| // 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::{endian::*, polyfill}; |
| |
| /// An array of 16 bytes that can (in the x86_64 and AAarch64 ABIs, at least) |
| /// be efficiently passed by value and returned by value (i.e. in registers), |
| /// and which meets the alignment requirements of `u32` and `u64` (at least) |
| /// for the target. |
| #[repr(C)] |
| #[derive(Copy, Clone)] |
| pub struct Block { |
| subblocks: [u64; 2], |
| } |
| |
| pub const BLOCK_LEN: usize = 16; |
| |
| impl Block { |
| #[inline] |
| pub fn zero() -> Self { |
| Self { subblocks: [0, 0] } |
| } |
| |
| // TODO: Remove this. |
| #[inline] |
| pub fn from_u64_le(first: LittleEndian<u64>, second: LittleEndian<u64>) -> Self { |
| #[allow(deprecated)] |
| Self { |
| subblocks: [first.into_raw_value(), second.into_raw_value()], |
| } |
| } |
| |
| // TODO: Remove this. |
| #[inline] |
| pub fn from_u64_be(first: BigEndian<u64>, second: BigEndian<u64>) -> Self { |
| #[allow(deprecated)] |
| Self { |
| subblocks: [first.into_raw_value(), second.into_raw_value()], |
| } |
| } |
| |
| pub fn u64s_be_to_native(&self) -> [u64; 2] { |
| [ |
| u64::from_be(self.subblocks[0]), |
| u64::from_be(self.subblocks[1]), |
| ] |
| } |
| |
| #[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(); |
| polyfill::slice::fill(&mut tmp[index..], 0); |
| *self = Self::from(&tmp) |
| } |
| |
| #[inline] |
| pub fn bitxor_assign(&mut self, a: Block) { |
| for (r, a) in self.subblocks.iter_mut().zip(a.subblocks.iter()) { |
| *r ^= *a; |
| } |
| } |
| } |
| |
| impl From<&'_ [u8; BLOCK_LEN]> for Block { |
| #[inline] |
| fn from(bytes: &[u8; BLOCK_LEN]) -> Self { |
| unsafe { core::mem::transmute_copy(bytes) } |
| } |
| } |
| |
| impl AsRef<[u8; BLOCK_LEN]> for Block { |
| #[allow(clippy::transmute_ptr_to_ptr)] |
| #[inline] |
| fn as_ref(&self) -> &[u8; BLOCK_LEN] { |
| unsafe { core::mem::transmute(self) } |
| } |
| } |
| |
| #[cfg(test)] |
| mod tests { |
| use super::*; |
| |
| #[test] |
| fn test_bitxor_assign() { |
| const ONES: u64 = -1i64 as u64; |
| const TEST_CASES: &[([u64; 2], [u64; 2], [u64; 2])] = &[ |
| ([0, 0], [0, 0], [0, 0]), |
| ([0, 0], [ONES, ONES], [ONES, ONES]), |
| ([0, ONES], [ONES, 0], [ONES, ONES]), |
| ([ONES, 0], [0, ONES], [ONES, ONES]), |
| ([ONES, ONES], [ONES, ONES], [0, 0]), |
| ]; |
| for (expected_result, a, b) in TEST_CASES { |
| let mut r = Block::from_u64_le(a[0].into(), a[1].into()); |
| r.bitxor_assign(Block::from_u64_le(b[0].into(), b[1].into())); |
| assert_eq!(*expected_result, r.subblocks); |
| |
| // XOR is symmetric. |
| let mut r = Block::from_u64_le(b[0].into(), b[1].into()); |
| r.bitxor_assign(Block::from_u64_le(a[0].into(), a[1].into())); |
| assert_eq!(*expected_result, r.subblocks); |
| } |
| } |
| } |