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extern crate generic_array;
extern crate typenum;
use std::cmp;
use std::ptr;
use std::fmt;
use generic_array::{ArrayLength, GenericArray};
use typenum::uint::Unsigned;
use typenum::consts::{U64, U128};
pub trait FixedBuf {
fn input<F: FnMut(&[u8])>(&mut self, input: &[u8], func: F);
fn reset(&mut self);
fn zero_until(&mut self, idx: usize);
fn next(&mut self, len: usize) -> &mut [u8];
fn full_buffer(&mut self) -> &mut [u8];
fn current_buffer(&self) -> &[u8];
fn position(&self) -> usize;
fn remaining(&self) -> usize;
fn size() -> usize;
}
pub struct FixedBuffer<N: ArrayLength<u8>> {
buffer: GenericArray<u8, N>,
position: usize,
}
pub type FixedBuffer64 = FixedBuffer<U64>;
pub type FixedBuffer128 = FixedBuffer<U128>;
impl<N: ArrayLength<u8>> FixedBuffer<N> {
pub fn new() -> Self {
FixedBuffer {
buffer: GenericArray::new(),
position: 0,
}
}
fn fill(&mut self, data: &[u8]) -> bool {
assert!(self.position + data.len() <= Self::size());
let start = self.position;
self.position += data.len();
unsafe {
ptr::copy_nonoverlapping(data.as_ptr(), self.buffer[start..].as_mut_ptr(), data.len());
}
self.position == Self::size()
}
}
impl<N: ArrayLength<u8>> FixedBuf for FixedBuffer<N> {
fn input<F: FnMut(&[u8])>(&mut self, input: &[u8], mut func: F) {
let len = input.len();
let remaining = cmp::min(self.remaining(), len);
if !self.fill(&input[..remaining]) {
return;
}
func(&self.buffer);
self.position = 0;
let will_remain = len - ((len - remaining) % Self::size());
for chunk in input[remaining..will_remain].chunks(Self::size()) {
func(&chunk)
}
self.fill(&input[will_remain..]);
}
fn reset(&mut self) {
self.position = 0;
}
fn zero_until(&mut self, idx: usize) {
assert!(idx >= self.position);
for b in &mut self.buffer[self.position..idx] {
*b = 0
}
self.position = idx;
}
fn next(&mut self, len: usize) -> &mut [u8] {
self.position += len;
&mut self.buffer[self.position - len..self.position]
}
fn full_buffer(&mut self) -> &mut [u8] {
assert!(self.position == Self::size());
self.position = 0;
&mut self.buffer[..]
}
fn current_buffer(&self) -> &[u8] {
&self.buffer[..self.position]
}
fn position(&self) -> usize {
self.position
}
fn remaining(&self) -> usize {
Self::size() - self.position
}
fn size() -> usize {
<N as Unsigned>::to_usize()
}
}
impl<N: ArrayLength<u8>> Clone for FixedBuffer<N> {
fn clone(&self) -> Self {
FixedBuffer {
buffer: GenericArray::from_slice(&self.buffer),
position: self.position,
}
}
}
impl<N: ArrayLength<u8>> fmt::Debug for FixedBuffer<N> {
fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
write!(f, "{:?}", &self.buffer[..self.position])
}
}
pub trait StandardPadding {
fn pad<F: FnMut(&[u8])>(&mut self, padding: u8, rem: usize, func: F);
fn standard_padding<F: FnMut(&[u8])>(&mut self, rem: usize, func: F) {
self.pad(0b10000000, rem, func)
}
}
impl<T: FixedBuf> StandardPadding for T {
fn pad<F: FnMut(&[u8])>(&mut self, padding: u8, rem: usize, mut func: F) {
let size = T::size();
self.next(1)[0] = padding;
if self.remaining() < rem {
self.zero_until(size);
func(self.full_buffer());
}
self.zero_until(size - rem);
}
}