Initial version

code/machine/network.h

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+// network.h 
+//	Data structures to emulate a physical network connection.
+//	The network provides the abstraction of ordered, unreliable,
+//	fixed-size packet delivery to other machines on the network.
+//
+//	You may note that the interface to the network is similar to 
+//	the console device -- both are full duplex channels.
+//
+//  DO NOT CHANGE -- part of the machine emulation
+//
+// Copyright (c) 1992-1993 The Regents of the University of California.
+// All rights reserved.  See copyright.h for copyright notice and limitation 
+// of liability and disclaimer of warranty provisions.
+
+#ifndef NETWORK_H
+#define NETWORK_H
+
+#include "copyright.h"
+#include "utility.h"
+
+// Network address -- uniquely identifies a machine.  This machine's ID 
+//  is given on the command line.
+typedef int NetworkAddress;	 
+
+// The following class defines the network packet header.
+// The packet header is prepended to the data payload by the Network driver, 
+// before the packet is sent over the wire.  The format on the wire is:  
+//	packet header (PacketHeader)
+//	data (containing MailHeader from the PostOffice!)
+
+class PacketHeader {
+  public:
+    NetworkAddress to;		// Destination machine ID
+    NetworkAddress from;	// source machine ID
+    unsigned length;	 	// bytes of packet data, excluding the 
+				// packet header (but including the 
+				// MailHeader prepended by the post office)
+};
+
+#define MaxWireSize 	64	// largest packet that can go out on the wire
+#define MaxPacketSize 	(MaxWireSize - sizeof(struct PacketHeader))	
+				// data "payload" of the largest packet
+
+
+// The following class defines a physical network device.  The network
+// is capable of delivering fixed sized packets, in order but unreliably, 
+// to other machines connected to the network.
+//
+// The "reliability" of the network can be specified to the constructor.
+// This number, between 0 and 1, is the chance that the network will lose 
+// a packet.  Note that you can change the seed for the random number 
+// generator, by changing the arguments to RandomInit() in Initialize().
+// The random number generator is used to choose which packets to drop.
+
+class Network {
+  public:
+    Network(NetworkAddress addr, double reliability,
+  	  VoidFunctionPtr readAvailHandler, VoidFunctionPtr writeDoneHandler, void *callArg);
+				// Allocate and initialize network driver
+    ~Network();			// De-allocate the network driver data
+    
+    void Send(PacketHeader hdr, const void* data);
+    				// Send the packet data to a remote machine,
+				// specified by "hdr".  Returns immediately.
+    				// "writeHandler" is invoked once the next 
+				// packet can be sent.  Note that writeHandler 
+				// is called whether or not the packet is 
+				// dropped, and note that the "from" field of 
+				// the PacketHeader is filled in automatically 
+				// by Send().
+
+    PacketHeader Receive(void* data);
+    				// Poll the network for incoming messages.  
+				// If there is a packet waiting, copy the 
+				// packet into "data" and return the header.
+				// If no packet is waiting, return a header 
+				// with length 0.
+
+    void SendDone();		// Interrupt handler, called when message is 
+				// sent
+    void CheckPktAvail();	// Check if there is an incoming packet
+
+  private:
+    NetworkAddress ident;	// This machine's network address
+    double chanceToWork;	// Likelihood packet will be dropped
+    int sock;			// UNIX socket number for incoming packets
+    char sockName[32];		// File name corresponding to UNIX socket
+    VoidFunctionPtr writeHandler; // Interrupt handler, signalling next packet 
+				//      can be sent.  
+    VoidFunctionPtr readHandler;  // Interrupt handler, signalling packet has 
+				// 	arrived.
+    void *handlerArg;		// Argument to be passed to interrupt handler
+				//   (pointer to post office)
+    bool sendBusy;		// Packet is being sent.
+    bool packetAvail;		// Packet has arrived, can be pulled off of
+				//   network
+    PacketHeader inHdr;		// Information about arrived packet
+    char inbox[MaxPacketSize];  // Data for arrived packet
+};
+
+#endif // NETWORK_H