COM.LZ4

COM.LZ4 provides LZ4 compression and decompression bindings for ActionScript 3 (AVM2), built using a native SWC. It currently implements block and stream operations from lz4.h, with partial support for lz4frame.h compression.

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⚡ Performance:
COM.LZ4 is multiple times faster than any built-in Flash/AS3 compression methods
(such as ByteArray.compress() using zlib or deflate).
This makes it ideal for real-time data streaming, multiplayer games, and large asset handling.

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Features

• ✅ Block-level compression and decompression
• ✅ Stream compression and decompression support
• ✅ Frame compression support
• ✅ Integration with ByteArray for seamless AS3 use
• ✅ Built from native LZ4 sources (lib/)

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Example

package
{
    import flash.display.Sprite;
    import flash.utils.ByteArray;
    import com.lz4.*;

    public class Main extends Sprite
    {
        public function Main()
        {
            testLibBlockOps();
        }

        private function testLibBlockOps():void
        {
            function repeatString(str:String, times:int):String
            {
                return new Array(times + 1).join(str);
            }

            var a:ByteArray = new ByteArray();
            var b:ByteArray = new ByteArray();
            var c:ByteArray = new ByteArray();

            var input:String = repeatString("hello world! ", 10000);
            a.writeUTFBytes(input);
            a.position = 0;

            // Call native functions from com.lz4 SWC
            var compressedSize:int = com.lz4.compress(a, b, 5);
            var decompressedSize:int = com.lz4.decompress(b, c, a.length);

            trace("raw size: " + a.length);
            trace("compressed size: " + compressedSize);
            trace("decompressed length: " + decompressedSize);
            trace("data equals: " + (c.toString() == input));
        }
    }
}

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Build

Compiler used: https://github.com/crossbridge-community/crossbridge

build-exe.bat => builds native EXE test
build-swc.bat => builds SWC (com.lz4)

Output files are placed in /bin.

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TODO

Implement frame decompression support from lz4frame.h, as many third-party LZ4 libraries use framed streams for cross-platform compatibility.

Frame decompression requires additional logic - specifically, polling or checking when a ByteArray is ready to be processed.

Planned API additions:

// Check if the frame data in src is ready to decompress
function frameIsReady(frameHandlePtr:uint, src:ByteArray):int
// Returns:
//   >0  -> number of bytes to be consumed before ready
//   <0  -> invalid data
//   0   -> not ready yet

// Get frame length (if available)
function frameLength(frameHandlePtr:uint, src:ByteArray):int

// Decompress a complete frame into dest
function decompressFrame(frameHandlePtr:uint, src:ByteArray, dest:ByteArray):int
// Ensures src.position matches frameLength when done

// Compress a frame from src into dest
function compressFrame(frameHandlePtr:uint, src:ByteArray, dest:ByteArray):int

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License

This project integrates the official LZ4 and XXHASH libary which are BSD-licensed.