cpp-d1064d

[cross.git] / i686-linux-gnu-4.7 / usr / include / c++ / 4.7 / parallel / random_number.h

diff --git a/i686-linux-gnu-4.7/usr/include/c++/4.7/parallel/random_number.h b/i686-linux-gnu-4.7/usr/include/c++/4.7/parallel/random_number.h
new file mode 100644 (file)
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+// -*- C++ -*-
+
+// Copyright (C) 2007, 2008, 2009 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the terms
+// of the GNU General Public License as published by the Free Software
+// Foundation; either version 3, or (at your option) any later
+// version.
+
+// This library is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// General Public License for more details.
+
+// Under Section 7 of GPL version 3, you are granted additional
+// permissions described in the GCC Runtime Library Exception, version
+// 3.1, as published by the Free Software Foundation.
+
+// You should have received a copy of the GNU General Public License and
+// a copy of the GCC Runtime Library Exception along with this program;
+// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+// <http://www.gnu.org/licenses/>.
+
+/** @file parallel/random_number.h
+ *  @brief Random number generator based on the Mersenne twister.
+ *  This file is a GNU parallel extension to the Standard C++ Library.
+ */
+
+// Written by Johannes Singler.
+
+#ifndef _GLIBCXX_PARALLEL_RANDOM_NUMBER_H
+#define _GLIBCXX_PARALLEL_RANDOM_NUMBER_H 1
+
+#include <parallel/types.h>
+#include <tr1/random>
+#include <limits>
+
+namespace __gnu_parallel
+{
+  /** @brief Random number generator, based on the Mersenne twister. */
+  class _RandomNumber
+  {
+  private:
+    std::tr1::mt19937   _M_mt;
+    uint64_t            _M_supremum;
+    uint64_t            _M_rand_sup;
+    double              _M_supremum_reciprocal;
+    double              _M_rand_sup_reciprocal;
+
+    // Assumed to be twice as long as the usual random number.
+    uint64_t              __cache;
+
+    // Bit results.
+    int __bits_left;
+    
+    static uint32_t
+    __scale_down(uint64_t __x,
+#if _GLIBCXX_SCALE_DOWN_FPU
+               uint64_t /*_M_supremum*/, double _M_supremum_reciprocal)
+#else
+               uint64_t _M_supremum, double /*_M_supremum_reciprocal*/)
+#endif
+        {
+#if _GLIBCXX_SCALE_DOWN_FPU
+          return uint32_t(__x * _M_supremum_reciprocal);
+#else
+          return static_cast<uint32_t>(__x % _M_supremum);
+#endif
+        }
+
+  public:
+    /** @brief Default constructor. Seed with 0. */
+    _RandomNumber()
+    : _M_mt(0), _M_supremum(0x100000000ULL),
+      _M_rand_sup(1ULL << std::numeric_limits<uint32_t>::digits),
+      _M_supremum_reciprocal(double(_M_supremum) / double(_M_rand_sup)),
+      _M_rand_sup_reciprocal(1.0 / double(_M_rand_sup)),
+      __cache(0), __bits_left(0) { }
+
+    /** @brief Constructor.
+     *  @param __seed Random __seed.
+     *  @param _M_supremum Generate integer random numbers in the
+     *                  interval @c [0,_M_supremum). */
+    _RandomNumber(uint32_t __seed, uint64_t _M_supremum = 0x100000000ULL)
+    : _M_mt(__seed), _M_supremum(_M_supremum),
+      _M_rand_sup(1ULL << std::numeric_limits<uint32_t>::digits),
+      _M_supremum_reciprocal(double(_M_supremum) / double(_M_rand_sup)),
+      _M_rand_sup_reciprocal(1.0 / double(_M_rand_sup)),
+      __cache(0), __bits_left(0) { }
+
+    /** @brief Generate unsigned random 32-bit integer. */
+    uint32_t
+    operator()()
+    { return __scale_down(_M_mt(), _M_supremum, _M_supremum_reciprocal); }
+
+    /** @brief Generate unsigned random 32-bit integer in the
+        interval @c [0,local_supremum). */
+    uint32_t
+    operator()(uint64_t local_supremum)
+    {
+      return __scale_down(_M_mt(), local_supremum,
+                        double(local_supremum * _M_rand_sup_reciprocal));
+    }
+
+    /** @brief Generate a number of random bits, run-time parameter.
+     *  @param __bits Number of bits to generate. */
+    unsigned long
+    __genrand_bits(int __bits)
+    {
+      unsigned long __res = __cache & ((1 << __bits) - 1);
+      __cache = __cache >> __bits;
+      __bits_left -= __bits;
+      if (__bits_left < 32)
+        {
+          __cache |= ((uint64_t(_M_mt())) << __bits_left);
+          __bits_left += 32;
+        }
+      return __res;
+    }
+};
+
+} // namespace __gnu_parallel
+
+#endif /* _GLIBCXX_PARALLEL_RANDOM_NUMBER_H */