lzss 0.8.2

A LZSS en-/decompressor (lossless data compression, no_std capable, in pure Rust)
Documentation 
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/* This file is based on the LZSS encoder-decoder  (c) Haruhiko Okumura */

use crate::bits::BitReader;
use crate::dynamic::LzssDyn;
use crate::{LzssError, Read, Write};

impl LzssDyn {
  #[inline(always)]
  pub(crate) fn decompress_internal<R: Read, W: Write>(
    &self,
    reader: &mut R,
    writer: &mut W,
    buffer: &mut [u8],
  ) -> Result<(), LzssError<R::Error, W::Error>> {
    let mut bit_reader = BitReader::new(reader);

    let mut r = self.n() - self.f();
    loop {
      if let Some(c) = bit_reader.read_bits(1).map_err(LzssError::ReadError)? {
        if c != 0 {
          if let Some(b) = bit_reader.read_bits(8).map_err(LzssError::ReadError)? {
            writer.write(b as u8).map_err(LzssError::WriteError)?;
            *unsafe { buffer.get_unchecked_mut(r) } = b as u8;
            r = (r + 1) & (self.n() - 1);
          } else {
            return Ok(());
          }
        } else if let Some(ij) = bit_reader
          .read_bits(self.ei + self.ej)
          .map_err(LzssError::ReadError)?
        {
          let i = (ij >> self.ej) as usize;
          let j = (ij & ((1 << self.ej) - 1)) as usize;
          for k in 0..=j + self.p() {
            let b = *unsafe { buffer.get_unchecked((i + k) & (self.n() - 1)) };
            writer.write(b).map_err(LzssError::WriteError)?;
            *unsafe { buffer.get_unchecked_mut(r) } = b;
            r = (r + 1) & (self.n() - 1);
          }
        } else {
          return Ok(());
        }
      } else {
        return Ok(());
      }
    }
  }
}