sdk: build libsupc++ from libstdc++ source

git-svn-id: svn://kolibrios.org@5134 a494cfbc-eb01-0410-851d-a64ba20cac60

contrib/sdk/sources/libstdc++-v3/include/parallel/queue.h

@@ -0,0 +1,155 @@
+// -*- C++ -*-
+
+// Copyright (C) 2007-2013 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/queue.h
+ *  @brief Lock-free double-ended queue.
+ *  This file is a GNU parallel extension to the Standard C++ Library.
+ */
+
+// Written by Johannes Singler.
+
+#ifndef _GLIBCXX_PARALLEL_QUEUE_H
+#define _GLIBCXX_PARALLEL_QUEUE_H 1
+
+#include <parallel/types.h>
+#include <parallel/base.h>
+#include <parallel/compatibility.h>
+
+/** @brief Decide whether to declare certain variable volatile in this file. */
+#define _GLIBCXX_VOLATILE volatile
+
+namespace __gnu_parallel
+{
+  /**@brief Double-ended queue of bounded size, allowing lock-free
+   *  atomic access.  push_front() and pop_front() must not be called
+   *  concurrently to each other, while pop_back() can be called
+   *  concurrently at all times.
+   *  @c empty(), @c size(), and @c top() are intentionally not provided.
+   *  Calling them would not make sense in a concurrent setting.
+   *  @param _Tp Contained element type. */
+  template<typename _Tp>
+    class _RestrictedBoundedConcurrentQueue
+    {
+    private:
+      /** @brief Array of elements, seen as cyclic buffer. */
+      _Tp* _M_base;
+
+      /** @brief Maximal number of elements contained at the same time. */
+      _SequenceIndex _M_max_size;
+
+      /** @brief Cyclic __begin and __end pointers contained in one
+          atomically changeable value. */
+      _GLIBCXX_VOLATILE _CASable _M_borders;
+
+    public:
+      /** @brief Constructor. Not to be called concurrent, of course.
+       *  @param __max_size Maximal number of elements to be contained. */
+      _RestrictedBoundedConcurrentQueue(_SequenceIndex __max_size)
+      {
+        _M_max_size = __max_size;
+        _M_base = new _Tp[__max_size];
+        _M_borders = __encode2(0, 0);
+#pragma omp flush
+      }
+
+      /** @brief Destructor. Not to be called concurrent, of course. */
+      ~_RestrictedBoundedConcurrentQueue()
+      { delete[] _M_base; }
+
+      /** @brief Pushes one element into the queue at the front end.
+       *  Must not be called concurrently with pop_front(). */
+      void
+      push_front(const _Tp& __t)
+      {
+        _CASable __former_borders = _M_borders;
+        int __former_front, __former_back;
+        __decode2(__former_borders, __former_front, __former_back);
+        *(_M_base + __former_front % _M_max_size) = __t;
+#if _GLIBCXX_ASSERTIONS
+        // Otherwise: front - back > _M_max_size eventually.
+        _GLIBCXX_PARALLEL_ASSERT(((__former_front + 1) - __former_back)
+                                 <= _M_max_size);
+#endif
+        __fetch_and_add(&_M_borders, __encode2(1, 0));
+      }
+
+      /** @brief Pops one element from the queue at the front end.
+       *  Must not be called concurrently with pop_front(). */
+      bool
+      pop_front(_Tp& __t)
+      {
+        int __former_front, __former_back;
+#pragma omp flush
+        __decode2(_M_borders, __former_front, __former_back);
+        while (__former_front > __former_back)
+          {
+            // Chance.
+            _CASable __former_borders = __encode2(__former_front,
+						  __former_back);
+            _CASable __new_borders = __encode2(__former_front - 1,
+					       __former_back);
+            if (__compare_and_swap(&_M_borders, __former_borders,
+				   __new_borders))
+              {
+                __t = *(_M_base + (__former_front - 1) % _M_max_size);
+                return true;
+              }
+#pragma omp flush
+            __decode2(_M_borders, __former_front, __former_back);
+          }
+        return false;
+      }
+
+      /** @brief Pops one element from the queue at the front end.
+       *  Must not be called concurrently with pop_front(). */
+      bool
+      pop_back(_Tp& __t)        //queue behavior
+      {
+        int __former_front, __former_back;
+#pragma omp flush
+        __decode2(_M_borders, __former_front, __former_back);
+        while (__former_front > __former_back)
+          {
+            // Chance.
+            _CASable __former_borders = __encode2(__former_front,
+						  __former_back);
+            _CASable __new_borders = __encode2(__former_front,
+					       __former_back + 1);
+            if (__compare_and_swap(&_M_borders, __former_borders,
+				   __new_borders))
+              {
+                __t = *(_M_base + __former_back % _M_max_size);
+                return true;
+              }
+#pragma omp flush
+            __decode2(_M_borders, __former_front, __former_back);
+          }
+        return false;
+      }
+  };
+}       //namespace __gnu_parallel
+
+#undef _GLIBCXX_VOLATILE
+
+#endif /* _GLIBCXX_PARALLEL_QUEUE_H */