//
// Copyright (c) 2008,2010 Advanced Micro Devices, Inc. All rights reserved.
//

#ifndef SEMAPHORE_HPP_
#define SEMAPHORE_HPP_

#include "top.hpp"
#include "thread/atomic.hpp"
#include "utils/util.hpp"

#if defined(__linux__)
# include <semaphore.h>
#endif /*linux*/


namespace amd {

/*! \addtogroup Threads
 *  @{
 *
 *  \addtogroup Synchronization
 *  @{
 */

class Thread;

//! \brief Counting semaphore
class Semaphore : public HeapObject
{
private:
    Atomic<int> state_; //!< This semaphore's value.

#ifdef _WIN32
    void* handle_; //!< The semaphore object's handle.
    char padding_[64-sizeof(void*)-sizeof(Atomic<int>)];
#else // !_WIN32
    sem_t sem_; //!< The semaphore object's identifier.
    char padding_[64-sizeof(sem_t)-sizeof(Atomic<int>)];
#endif /*!_WIN32*/

public:
    Semaphore();
    ~Semaphore();

    //! \brief Decrement this semaphore
    void wait();

    //! \brief Increment this semaphore
    void post();

    //! \brief Reset this semaphore.
    void reset()
    {
        state_.swap(0);
    }
};

/*! @}
 *  @}
 */

} // namespace amd

#endif /*SEMAPHORE_HPP_*/