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+/* IBM_PROLOG_BEGIN_TAG */
+/* This is an automatically generated prolog. */
+/* */
+/* $Source: src/include/util/nolockfree/stack.H $ */
+/* */
+/* OpenPOWER HostBoot Project */
+/* */
+/* Contributors Listed Below - COPYRIGHT 2010,2019 */
+/* [+] International Business Machines Corp. */
+/* */
+/* */
+/* Licensed under the Apache License, Version 2.0 (the "License"); */
+/* you may not use this file except in compliance with the License. */
+/* You may obtain a copy of the License at */
+/* */
+/* http://www.apache.org/licenses/LICENSE-2.0 */
+/* */
+/* Unless required by applicable law or agreed to in writing, software */
+/* distributed under the License is distributed on an "AS IS" BASIS, */
+/* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or */
+/* implied. See the License for the specific language governing */
+/* permissions and limitations under the License. */
+/* */
+/* IBM_PROLOG_END_TAG */
+
+#ifndef __UTIL_NOLOCKFREE_STACK_H
+#define __UTIL_NOLOCKFREE_STACK_H
+
+#include <stddef.h>
+#include <assert.h>
+
+namespace Util
+{
+ namespace NoLockFree
+ {
+
+ /**
+ * @brief Non-lockfree stack implementation
+ *
+ * This is an intrusive container design, meaning elements being
+ * added to the stack must have a 'next' member of _T* type. This
+ * container is not threadsafe.
+ *
+ * @note: For a lockfree stack implementation, see Util::LockFree::Stack
+ */
+ template <typename _T>
+ class Stack
+ {
+ public:
+
+ /**
+ * @brief Constructor
+ */
+ Stack()
+ : head(nullptr)
+ {
+ }
+
+ /**
+ * @brief Pop an element from the stack.
+ *
+ * @return _T* The pointer to the element popped from the stack
+ */
+ _T* pop();
+
+ /**
+ * @brief Push an element to the stack.
+ *
+ * @param[in] p Pointer to the element to add to the stack.
+ */
+ void push(_T* p);
+
+ /**
+ * @brief Get a pointer to the first element in the stack
+ *
+ * @return _T* The pointer to the first element
+ * @Note: SMP safety of this pointer is not guaranteed.
+ */
+ _T* first();
+
+ private:
+ _T* head;
+ };
+
+ template <typename _T>
+ _T* Stack<_T>::first()
+ {
+ return head;
+ }
+
+ template <typename _T>
+ _T* Stack<_T>::pop()
+ {
+ auto original = head;
+ if (unlikely(nullptr == original))
+ {
+ return nullptr;
+ }
+ head = original->next;
+ return original;
+ }
+
+ template <typename _T>
+ void Stack<_T>::push(_T* p)
+ {
+ p->next = head;
+ head = p;
+ }
+
+ } // End NoLockFree namespace
+
+} // End Util namespace
+
+#endif // __UTIL_NOLOCKFREE_STACK_H
+
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