random.c

来自「Hard Viterbi QPSK in AWGN, Rayleight so」· C语言 代码 · 共 216 行

/*====*====*====*====*====*====*====*====*====*====*====*====*====*====*====*

       抄荐 积己

GENERAL DESCRIPTION
    抄荐 积己

INITIALIZATION AND SEQUENCING REQUIREMENTS

  Copyright (c) 2007 by ARTLAB, ICU. All Rights Reserved.
*====*====*====*====*====*====*====*====*====*====*====*====*====*====*====*/

/*===========================================================================
                        EDIT HISTORY FOR MODULE
when      who         what, where, why
--------  ---         ----------------------------------------------------------
07/01/03  khpark      created
=========================================================================== */
#include <math.h>
#include <stdlib.h>
#include <time.h>
#include "random.h"

#define FALSE 0
#define TRUE 1
unsigned char is_initialized = FALSE;

/*=======================================================================
FUNCTION generate_random

DESCRIPTION

DEPENDENCIES

RETURN VALUE

SIDE EFFECTS
========================================================================== */
void generate_random(int *buffer, int size)
{
	int i = 0;
	/* Seed the random-number generator with current time so that
	* the numbers will be different every time we run.
	*/
	if( is_initialized == FALSE )
	{
		srand( (unsigned)time( NULL ) );
		is_initialized = TRUE;
	}

	for( i = 0; i < size; i++ )
	{
		*buffer++ = UniformRand() > 0.5? 1 : 0 ;
	}
}

/*=======================================================================
FUNCTION UniformRand

DESCRIPTION
	Generate Uniform random number [0, 1]
DEPENDENCIES

RETURN VALUE

SIDE EFFECTS
========================================================================== */
double UniformRand(void)
{
	double rv;

	/* Seed the random-number generator with current time so that
	* the numbers will be different every time we run.
	*/
	if( is_initialized == FALSE )
	{
		srand( (unsigned)time( NULL ) );
		is_initialized = TRUE;
	}

	rv = (double)rand()/(double)RAND_MAX;
	return (rv);
}


/*=======================================================================
FUNCTION GenerateOneRealWithUniformOver

DESCRIPTION
	Generate one real number using a uniform dist. over [Min - Max]
DEPENDENCIES

RETURN VALUE

SIDE EFFECTS
========================================================================== */
double GenerateOneRealWithUniformOver(double min, double max)
{
	double RV;
	RV = (max-min)*UniformRand() + min;
	return RV;
}

/*=======================================================================
FUNCTION GaussRandwithMeanVar

DESCRIPTION
	Gaussian Random Number Generator with any mean and any variance
DEPENDENCIES

RETURN VALUE

SIDE EFFECTS
========================================================================== */
double GaussRandwithMeanVar(double Mean, double Var)
{
	static double t=0.;
	double x, v1, v2, r;
	
	/* Seed the random-number generator with current time so that
	* the numbers will be different every time we run.
	*/
	if( is_initialized == FALSE )
	{
		srand( (unsigned)time( NULL ) );
		is_initialized = TRUE;
	}
	if (t==0) 
	{
		do
		{
			v1 = 2.*UniformRand() - 1.;
			v2 = 2.*UniformRand() - 1.;
			r = v1*v1 + v2*v2;
		}while ( r>=1.);

		r=sqrt(-2.*log(r)/r);
		t = v2*r;

		return (Mean+sqrt(Var)*v1*r);

	}
	else
	{
		x=t;
		t=0.;
		return (Mean+sqrt(Var)*x);
	}
}

/*=======================================================================
FUNCTION GaussRand

DESCRIPTION
	Gaussian Random Number Generator with mean 0 and variance 1
DEPENDENCIES

RETURN VALUE

SIDE EFFECTS
========================================================================== */
double GaussRand(void) 
{
/*
	static int sw=0;
	static double r1, r2, s;

	if (sw==0) {
		sw=1;
		do {
			r1 =2*rnd()-1;
			r2 =2*rnd()-1;
			s=r1*r1 + r2*r2;
		}while ( s>1 || s==0);
		s=sqrt(-2*log(s)/s);
		return r1*s;
	}else{
		sw=0;
		return r2*s;
	}
*/
	static double t=0.;
	double x, v1, v2, r;
	/* Seed the random-number generator with current time so that
	* the numbers will be different every time we run.
	*/
	if( is_initialized == FALSE )
	{
		srand( (unsigned)time( NULL ) );
		is_initialized = TRUE;
	}

	if (t==0) 
	{
		do
		{
			v1 = 2.*UniformRand() - 1.;
			v2 = 2.*UniformRand() - 1.;
			r = v1*v1 + v2*v2;
		}while ( r>=1.);

		r=sqrt(-2.*log(r)/r);
		t = v2*r;

		return v1*r;

	}
	else
	{
		x=t;
		t=0.;
		return x;
	}

}