mirror of https://github.com/CGAL/cgal
143 lines
3.5 KiB
C++
143 lines
3.5 KiB
C++
// Copyright (c) 1997-2001 Utrecht University (The Netherlands),
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// ETH Zurich (Switzerland), Freie Universitaet Berlin (Germany),
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// INRIA Sophia-Antipolis (France), Martin-Luther-University Halle-Wittenberg
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// (Germany), Max-Planck-Institute Saarbruecken (Germany), RISC Linz (Austria),
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// and Tel-Aviv University (Israel). All rights reserved.
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//
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// This file is part of CGAL (www.cgal.org); you can redistribute it and/or
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// modify it under the terms of the GNU Lesser General Public License as
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// published by the Free Software Foundation; version 2.1 of the License.
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// See the file LICENSE.LGPL distributed with CGAL.
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//
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// Licensees holding a valid commercial license may use this file in
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// accordance with the commercial license agreement provided with the software.
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//
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// This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
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// WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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//
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// $URL$
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// $Id$
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//
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//
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// Author(s) : Sven Schoenherr <sven@inf.ethz.ch>, Sylvain Pion
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#ifndef CGAL_RANDOM_H
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#define CGAL_RANDOM_H
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#include <utility>
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#include <CGAL/basic.h>
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CGAL_BEGIN_NAMESPACE
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class Random {
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public:
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// types
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typedef std::pair<unsigned int, unsigned int> State;
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// creation
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Random( );
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Random( unsigned int seed);
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// seed
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unsigned int get_seed ( ) const;
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// operations
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bool get_bool ( );
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int get_int ( int lower, int upper);
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double get_double( double lower = 0.0, double upper = 1.0);
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// state
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void save_state( State& state) const;
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void restore_state( const State& state);
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// Computes a random int value smaller than 2^b.
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// It's supposed to be fast, useful for randomized algorithms.
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// The distribution is not perfectly flat, but this is a sacrifice against
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// efficiency.
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template <int b>
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int get_bits()
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{
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CGAL_assertion(0<b && b<16);
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if (val == 0) {
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random_value = (421U * random_value + 2073U) % 32749U;
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val = random_value;
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}
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int ret = val & ((1<<b)-1);
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val >>= 1; // Shifting by b would be slightly better, but is slower.
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return ret;
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}
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int operator () ( int upper);
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bool operator==(Random rd) const
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{
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return
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rd.rand_max_plus_1 == rand_max_plus_1 &&
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rd.random_value == random_value &&
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rd.val == val;
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}
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private:
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// data members
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const double rand_max_plus_1;
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unsigned int random_value; // Current 15 bits random value.
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unsigned int val; // random_value shifted by used bits.
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unsigned int seed;
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};
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// Global variables
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// ================
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extern Random default_random;
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CGAL_END_NAMESPACE
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// ============================================================================
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// Class implementation (inline functions)
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// =======================================
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// includes
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# include <cstdlib>
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CGAL_BEGIN_NAMESPACE
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// operations
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inline
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bool
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Random::
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get_bool( )
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{
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return( static_cast< bool>( std::rand() & 1));
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}
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inline
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int
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Random::
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get_int( int lower, int upper)
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{
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return( lower + static_cast< int>(
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( static_cast< double>( upper) - lower) *
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std::rand() / rand_max_plus_1));
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}
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inline
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double
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Random::
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get_double( double lower, double upper)
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{
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return( lower + ( ( upper-lower) *
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std::rand() / rand_max_plus_1));
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}
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inline
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int
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Random::
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operator () ( int upper)
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{
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return( get_int( 0, upper));
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}
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CGAL_END_NAMESPACE
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#endif // CGAL_RANDOM_H
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// ===== EOF ==================================================================
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