--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/jdk.jdi/share/classes/com/sun/tools/jdi/Packet.java	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,132 @@
+/*
+ * Copyright (c) 1998, 2017, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package com.sun.tools.jdi;
+
+import java.io.IOException;
+
+public class Packet extends Object {
+    public final static short NoFlags = 0x0;
+    public final static short Reply = 0x80;
+    public final static short ReplyNoError = 0x0;
+
+    static int uID = 1;
+    final static byte[] nullData = new byte[0];
+
+    // Note! flags, cmdSet, and cmd are all byte values.
+    // We represent them as shorts to make them easier
+    // to work with.
+    int id;
+    short flags;
+    short cmdSet;
+    short cmd;
+    short errorCode;
+    byte[] data;
+    volatile boolean replied = false;
+
+    /**
+     * Return byte representation of the packet
+     */
+    public byte[] toByteArray() {
+        int len = data.length + 11;
+        byte b[] = new byte[len];
+        b[0] = (byte)((len >>> 24) & 0xff);
+        b[1] = (byte)((len >>> 16) & 0xff);
+        b[2] = (byte)((len >>>  8) & 0xff);
+        b[3] = (byte)((len >>>  0) & 0xff);
+        b[4] = (byte)((id >>> 24) & 0xff);
+        b[5] = (byte)((id >>> 16) & 0xff);
+        b[6] = (byte)((id >>>  8) & 0xff);
+        b[7] = (byte)((id >>>  0) & 0xff);
+        b[8] = (byte)flags;
+        if ((flags & Packet.Reply) == 0) {
+            b[9] = (byte)cmdSet;
+            b[10] = (byte)cmd;
+        } else {
+            b[9] = (byte)((errorCode >>>  8) & 0xff);
+            b[10] = (byte)((errorCode >>>  0) & 0xff);
+        }
+        if (data.length > 0) {
+            System.arraycopy(data, 0, b, 11, data.length);
+        }
+        return b;
+    }
+
+    /**
+     * Create a packet from its byte array representation
+     */
+    public static Packet fromByteArray(byte b[]) throws IOException {
+        if (b.length < 11) {
+            throw new IOException("packet is insufficient size");
+        }
+
+        int b0 = b[0] & 0xff;
+        int b1 = b[1] & 0xff;
+        int b2 = b[2] & 0xff;
+        int b3 = b[3] & 0xff;
+        int len = ((b0 << 24) | (b1 << 16) | (b2 << 8) | (b3 << 0));
+        if (len != b.length) {
+            throw new IOException("length size mis-match");
+        }
+
+        int b4 = b[4] & 0xff;
+        int b5 = b[5] & 0xff;
+        int b6 = b[6] & 0xff;
+        int b7 = b[7] & 0xff;
+
+        Packet p = new Packet();
+        p.id = ((b4 << 24) | (b5 << 16) | (b6 << 8) | (b7 << 0));
+
+        p.flags = (short)(b[8] & 0xff);
+
+        if ((p.flags & Packet.Reply) == 0) {
+            p.cmdSet = (short)(b[9] & 0xff);
+            p.cmd = (short)(b[10] & 0xff);
+        } else {
+            short b9 = (short)(b[9] & 0xff);
+            short b10 = (short)(b[10] & 0xff);
+            p.errorCode = (short)((b9 << 8) + (b10 << 0));
+        }
+
+        p.data = new byte[b.length - 11];
+        System.arraycopy(b, 11, p.data, 0, p.data.length);
+        return p;
+    }
+
+    Packet() {
+        id = uniqID();
+        flags = NoFlags;
+        data = nullData;
+    }
+
+    static synchronized private int uniqID() {
+        /*
+         * JDWP spec does not require this id to be sequential and
+         * increasing, but our implementation does. See
+         * VirtualMachine.notifySuspend, for example.
+         */
+        return uID++;
+    }
+}