mst.c

MANTIS是由科罗拉多大学开发的传感器网络嵌入式操作系统。 这是mantis的0.9.5版本的源码。

//  This file is part of MANTIS OS, Operating System
//  See http://mantis.cs.colorado.edu/
//
//  Copyright (C) 2003,2004,2005 University of Colorado, Boulder
//
//  This program is free software; you can redistribute it and/or
//  modify it under the terms of the mos license (see file LICENSE)

/**************************************************************************/
/* File:       mst.c                                             */
/* Author:     Anmol Sheth: [e-mail]                */
/*   Date: 11/12/04                                                       */
/*                                                                        */
/* MST protocol example                                                */
/**************************************************************************/

/** @file mst.c
 * @brief MST protocol example * @author Carl Hartung
 * @date Created: 11/12/2004
 */

#include <stdlib.h>
#include <string.h>

#include "led.h"
#include "node_id.h"
#include "mutex.h"
#include "mst.h"
#include "net.h"

uint8_t myDtb; // my distance (hop count) to the base station
uint8_t myParentID; //upstream parent ID ( == rtable[0])
uint8_t myID;
uint8_t seqNo;
uint8_t beaconSeqNo;
uint8_t lstctrlfwd;   //the seqno of the last control pkt this node forwarded

#define MAX_DIAMETER_NETWORK 20
#define MAX_NODES 256   //1-byte address allows for 256 - 1 nodes(1 broadcaast)

uint8_t rtable [MAX_NODES] = {0}; 	//Downstream routing table indexed by 
				 	// dest address	
uint8_t mst_dtb(){   return myDtb;}
uint8_t mst_parent(){ return myParentID;}
void mst_proto_init()
{
  /* must be called by all protocols */
   net_proto_register(MST_PROTO_ID, mst_proto_send, mst_proto_recv, mst_proto_ioctl);
   myDtb = MAX_DIAMETER_NETWORK;
   myID = 0xFF;
   seqNo = 0;
   beaconSeqNo = 0;
   lstctrlfwd = 0;
}


/*Send function for MST
 * Required args: 
 *      uint8_t fromApp: 1 if sender is source
 *      uint8_t pkt_type: Type of packet
 *      uint8_t dest: Final destination of packet
 */


int8_t mst_proto_send(comBuf *pkt, va_list args)
{
   uint8_t fromApp;
   uint8_t pkt_type;
   uint8_t dest;
   
   fromApp = va_arg(args, int);
   pkt_type = va_arg(args, int);
   dest = va_arg(args, int);
   
   
   if (!fromApp) {
      //This is a packet in mid path.  Just send it off.
      return 0;
   }
   else{
      //It is a data packet from the application. Initialize it and send
      //it off

      //Sender DTB
      pkt->data[pkt->size] = myDtb;
      pkt->size++;
      
      
      //Last Hop
      pkt->data[pkt->size] = myID;
      pkt->size++;

      //Source address
      pkt->data[pkt->size] = myID;
      pkt->size++;

      //Destination address
      pkt->data[pkt->size] = dest; 
      pkt->size++;

      //Type
      pkt->data[pkt->size] = pkt_type;
      pkt->size++;

      //SeqNo 
      if (pkt_type == MST_CONTROL){  
      	pkt->data[pkt->size] = beaconSeqNo++;
      }
      else {
      	pkt->data[pkt->size] = seqNo++;
      }		
      pkt->size++;

      //DTB
      pkt->data[pkt->size] = myDtb;
      pkt->size++;

      //TTL
      pkt->data[pkt->size] = 10;
      pkt->size++;

      //Next Hop
      pkt->data[pkt->size] = rtable[dest];
      
      pkt->size++;
      /*printf("Initial Send Src:%C Dest:%C Type:%C LH:%C NH:%C Seq:%C Size:%C\n", 
	     pkt->data[pkt->size-7],
	     pkt->data[pkt->size-6],
	     pkt->data[pkt->size-5],
	     pkt->data[pkt->size-8],
	     pkt->data[pkt->size-1],
	     pkt->data[pkt->size-4],
	     pkt->size);*/
      return 1;
   }
}


boolean mst_proto_recv(comBuf *pkt, uint8_t **footer, uint8_t port)
{
  
   
   
   uint8_t nxt_hop, ttl, pkt_dtb, seqno, type, dest, src, lst_hop;
   //We have received a packet from the net_thread. We need to check
   //whether it is a control or a data packet and send it off to the
   //higher app layer.

   
   // We extract Next Hop, TTL, DTB, SeqNo, type, Dest, Src, and Last Hop
   nxt_hop = pkt->data[pkt->size-1];
   ttl = pkt->data[pkt->size-2];
   pkt_dtb = pkt->data[pkt->size-3];
   seqno = pkt->data[pkt->size-4];
   type = pkt->data[pkt->size-5];
   dest = pkt->data[pkt->size-6];
   src = pkt->data[pkt->size-7];
   lst_hop = pkt->data[pkt->size-8];
   
  
   
   //printf("Recv myID:%C Src:%C Dest:%C Type:%C LH:%C Seq:%C Size:%C port:%C\n",myID,src,dest,type,lst_hop,seqno, pkt->size, port);
   if (type == MST_CONTROL) {
     
     //Control packet update the Dtb if needed. Change the parent
     //only if the new DTB is < Current DTB. Do not change otherwise
     //(prevent ping-ponging between 2 parent nodes with same DTB)
     
     //Node lost its parent and has no better candidate
     //myDtb = max to find best available parent
     //(seqno - 2): 2 missed cycles of broadcast to indicate a lost link 
     if (seqno - 2 > lstctrlfwd && src != myID){
       myDtb = MAX_DIAMETER_NETWORK;
     }

     //If control packet is from parent or better, store seqno and forward
     if((pkt_dtb + 1 < myDtb || (pkt_dtb + 1 == myDtb && lst_hop == rtable[src])) && ttl != 1) {
	
	//Update routing table
	rtable[src] = lst_hop;
	     
         lstctrlfwd = seqno;   
       
         //Found a better path
	 if(pkt_dtb + 1 < myDtb) {
	    myDtb = pkt_dtb +1;
	   
	 }

	 //Dec TTL
	 pkt->data[pkt->size-2] = ttl - 1;
	 //Inc DTB
	 pkt->data[pkt->size-3] = myDtb ;
	 //Change the last hop address
	 pkt->data[pkt->size-8] = myID;
    	 
	 net_send(pkt, MST_PROTO_ID, port, false, type, dest);
	    
      }
      //A return value of 0 causes the net thread to return the buffer
      //to the common pool.
      return 0;
   }
   if (type == MST_DATA) {
      //Data frame so we need to send it up to the app only if the
      //dest addr == myaddr. If not check if I am on the path and
      //forward it upstream if necessary
     
      
      if(dest == myID) { //dest is the final dest of the packet
	 //Update routing table
	 
	 rtable[src] = lst_hop;
	      
	 /* must be called if the protocol wants to try to send the packet
	  * to the app */
	 
	 
	 return is_app_waiting_on(port);
      }
      else  {
	 //I may be on the path. net_send would check if I am on the
	 //path and forward the packet upstream if necessary.
	 
	 if(ttl != 1 && nxt_hop == myID) {
	    //Update routing table
	    rtable[src] = lst_hop;
		 
	    //need to forward the packet upstream
	    pkt->data[pkt->size-8] = myID;   //add self as last hop
	    pkt->data[pkt->size-3] = pkt_dtb - 1; //decrement the DtB
	    pkt->data[pkt->size-1] = rtable[dest]; //change the next hop ID
	    
	    pkt->data[pkt->size-2] = ttl - 1; //decrement the ttl
	
	    net_send(pkt, MST_PROTO_ID, port, false, type, dest);
	    return 0; // Free the buffer after sending it out
	 }
      }
   }
   // unknown type, shouldn't get here
   return 0;
}

int8_t mst_proto_ioctl(uint8_t request, va_list args)
{
   switch(request) {
   case SET_ADDR:
      myID = va_arg(args, int);
      printf("Set my ID to %C\n", myID);
      break;
   case SET_DTB:
      myDtb = va_arg(args, int);
      printf("Set my DTB to %C\n", myDtb);
      break;
   default:
      return 0;
      break;
   }
   return 0;
}