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//! Various compression formats support.
#[cfg(feature="deflate")]
pub mod deflate;
use crate::io::byteio::ByteIOError;
use crate::io::bitreader::BitReaderError;
use crate::io::codebook::CodebookError;
/// A list specifying general compression errors.
#[derive(Debug)]
pub enum DecompressError {
/// Compressed stream header contains errors.
InvalidHeader,
/// Compressed stream checksum does not match unpacked contents.
CRCError,
/// Compressed stream contains a combination of bits that cannot be decoded.
InvalidData,
/// Compressed stream ended prematurely.
ShortData,
/// There is more data than what can fit output buffer.
OutputFull,
/// Provided function argument is invalid.
InvalidArgument,
/// Compressed stream contains features that cannot be decoded.
Unsupported,
/// Underlying input reader had a problem.
IOError,
}
/// A specialised `Result` type for codebook operations.
pub type DecompressResult<T> = Result<T, DecompressError>;
impl From<ByteIOError> for DecompressError {
fn from(e: ByteIOError) -> Self {
match e {
ByteIOError::EOF => DecompressError::ShortData,
_ => DecompressError::IOError,
}
}
}
impl From<BitReaderError> for DecompressError {
fn from(e: BitReaderError) -> Self {
match e {
BitReaderError::BitstreamEnd => DecompressError::ShortData,
_ => DecompressError::InvalidData,
}
}
}
impl From<CodebookError> for DecompressError {
fn from(_: CodebookError) -> Self {
DecompressError::InvalidData
}
}
///! Copies requested amount of bytes from previous position in the same buffer.
///! 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.
pub fn lz_copy(buf: &mut [u8], dst_pos: usize, offset: usize, len: usize) {
if dst_pos < offset {
panic!("Copy offset is before buffer start.");
}
let ipos = dst_pos - offset;
let buf = &mut buf[ipos..];
if ipos + len <= dst_pos {
let (src, dst) = buf.split_at_mut(offset);
(&mut dst[..len]).copy_from_slice(&src[..len]);
} else {
for i in 0..len {
buf[offset + i] = buf[i];
}
}
}
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