FastLZMA2Net 1.1.0 (original) (raw)

Fast LZMA2 Compression algorithm Wrapper for .NET

Change Log

With respect to Fast LZMA2 repo

Requirements

.NET 8 / .NET 10

x86 may have potential malfunction.

Installation

PM> Install-Package FastLZMA2Net

API Overview

Usage

Simple compression

byte[] origin       = File.ReadAllBytes(sourceFilePath);
byte[] compressed   = FL2.Compress(origin, level: 6);
byte[] decompressed = FL2.Decompress(compressed);

ReadOnlySpan<byte> overloads are available to avoid a copy when data is already in a pooled or stack-allocated buffer:

ReadOnlySpan<byte> span = ...;
byte[] compressed = FL2.Compress(span, level: 6);

Multi-threaded one-shot compression

byte[] compressed   = FL2.CompressMT(origin, level: 6, nbThreads: 0);  // 0 = all cores
byte[] decompressed = FL2.DecompressMT(compressed, nbThreads: 0);

Context Compression

Reuse a Compressor / Decompressor to amortize context-allocation cost across many calls (e.g. batches of small files).

using Compressor compressor = new(nbThreads: 0) { CompressLevel = 10 };
byte[] c1 = compressor.Compress(data1);
byte[] c2 = compressor.Compress(data2);

using Decompressor decompressor = new();
byte[] d1 = decompressor.Decompress(c1);
byte[] d2 = decompressor.Decompress(c2);

Async compression

using Compressor compressor = new(nbThreads: 0) { CompressLevel = 6 };
byte[] compressed = await compressor.CompressAsync(origin, cancellationToken);

using Decompressor decompressor = new();
byte[] decompressed = await decompressor.DecompressAsync(compressed, cancellationToken);

File-to-file compression (no memory copy)

Uses memory-mapped I/O — no full read into managed memory.

using Compressor compressor = new(nbThreads: 0) { CompressLevel = 6 };
nuint compressedBytes = compressor.Compress(sourceFilePath, destFilePath);

Streaming Compression — small data (< 2 GB)

// compress
using MemoryStream ms = new();
using (CompressStream cs = new(ms))
    cs.Write(origin);
byte[] compressed = ms.ToArray();

// decompress
using MemoryStream recoveryStream = new();
using (DecompressStream ds = new(new MemoryStream(compressed)))
    ds.CopyTo(recoveryStream);
byte[] decompressed = recoveryStream.ToArray();

Streaming Compression — large files (> 2 GB)

.NET byte arrays are limited to ~2 GB. For larger payloads use streaming with Append.

Call Write() as many times as needed to feed data in chunks. The stream is automatically finalised when Dispose() is called (i.e. at the end of a using block). You may also call Flush() explicitly.

Compress

byte[] buffer = new byte[64 * 1024 * 1024]; // 64 MB read buffer

using FileStream sourceFile     = File.OpenRead(sourceFilePath);
using FileStream compressedFile = File.Create(compressedFilePath);
using (CompressStream cs = new(compressedFile))
{
    cs.CompressLevel = 10;
    long offset = 0;
    while (offset < sourceFile.Length)
    {
        int bytesToRead = (int)Math.Min(buffer.Length, sourceFile.Length - offset);
        int bytesRead   = sourceFile.Read(buffer, 0, bytesToRead);
        cs.Write(buffer, 0, bytesRead);
        offset += bytesRead;
    }
}   // Dispose() automatically finalises the stream and writes the end checksum.

Decompress

using FileStream compressedFile = File.OpenRead(compressedFilePath);
using FileStream recoveryFile   = File.Create(decompressedFilePath);
using (DecompressStream ds = new(compressedFile))
{
    ds.CopyTo(recoveryFile);
}

Fine-tune compression parameters

using Compressor compressor = new(nbThreads: 0) { CompressLevel = 10 };
compressor.SetParameter(FL2Parameter.FastLength, 48);
compressor.SetParameter(FL2Parameter.SearchDepth, 60);

Estimate memory usage

// By compression level and thread count
nuint size = FL2.EstimateCompressMemoryUsage(compressionLevel: 10, nbThreads: 8);

// Using an existing context's settings
using Compressor compressor = new(nbThreads: 4) { CompressLevel = 10 };
nuint size = FL2.EstimateCompressMemoryUsage(compressor.CompressLevel, compressor.ThreadCount);

Find decompressed size

// From a byte array
nuint size = FL2.FindDecompressedSize(compressedData);

// From a file path (uses memory-mapped I/O — no full read into memory)
nuint size = FL2.FindDecompressedSize(compressedFilePath);

Bug report

Open an issue.

Contribution

PR is welcome.