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/* $Id: thread.hh,v 1.2 2008-04-11 11:34:30 sybreon Exp $

**

** AEMB2 HI-PERFORMANCE CPU

** Copyright (C) 2004-2007 Shawn Tan Ser Ngiap 

**

** This file is part of AEMB.

**

** AEMB is free software: you can redistribute it and/or modify it

** under the terms of the GNU Lesser General Public License as

** published by the Free Software Foundation, either version 3 of the

** License, or (at your option) any later version.

**

** AEMB 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 Lesser General

** Public License for more details.

**

** You should have received a copy of the GNU Lesser General Public

** License along with AEMB. If not, see .

*/

/**

   Basic thread functions

   @file thread.hh

   These functions deal with the various hardware threads. It also

   provides simple mechanisms for toggling semaphores.

 */

#include "aemb/msr.hh"

#ifndef AEMB_THREAD_HH

#define AEMB_THREAD_HH

namespace aemb {

  /**

  Checks to see if currently executing Thread 1

  @return true if is Thread 1

  */

  inline bool isThread1()

  {

    int rmsr = aemb::getMSR();

    return ((rmsr & aemb::MSR_HTE) and (rmsr & aemb::MSR_PHA));

  }

  /**

  Checks to see if currently executing Thread 0

  @return true if is Thread 0

  */

  inline bool isThread0()

  {

    int rmsr = aemb::getMSR();

    return ((rmsr & aemb::MSR_HTE) and (not (rmsr & aemb::MSR_PHA)));

  }

  /**

  Checks to see if it is multi-threaded or not

  @return true if thread capable

  */

  inline bool isThreaded()

  {

    int rmsr = aemb::getMSR();

    return (rmsr & aemb::MSR_HTE);

  }

  // TODO: Extend this library to include threading mechanisms such as

  // semaphores, mutexes and such.

  /**

  Semaphore class

  Based on: Little Book of Semaphores, The - Downey, Allen B.

  Presently implemented as software solution but a hardware one may be

  required as the threads are hardware. This can be implemented using

  a specialised add/sub/load register.

  */

  class semaphore {

    volatile int _sem; ///< Semaphore in Memory

  public:

    /**

    Preload the semaphore

    @param pval preload value

    */

    semaphore(int pval) { _sem = pval; }

    /**

    Increment the semaphore

    */

    inline void signal() { _sem++; }

    /**

    Decrement the semaphore and block if < 0

    */

    inline void wait() { _sem--; while (_sem < 0); } // block while

                                                     // semaphore is

                                                     // negative

  };

}

#endif

/*

  $Log: not supported by cvs2svn $

  Revision 1.1  2008/04/09 19:48:37  sybreon

  Added new C++ files

*/