capnproto-java-rpc/runtime/src/main/java/org/capnproto/Serialize.java

package org.capnproto;

import java.io.IOException;
import java.nio.channels.WritableByteChannel;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;

public final class Serialize {

    public static void writeMessage(WritableByteChannel outputChannel,
                                    MessageBuilder message) throws IOException {
        ByteBuffer[] segments = message.getSegmentsForOutput();
        int tableSize = (segments.length + 2) & (~1);

        ByteBuffer table = ByteBuffer.allocate(4 * tableSize);
        table.order(ByteOrder.LITTLE_ENDIAN);

        table.putInt(0, segments.length - 1);

        for (int i = 0; i < segments.length; ++i) {
            table.putInt(4 * (i + 1), segments[i].limit() / 8);
        }

        // Any padding is already zeroed.
        while (table.hasRemaining()) {
            outputChannel.write(table);
        }

        for (ByteBuffer buffer : segments) {
            while(buffer.hasRemaining()) {
                outputChannel.write(buffer);
            }
        }
    }
}