/* 

 * Motif

 *

 * Copyright (c) 1987-2012, The Open Group. All rights reserved.

 *

 * These libraries and programs are free software; you can

 * redistribute them and/or modify them under the terms of the GNU

 * Lesser General Public License as published by the Free Software

 * Foundation; either version 2 of the License, or (at your option)

 * any later version.

 *

 * These libraries and programs are distributed in the hope that

 * they will be useful, but WITHOUT ANY WARRANTY; without even the

 * implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR

 * PURPOSE. See the GNU Lesser General Public License for more

 * details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with these librararies and programs; if not, write

 * to the Free Software Foundation, Inc., 51 Franklin Street, Fifth

 * Floor, Boston, MA 02110-1301 USA

*/ 

/* 

 * HISTORY

*/ 

#ifdef REV_INFO

#ifndef lint

static char rcsid[] = "$XConsortium: Random.c /main/7 1995/07/14 11:36:33 drk $"

#endif

#endif

/***********************************************************************

  	@(#)Random.c	1.3.1.1	Date:1/22/91

  	Author: TAT

	History:

            05/24/90 SJS add to sccs

	Calls:

	Summary:

            This file contains routines that manipulate RANDOM NUMBERS

************************************************************************/

#include "xislib.h"

#include <math.h>

#define MAX_ERROR 1e-8

#define INV_MAX_ERROR 1e8

#define ROUND(x) ( floor((double)(x)*INV_MAX_ERROR + 0.5) * MAX_ERROR )

#define RANDOM_TABLE_SIZE 97

/*************************************************************

*           RANDOM INTEGER FROM 0.0 to 1.0                   *

**************************************************************

*

*       Returns a uniform random deviate between 0.0 and 1.0. 

*       Set seed to any negative value to reinitialize sequence.

*

**************************************************************/

static double xisPortableRandom(seed)           

long seed; 

{

    static first_pass = 1;

    static long m1=259200, ia1=7141, ic1=54773;

    static long m2=134456, ia2=8121, ic2=28411;

    static long m3=243000, ia3=4561, ic3=51349;

    static long glix1,glix2,glix3;

    static double glr[RANDOM_TABLE_SIZE];

    static double rm1,rm2;

    long j;

    double return_value;

    /** initialize table and glix's on first call **/

    if ((seed < 0)||first_pass) {  

        first_pass = 0;

        rm1 = (double)1.0/m1;

        rm2 = (double)1.0/m2;

        glix1 = (ic1 - seed) % m1;   /* Seed the first routine */                                               

        glix1 = (ia1*glix1 + ic1) % m1;

        glix2 = glix1 % m2;        /* and use it to seed the second */

        glix1 = (ia1*glix1 + ic1) % m1;

        glix3 = glix1 % m3;          /* and third routines. */

        /* Fill the table with sequential uniform deviates generated by the */

        /* first two routines.                                              */

        for (j=0; j < RANDOM_TABLE_SIZE; j++) {   

            glix1 = (ia1*glix1 + ic1) % m1;

            glix2 = (ia2*glix2 + ic2) % m2;

            glr[j] = (glix1 + glix2*rm2)*rm1; /* Combine low,high order pieces*/

        }

    }

    /*** Except when initializing, this is where we start. ****/

    /* Generate the next number for each sequence. */

    glix1 = (ia1*glix1 + ic1) % m1;  

    glix2 = (ia2*glix2 + ic2) % m2;  

    glix3 = (ia3*glix3 + ic3) % m3;  

    /* Use the third sequence to get an integer */

    j = (RANDOM_TABLE_SIZE*glix3) / m3;   

    if ((j >= RANDOM_TABLE_SIZE) || (j < 0))

        (*xisWarningMsg)("in xisPortableRandom() j=%d is out of range\n",j);

    return_value = glr[j];                   /* Return that table entry and */

    glr[j] = ROUND((glix1 + glix2*rm2)*rm1); /* fill it with a new table entry*/

    return (return_value);

}

/*************************************************************

*           INITIALIZE RANDOM

**************************************************************                         

*

*  Initializes the psuedo random number generator.

*

**************************************************************/

void xisInitRandom(num)

int num;

{

    if (num > 0)

        num = (-num);

    else if (num == 0)

        num = -5678;

    xisPortableRandom((long)(num));

}

/*************************************************************

*           SELECT AN ARBITRARY INTEGER

**************************************************************                         

*

*  Selects an arbitrary integer between lo and hi.

*

**************************************************************/

int xisArbitrary(lo,hi)

int lo,hi;

{

    long i;

    i = ROUND(((hi+0.9999)-lo)*xisPortableRandom(1) + lo);

    return(i);

}