blob: 2e5cf09727848b61bf67df4449b2e39162abb144 [file] [log] [blame]
// 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 super::block::{Block, BLOCK_LEN};
use crate::polyfill::convert::*;
pub fn shift_full_blocks<F>(in_out: &mut [u8], in_prefix_len: usize, mut transform: F)
where
F: FnMut(&[u8; BLOCK_LEN]) -> Block,
{
let in_out_len = in_out.len().checked_sub(in_prefix_len).unwrap();
for i in (0..in_out_len).step_by(BLOCK_LEN) {
let block = {
let input =
<&[u8; BLOCK_LEN]>::try_from_(&in_out[(in_prefix_len + i)..][..BLOCK_LEN]).unwrap();
transform(input)
};
let output = <&mut [u8; BLOCK_LEN]>::try_from_(&mut in_out[i..][..BLOCK_LEN]).unwrap();
*output = *block.as_ref();
}
}
pub fn shift_partial<F>((in_prefix_len, in_out): (usize, &mut [u8]), transform: F)
where
F: FnOnce(&[u8]) -> Block,
{
let (block, in_out_len) = {
let input = &in_out[in_prefix_len..];
let in_out_len = input.len();
if in_out_len == 0 {
return;
}
debug_assert!(in_out_len < BLOCK_LEN);
(transform(input), in_out_len)
};
in_out[..in_out_len].copy_from_slice(&block.as_ref()[..in_out_len]);
}