Files
cryptonum/src/unsigned/codec.rs

90 lines
2.2 KiB
Rust

/// Conversion from bytes into the numeric type.
pub trait Decoder {
fn from_bytes(x: &[u8]) -> Self;
}
/// Conversion from the numeric types into a byte buffer.
pub trait Encoder {
fn to_bytes(&self) -> Vec<u8>;
}
pub(crate) fn raw_decoder(input: &[u8], output: &mut [u64])
{
let mut item = 0;
let mut shift = 0;
let mut idx = 0;
for v in input.iter().rev() {
item |= (*v as u64) << shift;
shift += 8;
if shift == 64 {
shift = 0;
output[idx] = item;
idx += 1;
item = 0;
}
}
if item != 0 {
output[idx] = item;
}
}
macro_rules! generate_decoder {
($name: ident) => {
impl Decoder for $name {
fn from_bytes(x: &[u8]) -> $name {
let mut res = $name::zero();
raw_decoder(x, &mut res.value);
res
}
}
}
}
macro_rules! generate_encoder {
($name: ident) => {
impl Encoder for $name {
fn to_bytes(&self) -> Vec<u8> {
let mut res = Vec::with_capacity(self.value.len() * 8);
for v in self.value.iter().rev() {
let val = *v;
res.push( (val >> 56) as u8);
res.push( (val >> 48) as u8);
res.push( (val >> 40) as u8);
res.push( (val >> 32) as u8);
res.push( (val >> 24) as u8);
res.push( (val >> 16) as u8);
res.push( (val >> 8) as u8);
res.push( (val >> 0) as u8);
}
res
}
}
}
}
macro_rules! generate_codec
{
($name: ident) => {
generate_decoder!($name);
generate_encoder!($name);
}
}
#[cfg(test)]
macro_rules! generate_codec_tests {
($name: ident, $lname: ident) => {
#[cfg(test)]
mod $lname {
use super::super::super::*;
quickcheck! {
fn decode_encode(x: $name) -> bool {
let bytes = x.to_bytes();
let x2 = $name::from_bytes(&bytes);
x == x2
}
}
}
};
}