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/* $Id: thread.hh,v 1.5 2008-04-20 16:35:53 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

#ifdef __cplusplus

namespace aemb {

#endif

  /**

     Checks to see if currently executing Thread 1

     @return true if is Thread 1

  */

  inline bool isThread1()

  {

    int rmsr = getMSR();

    return ((rmsr & MSR_HTX) && (rmsr & MSR_PHA));

  }

  /**

     Checks to see if currently executing Thread 0

     @return true if is Thread 0

  */

  inline bool isThread0()

  {

    int rmsr = getMSR();

    return ((rmsr & MSR_HTX) && (!(rmsr & MSR_PHA)));

  }

  /**

     Checks to see if it is multi-threaded or not.

     @return true if thread capable

  */

  inline bool isThreaded()

  {

    int rmsr = getMSR();

    return (rmsr & MSR_HTX);

  }

  /**

     Hardware Mutex Signal.

     Unlock the hardware mutex, which is unlocked on reset.

   */

  inline void signalMutex()

  {

    int tmp;

    asm volatile ("msrclr %0, 0x0010":"=r"(tmp));

  }

  /**

     Hardware Mutex Wait.

     Waits until the hardware mutex is unlocked.

   */

  inline void waitMutex()

  {

    int rmsr;

    do

      {

        asm volatile ("msrset %0, 0x0010":"=r"(rmsr));

      }

    while (rmsr & MSR_MTX);

  }

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

  // semaphores, mutexes and such.

  /**

     Semaphore class.

     Presently implemented as software solution but a hardware one may be

     required as the threads are hardware.

  */

  class semaphore {

  private:

    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

  };

  semaphore __mutex_rendezvous0(0); ///< internal rendezvous mutex

  semaphore __mutex_rendezvous1(1); ///< internal rendezvous mutex

  /**

     Implements a simple rendezvous mechanism

   */

  void rendezvous()

  {

    if (isThread1())

      {

        __mutex_rendezvous0.wait();

        __mutex_rendezvous1.signal();

      }

    else

      {

        __mutex_rendezvous0.signal();

        __mutex_rendezvous1.wait();

      }

  }

#ifdef __cplusplus

}

#endif

#endif

/*

  $Log: not supported by cvs2svn $

  Revision 1.4  2008/04/12 14:07:26  sybreon

  added a rendezvous function

  Revision 1.3  2008/04/11 15:53:24  sybreon

  changed MSR bits

  Revision 1.2  2008/04/11 11:34:30  sybreon

  changed semaphore case

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

  Added new C++ files

*/