nihav-core/src/compr/mod.rs

   1 //! Various compression formats support.
   2 #[cfg(feature="deflate")]
   3 pub mod deflate;
   4
   5 use crate::io::byteio::ByteIOError;
   6 use crate::io::bitreader::BitReaderError;
   7 use crate::io::codebook::CodebookError;
   8
   9 /// A list specifying general compression errors.
  10 #[derive(Debug)]
  11 pub enum DecompressError {
  12     /// Compressed stream header contains errors.
  13     InvalidHeader,
  14     /// Compressed stream checksum does not match unpacked contents.
  15     CRCError,
  16     /// Compressed stream contains a combination of bits that cannot be decoded.
  17     InvalidData,
  18     /// Compressed stream ended prematurely.
  19     ShortData,
  20     /// There is more data than what can fit output buffer.
  21     OutputFull,
  22     /// Provided function argument is invalid.
  23     InvalidArgument,
  24     /// Compressed stream contains features that cannot be decoded.
  25     Unsupported,
  26     /// Underlying input reader had a problem.
  27     IOError,
  28 }
  29
  30 /// A specialised `Result` type for codebook operations.
  31 pub type DecompressResult<T> = Result<T, DecompressError>;
  32
  33 impl From<ByteIOError> for DecompressError {
  34     fn from(e: ByteIOError) -> Self {
  35         match e {
  36             ByteIOError::EOF => DecompressError::ShortData,
  37             _ => DecompressError::IOError,
  38         }
  39     }
  40 }
  41
  42 impl From<BitReaderError> for DecompressError {
  43     fn from(e: BitReaderError) -> Self {
  44         match e {
  45             BitReaderError::BitstreamEnd => DecompressError::ShortData,
  46             _ => DecompressError::InvalidData,
  47         }
  48     }
  49 }
  50
  51 impl From<CodebookError> for DecompressError {
  52     fn from(_: CodebookError) -> Self {
  53         DecompressError::InvalidData
  54     }
  55 }
  56
  57 ///! Copies requested amount of bytes from previous position in the same buffer.
  58 ///! If source area overlaps with destination area already copied values should be used e.g. copying with offset 1 means essentially to repeat previous byte requested number of times.
  59 pub fn lz_copy(buf: &mut [u8], dst_pos: usize, offset: usize, len: usize) {
  60     if dst_pos < offset {
  61         panic!("Copy offset is before buffer start.");
  62     }
  63     let ipos = dst_pos - offset;
  64     let buf = &mut buf[ipos..];
  65     if ipos + len <= dst_pos {
  66         let (src, dst) = buf.split_at_mut(offset);
  67         (&mut dst[..len]).copy_from_slice(&src[..len]);
  68     } else {
  69         for i in 0..len {
  70             buf[offset + i] = buf[i];
  71         }
  72     }
  73 }