sc_host_semaphore.h

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  more contributor license agreements.  See the NOTICE file distributed
  with this work for additional information regarding copyright ownership.
  Accellera licenses this file to you under the Apache License, Version 2.0
  (the "License"); you may not use this file except in compliance with the
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/*****************************************************************************
 
  sc_host_semaphore.h -- A "real" semaphore for the underlying host system
 
  Original Author: Philipp A. Hartmann, Intel
 
 CHANGE LOG AT THE END OF THE FILE
 *****************************************************************************/
 
#ifndef SC_HOST_SEMAPHORE_H_INCLUDED_
#define SC_HOST_SEMAPHORE_H_INCLUDED_
 
#include "sysc/kernel/sc_cmnhdr.h" // SC_CPLUSPLUS
#include "sysc/communication/sc_semaphore_if.h"
 
#include <mutex>
#include <condition_variable>
 
#if defined(_MSC_VER) && !defined(SC_WIN_DLL_WARN)
#pragma warning(disable: 4251) // DLL import for std::mutex
#endif
 
namespace sc_core {
 
// ----------------------------------------------------------------------------
//  CLASS : sc_host_semaphore
//
//   Wrapping an OS semaphore on the simulation host
// ----------------------------------------------------------------------------
 
class SC_API sc_host_semaphore : public sc_semaphore_if
{
public:
 
    // constructors and destructor
 
    explicit sc_host_semaphore(int init = 0) : m_value(init) {}
    virtual ~sc_host_semaphore() = default;
 
    // interface methods
 
    // lock (take) the semaphore, block if not available
    virtual int wait()
    {
      std::unique_lock lock(m_mtx);
      while (m_value <= 0) {
        m_cond_var.wait(lock);
      }
      --m_value;
      return 0;
    }
 
    // lock (take) the semaphore, return -1 if not available
    virtual int trywait()
    {
      std::unique_lock lock(m_mtx);
      if (m_value <= 0)
        return -1;
      --m_value;
      return 0;
    }
 
    // unlock (give) the semaphore
    virtual int post()
    {
      std::unique_lock lock(m_mtx);
      ++m_value;
      m_cond_var.notify_one();
      return 0;
    }
 
    // get the value of the semaphore
    virtual int get_value() const
    {
      return m_value;
    }
 
private:
    std::mutex m_mtx;
    std::condition_variable m_cond_var;
    int m_value = 0;
};
 
} // namespace sc_core
 
#endif // SC_HOST_SEMAPHORE_H_INCLUDED_
// Taf!