myrandomlfsr.nc.svn-base

802.15.4协议的实现

// $Id: RandomLFSR.nc,v 1.4 2003/10/07 21:46:37 idgay Exp $

/*									tab:4
 * "Copyright (c) 2000-2003 The Regents of the University  of California.  
 * All rights reserved.
 *
 * Permission to use, copy, modify, and distribute this software and its
 * documentation for any purpose, without fee, and without written agreement is
 * hereby granted, provided that the above copyright notice, the following
 * two paragraphs and the author appear in all copies of this software.
 * 
 * IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY FOR
 * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT
 * OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF THE UNIVERSITY OF
 * CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * 
 * THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
 * ON AN "AS IS" BASIS, AND THE UNIVERSITY OF CALIFORNIA HAS NO OBLIGATION TO
 * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS."
 *
 * Copyright (c) 2002-2003 Intel Corporation
 * All rights reserved.
 *
 * This file is distributed under the terms in the attached INTEL-LICENSE     
 * file. If you do not find these files, copies can be found by writing to
 * Intel Research Berkeley, 2150 Shattuck Avenue, Suite 1300, Berkeley, CA, 
 * 94704.  Attention:  Intel License Inquiry.
 */
/*
 *
 * Authors:		Alec Woo, David Gay, Philip Levis
 * Date last modified:  6/25/02
 *
 * +1 necessary to prevent spinning on zero.
 */

/* This is a 16 bit Linear Feedback Shift Register pseudo random number
   generator */

/**
 * @author Alec Woo
 * @author David Gay
 * @author Philip Levis
 */

includes PrintfUART;

module MyRandomLFSR 
{
  provides interface MyRandom;
}
implementation
{
  uint16_t shiftReg;
  uint16_t initSeed;
  uint16_t mask;




  /* Initialize the seed from the ID of the node */
  async command result_t MyRandom.init() {
    dbg(DBG_BOOT, "RANDOM_LFSR initialized.\n");
    atomic {
      shiftReg = 119 * 119 * (TOS_LOCAL_ADDRESS + 1);

      initSeed = shiftReg;
      mask = 137 * 29 * (TOS_LOCAL_ADDRESS + 1);
	  
	  printfUART("INIT SEED: %i MASK: %i\n", initSeed,mask); 
    }
    return SUCCESS;
  }

  /* Return the next 16 bit random number */
  async command uint16_t MyRandom.rand() {
    bool endbit;
    uint16_t tmpShiftReg;
    atomic {
      tmpShiftReg = shiftReg;
      endbit = ((tmpShiftReg & 0x8000) != 0);
      tmpShiftReg <<= 1;
      if (endbit) 
	tmpShiftReg ^= 0x100b;
      tmpShiftReg++;
      shiftReg = tmpShiftReg;
      tmpShiftReg = tmpShiftReg ^ mask;
    }
	
    return tmpShiftReg;
  }
  
  uint16_t TOSH_rand() __attribute__((C)) {
    return call MyRandom.rand();
  }
  


  
}