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use byteorder::{BigEndian, ReadBytesExt, WriteBytesExt};
use std::io;
#[derive(Debug)]
pub struct MaskDecoder<R: io::Read> {
stream: R,
current_val: u32,
bits_left_in_current: usize,
}
impl<R: io::Read> MaskDecoder<R> {
pub fn new(stream: R) -> Self {
MaskDecoder {
stream: stream,
current_val: 0,
bits_left_in_current: 0,
}
}
pub fn expand(&mut self, dest: &mut [bool]) -> Result<(), io::Error> {
let mut ofs = 0;
let mut cur = self.current_val;
let mut n_bits = dest.len();
while n_bits > 0 {
if self.bits_left_in_current > 0 {
let mut toread = ::std::cmp::min(self.bits_left_in_current, n_bits);
let mut i = 31 - self.bits_left_in_current;
n_bits -= toread;
self.bits_left_in_current -= toread;
while toread > 0 {
dest[ofs] = if cur & (1 << i) != 0 { true } else { false };
ofs += 1;
i += 1;
toread -= 1;
}
}
if n_bits == 0 {
return Ok(());
}
cur = self.stream.read_u32::<BigEndian>()?;
self.current_val = cur;
self.bits_left_in_current = 31;
}
return Ok(());
}
}
#[derive(Debug)]
pub struct MaskEncoder<W: io::Write> {
stream: W,
current_val: u32,
bits_left_in_current: usize,
closed: bool,
}
impl<W: io::Write> MaskEncoder<W> {
pub fn new(stream: W) -> Self {
MaskEncoder {
stream: stream,
current_val: 0,
bits_left_in_current: 0,
closed: false,
}
}
pub fn append_mask(&mut self, data: &[bool]) -> Result<(), io::Error> {
if self.closed {
panic!("cannot append to mask after closing it");
}
let mut ofs = 0;
let mut n_bits = data.len();
let mut cur = self.current_val;
let mut bits_left = self.bits_left_in_current;
while n_bits > 0 {
let mut towrite = ::std::cmp::min(bits_left, n_bits);
let mut i = 31 - bits_left;
n_bits -= towrite;
bits_left -= towrite;
while towrite > 0 {
if data[ofs] {
cur |= 1 << i;
}
ofs += 1;
i += 1;
towrite -= 1;
}
if bits_left == 0 {
self.stream.write_u32::<BigEndian>(cur)?;
cur = 0;
bits_left = 31;
}
}
self.current_val = cur;
self.bits_left_in_current = bits_left;
return Ok(());
}
pub fn close(&mut self) -> Result<(), io::Error> {
if self.closed {
return Ok(());
}
if self.bits_left_in_current != 31 {
self.stream.write_u32::<BigEndian>(self.current_val)?;
}
self.stream.flush()?;
self.closed = true;
Ok(())
}
}
impl<W: io::Write> Drop for MaskEncoder<W> {
fn drop(&mut self) {
if !self.closed {
let _r = self.close();
}
}
}