Initial vendor packages

Signed-off-by: Valentin Popov <valentin@popov.link>

1 files changed, 1126 insertions, 0 deletions

diff --git a/vendor/weezl/src/encode.rs b/vendor/weezl/src/encode.rs
new file mode 100644
index 0000000..492b18c
--- /dev/null
+++ b/vendor/weezl/src/encode.rs
@@ -0,0 +1,1126 @@
+//! A module for all encoding needs.
+use crate::error::{BufferResult, LzwError, LzwStatus, VectorResult};
+use crate::{BitOrder, Code, StreamBuf, MAX_CODESIZE, MAX_ENTRIES, STREAM_BUF_SIZE};
+
+use crate::alloc::{boxed::Box, vec::Vec};
+#[cfg(feature = "std")]
+use crate::error::StreamResult;
+#[cfg(feature = "std")]
+use std::io::{self, BufRead, Write};
+
+/// The state for encoding data with an LZW algorithm.
+///
+/// The same structure can be utilized with streams as well as your own buffers and driver logic.
+/// It may even be possible to mix them if you are sufficiently careful not to lose any written
+/// data in the process.
+///
+/// This is a sans-IO implementation, meaning that it only contains the state of the encoder and
+/// the caller will provide buffers for input and output data when calling the basic
+/// [`encode_bytes`] method. Nevertheless, a number of _adapters_ are provided in the `into_*`
+/// methods for enoding with a particular style of common IO.
+///
+/// * [`encode`] for encoding once without any IO-loop.
+/// * [`into_async`] for encoding with the `futures` traits for asynchronous IO.
+/// * [`into_stream`] for encoding with the standard `io` traits.
+/// * [`into_vec`] for in-memory encoding.
+///
+/// [`encode_bytes`]: #method.encode_bytes
+/// [`encode`]: #method.encode
+/// [`into_async`]: #method.into_async
+/// [`into_stream`]: #method.into_stream
+/// [`into_vec`]: #method.into_vec
+pub struct Encoder {
+    /// Internally dispatch via a dynamic trait object. This did not have any significant
+    /// performance impact as we batch data internally and this pointer does not change after
+    /// creation!
+    state: Box<dyn Stateful + Send + 'static>,
+}
+
+/// A encoding stream sink.
+///
+/// See [`Encoder::into_stream`] on how to create this type.
+///
+/// [`Encoder::into_stream`]: struct.Encoder.html#method.into_stream
+#[cfg_attr(
+    not(feature = "std"),
+    deprecated = "This type is only useful with the `std` feature."
+)]
+#[cfg_attr(not(feature = "std"), allow(dead_code))]
+pub struct IntoStream<'d, W> {
+    encoder: &'d mut Encoder,
+    writer: W,
+    buffer: Option<StreamBuf<'d>>,
+    default_size: usize,
+}
+
+/// An async decoding sink.
+///
+/// See [`Encoder::into_async`] on how to create this type.
+///
+/// [`Encoder::into_async`]: struct.Encoder.html#method.into_async
+#[cfg(feature = "async")]
+pub struct IntoAsync<'d, W> {
+    encoder: &'d mut Encoder,
+    writer: W,
+    buffer: Option<StreamBuf<'d>>,
+    default_size: usize,
+}
+
+/// A encoding sink into a vector.
+///
+/// See [`Encoder::into_vec`] on how to create this type.
+///
+/// [`Encoder::into_vec`]: struct.Encoder.html#method.into_vec
+pub struct IntoVec<'d> {
+    encoder: &'d mut Encoder,
+    vector: &'d mut Vec<u8>,
+}
+
+trait Stateful {
+    fn advance(&mut self, inp: &[u8], out: &mut [u8]) -> BufferResult;
+    fn mark_ended(&mut self) -> bool;
+    /// Reset the state tracking if end code has been written.
+    fn restart(&mut self);
+    /// Reset the encoder to the beginning, dropping all buffers etc.
+    fn reset(&mut self);
+}
+
+struct EncodeState<B: Buffer> {
+    /// The configured minimal code size.
+    min_size: u8,
+    /// The current encoding symbol tree.
+    tree: Tree,
+    /// If we have pushed the end code.
+    has_ended: bool,
+    /// If tiff then bumps are a single code sooner.
+    is_tiff: bool,
+    /// The code corresponding to the currently read characters.
+    current_code: Code,
+    /// The clear code for resetting the dictionary.
+    clear_code: Code,
+    /// The bit buffer for encoding.
+    buffer: B,
+}
+
+struct MsbBuffer {
+    /// The current code length.
+    code_size: u8,
+    /// The buffer bits.
+    buffer: u64,
+    /// The number of valid buffer bits.
+    bits_in_buffer: u8,
+}
+
+struct LsbBuffer {
+    /// The current code length.
+    code_size: u8,
+    /// The buffer bits.
+    buffer: u64,
+    /// The number of valid buffer bits.
+    bits_in_buffer: u8,
+}
+
+trait Buffer {
+    fn new(size: u8) -> Self;
+    /// Reset the code size in the buffer.
+    fn reset(&mut self, min_size: u8);
+    /// Apply effects of a Clear Code.
+    fn clear(&mut self, min_size: u8);
+    /// Insert a code into the buffer.
+    fn buffer_code(&mut self, code: Code);
+    /// Push bytes if the buffer space is getting small.
+    fn push_out(&mut self, out: &mut &mut [u8]) -> bool;
+    /// Flush all full bytes, returning if at least one more byte remains.
+    fn flush_out(&mut self, out: &mut &mut [u8]) -> bool;
+    /// Pad the buffer to a full byte.
+    fn buffer_pad(&mut self);
+    /// Increase the maximum code size.
+    fn bump_code_size(&mut self);
+    /// Return the maximum code with the current code size.
+    fn max_code(&self) -> Code;
+    /// Return the current code size in bits.
+    fn code_size(&self) -> u8;
+}
+
+/// One tree node for at most each code.
+/// To avoid using too much memory we keep nodes with few successors in optimized form. This form
+/// doesn't offer lookup by indexing but instead does a linear search.
+#[derive(Default)]
+struct Tree {
+    simples: Vec<Simple>,
+    complex: Vec<Full>,
+    keys: Vec<CompressedKey>,
+}
+
+#[derive(Clone, Copy)]
+enum FullKey {
+    NoSuccessor,
+    Simple(u16),
+    Full(u16),
+}
+
+#[derive(Clone, Copy)]
+struct CompressedKey(u16);
+
+const SHORT: usize = 16;
+
+#[derive(Clone, Copy)]
+struct Simple {
+    codes: [Code; SHORT],
+    chars: [u8; SHORT],
+    count: u8,
+}
+
+#[derive(Clone, Copy)]
+struct Full {
+    char_continuation: [Code; 256],
+}
+
+impl Encoder {
+    /// Create a new encoder with the specified bit order and symbol size.
+    ///
+    /// The algorithm for dynamically increasing the code symbol bit width is compatible with the
+    /// original specification. In particular you will need to specify an `Lsb` bit oder to encode
+    /// the data portion of a compressed `gif` image.
+    ///
+    /// # Panics
+    ///
+    /// The `size` needs to be in the interval `2..=12`.
+    pub fn new(order: BitOrder, size: u8) -> Self {
+        type Boxed = Box<dyn Stateful + Send + 'static>;
+        super::assert_encode_size(size);
+        let state = match order {
+            BitOrder::Lsb => Box::new(EncodeState::<LsbBuffer>::new(size)) as Boxed,
+            BitOrder::Msb => Box::new(EncodeState::<MsbBuffer>::new(size)) as Boxed,
+        };
+
+        Encoder { state }
+    }
+
+    /// Create a TIFF compatible encoder with the specified bit order and symbol size.
+    ///
+    /// The algorithm for dynamically increasing the code symbol bit width is compatible with the
+    /// TIFF specification, which is a misinterpretation of the original algorithm for increasing
+    /// the code size. It switches one symbol sooner.
+    ///
+    /// # Panics
+    ///
+    /// The `size` needs to be in the interval `2..=12`.
+    pub fn with_tiff_size_switch(order: BitOrder, size: u8) -> Self {
+        type Boxed = Box<dyn Stateful + Send + 'static>;
+        super::assert_encode_size(size);
+        let state = match order {
+            BitOrder::Lsb => {
+                let mut state = Box::new(EncodeState::<LsbBuffer>::new(size));
+                state.is_tiff = true;
+                state as Boxed
+            }
+            BitOrder::Msb => {
+                let mut state = Box::new(EncodeState::<MsbBuffer>::new(size));
+                state.is_tiff = true;
+                state as Boxed
+            }
+        };
+
+        Encoder { state }
+    }
+
+    /// Encode some bytes from `inp` into `out`.
+    ///
+    /// See [`into_stream`] for high-level functions (this interface is only available with the
+    /// `std` feature) and [`finish`] for marking the input data as complete.
+    ///
+    /// When some input byte is invalid, i.e. is not smaller than `1 << size`, then that byte and
+    /// all following ones will _not_ be consumed and the `status` of the result will signal an
+    /// error. The result will also indicate that all bytes up to but not including the offending
+    /// byte have been consumed. You may try again with a fixed byte.
+    ///
+    /// [`into_stream`]: #method.into_stream
+    /// [`finish`]: #method.finish
+    pub fn encode_bytes(&mut self, inp: &[u8], out: &mut [u8]) -> BufferResult {
+        self.state.advance(inp, out)
+    }
+
+    /// Encode a single chunk of data.
+    ///
+    /// This method will add an end marker to the encoded chunk.
+    ///
+    /// This is a convenience wrapper around [`into_vec`]. Use the `into_vec` adapter to customize
+    /// buffer size, to supply an existing vector, to control whether an end marker is required, or
+    /// to preserve partial data in the case of a decoding error.
+    ///
+    /// [`into_vec`]: #into_vec
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use weezl::{BitOrder, encode::Encoder};
+    ///
+    /// let data = b"Hello, world";
+    /// let encoded = Encoder::new(BitOrder::Msb, 9)
+    ///     .encode(data)
+    ///     .expect("All bytes valid for code size");
+    /// ```
+    pub fn encode(&mut self, data: &[u8]) -> Result<Vec<u8>, LzwError> {
+        let mut output = Vec::new();
+        self.into_vec(&mut output).encode_all(data).status?;
+        Ok(output)
+    }
+
+    /// Construct a encoder into a writer.
+    #[cfg(feature = "std")]
+    pub fn into_stream<W: Write>(&mut self, writer: W) -> IntoStream<'_, W> {
+        IntoStream {
+            encoder: self,
+            writer,
+            buffer: None,
+            default_size: STREAM_BUF_SIZE,
+        }
+    }
+
+    /// Construct a encoder into an async writer.
+    #[cfg(feature = "async")]
+    pub fn into_async<W: futures::io::AsyncWrite>(&mut self, writer: W) -> IntoAsync<'_, W> {
+        IntoAsync {
+            encoder: self,
+            writer,
+            buffer: None,
+            default_size: STREAM_BUF_SIZE,
+        }
+    }
+
+    /// Construct an encoder into a vector.
+    ///
+    /// All encoded data is appended and the vector is __not__ cleared.
+    ///
+    /// Compared to `into_stream` this interface allows a high-level access to encoding without
+    /// requires the `std`-feature. Also, it can make full use of the extra buffer control that the
+    /// special target exposes.
+    pub fn into_vec<'lt>(&'lt mut self, vec: &'lt mut Vec<u8>) -> IntoVec<'lt> {
+        IntoVec {
+            encoder: self,
+            vector: vec,
+        }
+    }
+
+    /// Mark the encoding as in the process of finishing.
+    ///
+    /// The next following call to `encode_bytes` which is able to consume the complete input will
+    /// also try to emit an end code. It's not recommended, but also not unsound, to use different
+    /// byte slices in different calls from this point forward and thus to 'delay' the actual end
+    /// of the data stream. The behaviour after the end marker has been written is unspecified but
+    /// sound.
+    pub fn finish(&mut self) {
+        self.state.mark_ended();
+    }
+
+    /// Undo marking this data stream as ending.
+    /// FIXME: clarify how this interacts with padding introduced after end code.
+    #[allow(dead_code)]
+    pub(crate) fn restart(&mut self) {
+        self.state.restart()
+    }
+
+    /// Reset all internal state.
+    ///
+    /// This produce an encoder as if just constructed with `new` but taking slightly less work. In
+    /// particular it will not deallocate any internal allocations. It will also avoid some
+    /// duplicate setup work.
+    pub fn reset(&mut self) {
+        self.state.reset()
+    }
+}
+
+#[cfg(feature = "std")]
+impl<'d, W: Write> IntoStream<'d, W> {
+    /// Encode data from a reader.
+    ///
+    /// This will drain the supplied reader. It will not encode an end marker after all data has
+    /// been processed.
+    pub fn encode(&mut self, read: impl BufRead) -> StreamResult {
+        self.encode_part(read, false)
+    }
+
+    /// Encode data from a reader and an end marker.
+    pub fn encode_all(mut self, read: impl BufRead) -> StreamResult {
+        self.encode_part(read, true)
+    }
+
+    /// Set the size of the intermediate encode buffer.
+    ///
+    /// A buffer of this size is allocated to hold one part of the encoded stream when no buffer is
+    /// available and any encoding method is called. No buffer is allocated if `set_buffer` has
+    /// been called. The buffer is reused.
+    ///
+    /// # Panics
+    /// This method panics if `size` is `0`.
+    pub fn set_buffer_size(&mut self, size: usize) {
+        assert_ne!(size, 0, "Attempted to set empty buffer");
+        self.default_size = size;
+    }
+
+    /// Use a particular buffer as an intermediate encode buffer.
+    ///
+    /// Calling this sets or replaces the buffer. When a buffer has been set then it is used
+    /// instead of a dynamically allocating a buffer. Note that the size of the buffer is relevant
+    /// for efficient encoding as there is additional overhead from `write` calls each time the
+    /// buffer has been filled.
+    ///
+    /// # Panics
+    /// This method panics if the `buffer` is empty.
+    pub fn set_buffer(&mut self, buffer: &'d mut [u8]) {
+        assert_ne!(buffer.len(), 0, "Attempted to set empty buffer");
+        self.buffer = Some(StreamBuf::Borrowed(buffer));
+    }
+
+    fn encode_part(&mut self, mut read: impl BufRead, finish: bool) -> StreamResult {
+        let IntoStream {
+            encoder,
+            writer,
+            buffer,
+            default_size,
+        } = self;
+        enum Progress {
+            Ok,
+            Done,
+        }
+
+        let mut bytes_read = 0;
+        let mut bytes_written = 0;
+
+        let read_bytes = &mut bytes_read;
+        let write_bytes = &mut bytes_written;
+
+        let outbuf: &mut [u8] =
+            match { buffer.get_or_insert_with(|| StreamBuf::Owned(vec![0u8; *default_size])) } {
+                StreamBuf::Borrowed(slice) => &mut *slice,
+                StreamBuf::Owned(vec) => &mut *vec,
+            };
+        assert!(!outbuf.is_empty());
+
+        let once = move || {
+            let data = read.fill_buf()?;
+
+            if data.is_empty() {
+                if finish {
+                    encoder.finish();
+                } else {
+                    return Ok(Progress::Done);
+                }
+            }
+
+            let result = encoder.encode_bytes(data, &mut outbuf[..]);
+            *read_bytes += result.consumed_in;
+            *write_bytes += result.consumed_out;
+            read.consume(result.consumed_in);
+
+            let done = result.status.map_err(|err| {
+                io::Error::new(io::ErrorKind::InvalidData, &*format!("{:?}", err))
+            })?;
+
+            if let LzwStatus::Done = done {
+                writer.write_all(&outbuf[..result.consumed_out])?;
+                return Ok(Progress::Done);
+            }
+
+            if let LzwStatus::NoProgress = done {
+                return Err(io::Error::new(
+                    io::ErrorKind::UnexpectedEof,
+                    "No more data but no end marker detected",
+                ));
+            }
+
+            writer.write_all(&outbuf[..result.consumed_out])?;
+            Ok(Progress::Ok)
+        };
+
+        let status = core::iter::repeat_with(once)
+            // scan+fuse can be replaced with map_while
+            .scan((), |(), result| match result {
+                Ok(Progress::Ok) => Some(Ok(())),
+                Err(err) => Some(Err(err)),
+                Ok(Progress::Done) => None,
+            })
+            .fuse()
+            .collect();
+
+        StreamResult {
+            bytes_read,
+            bytes_written,
+            status,
+        }
+    }
+}
+
+impl IntoVec<'_> {
+    /// Encode data from a slice.
+    pub fn encode(&mut self, read: &[u8]) -> VectorResult {
+        self.encode_part(read, false)
+    }
+
+    /// Decode data from a reader, adding an end marker.
+    pub fn encode_all(mut self, read: &[u8]) -> VectorResult {
+        self.encode_part(read, true)
+    }
+
+    fn grab_buffer(&mut self) -> (&mut [u8], &mut Encoder) {
+        const CHUNK_SIZE: usize = 1 << 12;
+        let decoder = &mut self.encoder;
+        let length = self.vector.len();
+
+        // Use the vector to do overflow checks and w/e.
+        self.vector.reserve(CHUNK_SIZE);
+        // FIXME: encoding into uninit buffer?
+        self.vector.resize(length + CHUNK_SIZE, 0u8);
+
+        (&mut self.vector[length..], decoder)
+    }
+
+    fn encode_part(&mut self, part: &[u8], finish: bool) -> VectorResult {
+        let mut result = VectorResult {
+            consumed_in: 0,
+            consumed_out: 0,
+            status: Ok(LzwStatus::Ok),
+        };
+
+        enum Progress {
+            Ok,
+            Done,
+        }
+
+        // Converting to mutable refs to move into the `once` closure.
+        let read_bytes = &mut result.consumed_in;
+        let write_bytes = &mut result.consumed_out;
+        let mut data = part;
+
+        // A 64 MB buffer is quite large but should get alloc_zeroed.
+        // Note that the decoded size can be up to quadratic in code block.
+        let once = move || {
+            // Grab a new output buffer.
+            let (outbuf, encoder) = self.grab_buffer();
+
+            if finish {
+                encoder.finish();
+            }
+
+            // Decode as much of the buffer as fits.
+            let result = encoder.encode_bytes(data, &mut outbuf[..]);
+            // Do the bookkeeping and consume the buffer.
+            *read_bytes += result.consumed_in;
+            *write_bytes += result.consumed_out;
+            data = &data[result.consumed_in..];
+
+            let unfilled = outbuf.len() - result.consumed_out;
+            let filled = self.vector.len() - unfilled;
+            self.vector.truncate(filled);
+
+            // Handle the status in the result.
+            let done = result.status?;
+            if let LzwStatus::Done = done {
+                Ok(Progress::Done)
+            } else {
+                Ok(Progress::Ok)
+            }
+        };
+
+        // Decode chunks of input data until we're done.
+        let status: Result<(), _> = core::iter::repeat_with(once)
+            // scan+fuse can be replaced with map_while
+            .scan((), |(), result| match result {
+                Ok(Progress::Ok) => Some(Ok(())),
+                Err(err) => Some(Err(err)),
+                Ok(Progress::Done) => None,
+            })
+            .fuse()
+            .collect();
+
+        if let Err(err) = status {
+            result.status = Err(err);
+        }
+
+        result
+    }
+}
+
+// This is implemented in a separate file, so that 1.34.2 does not parse it. Otherwise, it would
+// trip over the usage of await, which is a reserved keyword in that edition/version. It only
+// contains an impl block.
+#[cfg(feature = "async")]
+#[path = "encode_into_async.rs"]
+mod impl_encode_into_async;
+
+impl<B: Buffer> EncodeState<B> {
+    fn new(min_size: u8) -> Self {
+        let clear_code = 1 << min_size;
+        let mut tree = Tree::default();
+        tree.init(min_size);
+        let mut state = EncodeState {
+            min_size,
+            tree,
+            has_ended: false,
+            is_tiff: false,
+            current_code: clear_code,
+            clear_code,
+            buffer: B::new(min_size),
+        };
+        state.buffer_code(clear_code);
+        state
+    }
+}
+
+impl<B: Buffer> Stateful for EncodeState<B> {
+    fn advance(&mut self, mut inp: &[u8], mut out: &mut [u8]) -> BufferResult {
+        let c_in = inp.len();
+        let c_out = out.len();
+        let mut status = Ok(LzwStatus::Ok);
+
+        'encoding: loop {
+            if self.push_out(&mut out) {
+                break;
+            }
+
+            if inp.is_empty() && self.has_ended {
+                let end = self.end_code();
+                if self.current_code != end {
+                    if self.current_code != self.clear_code {
+                        self.buffer_code(self.current_code);
+
+                        // When reading this code, the decoder will add an extra entry to its table
+                        // before reading th end code. Thusly, it may increase its code size based
+                        // on this additional entry.
+                        if self.tree.keys.len() + usize::from(self.is_tiff)
+                            > usize::from(self.buffer.max_code())
+                            && self.buffer.code_size() < MAX_CODESIZE
+                        {
+                            self.buffer.bump_code_size();
+                        }
+                    }
+                    self.buffer_code(end);
+                    self.current_code = end;
+                    self.buffer_pad();
+                }
+
+                break;
+            }
+
+            let mut next_code = None;
+            let mut bytes = inp.iter();
+            while let Some(&byte) = bytes.next() {
+                if self.min_size < 8 && byte >= 1 << self.min_size {
+                    status = Err(LzwError::InvalidCode);
+                    break 'encoding;
+                }
+
+                inp = bytes.as_slice();
+                match self.tree.iterate(self.current_code, byte) {
+                    Ok(code) => self.current_code = code,
+                    Err(_) => {
+                        next_code = Some(self.current_code);
+
+                        self.current_code = u16::from(byte);
+                        break;
+                    }
+                }
+            }
+
+            match next_code {
+                // No more bytes, no code produced.
+                None => break,
+                Some(code) => {
+                    self.buffer_code(code);
+
+                    if self.tree.keys.len() + usize::from(self.is_tiff)
+                        > usize::from(self.buffer.max_code()) + 1
+                        && self.buffer.code_size() < MAX_CODESIZE
+                    {
+                        self.buffer.bump_code_size();
+                    }
+
+                    if self.tree.keys.len() > MAX_ENTRIES {
+                        self.buffer_code(self.clear_code);
+                        self.tree.reset(self.min_size);
+                        self.buffer.clear(self.min_size);
+                    }
+                }
+            }
+        }
+
+        if inp.is_empty() && self.current_code == self.end_code() {
+            if !self.flush_out(&mut out) {
+                status = Ok(LzwStatus::Done);
+            }
+        }
+
+        BufferResult {
+            consumed_in: c_in - inp.len(),
+            consumed_out: c_out - out.len(),
+            status,
+        }
+    }
+
+    fn mark_ended(&mut self) -> bool {
+        core::mem::replace(&mut self.has_ended, true)
+    }
+
+    fn restart(&mut self) {
+        self.has_ended = false;
+    }
+
+    fn reset(&mut self) {
+        self.restart();
+        self.current_code = self.clear_code;
+        self.tree.reset(self.min_size);
+        self.buffer.reset(self.min_size);
+        self.buffer_code(self.clear_code);
+    }
+}
+
+impl<B: Buffer> EncodeState<B> {
+    fn push_out(&mut self, out: &mut &mut [u8]) -> bool {
+        self.buffer.push_out(out)
+    }
+
+    fn flush_out(&mut self, out: &mut &mut [u8]) -> bool {
+        self.buffer.flush_out(out)
+    }
+
+    fn end_code(&self) -> Code {
+        self.clear_code + 1
+    }
+
+    fn buffer_pad(&mut self) {
+        self.buffer.buffer_pad();
+    }
+
+    fn buffer_code(&mut self, code: Code) {
+        self.buffer.buffer_code(code);
+    }
+}
+
+impl Buffer for MsbBuffer {
+    fn new(min_size: u8) -> Self {
+        MsbBuffer {
+            code_size: min_size + 1,
+            buffer: 0,
+            bits_in_buffer: 0,
+        }
+    }
+
+    fn reset(&mut self, min_size: u8) {
+        self.code_size = min_size + 1;
+        self.buffer = 0;
+        self.bits_in_buffer = 0;
+    }
+
+    fn clear(&mut self, min_size: u8) {
+        self.code_size = min_size + 1;
+    }
+
+    fn buffer_code(&mut self, code: Code) {
+        let shift = 64 - self.bits_in_buffer - self.code_size;
+        self.buffer |= u64::from(code) << shift;
+        self.bits_in_buffer += self.code_size;
+    }
+
+    fn push_out(&mut self, out: &mut &mut [u8]) -> bool {
+        if self.bits_in_buffer + 2 * self.code_size < 64 {
+            return false;
+        }
+
+        self.flush_out(out)
+    }
+
+    fn flush_out(&mut self, out: &mut &mut [u8]) -> bool {
+        let want = usize::from(self.bits_in_buffer / 8);
+        let count = want.min((*out).len());
+        let (bytes, tail) = core::mem::replace(out, &mut []).split_at_mut(count);
+        *out = tail;
+
+        for b in bytes {
+            *b = ((self.buffer & 0xff00_0000_0000_0000) >> 56) as u8;
+            self.buffer <<= 8;
+            self.bits_in_buffer -= 8;
+        }
+
+        count < want
+    }
+
+    fn buffer_pad(&mut self) {
+        let to_byte = self.bits_in_buffer.wrapping_neg() & 0x7;
+        self.bits_in_buffer += to_byte;
+    }
+
+    fn bump_code_size(&mut self) {
+        self.code_size += 1;
+    }
+
+    fn max_code(&self) -> Code {
+        (1 << self.code_size) - 1
+    }
+
+    fn code_size(&self) -> u8 {
+        self.code_size
+    }
+}
+
+impl Buffer for LsbBuffer {
+    fn new(min_size: u8) -> Self {
+        LsbBuffer {
+            code_size: min_size + 1,
+            buffer: 0,
+            bits_in_buffer: 0,
+        }
+    }
+
+    fn reset(&mut self, min_size: u8) {
+        self.code_size = min_size + 1;
+        self.buffer = 0;
+        self.bits_in_buffer = 0;
+    }
+
+    fn clear(&mut self, min_size: u8) {
+        self.code_size = min_size + 1;
+    }
+
+    fn buffer_code(&mut self, code: Code) {
+        self.buffer |= u64::from(code) << self.bits_in_buffer;
+        self.bits_in_buffer += self.code_size;
+    }
+
+    fn push_out(&mut self, out: &mut &mut [u8]) -> bool {
+        if self.bits_in_buffer + 2 * self.code_size < 64 {
+            return false;
+        }
+
+        self.flush_out(out)
+    }
+
+    fn flush_out(&mut self, out: &mut &mut [u8]) -> bool {
+        let want = usize::from(self.bits_in_buffer / 8);
+        let count = want.min((*out).len());
+        let (bytes, tail) = core::mem::replace(out, &mut []).split_at_mut(count);
+        *out = tail;
+
+        for b in bytes {
+            *b = (self.buffer & 0x0000_0000_0000_00ff) as u8;
+            self.buffer >>= 8;
+            self.bits_in_buffer -= 8;
+        }
+
+        count < want
+    }
+
+    fn buffer_pad(&mut self) {
+        let to_byte = self.bits_in_buffer.wrapping_neg() & 0x7;
+        self.bits_in_buffer += to_byte;
+    }
+
+    fn bump_code_size(&mut self) {
+        self.code_size += 1;
+    }
+
+    fn max_code(&self) -> Code {
+        (1 << self.code_size) - 1
+    }
+
+    fn code_size(&self) -> u8 {
+        self.code_size
+    }
+}
+
+impl Tree {
+    fn init(&mut self, min_size: u8) {
+        // We need a way to represent the state of a currently empty buffer. We use the clear code
+        // for this, thus create one complex mapping that leads to the one-char base codes.
+        self.keys
+            .resize((1 << min_size) + 2, FullKey::NoSuccessor.into());
+        self.complex.push(Full {
+            char_continuation: [0; 256],
+        });
+        let map_of_begin = self.complex.last_mut().unwrap();
+        for ch in 0u16..256 {
+            map_of_begin.char_continuation[usize::from(ch)] = ch;
+        }
+        self.keys[1 << min_size] = FullKey::Full(0).into();
+    }
+
+    fn reset(&mut self, min_size: u8) {
+        self.simples.clear();
+        self.keys.truncate((1 << min_size) + 2);
+        // Keep entry for clear code.
+        self.complex.truncate(1);
+        // The first complex is not changed..
+        for k in self.keys[..(1 << min_size) + 2].iter_mut() {
+            *k = FullKey::NoSuccessor.into();
+        }
+        self.keys[1 << min_size] = FullKey::Full(0).into();
+    }
+
+    fn at_key(&self, code: Code, ch: u8) -> Option<Code> {
+        let key = self.keys[usize::from(code)];
+        match FullKey::from(key) {
+            FullKey::NoSuccessor => None,
+            FullKey::Simple(idx) => {
+                let nexts = &self.simples[usize::from(idx)];
+                let successors = nexts
+                    .codes
+                    .iter()
+                    .zip(nexts.chars.iter())
+                    .take(usize::from(nexts.count));
+                for (&scode, &sch) in successors {
+                    if sch == ch {
+                        return Some(scode);
+                    }
+                }
+
+                None
+            }
+            FullKey::Full(idx) => {
+                let full = &self.complex[usize::from(idx)];
+                let precode = full.char_continuation[usize::from(ch)];
+                if usize::from(precode) < MAX_ENTRIES {
+                    Some(precode)
+                } else {
+                    None
+                }
+            }
+        }
+    }
+
+    /// Iterate to the next char.
+    /// Return Ok when it was already in the tree or creates a new entry for it and returns Err.
+    fn iterate(&mut self, code: Code, ch: u8) -> Result<Code, Code> {
+        if let Some(next) = self.at_key(code, ch) {
+            Ok(next)
+        } else {
+            Err(self.append(code, ch))
+        }
+    }
+
+    fn append(&mut self, code: Code, ch: u8) -> Code {
+        let next: Code = self.keys.len() as u16;
+        let key = self.keys[usize::from(code)];
+        // TODO: with debug assertions, check for non-existence
+        match FullKey::from(key) {
+            FullKey::NoSuccessor => {
+                let new_key = FullKey::Simple(self.simples.len() as u16);
+                self.simples.push(Simple::default());
+                let simples = self.simples.last_mut().unwrap();
+                simples.codes[0] = next;
+                simples.chars[0] = ch;
+                simples.count = 1;
+                self.keys[usize::from(code)] = new_key.into();
+            }
+            FullKey::Simple(idx) if usize::from(self.simples[usize::from(idx)].count) < SHORT => {
+                let nexts = &mut self.simples[usize::from(idx)];
+                let nidx = usize::from(nexts.count);
+                nexts.chars[nidx] = ch;
+                nexts.codes[nidx] = next;
+                nexts.count += 1;
+            }
+            FullKey::Simple(idx) => {
+                let new_key = FullKey::Full(self.complex.len() as u16);
+                let simples = &self.simples[usize::from(idx)];
+                self.complex.push(Full {
+                    char_continuation: [Code::max_value(); 256],
+                });
+                let full = self.complex.last_mut().unwrap();
+                for (&pch, &pcont) in simples.chars.iter().zip(simples.codes.iter()) {
+                    full.char_continuation[usize::from(pch)] = pcont;
+                }
+                self.keys[usize::from(code)] = new_key.into();
+            }
+            FullKey::Full(idx) => {
+                let full = &mut self.complex[usize::from(idx)];
+                full.char_continuation[usize::from(ch)] = next;
+            }
+        }
+        self.keys.push(FullKey::NoSuccessor.into());
+        next
+    }
+}
+
+impl Default for FullKey {
+    fn default() -> Self {
+        FullKey::NoSuccessor
+    }
+}
+
+impl Default for Simple {
+    fn default() -> Self {
+        Simple {
+            codes: [0; SHORT],
+            chars: [0; SHORT],
+            count: 0,
+        }
+    }
+}
+
+impl From<CompressedKey> for FullKey {
+    fn from(CompressedKey(key): CompressedKey) -> Self {
+        match (key >> MAX_CODESIZE) & 0xf {
+            0 => FullKey::Full(key & 0xfff),
+            1 => FullKey::Simple(key & 0xfff),
+            _ => FullKey::NoSuccessor,
+        }
+    }
+}
+
+impl From<FullKey> for CompressedKey {
+    fn from(full: FullKey) -> Self {
+        CompressedKey(match full {
+            FullKey::NoSuccessor => 0x2000,
+            FullKey::Simple(code) => 0x1000 | code,
+            FullKey::Full(code) => code,
+        })
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::{BitOrder, Encoder, LzwError, LzwStatus};
+    use crate::alloc::vec::Vec;
+    use crate::decode::Decoder;
+    #[cfg(feature = "std")]
+    use crate::StreamBuf;
+
+    #[test]
+    fn invalid_input_rejected() {
+        const BIT_LEN: u8 = 2;
+        let ref input = [0, 1 << BIT_LEN /* invalid */, 0];
+        let ref mut target = [0u8; 128];
+        let mut encoder = Encoder::new(BitOrder::Msb, BIT_LEN);
+
+        encoder.finish();
+        // We require simulation of normality, that is byte-for-byte compression.
+        let result = encoder.encode_bytes(input, target);
+        assert!(if let Err(LzwError::InvalidCode) = result.status {
+            true
+        } else {
+            false
+        });
+        assert_eq!(result.consumed_in, 1);
+
+        let fixed = encoder.encode_bytes(&[1, 0], &mut target[result.consumed_out..]);
+        assert!(if let Ok(LzwStatus::Done) = fixed.status {
+            true
+        } else {
+            false
+        });
+        assert_eq!(fixed.consumed_in, 2);
+
+        // Okay, now test we actually fixed it.
+        let ref mut compare = [0u8; 4];
+        let mut todo = &target[..result.consumed_out + fixed.consumed_out];
+        let mut free = &mut compare[..];
+        let mut decoder = Decoder::new(BitOrder::Msb, BIT_LEN);
+
+        // Decode with up to 16 rounds, far too much but inconsequential.
+        for _ in 0..16 {
+            if decoder.has_ended() {
+                break;
+            }
+
+            let result = decoder.decode_bytes(todo, free);
+            assert!(result.status.is_ok());
+            todo = &todo[result.consumed_in..];
+            free = &mut free[result.consumed_out..];
+        }
+
+        let remaining = { free }.len();
+        let len = compare.len() - remaining;
+        assert_eq!(todo, &[]);
+        assert_eq!(compare[..len], [0, 1, 0]);
+    }
+
+    #[test]
+    #[should_panic]
+    fn invalid_code_size_low() {
+        let _ = Encoder::new(BitOrder::Msb, 1);
+    }
+
+    #[test]
+    #[should_panic]
+    fn invalid_code_size_high() {
+        let _ = Encoder::new(BitOrder::Msb, 14);
+    }
+
+    fn make_decoded() -> Vec<u8> {
+        const FILE: &'static [u8] =
+            include_bytes!(concat!(env!("CARGO_MANIFEST_DIR"), "/Cargo.lock"));
+        return Vec::from(FILE);
+    }
+
+    #[test]
+    #[cfg(feature = "std")]
+    fn into_stream_buffer_no_alloc() {
+        let encoded = make_decoded();
+        let mut encoder = Encoder::new(BitOrder::Msb, 8);
+
+        let mut output = vec![];
+        let mut buffer = [0; 512];
+        let mut istream = encoder.into_stream(&mut output);
+        istream.set_buffer(&mut buffer[..]);
+        istream.encode(&encoded[..]).status.unwrap();
+
+        match istream.buffer {
+            Some(StreamBuf::Borrowed(_)) => {}
+            None => panic!("Decoded without buffer??"),
+            Some(StreamBuf::Owned(_)) => panic!("Unexpected buffer allocation"),
+        }
+    }
+
+    #[test]
+    #[cfg(feature = "std")]
+    fn into_stream_buffer_small_alloc() {
+        struct WriteTap<W: std::io::Write>(W);
+        const BUF_SIZE: usize = 512;
+
+        impl<W: std::io::Write> std::io::Write for WriteTap<W> {
+            fn write(&mut self, buf: &[u8]) -> std::io::Result<usize> {
+                assert!(buf.len() <= BUF_SIZE);
+                self.0.write(buf)
+            }
+            fn flush(&mut self) -> std::io::Result<()> {
+                self.0.flush()
+            }
+        }
+
+        let encoded = make_decoded();
+        let mut encoder = Encoder::new(BitOrder::Msb, 8);
+
+        let mut output = vec![];
+        let mut istream = encoder.into_stream(WriteTap(&mut output));
+        istream.set_buffer_size(512);
+        istream.encode(&encoded[..]).status.unwrap();
+
+        match istream.buffer {
+            Some(StreamBuf::Owned(vec)) => assert!(vec.len() <= BUF_SIZE),
+            Some(StreamBuf::Borrowed(_)) => panic!("Unexpected borrowed buffer, where from?"),
+            None => panic!("Decoded without buffer??"),
+        }
+    }
+
+    #[test]
+    #[cfg(feature = "std")]
+    fn reset() {
+        let encoded = make_decoded();
+        let mut encoder = Encoder::new(BitOrder::Msb, 8);
+        let mut reference = None;
+
+        for _ in 0..2 {
+            let mut output = vec![];
+            let mut buffer = [0; 512];
+            let mut istream = encoder.into_stream(&mut output);
+            istream.set_buffer(&mut buffer[..]);
+            istream.encode_all(&encoded[..]).status.unwrap();
+
+            encoder.reset();
+            if let Some(reference) = &reference {
+                assert_eq!(output, *reference);
+            } else {
+                reference = Some(output);
+            }
+        }
+    }
+}