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/*
* asim.h
* Copyright (C) 2000 by the University of Southern California
* $Id: asim.h,v 1.3 2005/08/25 18:58:01 johnh Exp $
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
*
*
* The copyright of this module includes the following
* linking-with-specific-other-licenses addition:
*
* In addition, as a special exception, the copyright holders of
* this module give you permission to combine (via static or
* dynamic linking) this module with free software programs or
* libraries that are released under the GNU LGPL and with code
* included in the standard release of ns-2 under the Apache 2.0
* license or under otherwise-compatible licenses with advertising
* requirements (or modified versions of such code, with unchanged
* license). You may copy and distribute such a system following the
* terms of the GNU GPL for this module and the licenses of the
* other code concerned, provided that you include the source code of
* that other code when and as the GNU GPL requires distribution of
* source code.
*
* Note that people who make modified versions of this module
* are not obligated to grant this special exception for their
* modified versions; it is their choice whether to do so. The GNU
* General Public License gives permission to release a modified
* version without this exception; this exception also makes it
* possible to release a modified version which carries forward this
* exception.
*
*/
// author: Debojyoti Dutta
#ifndef _RED_ROUTER_H_
#define _RED_ROUTER_H_
#include <assert.h>
#include <stdio.h>
#include <math.h>
class RedRouter {
double MinTh, MaxTh, MaxP;
double Lambda_L;
double Lambda_H;
void Populate();
public:
RedRouter(int mTh, int MTh, double MP) {
MinTh = mTh;
MaxTh = MTh;
MaxP = MP;
Populate();
}
double ComputeProbability(double Lambda, double &Delay);
short Identical(int mTh, int MTh, double MP) {
return (mTh == MinTh &&
MTh == MaxTh &&
MP == MaxP);
}
};
void RedRouter::Populate() {
// rho = Lambda_L: p = 0 => rho/(1-rho) = MinTh
Lambda_L = ((double)MinTh)/((double)(1+MinTh));
// rho = Lambda_H: p = Max_p => rho(1-Max_p)/(1-rho(1-Max_p)) = MaxTh;
if (MaxP < 1)
Lambda_H = ((double)MaxTh)/((double)(1+MaxTh))/(1-MaxP);
}
double RedRouter::ComputeProbability(double Lambda, double &delay) {
double p;
if (Lambda <= Lambda_L) {
delay = Lambda/(1-Lambda);
return 0;
}
if (MaxP < 1 && Lambda > Lambda_H) {
delay = MaxTh;
p = (Lambda - Lambda_H*(1 - MaxP))/Lambda;
return p;
}
// Solve the quadratic a.p^2 + b.p + c = 0
double a, b, c;
a = Lambda * (MaxTh - MinTh)/(MaxP);
b = (MaxTh - MinTh)*(1-Lambda)/MaxP + MinTh * Lambda + Lambda;
c = MinTh*(1-Lambda)-Lambda;
p = (-b + sqrt(b*b - 4 * a * c))/(2 * a);
delay = Lambda*(1-p)/(1-(Lambda*(1-p)));
return p;
}
#endif
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