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use super::block::Block;
pub struct BlockAccessor<'a> {
data: &'a mut [u8],
m_uv_len: usize,
m_u_len: usize,
m_v_len: usize,
num_block_pairs: usize,
}
impl<'a> BlockAccessor<'a> {
pub fn new(message: &'a mut [u8]) -> Self {
let num_block_pairs = (message.len() - 16 - 16) / 32;
let m_uv_len = (message.len() % 32) * 8;
Self {
data: message,
m_uv_len,
m_u_len: 128.min(m_uv_len),
m_v_len: m_uv_len.saturating_sub(128),
num_block_pairs,
}
}
pub fn m_uv_len(&self) -> usize {
self.m_uv_len
}
fn suffix_start(&self) -> usize {
self.num_block_pairs * 32
}
pub fn m_u(&self) -> Block {
let start = self.suffix_start();
Block::from_slice(&self.data[start..start + self.m_u_len / 8])
}
pub fn set_m_u(&mut self, m_u: Block) {
let start = self.suffix_start();
self.data[start..start + self.m_u_len / 8]
.copy_from_slice(&m_u.bytes()[..self.m_u_len / 8]);
}
pub fn m_v(&self) -> Block {
let start = self.suffix_start();
Block::from_slice(&self.data[start + self.m_u_len / 8..start + self.m_uv_len / 8])
}
pub fn set_m_v(&mut self, m_v: Block) {
let start = self.suffix_start();
self.data[start + self.m_u_len / 8..start + self.m_uv_len / 8]
.copy_from_slice(&m_v.bytes()[..self.m_v_len / 8]);
}
pub fn m_x(&self) -> Block {
let start = self.suffix_start() + self.m_uv_len / 8;
Block::from_slice(&self.data[start..start + 16])
}
pub fn set_m_x(&mut self, m_x: Block) {
let start = self.suffix_start() + self.m_uv_len / 8;
self.data[start..start + 16].copy_from_slice(&m_x.bytes());
}
pub fn m_y(&self) -> Block {
let start = self.suffix_start() + self.m_uv_len / 8;
Block::from_slice(&self.data[start + 16..start + 32])
}
pub fn set_m_y(&mut self, m_y: Block) {
let start = self.suffix_start() + self.m_uv_len / 8;
self.data[start + 16..start + 32].copy_from_slice(&m_y.bytes());
}
pub fn pairs_mut<'b>(
&'b mut self,
) -> impl Iterator<Item = (&'b mut [u8; 16], &'b mut [u8; 16])> {
let stop = self.suffix_start();
self.data[..stop]
.chunks_exact_mut(32)
.map(move |x| x.split_at_mut(16))
.map(move |(x, y)| (x.try_into().unwrap(), y.try_into().unwrap()))
}
}
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