DOOM/ipx/IPXNET.C

// ipxnet.c

#include <stdio.h>
#include <stdlib.h>
#include <dos.h>
#include <string.h>
#include <process.h>
#include <values.h>

#include "ipxnet.h"

/*
==========================================================================
===

                              IPX PACKET DRIVER

==========================================================================
===
*/

packet_t        packets[NUMPACKETS];

nodeadr_t      nodeadr[MAXNETNODES+1];  // first is local, last is broadcast

nodeadr_t      remoteadr;               // set by each GetPacket

localadr_t          localadr;           // set at startup

extern int socketid;

void far (*IPX)(void);

long           localtime;          // for time stamp in packets
long           remotetime;

//===========================================================================

int OpenSocket(short socketNumber)
{
     _DX = socketNumber;
     _BX = 0;
     _AL = 0;
     IPX();
     if(_AL)
	  Error ("OpenSocket: 0x%x", _AL);
     return _DX;
}


void CloseSocket(short socketNumber)
{
     _DX = socketNumber;
     _BX = 1;
     IPX();
}

void ListenForPacket(ECB *ecb)
{
     _SI = FP_OFF(ecb);
     _ES = FP_SEG(ecb);
     _BX = 4;
     IPX();
     if(_AL)
          Error ("ListenForPacket: 0x%x", _AL);
}


void GetLocalAddress (void)
{
     _SI = FP_OFF(&localadr);
     _ES = FP_SEG(&localadr);
     _BX = 9;
     IPX();
}



/*
====================
=
= InitNetwork
=
====================
*/

void InitNetwork (void)
{
     int     i,j;

//
// get IPX function address
//
     _AX = 0x7a00;
     geninterrupt(0x2f);
     if(_AL != 0xff)
	  Error ("IPX not detected\n");
     IPX = MK_FP(_ES, _DI);


//
// allocate a socket for sending and receiving
//
     socketid = OpenSocket ( (socketid>>8) + ((socketid&255)<<8) );

     GetLocalAddress();

//
// set up several receiving ECBs
//
     memset (packets,0,NUMPACKETS*sizeof(packet_t));

     for (i=1 ; i<NUMPACKETS ; i++)
     {
          packets[i].ecb.ECBSocket = socketid;
          packets[i].ecb.FragmentCount = 1;
          packets[i].ecb.fAddress[0] = FP_OFF(&packets[i].ipx);
          packets[i].ecb.fAddress[1] = FP_SEG(&packets[i].ipx);
          packets[i].ecb.fSize = sizeof(packet_t)-sizeof(ECB);

          ListenForPacket (&packets[i].ecb);
     }

//
// set up a sending ECB
//
     memset (&packets[0],0,sizeof(packets[0]));

     packets[0].ecb.ECBSocket = socketid;
     packets[0].ecb.FragmentCount = 2;
     packets[0].ecb.fAddress[0] = FP_OFF(&packets[0].ipx);
     packets[0].ecb.fAddress[1] = FP_SEG(&packets[0].ipx);
     for (j=0 ; j<4 ; j++)
          packets[0].ipx.dNetwork[j] = localadr.network[j];
     packets[0].ipx.dSocket[0] = socketid&255;
     packets[0].ipx.dSocket[1] = socketid>>8;
     packets[0].ecb.f2Address[0] = FP_OFF(&doomcom.data);
     packets[0].ecb.f2Address[1] = FP_SEG(&doomcom.data);

// known local node at 0
     for (i=0 ; i<6 ; i++)
	  nodeadr[0].node[i] = localadr.node[i];

// broadcast node at MAXNETNODES
     for (j=0 ; j<6 ; j++)
          nodeadr[MAXNETNODES].node[j] = 0xff;
}


/*
====================
=
= ShutdownNetwork
=
====================
*/

void ShutdownNetwork (void)
{
	if (IPX)
			CloseSocket (socketid);
}


/*
==============
=
= SendPacket
=
= A destination of MAXNETNODES is a broadcast
==============
*/

void SendPacket (int destination)
{
     int             j;

// set the time
     packets[0].time = localtime;

// set the address
          for (j=0 ; j<6 ; j++)
               packets[0].ipx.dNode[j] = 
packets[0].ecb.ImmediateAddress[j] =
               nodeadr[destination].node[j];

// set the length (ipx + time + datalength)
     packets[0].ecb.fSize = sizeof(IPXPacket) + 4;
     packets[0].ecb.f2Size = doomcom.datalength + 4;

// send the packet
     _SI = FP_OFF(&packets[0]);
     _ES = FP_SEG(&packets[0]);
     _BX = 3;
     IPX();
     if(_AL)
          Error("SendPacket: 0x%x", _AL);

     while(packets[0].ecb.InUseFlag != 0)
     {
          // IPX Relinquish Control - polled drivers MUST have this here!
          _BX = 10;
          IPX();
     }
}


unsigned short ShortSwap (unsigned short i)
{
     return ((i&255)<<8) + ((i>>8)&255);
}

/*
==============
=
= GetPacket
=
= Returns false if no packet is waiting
=
==============
*/

int GetPacket (void)
{
     int             packetnum;
     int             i, j;
     long           besttic;
     packet_t       *packet;

// if multiple packets are waiting, return them in order by time

     besttic = MAXLONG;
     packetnum = -1;
     doomcom.remotenode = -1;

     for ( i = 1 ; i < NUMPACKETS ; i++)
     {
          if (packets[i].ecb.InUseFlag)
          {
               continue;
          }

          if (packets[i].time < besttic)
          {
               besttic = packets[i].time;
               packetnum = i;
          }
     }

     if (besttic == MAXLONG)
          return 0;                           // no packets

     packet = &packets[packetnum];

     if (besttic == -1 && localtime != -1)
     {
          ListenForPacket (&packet->ecb);
	  return 0;            	// setup broadcast from other game
     }

     remotetime = besttic;

//
// got a good packet
//
     if (packet->ecb.CompletionCode)
	  Error ("GetPacket: ecb.ComletionCode = 0x%x",packet->ecb.CompletionCode);

// set remoteadr to the sender of the packet
     memcpy (&remoteadr, packet->ipx.sNode, sizeof(remoteadr));
     for (i=0 ; i<doomcom.numnodes ; i++)
          if (!memcmp(&remoteadr, &nodeadr[i], sizeof(remoteadr)))
               break;
     if (i < doomcom.numnodes)
          doomcom.remotenode = i;
     else
     {
	  if (localtime != -1)
          {    // this really shouldn't happen
               ListenForPacket (&packet->ecb);
               return 0;
          }
     }

// copy out the data
     doomcom.datalength = ShortSwap(packet->ipx.PacketLength) - 38;
     memcpy (&doomcom.data, &packet->data, doomcom.datalength);

// repost the ECB
     ListenForPacket (&packet->ecb);

     return 1;
}