static byte[] DecompressPacket6D(byte[] data)
{
    // Move up to the subpacket data we need
    int dataPos = 0x10;
    int dataEnd;

    byte[] dec = new byte[8688 * 4];
    int decPos = 0;
    byte[] tmp = new byte[10000];

    int decompressedSize = BitConverter.ToInt32(data, dataPos);
    dataPos += 4;
    int compressedSize = BitConverter.ToInt32(data, dataPos);
    dataPos += 4;

    dataEnd = dataPos + compressedSize;

    byte u8;
    int v5;
    uint v6;
    int v18;
    byte v19;
    int v21;
    int v22;
    int v23;
    int v33;
    uint v34;
    uint v39;
    int v40;
    uint v41;
    int v42;
    uint v43;

    v5 = 4078;
    v6 = 0;

    while (true)
    {
        while (true)
        {
            v6 >>= 1;

            if ((v6 & 0x100) == 0)
            {
                if (dataPos >= dataEnd)
                {
                    break;
                }

                v6 = (uint)(data[dataPos] | 0xFF00);
                dataPos += 1;
            }

            if ((v6 & 1) == 0)
            {
                break;
            }

            if ((dataPos + 1) > dataEnd)
            {
                break;
            }

            u8 = data[dataPos];
            dataPos += 1;

            dec[decPos] = u8;
            decPos += 1;
            tmp[v5] = u8;
            v5 = (v5 + 1) & 0xFFF;
        }

        // There is a goto (to outside of the loop) in the decompiled code
        // Check it's condition again here so we can exit the outer loop early, too.
        if (dataPos >= dataEnd)
        {
            break;
        }

        if ((dataPos + 2) > dataEnd)
        {
            break;
        }

        v18 = data[dataPos];
        dataPos += 1;
        v19 = data[dataPos];
        dataPos += 1;

        v21 = 16 * (v19 & 0xF0) | v18;
        v39 = (uint)((v19 & 0xF) + 2);
        v41 = 0;

        if (v39 >= 4)
        {
            v43 = (uint)((v19 & 0xF) - 2);
            v40 = v21;
            v42 = v21;
            v22 = v21 + 2;
            v23 = v21 + 1;

            do
            {
                u8 = tmp[v21 & 0xFFF];
                dec[decPos] = u8;
                decPos += 1;
                tmp[v5] = u8;
                v5 = ((v5 + 1) & 0xFFF);
                v21 += 1;

                u8 = tmp[v21 & 0xFFF];
                dec[decPos] = u8;
                decPos += 1;
                tmp[v5] = u8;
                v5 = ((v5 + 1) & 0xFFF);
                v21 += 1;

                u8 = tmp[v21 & 0xFFF];
                dec[decPos] = u8;
                decPos += 1;
                tmp[v5] = u8;
                v5 = ((v5 + 1) & 0xFFF);
                v21 += 1;

                v22 += 3;
                v23 += 3;
                v41 += 3;
                v42 += 3;
            } while (v41 <= v43);

            v21 = v40;
        }

        v33 = (int)(v41 + v21);
        v34 = v41;
        do
        {
            u8 = tmp[v33 & 0xFFF];
            dec[decPos] = u8;
            decPos += 1;
            tmp[v5] = u8;
            v5 = ((v5 + 1) & 0xFFF);

            ++v33;
            ++v34;
        } while (v34 <= v39);
    }

    if (decPos != decompressedSize)
    {
        Console.WriteLine("Decompressed data size mismatch");
        return null;
    }

    Array.Resize(ref dec, decPos);
    return dec;
}