#ifndef lint
static const char RCSid[] = "$Id: urand.c,v 2.5 2003/02/22 02:07:22 greg Exp $";
#endif
/*
* Anticorrelated random function due to Christophe Schlick
*/
/* ====================================================================
* The Radiance Software License, Version 1.0
*
* Copyright (c) 1990 - 2002 The Regents of the University of California,
* through Lawrence Berkeley National Laboratory. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. The end-user documentation included with the redistribution,
* if any, must include the following acknowledgment:
* "This product includes Radiance software
* (http://radsite.lbl.gov/)
* developed by the Lawrence Berkeley National Laboratory
* (http://www.lbl.gov/)."
* Alternately, this acknowledgment may appear in the software itself,
* if and wherever such third-party acknowledgments normally appear.
*
* 4. The names "Radiance," "Lawrence Berkeley National Laboratory"
* and "The Regents of the University of California" must
* not be used to endorse or promote products derived from this
* software without prior written permission. For written
* permission, please contact radiance@radsite.lbl.gov.
*
* 5. Products derived from this software may not be called "Radiance",
* nor may "Radiance" appear in their name, without prior written
* permission of Lawrence Berkeley National Laboratory.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL Lawrence Berkeley National Laboratory OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
* ====================================================================
*
* This software consists of voluntary contributions made by many
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* .
*/
#include
#include "random.h"
#undef initurand
#define MAXORDER (8*sizeof(unsigned short))
unsigned short *urperm = NULL; /* urand() permutation */
int urmask; /* bits used in permutation */
int
initurand(size) /* initialize urand() for size entries */
int size;
{
int order, n;
register int i, offset;
if (urperm != NULL)
free((void *)urperm);
if (--size <= 0) {
urperm = NULL;
urmask = 0;
return(0);
}
for (i = 1; size >>= 1; i++)
;
order = i>MAXORDER ? MAXORDER : i;
urmask = (1< 0)
hval += *d++ * tab[n&7];
return(hval);
}