module Protobuf::Decoder

def read_varint(stream)
  read_method = stream.respond_to?(:readbyte) ? :readbyte : :readchar
  value = index = 0
  begin
    byte = stream.__send__(read_method)
    value |= (byte & 0x7f) << (7 * index)
    index += 1
  end while (byte & 0x80).nonzero?
  value
end