private void refreshBuffer() throws IOException
    {
        if (output == null)
        {
            // We're writing to a single buffer.
            throw new OutOfSpaceException();
        }

        // Since we have an output stream, this is our buffer
        // and buffer offset == 0
        output.write(buffer, 0, position);
        position = 0;
    }
Internal helper that writes the current buffer to the output. The buffer position is reset to its initial value
when this returns.
protostuff-core/src/test/java/io/protostuff/CodedOutput.java