Crate lzma_turbo 

LZMA and LZMA2 decoding, ported from the 7-Zip reference decoder.

The decoder in this crate is a port of Igor Pavlov’s LzmaDec.c and Lzma2Dec.c from the LZMA SDK (public domain), kept structurally faithful to the original so that its speed carries over: one large decode loop with the range coder, probability base and dictionary pointers held in locals, limits checked once per symbol under a caller-guaranteed margin, and a separate careful path for the bytes near buffer edges.

The encoder is a port of the same SDK’s LzFind.c, LzmaEnc.c and Lzma2Enc.c, and is bit-exact with it. See docs/encoder.md.

Example

The reader adapters need std; without it the example below cannot run, so it is compiled only when the std feature is on.

use std::fs::File;
use std::io::Read;
use lzma_turbo::LzmaReader;

let mut out = Vec::new();
LzmaReader::new(File::open("archive.lzma")?)?.read_to_end(&mut out)?;

Provenance

Derived from C/LzmaDec.c and C/Lzma2Dec.c of the LZMA SDK, which are in the public domain. Each ported function names its C counterpart in a comment.

Re-exports

pub use xz::XzAdaptiveDecoder;

pub use xz::XzError;

pub use xz::XzOptions;

pub use xz::XzParallelReader;

pub use xz::XzReader;

Modules

checksum

Checksums computed where the bytes are, not where they are written.

crc

The checksums the container formats around LZMA use.

crypto

SHA-256, as the xz container uses it.

filters

The in-place converters that sit in front of an LZMA2 stream: the branch/call/jump family (bcj) and the delta filter (delta).

run

Bounded dictionary decoding of one independently reset LZMA2 run.

xz

The .xz container.

Structs

AdaptiveLedger

Where the decoder’s memory is, and why it last held work back: what a caller tuning its read-ahead, or a harness explaining a decode, reads to see the mechanism rather than guess at it.

BlockChecks

What one worker computed for one output block.

ChecksumPlan

What to compute, and where the consumer’s boundaries fall.

Lzma2AdaptiveDecoder

An LZMA2 decoder that is fed input and switches between single- and multi-threaded decoding while it runs.

Lzma2Decoder

LZMA2 decoder.

Lzma2Encoder

An LZMA2 encoder: blocks of LZMA2 chunks, ending in the end-of-stream control byte.

Lzma2MtOptions

How a multi-threaded decode is to be run.

Lzma2ParallelDecoder

A prepared multi-threaded LZMA2 decode.

Lzma2ParallelReader

Streaming multi-threaded LZMA2 decoder over any Read.

Lzma2PushEncoder

A raw LZMA2 stream, one solid block, encoded from pushed input.

Lzma2Reader

Streaming LZMA2 decoder over any Read.

Lzma2Run

One independently decodable region of an LZMA2 stream.

Lzma2RunChunks

The chunks of one Lzma2Run, counted and sized by kind.

Lzma2RunScanner

Incremental discovery of the runs in an LZMA2 stream.

Lzma2Writer

Writes a raw LZMA2 stream, the payload an .xz block or a 7z coder holds.

LzmaAloneHeader

A parsed .lzma header.

LzmaDecoder

LZMA1 decoder.

LzmaEncProps

C: CLzmaEncProps. The affinity fields are not carried - nothing in this port pins a thread - but numThreads is: it is what turns on the threaded match finder.

LzmaEncoder

An LZMA1 encoder.

LzmaProps

Parsed LZMA properties: the literal-context, literal-position and position bit counts, and the dictionary size.

LzmaPushEncoder

A raw LZMA stream encoded from pushed input.

LzmaReader

Streaming LZMA1 decoder over any Read.

LzmaWriter

Writes a .lzma (LZMA-Alone) file.

NormalizedProps

An LzmaEncProps with every default resolved.

Progress

What one decode call did.

Segment

One piece of decoded output and its checksum.

SliceStream

A SeqInStream over a slice already in memory.

XzEncoder

The .xz writer, behind the xz feature. The .xz writer, behind the xz feature. The .xz writer, behind the xz feature. An .xz stream writer.

XzWriter

The .xz writer, behind the xz feature. The .xz writer, behind the xz feature. The .xz writer, behind the xz feature. Writes an .xz stream.

Enums

Checksum

Which checksum the decoder should compute for each block it produces.

DrainStatus

Why Lzma2AdaptiveDecoder::drain stopped.

Error

Reasons a decode or encode call can fail.

FinishMode

Whether the current output buffer is expected to cover the end of the stream.

MatchFinderKind

Which match finder to use.

SegmentCheck

The checksum of one segment, at whichever width was asked for.

Status

Where a decode call stopped.

XzErrorKind

Why an xz read failed.

Constants

ASM_LOOP

Whether this build decodes with the assembly loop ported from the LZMA SDK’s Asm/ tree rather than with the portable Rust port of the C loop. False without the asm feature and on every target that has no such loop.

BLOCK_SIZE_AUTO

C: LZMA2_ENC_PROPS_BLOCK_SIZE_AUTO. The size auto_block_size derives from the dictionary.

BLOCK_SIZE_SOLID

C: LZMA2_ENC_PROPS_BLOCK_SIZE_SOLID. One block for the whole input.

DEFAULT_BLOCK_SIZE

The .xz writer, behind the xz feature. The .xz writer, behind the xz feature. The .xz writer, behind the xz feature. The default block size: what one block may decode to before the writer starts another.

LZMA_ALONE_HEADER_SIZE

Size of a .lzma header in bytes.

LZMA_MATCH_LEN_MAX

C: LZMA_MATCH_LEN_MAX.

LZMA_MATCH_LEN_MIN

C: LZMA_MATCH_LEN_MIN.

LZMA_PROPS_SIZE

C: LZMA_PROPS_SIZE (C/LzmaDec.h).

LZMA_REQUIRED_INPUT_MAX

C: LZMA_REQUIRED_INPUT_MAX (C/LzmaDec.h). Number of input bytes needed for the worst-case single LZMA symbol; the margin the fast loop relies on.

VERSION

Crate version, for consumers that record which decoder produced an output.

Traits

SeqInStream

A byte source the match finder reads its window from.

SeqOutStream

The output a range encoder flushes into.

Functions

auto_block_size

The block size Lzma2EncProps_Normalize derives from a dictionary size.

encode_lzma2

Encode src as a raw LZMA2 stream, returning it with its property byte.

encode_lzma2_mt

Encode src as a raw LZMA2 stream with block threads.

encode_lzma_alone

Encode src as a .lzma (LZMA-Alone) file.

encode_xz

The .xz writer, behind the xz feature. The .xz writer, behind the xz feature. The .xz writer, behind the xz feature. Encode src as a whole .xz stream.

encode_xz_mt

The .xz writer, behind the xz feature. The .xz writer, behind the xz feature. The .xz writer, behind the xz feature. Encode src as a whole .xz stream, compressing blocks in parallel.

encode_xz_with_filters

The .xz writer, behind the xz feature. The .xz writer, behind the xz feature. The .xz writer, behind the xz feature. Encode src as a whole .xz stream through a filter chain.

mt_memory_estimate

An upper bound on the memory Lzma2ParallelDecoder would allocate for these options, without building one.

run_boundaries

The runs of an LZMA2 stream in a seekable source, without decoding it.