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Pure C# MiniLZO port

, 22 Dec 2006
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Fast stream compression using a ported minilzo for .NET.

Introduction

I was recently in a position where I needed to find a fast streamable compression solution.  The great source by Markus Oberhumer provided the answer. After using the C code for a while, I realized C#/.NET lacked a similar library, short of one I found which was commercial.

As a result, I decided to attempt a minimalistic port of MiniLZO compression and decompression into pure C#. At this point, the code uses unsafe/fixed blocks to best mimic the original minilzo implementation. A pure managed solution may be soon to follow (at the cost of speed).

The code has not been unit tested 100%, but all initial tests have been successful. If anyone finds any bugs, please report them so I may fix it. I also have not done any profiling of the speed yet, if anyone feels upto the task of comparing it against the C implementation.

Use of the code is relatively simple, here is a quick example.

Compression

byte[] original = File.ReadAllBytes("...");
byte[] destination;
MiniLZO.Compress(original, out destination);

Decompression

byte[] destination = ...; /* Resulting buffer from above */
byte[] original = new byte[x];
MiniLZO.Decompress(destination, original);

Note that with compression, the destination buffer will be assigned and trimmed to the correct size. With decompression, the "original" buffer must be preallocated with the correct original size. Also note that my implementation removed all use of goto from the original source, and replaces certain uses with OverflowExceptions.

License

This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

A list of licenses authors might use can be found here

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About the Author

Astaelan
Web Developer
Canada Canada
Short and simple, I'm a self contracted programmer, my strongest programming skills are in C/C++ and C#/.NET. I have a nack for porting C algorithms to C#.

Comments and Discussions

 
GeneralRe: Another such library... PinmemberAstaelan23-Dec-06 4:10 
GeneralRe: Another such library... Pinmemberomaurice23-Dec-06 4:32 
GeneralRe: Another such library... PinmemberAstaelan23-Dec-06 4:46 
GeneralRe: Another such library... PinmemberWorldNomad23-Dec-06 3:32 
GeneralRe: Another such library... Pinmemberomaurice23-Dec-06 4:00 
Generalwhy not adding the original size to the header of the buffer PinmemberUnruled Boy5-Nov-06 15:19 
GeneralRe: why not adding the original size to the header of the buffer PinmemberAstaelan6-Nov-06 17:01 
GeneralRe: why not adding the original size to the header of the buffer PinmemberSimmoTech6-Nov-06 20:44 
How should the original size be calculated from just the destination byte array (I don't know the LZO format)? I've done the size prepend for now but it would be nice to know.
 
Also, the M3_MAX_LEN and M1_MAX_OFFSET constants aren't used - is this just because this is a subset?
 
Thanks for the great code BTW!
 
Another change I made was to allow a maximum length to be specified as an optional parameter for the Compress routine. This is helpful if you have a MemoryStream where the internal buffer is available (via GetBuffer()) but now I can pass MemoryStream.Length and extract a compressed byte array directly.
 
Cheers
Simon
 
Cheers
Simon

GeneralRe: why not adding the original size to the header of the buffer PinmemberAstaelan6-Nov-06 21:12 
GeneralImpressive, but... Pinmemberwoudwijk4-Nov-06 1:11 
GeneralRe: Impressive, but... PinmemberAstaelan4-Nov-06 10:29 
GeneralAgreement PinmemberBehind The Scene22-Dec-06 12:44 

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