// $Id: RandomLFSR.nc,v 1.3.4.4 2003/08/26 09:08:17 cssharp 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 */module RandomM {  provides interface Random;}implementation{  uint16_t shiftReg;  uint16_t initSeed;  uint16_t mask;  /* Initialize the seed from the ID of the node */  async command result_t Random.init() {    dbg(DBG_BOOT, "RANDOM_LFSR initialized.\n");    atomic {      shiftReg = 119 * 119 * (1 + 1);      initSeed = shiftReg;      mask = 137 * 29 * (1 + 1);    }    return SUCCESS;  }  /* Return the next 16 bit random number */  async command uint16_t Random.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 Random.rand();//  }}