209 lines
7.1 KiB
Plaintext
209 lines
7.1 KiB
Plaintext
/* boost random/xor_combine.hpp header file
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*
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* Copyright Jens Maurer 2002
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* Distributed under the Boost Software License, Version 1.0. (See
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* accompanying file LICENSE_1_0.txt or copy at
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* http://www.boost.org/LICENSE_1_0.txt)
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*
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* See http://www.boost.org for most recent version including documentation.
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*
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* $Id$
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*
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*/
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#ifndef BOOST_RANDOM_XOR_COMBINE_HPP
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#define BOOST_RANDOM_XOR_COMBINE_HPP
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#include <istream>
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#include <iosfwd>
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#include <cassert>
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#include <algorithm> // for std::min and std::max
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#include <boost/config.hpp>
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#include <boost/limits.hpp>
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#include <boost/cstdint.hpp> // uint32_t
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#include <boost/random/detail/config.hpp>
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#include <boost/random/detail/seed.hpp>
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#include <boost/random/detail/seed_impl.hpp>
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#include <boost/random/detail/operators.hpp>
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namespace boost {
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namespace random {
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/**
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* Instantiations of @c xor_combine_engine model a
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* \pseudo_random_number_generator. To produce its output it
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* invokes each of the base generators, shifts their results
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* and xors them together.
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*/
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template<class URNG1, int s1, class URNG2, int s2>
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class xor_combine_engine
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{
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public:
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typedef URNG1 base1_type;
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typedef URNG2 base2_type;
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typedef typename base1_type::result_type result_type;
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BOOST_STATIC_CONSTANT(bool, has_fixed_range = false);
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BOOST_STATIC_CONSTANT(int, shift1 = s1);
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BOOST_STATIC_CONSTANT(int, shift2 = s2);
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/**
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* Constructors a @c xor_combine_engine by default constructing
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* both base generators.
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*/
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xor_combine_engine() : _rng1(), _rng2() { }
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/** Constructs a @c xor_combine by copying two base generators. */
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xor_combine_engine(const base1_type & rng1, const base2_type & rng2)
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: _rng1(rng1), _rng2(rng2) { }
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/**
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* Constructs a @c xor_combine_engine, seeding both base generators
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* with @c v.
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*
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* @xmlwarning
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* The exact algorithm used by this function may change in the future.
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* @endxmlwarning
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*/
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BOOST_RANDOM_DETAIL_ARITHMETIC_CONSTRUCTOR(xor_combine_engine,
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result_type, v)
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{ seed(v); }
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/**
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* Constructs a @c xor_combine_engine, seeding both base generators
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* with values produced by @c seq.
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*/
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BOOST_RANDOM_DETAIL_SEED_SEQ_CONSTRUCTOR(xor_combine_engine,
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SeedSeq, seq)
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{ seed(seq); }
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/**
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* Constructs a @c xor_combine_engine, seeding both base generators
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* with values from the iterator range [first, last) and changes
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* first to point to the element after the last one used. If there
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* are not enough elements in the range to seed both generators,
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* throws @c std::invalid_argument.
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*/
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template<class It> xor_combine_engine(It& first, It last)
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: _rng1(first, last), _rng2( /* advanced by other call */ first, last) { }
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/** Calls @c seed() for both base generators. */
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void seed() { _rng1.seed(); _rng2.seed(); }
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/** @c seeds both base generators with @c v. */
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BOOST_RANDOM_DETAIL_ARITHMETIC_SEED(xor_combine_engine, result_type, v)
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{ _rng1.seed(v); _rng2.seed(v); }
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/** @c seeds both base generators with values produced by @c seq. */
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BOOST_RANDOM_DETAIL_SEED_SEQ_SEED(xor_combine_engine, SeedSeq, seq)
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{ _rng1.seed(seq); _rng2.seed(seq); }
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/**
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* seeds both base generators with values from the iterator
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* range [first, last) and changes first to point to the element
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* after the last one used. If there are not enough elements in
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* the range to seed both generators, throws @c std::invalid_argument.
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*/
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template<class It> void seed(It& first, It last)
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{
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_rng1.seed(first, last);
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_rng2.seed(first, last);
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}
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/** Returns the first base generator. */
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const base1_type& base1() const { return _rng1; }
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/** Returns the second base generator. */
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const base2_type& base2() const { return _rng2; }
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/** Returns the next value of the generator. */
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result_type operator()()
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{
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return (_rng1() << s1) ^ (_rng2() << s2);
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}
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/** Fills a range with random values */
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template<class Iter>
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void generate(Iter first, Iter last)
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{ detail::generate_from_int(*this, first, last); }
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/** Advances the state of the generator by @c z. */
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void discard(boost::uintmax_t z)
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{
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_rng1.discard(z);
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_rng2.discard(z);
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}
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/** Returns the smallest value that the generator can produce. */
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static result_type min BOOST_PREVENT_MACRO_SUBSTITUTION () { return (std::min)((URNG1::min)(), (URNG2::min)()); }
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/** Returns the largest value that the generator can produce. */
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static result_type max BOOST_PREVENT_MACRO_SUBSTITUTION () { return (std::max)((URNG1::min)(), (URNG2::max)()); }
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/**
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* Writes the textual representation of the generator to a @c std::ostream.
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*/
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BOOST_RANDOM_DETAIL_OSTREAM_OPERATOR(os, xor_combine_engine, s)
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{
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os << s._rng1 << ' ' << s._rng2;
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return os;
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}
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/**
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* Reads the textual representation of the generator from a @c std::istream.
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*/
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BOOST_RANDOM_DETAIL_ISTREAM_OPERATOR(is, xor_combine_engine, s)
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{
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is >> s._rng1 >> std::ws >> s._rng2;
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return is;
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}
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/** Returns true if the two generators will produce identical sequences. */
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BOOST_RANDOM_DETAIL_EQUALITY_OPERATOR(xor_combine_engine, x, y)
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{ return x._rng1 == y._rng1 && x._rng2 == y._rng2; }
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/** Returns true if the two generators will produce different sequences. */
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BOOST_RANDOM_DETAIL_INEQUALITY_OPERATOR(xor_combine_engine)
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private:
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base1_type _rng1;
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base2_type _rng2;
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};
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#ifndef BOOST_NO_INCLASS_MEMBER_INITIALIZATION
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// A definition is required even for integral static constants
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template<class URNG1, int s1, class URNG2, int s2>
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const bool xor_combine_engine<URNG1, s1, URNG2, s2>::has_fixed_range;
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template<class URNG1, int s1, class URNG2, int s2>
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const int xor_combine_engine<URNG1, s1, URNG2, s2>::shift1;
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template<class URNG1, int s1, class URNG2, int s2>
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const int xor_combine_engine<URNG1, s1, URNG2, s2>::shift2;
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#endif
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/// \cond show_private
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/** Provided for backwards compatibility. */
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template<class URNG1, int s1, class URNG2, int s2,
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typename URNG1::result_type v = 0>
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class xor_combine : public xor_combine_engine<URNG1, s1, URNG2, s2>
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{
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typedef xor_combine_engine<URNG1, s1, URNG2, s2> base_type;
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public:
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typedef typename base_type::result_type result_type;
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xor_combine() {}
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xor_combine(result_type val) : base_type(val) {}
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template<class It>
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xor_combine(It& first, It last) : base_type(first, last) {}
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xor_combine(const URNG1 & rng1, const URNG2 & rng2)
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: base_type(rng1, rng2) { }
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result_type min BOOST_PREVENT_MACRO_SUBSTITUTION () const { return (std::min)((this->base1().min)(), (this->base2().min)()); }
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result_type max BOOST_PREVENT_MACRO_SUBSTITUTION () const { return (std::max)((this->base1().min)(), (this->base2().max)()); }
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};
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/// \endcond
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} // namespace random
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} // namespace boost
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#endif // BOOST_RANDOM_XOR_COMBINE_HPP
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