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use crate::{
arch::word::Word,
buffer::Buffer,
div,
ibig::IBig,
memory::MemoryAllocation,
modular::{
modulo::{Modulo, ModuloLarge, ModuloRepr, ModuloSmall},
modulo_ring::{ModuloRing, ModuloRingLarge, ModuloRingRepr, ModuloRingSmall},
},
primitive::extend_word,
shift,
sign::Sign::*,
ubig::{Repr, UBig},
};
use alloc::vec::Vec;
use core::iter;
impl ModuloRing {
pub fn modulus(&self) -> UBig {
match self.repr() {
ModuloRingRepr::Small(self_small) => UBig::from_word(self_small.modulus()),
ModuloRingRepr::Large(self_large) => self_large.modulus(),
}
}
pub fn from<T: IntoModulo>(&self, x: T) -> Modulo {
x.into_modulo(self)
}
}
impl ModuloRingSmall {
pub(crate) fn modulus(&self) -> Word {
self.normalized_modulus() >> self.shift()
}
}
impl ModuloRingLarge {
pub(crate) fn modulus(&self) -> UBig {
let normalized_modulus = self.normalized_modulus();
let mut buffer = Buffer::allocate(normalized_modulus.len());
buffer.extend(normalized_modulus);
let low_bits = shift::shr_in_place(&mut buffer, self.shift());
assert!(low_bits == 0);
buffer.into()
}
}
impl Modulo<'_> {
pub fn residue(&self) -> UBig {
match self.repr() {
ModuloRepr::Small(self_small) => UBig::from_word(self_small.residue()),
ModuloRepr::Large(self_large) => self_large.residue(),
}
}
}
impl ModuloSmall<'_> {
pub(crate) fn residue(&self) -> Word {
self.normalized_value() >> self.ring().shift()
}
}
impl ModuloLarge<'_> {
pub(crate) fn residue(&self) -> UBig {
let words = self.normalized_value();
let mut buffer = Buffer::allocate(words.len());
buffer.extend(words);
let low_bits = shift::shr_in_place(&mut buffer, self.ring().shift());
assert!(low_bits == 0);
buffer.into()
}
}
pub trait IntoModulo {
fn into_modulo(self, ring: &ModuloRing) -> Modulo;
}
impl IntoModulo for UBig {
fn into_modulo(self, ring: &ModuloRing) -> Modulo {
match ring.repr() {
ModuloRingRepr::Small(ring_small) => ModuloSmall::from_ubig(&self, ring_small).into(),
ModuloRingRepr::Large(ring_large) => ModuloLarge::from_ubig(self, ring_large).into(),
}
}
}
impl IntoModulo for &UBig {
fn into_modulo(self, ring: &ModuloRing) -> Modulo {
match ring.repr() {
ModuloRingRepr::Small(ring_small) => ModuloSmall::from_ubig(self, ring_small).into(),
ModuloRingRepr::Large(ring_large) => {
ModuloLarge::from_ubig(self.clone(), ring_large).into()
}
}
}
}
impl IntoModulo for IBig {
fn into_modulo(self, ring: &ModuloRing) -> Modulo {
let (sign, mag) = self.into_sign_magnitude();
let modulo = mag.into_modulo(ring);
match sign {
Positive => modulo,
Negative => -modulo,
}
}
}
impl IntoModulo for &IBig {
fn into_modulo(self, ring: &ModuloRing) -> Modulo {
let modulo = self.magnitude().into_modulo(ring);
match self.sign() {
Positive => modulo,
Negative => -modulo,
}
}
}
impl<'a> ModuloSmall<'a> {
pub(crate) fn from_ubig(x: &UBig, ring: &'a ModuloRingSmall) -> ModuloSmall<'a> {
let rem = match x.repr() {
Repr::Small(word) => ring.fast_div().div_rem_word(*word).1,
Repr::Large(words) => div::fast_rem_by_normalized_word(words, *ring.fast_div()),
};
let (_, rem) = ring.fast_div().div_rem(extend_word(rem) << ring.shift());
ModuloSmall::new(rem, ring)
}
}
impl<'a> ModuloLarge<'a> {
pub(crate) fn from_ubig(mut x: UBig, ring: &'a ModuloRingLarge) -> ModuloLarge<'a> {
x <<= ring.shift() as usize;
let modulus = ring.normalized_modulus();
let mut vec = Vec::with_capacity(modulus.len());
match x.into_repr() {
Repr::Small(word) => vec.push(word),
Repr::Large(mut words) => {
if words.len() < modulus.len() {
vec.extend(&*words);
} else {
let mut allocation = MemoryAllocation::new(div::memory_requirement_exact(
words.len(),
modulus.len(),
));
let mut memory = allocation.memory();
let _overflow = div::div_rem_in_place(
&mut words,
modulus,
*ring.fast_div_top(),
&mut memory,
);
vec.extend(&words[..modulus.len()]);
}
}
}
vec.extend(iter::repeat(0).take(modulus.len() - vec.len()));
ModuloLarge::new(vec, ring)
}
}
macro_rules! impl_into_modulo_for_unsigned {
($t:ty) => {
impl IntoModulo for $t {
fn into_modulo<'a>(self, ring: &'a ModuloRing) -> Modulo<'a> {
UBig::from(self).into_modulo(ring)
}
}
};
}
macro_rules! impl_into_modulo_for_signed {
($t:ty) => {
impl IntoModulo for $t {
fn into_modulo<'a>(self, ring: &'a ModuloRing) -> Modulo<'a> {
IBig::from(self).into_modulo(ring)
}
}
};
}
impl_into_modulo_for_unsigned!(bool);
impl_into_modulo_for_unsigned!(u8);
impl_into_modulo_for_unsigned!(u16);
impl_into_modulo_for_unsigned!(u32);
impl_into_modulo_for_unsigned!(u64);
impl_into_modulo_for_unsigned!(u128);
impl_into_modulo_for_unsigned!(usize);
impl_into_modulo_for_signed!(i8);
impl_into_modulo_for_signed!(i16);
impl_into_modulo_for_signed!(i32);
impl_into_modulo_for_signed!(i64);
impl_into_modulo_for_signed!(i128);
impl_into_modulo_for_signed!(isize);