LowerHex for Limb {
#[inline]
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "{:0width$x}", &self.0, width = Self::BYTE_SIZE * 2)
}
}
impl fmt::UpperHex for Limb {
#[inline]
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "{:0width$X}", &self.0, width = Self::BYTE_SIZE * 2)
}
}
#[cfg(feature = "serde")]
#[cfg_attr(docsrs, doc(cfg(feature = "serde")))]
impl<'de> Deserialize<'de> for Limb {
fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
where
D: Deserializer<'de>,
{
Ok(Self(Word::deserialize(deserializer)?))
}
}
#[cfg(feature = "serde")]
#[cfg_attr(docsrs, doc(cfg(feature = "serde")))]
impl<'de> Serialize for Limb {
fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
where
S: Serializer,
{
self.0.serialize(serializer)
}
}
#[cfg(feature = "zeroize")]
#[cfg_attr(docsrs, doc(cfg(feature = "zeroize")))]
impl zeroize::DefaultIsZeroes for Limb {}
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