/home/andref/projetos/epos--/include/semaphore.h

// EPOS-- Semaphore Abstraction Declarations

// This work is licensed under the Creative Commons
// Attribution-NonCommercial-NoDerivs License. To view a copy of this license,
// visit http://creativecommons.org/licenses/by-nc-nd/2.0/ or send a letter to
// Creative Commons, 559 Nathan Abbott Way, Stanford, California 94305, USA.

#ifndef __semaphore_h
#define __semaphore_h

#include <common/synchronizer.h>
#include <scheduler_disabler.h>

__BEGIN_SYS

class Semaphore: public Synchronizer_Common {
public:
        inline Semaphore(int v = 1) : _value(v) {
                db<Semaphore>(TRC) << "Semaphore(value= " << _value << ")\n";
        }

        inline ~Semaphore() {
                db<Semaphore>(TRC) << "~Semaphore()\n";
                //Frees all all threads waiting on this semaphore
                wakeupAll();
        }

        inline void p() {
                db<Semaphore>(TRC) << "Semaphore::p(value=" << _value << ")\n";
                if(dec(_value) < 1) sleep();
                Scheduler::getInstance().getRunning().addSemaphore(this);
        }

        inline void v() {
                db<Semaphore>(TRC) << "Semaphore::v(value=" << _value << ")\n";
                if(inc(_value) < 0) wakeup();
                Scheduler::getInstance().getRunning().removeSemaphore(this);
        }

        inline void freeResources() {
                wakeupAll();
        }

    static int init(System_Info *si);

private:
        static const Type_Id TYPE = Type<Semaphore>::TYPE;
    volatile int _value;
};

__END_SYS

#endif

---