public long readRawVarint64() throws IOException
    {
        int shift = 0;
        long result = 0;
        while (shift < 64)
        {
            final byte b = readRawByte();
            result |= (long) (b & 0x7F) << shift;
            if ((b & 0x80) == 0)
            {
                return result;
            }
            shift += 7;
        }
        throw ProtobufException.malformedVarint();
    }
Read a raw Varint from the stream.
protostuff-core/src/main/java/io/protostuff/CodedInput.java