Parameters of DStorage.CreateCompressionCodec()

[sk-zk]

I want to decompress a byte[] compressed with GDeflate. The documentation for DirectStorage contains the following sample code for instantiating a GDeflate codec:

com_ptr<IDStorageCompressionCodec> compression;
constexpr uint32_t DEFAULT_THREAD_COUNT = 0;
check_hresult(DStorageCreateCompressionCodec(DSTORAGE_COMPRESSION_FORMAT_GDEFLATE, DEFAULT_THREAD_COUNT, IID_PPV_ARGS(compression.put())));

How do I translate this to Silk? This is as far as I've gotten:

var api = DStorage.GetApi();
var guid = typeof(IDStorageCompressionCodec).GUID;
unsafe
{
    var result = api.CreateCompressionCodec(
        CompressionFormat.CompressionFormatGdeflate,
        0,
        &guid,
        /* what do I put here? */);
}

Is that the correct riid? And what do I pass for the ppv parameter?