96 lines
2.4 KiB
C
96 lines
2.4 KiB
C
/**
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* \file sg_random.h
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* Routines to handle random number generation and hide platform differences.
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*/
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// Written by Curtis Olson, started July 1997.
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//
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// Copyright (C) 1997 Curtis L. Olson - http://www.flightgear.org/~curt
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//
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// This library is free software; you can redistribute it and/or
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// modify it under the terms of the GNU Library General Public
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// License as published by the Free Software Foundation; either
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// version 2 of the License, or (at your option) any later version.
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//
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// Library General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program; if not, write to the Free Software
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// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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//
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// $Id$
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#ifndef _SG_RANDOM_H
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#define _SG_RANDOM_H
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#ifdef __cplusplus
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extern "C" {
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#endif
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#define MT_N 624
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#define MT_M 397
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/**
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* Structure to hold MT algorithm state to easily allow independant
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* sets of random numbers with different seeds.
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*/
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typedef struct {unsigned int array[MT_N]; int index; } mt;
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/**
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* Initialize a new MT state with a given seed.
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*/
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void mt_init(mt *mt, unsigned int seed);
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/**
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* Generate a new 32-bit random number based on the given MT state.
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*/
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unsigned int mt_rand32( mt *mt);
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/**
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* Generate a new random number between [0.0, 1.0) based
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* on the given MT state.
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*/
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double mt_rand(mt *mt);
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/**
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* Seed the random number generater with time() so we don't see the
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* same sequence every time.
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*/
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void sg_srandom_time();
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/**
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* Seed the random number generater with time() in 10 minute intervals
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* so we get the same sequence within 10 minutes interval.
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* This is useful for synchronizing two display systems.
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*/
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void sg_srandom_time_10();
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/**
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* Seed the random number generater with your own seed so can set up
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* repeatable randomization.
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* @param seed random number generator seed
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*/
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void sg_srandom(unsigned int seed );
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/**
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* Return a random number between [0.0, 1.0)
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* @return next "random" number in the "random" sequence
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*/
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double sg_random();
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#ifdef __cplusplus
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}
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#endif
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#endif // _SG_RANDOM_H
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