Is there any pure PHP implementation of LZMA

问题:

So I'm building a web app to decompress an LZMA compressed CSV file and then let the user edit it, when saved it will be recompressed.

I have the code to compress/decompress in C# using the 7-Zip LZMA SDK, but with my hosting plan I can't use exec() to call the exe.

Is there any pure php implementation of LZMA I could use? Or if not is there any way to convert the C# code into php code?