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// Copyright 2018 Brian Smith.
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice appear in all copies.
//
// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHORS DISCLAIM ALL WARRANTIES
// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
// SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
// OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
// CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
use crate::polyfill::ArrayFlatten;
use core::ops::{BitXor, BitXorAssign};
#[repr(transparent)]
#[derive(Copy, Clone)]
pub struct Block([u8; 16]);
pub const BLOCK_LEN: usize = 16;
impl Block {
#[inline]
pub fn zero() -> Self {
Self([0; 16])
}
#[inline]
pub fn overwrite_part_at(&mut self, index: usize, a: &[u8]) {
let mut tmp: [u8; BLOCK_LEN] = *self.as_ref();
tmp[index..][..a.len()].copy_from_slice(a);
*self = Self::from(&tmp)
}
#[inline]
pub fn zero_from(&mut self, index: usize) {
let mut tmp: [u8; BLOCK_LEN] = *self.as_ref();
tmp[index..].fill(0);
*self = Self::from(&tmp)
}
}
impl BitXorAssign for Block {
#[inline]
fn bitxor_assign(&mut self, a: Self) {
// Relies heavily on optimizer to optimize this into word- or vector-
// level XOR.
for (r, a) in self.0.iter_mut().zip(a.0.iter()) {
*r ^= *a;
}
}
}
impl BitXor for Block {
type Output = Self;
#[inline]
fn bitxor(self, a: Self) -> Self {
let mut r = self;
r.bitxor_assign(a);
r
}
}
impl<T> From<T> for Block
where
T: ArrayFlatten<Output = [u8; 16]>,
{
#[inline]
fn from(bytes: T) -> Self {
Self(bytes.array_flatten())
}
}
impl From<&'_ [u8; BLOCK_LEN]> for Block {
#[inline]
fn from(bytes: &[u8; BLOCK_LEN]) -> Self {
Self(*bytes)
}
}
impl AsRef<[u8; BLOCK_LEN]> for Block {
#[inline]
fn as_ref(&self) -> &[u8; BLOCK_LEN] {
&self.0
}
}