-/* boost random/tausworthe.hpp header file
+/* boost random/linear_feedback_shift.hpp header file
*
* Copyright Jens Maurer 2002
+ * Copyright Steven Watanabe 2011
* Distributed under the Boost Software License, Version 1.0. (See
* accompanying file LICENSE_1_0.txt or copy at
* http://www.boost.org/LICENSE_1_0.txt)
*
* See http://www.boost.org for most recent version including documentation.
*
- * $Id: linear_feedback_shift.hpp 60755 2010-03-22 00:45:06Z steven_watanabe $
+ * $Id: linear_feedback_shift.hpp 71018 2011-04-05 21:27:52Z steven_watanabe $
*
*/
#ifndef BOOST_RANDOM_LINEAR_FEEDBACK_SHIFT_HPP
#define BOOST_RANDOM_LINEAR_FEEDBACK_SHIFT_HPP
-#include <iostream>
-#include <cassert>
+#include <iosfwd>
#include <stdexcept>
#include <boost/config.hpp>
+#include <boost/cstdint.hpp>
#include <boost/static_assert.hpp>
-#include <boost/limits.hpp>
+#include <boost/integer/integer_mask.hpp>
#include <boost/random/detail/config.hpp>
+#include <boost/random/detail/seed.hpp>
+#include <boost/random/detail/operators.hpp>
+#include <boost/random/detail/seed_impl.hpp>
namespace boost {
namespace random {
/**
- * Instatiation of @c linear_feedback_shift model a
+ * Instatiations of @c linear_feedback_shift model a
* \pseudo_random_number_generator. It was originally
* proposed in
*
* Tausworthe, R. C.(1965), Mathematics of Computation 19, 201-209.
* @endblockquote
*/
-template<class UIntType, int w, int k, int q, int s, UIntType val>
-class linear_feedback_shift
+template<class UIntType, int w, int k, int q, int s>
+class linear_feedback_shift_engine
{
public:
- typedef UIntType result_type;
- // avoid the warning trouble when using (1<<w) on 32 bit machines
- BOOST_STATIC_CONSTANT(bool, has_fixed_range = false);
- BOOST_STATIC_CONSTANT(int, word_size = w);
- BOOST_STATIC_CONSTANT(int, exponent1 = k);
- BOOST_STATIC_CONSTANT(int, exponent2 = q);
- BOOST_STATIC_CONSTANT(int, step_size = s);
-
- result_type min BOOST_PREVENT_MACRO_SUBSTITUTION () const { return 0; }
- result_type max BOOST_PREVENT_MACRO_SUBSTITUTION () const { return wordmask; }
-
- // MSVC 6 and possibly others crash when encountering complicated integral
- // constant expressions. Avoid the checks for now.
- // BOOST_STATIC_ASSERT(w > 0);
- // BOOST_STATIC_ASSERT(q > 0);
- // BOOST_STATIC_ASSERT(k < w);
- // BOOST_STATIC_ASSERT(0 < 2*q && 2*q < k);
- // BOOST_STATIC_ASSERT(0 < s && s <= k-q);
-
- explicit linear_feedback_shift(UIntType s0 = 341) : wordmask(0)
- {
- // MSVC fails BOOST_STATIC_ASSERT with std::numeric_limits at class scope
-#ifndef BOOST_NO_LIMITS_COMPILE_TIME_CONSTANTS
- BOOST_STATIC_ASSERT(std::numeric_limits<UIntType>::is_integer);
- BOOST_STATIC_ASSERT(!std::numeric_limits<UIntType>::is_signed);
-#endif
-
- // avoid "left shift count >= with of type" warning
- for(int i = 0; i < w; ++i)
- wordmask |= (1u << i);
- seed(s0);
- }
-
- template<class It> linear_feedback_shift(It& first, It last) : wordmask(0)
- {
- // MSVC fails BOOST_STATIC_ASSERT with std::numeric_limits at class scope
-#ifndef BOOST_NO_LIMITS_COMPILE_TIME_CONSTANTS
- BOOST_STATIC_ASSERT(std::numeric_limits<UIntType>::is_integer);
- BOOST_STATIC_ASSERT(!std::numeric_limits<UIntType>::is_signed);
-#endif
-
- // avoid "left shift count >= with of type" warning
- for(int i = 0; i < w; ++i)
- wordmask |= (1u << i);
- seed(first, last);
- }
-
- void seed(UIntType s0 = 341) {
- if(s0 < (1 << (w-k))) {
- s0 += 1 << (w-k);
- }
- value = s0;
- }
- template<class It> void seed(It& first, It last)
- {
- if(first == last)
- throw std::invalid_argument("linear_feedback_shift::seed");
- value = *first++;
- assert(value >= (1 << (w-k)));
- }
-
- result_type operator()()
- {
- const UIntType b = (((value << q) ^ value) & wordmask) >> (k-s);
- const UIntType mask = ( (~static_cast<UIntType>(0)) << (w-k) ) & wordmask;
- value = ((value & mask) << s) ^ b;
- return value;
- }
- static bool validation(result_type x) { return val == x; }
-
-#ifndef BOOST_NO_OPERATORS_IN_NAMESPACE
-
-#ifndef BOOST_RANDOM_NO_STREAM_OPERATORS
- template<class CharT, class Traits>
- friend std::basic_ostream<CharT,Traits>&
- operator<<(std::basic_ostream<CharT,Traits>& os, linear_feedback_shift x)
- { os << x.value; return os; }
-
- template<class CharT, class Traits>
- friend std::basic_istream<CharT,Traits>&
- operator>>(std::basic_istream<CharT,Traits>& is, linear_feedback_shift& x)
- { is >> x.value; return is; }
-#endif
-
- friend bool operator==(linear_feedback_shift x, linear_feedback_shift y)
- { return x.value == y.value; }
- friend bool operator!=(linear_feedback_shift x, linear_feedback_shift y)
- { return !(x == y); }
-#else
- // Use a member function; Streamable concept not supported.
- bool operator==(linear_feedback_shift rhs) const
- { return value == rhs.value; }
- bool operator!=(linear_feedback_shift rhs) const
- { return !(*this == rhs); }
-#endif
+ typedef UIntType result_type;
+ BOOST_STATIC_CONSTANT(bool, has_fixed_range = false);
+ BOOST_STATIC_CONSTANT(int, word_size = w);
+ BOOST_STATIC_CONSTANT(int, exponent1 = k);
+ BOOST_STATIC_CONSTANT(int, exponent2 = q);
+ BOOST_STATIC_CONSTANT(int, step_size = s);
+ BOOST_STATIC_CONSTANT(UIntType, default_seed = 341);
+
+ /** Returns the smallest value that the generator can produce. */
+ static result_type min BOOST_PREVENT_MACRO_SUBSTITUTION () { return 0; }
+ /** Returns the largest value that the generator can produce. */
+ static result_type max BOOST_PREVENT_MACRO_SUBSTITUTION ()
+ { return wordmask(); }
+
+ BOOST_STATIC_ASSERT(w > 0);
+ BOOST_STATIC_ASSERT(q > 0);
+ BOOST_STATIC_ASSERT(k < w);
+ BOOST_STATIC_ASSERT(0 < 2*q && 2*q < k);
+ BOOST_STATIC_ASSERT(0 < s && s <= k-q);
+
+ /** Constructs a @c linear_feedback_shift_engine, using the default seed. */
+ linear_feedback_shift_engine() { seed(); }
+
+ /** Constructs a @c linear_feedback_shift_engine, seeding it with s0. */
+ BOOST_RANDOM_DETAIL_ARITHMETIC_CONSTRUCTOR(linear_feedback_shift_engine,
+ UIntType, s0)
+ { seed(s0); }
+
+ /** Constructs a @c linear_feedback_shift_engine, seeding it with seq. */
+ BOOST_RANDOM_DETAIL_SEED_SEQ_CONSTRUCTOR(linear_feedback_shift_engine,
+ SeedSeq, seq)
+ { seed(seq); }
+
+ /**
+ * Constructs a @c linear_feedback_shift_engine, seeding it with
+ * values from the range [first, last).
+ */
+ template<class It> linear_feedback_shift_engine(It& first, It last)
+ { seed(first, last); }
+
+ /** Seeds a @c linear_feedback_shift_engine with the default seed. */
+ void seed() { seed(default_seed); }
+
+ /** Seeds a @c linear_feedback_shift_engine with @c s0. */
+ BOOST_RANDOM_DETAIL_ARITHMETIC_SEED(linear_feedback_shift_engine,
+ UIntType, s0)
+ {
+ value = s0 & wordmask();
+ if(value < (1 << (w-k))) {
+ value += 1 << (w-k);
+ }
+ }
+
+ /**
+ * Seeds a @c linear_feedback_shift_engine with values
+ * produced by @c seq.generate().
+ */
+ BOOST_RANDOM_DETAIL_SEED_SEQ_SEED(linear_feedback_shift_engine,
+ SeedSeq, seq)
+ { seed(detail::seed_one_int<UIntType, (UIntType(2) << (w - 1))>(seq)); }
+
+ /**
+ * Seeds a @c linear_feedback_shift_engine with values
+ * from the range [first, last).
+ */
+ template<class It> void seed(It& first, It last)
+ {
+ seed(detail::get_one_int<UIntType, (UIntType(2) << (w - 1))>(first, last));
+ }
+
+ /** Returns the next value of the generator. */
+ result_type operator()()
+ {
+ const UIntType b = (((value << q) ^ value) & wordmask()) >> (k-s);
+ const UIntType mask = (wordmask() << (w-k)) & wordmask();
+ value = ((value & mask) << s) ^ b;
+ return value;
+ }
+
+ /** Fills a range with random values */
+ template<class Iter>
+ void generate(Iter first, Iter last)
+ { detail::generate_from_int(*this, first, last); }
+
+ /** Advances the state of the generator by @c z. */
+ void discard(boost::uintmax_t z)
+ {
+ for(boost::uintmax_t j = 0; j < z; ++j) {
+ (*this)();
+ }
+ }
+
+ /**
+ * Writes the textual representation of the generator to a @c std::ostream.
+ */
+ BOOST_RANDOM_DETAIL_OSTREAM_OPERATOR(os, linear_feedback_shift_engine, x)
+ {
+ os << x.value;
+ return os;
+ }
+
+ /**
+ * Reads the textual representation of the generator from a @c std::istream.
+ */
+ BOOST_RANDOM_DETAIL_ISTREAM_OPERATOR(is, linear_feedback_shift_engine, x)
+ {
+ is >> x.value;
+ return is;
+ }
+
+ /**
+ * Returns true if the two generators will produce identical
+ * sequences of outputs.
+ */
+ BOOST_RANDOM_DETAIL_EQUALITY_OPERATOR(linear_feedback_shift_engine, x, y)
+ { return x.value == y.value; }
+
+ /**
+ * Returns true if the two generators will produce different
+ * sequences of outputs.
+ */
+ BOOST_RANDOM_DETAIL_INEQUALITY_OPERATOR(linear_feedback_shift_engine)
private:
- UIntType wordmask; // avoid "left shift count >= width of type" warnings
- UIntType value;
+ /// \cond show_private
+ static UIntType wordmask() { return boost::low_bits_mask_t<w>::sig_bits; }
+ /// \endcond
+ UIntType value;
};
#ifndef BOOST_NO_INCLASS_MEMBER_INITIALIZATION
// A definition is required even for integral static constants
-template<class UIntType, int w, int k, int q, int s, UIntType val>
-const bool linear_feedback_shift<UIntType, w, k, q, s, val>::has_fixed_range;
-template<class UIntType, int w, int k, int q, int s, UIntType val>
-const int linear_feedback_shift<UIntType, w, k, q, s, val>::word_size;
-template<class UIntType, int w, int k, int q, int s, UIntType val>
-const int linear_feedback_shift<UIntType, w, k, q, s, val>::exponent1;
-template<class UIntType, int w, int k, int q, int s, UIntType val>
-const int linear_feedback_shift<UIntType, w, k, q, s, val>::exponent2;
-template<class UIntType, int w, int k, int q, int s, UIntType val>
-const int linear_feedback_shift<UIntType, w, k, q, s, val>::step_size;
+template<class UIntType, int w, int k, int q, int s>
+const bool linear_feedback_shift_engine<UIntType, w, k, q, s>::has_fixed_range;
+template<class UIntType, int w, int k, int q, int s>
+const int linear_feedback_shift_engine<UIntType, w, k, q, s>::word_size;
+template<class UIntType, int w, int k, int q, int s>
+const int linear_feedback_shift_engine<UIntType, w, k, q, s>::exponent1;
+template<class UIntType, int w, int k, int q, int s>
+const int linear_feedback_shift_engine<UIntType, w, k, q, s>::exponent2;
+template<class UIntType, int w, int k, int q, int s>
+const int linear_feedback_shift_engine<UIntType, w, k, q, s>::step_size;
+template<class UIntType, int w, int k, int q, int s>
+const UIntType linear_feedback_shift_engine<UIntType, w, k, q, s>::default_seed;
#endif
+/// \cond show_deprecated
+
+/** Provided for backwards compatibility. */
+template<class UIntType, int w, int k, int q, int s, UIntType v = 0>
+class linear_feedback_shift :
+ public linear_feedback_shift_engine<UIntType, w, k, q, s>
+{
+ typedef linear_feedback_shift_engine<UIntType, w, k, q, s> base_type;
+public:
+ linear_feedback_shift() {}
+ BOOST_RANDOM_DETAIL_SEED_SEQ_CONSTRUCTOR(linear_feedback_shift,
+ SeedSeq, seq)
+ { seed(seq); }
+ BOOST_RANDOM_DETAIL_ARITHMETIC_CONSTRUCTOR(linear_feedback_shift,
+ UIntType, val)
+ { seed(val); }
+ template<class It>
+ linear_feedback_shift(It& first, It last) : base_type(first, last) {}
+};
+
+/// \endcond
+
} // namespace random
} // namespace boost
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