#ifndef CA_UWATERLOO_ALUMNI_DWHARDER_DISK_REQUEST_EVENT_SUPPORT
#define CA_UWATERLOO_ALUMNI_DWHARDER_DISK_REQUEST_EVENT_SUPPORT

// Author:  Douglas Wilhelm Harder
// Copyright (c) 2012 by Douglas Wilhelm Harder.  All rights reserved.

#include <cmath>
#include <cstdlib>

/*
 *  Choose a random track.
 */

int random_track( int const &n ) {
	//                                    31
	// lrand48 returns a number 0 <= n < 2

	return lrand48() % n;
}

/*
 *  Return a value from an exponential distribution
 *
 *  Generate a uniform random variable in (0, 1) and take the
 *  inverse of the cummulative distribution function.
 */

int random_exponential( double lambda ) {
	double d;

	// Must avoid having d == 0

	do {
		d = drand48();
	} while ( d == 0.0 );

	return static_cast<int>( std::floor( -std::log(1 - d )/lambda + 0.5 ) );
}

#endif