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//==========================================================================

//

//      flag.cxx

//

//      Flag class implementation

//

//==========================================================================

//####ECOSGPLCOPYRIGHTBEGIN####

// -------------------------------------------

// This file is part of eCos, the Embedded Configurable Operating System.

// Copyright (C) 1998, 1999, 2000, 2001, 2002 Red Hat, Inc.

//

// eCos is free software; you can redistribute it and/or modify it under

// the terms of the GNU General Public License as published by the Free

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// FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

// for more details.

//

// You should have received a copy of the GNU General Public License along

// with eCos; if not, write to the Free Software Foundation, Inc.,

// 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.

//

// As a special exception, if other files instantiate templates or use macros

// or inline functions from this file, or you compile this file and link it

// with other works to produce a work based on this file, this file does not

// by itself cause the resulting work to be covered by the GNU General Public

// License. However the source code for this file must still be made available

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//####ECOSGPLCOPYRIGHTEND####

//==========================================================================

//#####DESCRIPTIONBEGIN####

//

// Author(s):   hmt

// Contributors:        hmt

// Date:        1998-02-11

// Purpose:     Flag implementation

// Description: This file contains the implementations of the flag class

//

//####DESCRIPTIONEND####

//

//==========================================================================

#include <pkgconf/kernel.h>

#include <cyg/kernel/ktypes.h>         // base kernel types

#include <cyg/infra/cyg_trac.h>        // tracing macros

#include <cyg/infra/cyg_ass.h>         // assertion macros

#include <cyg/kernel/instrmnt.h>       // instrumentation

#include <cyg/kernel/thread.inl>       // thread inlines

#include <cyg/kernel/flag.hxx>         // our own header

#include <cyg/kernel/sched.inl>        // scheduler inlines

#include <cyg/kernel/clock.inl>        // clock inlines

// -------------------------------------------------------------------------

// Constructor

Cyg_Flag::Cyg_Flag( Cyg_FlagValue init )

{

    CYG_REPORT_FUNCTION();

    value = init;

    CYG_REPORT_RETURN();

}

// -------------------------------------------------------------------------

// Destructor

Cyg_Flag::~Cyg_Flag()

{

    CYG_REPORT_FUNCTION();

#if 0

    CYG_ASSERT( queue.empty(), "Deleting flag with threads waiting");

#endif

    // Prevent preemption

    Cyg_Scheduler::lock();

    while ( ! queue.empty() ) {

        Cyg_Thread *thread = queue.dequeue();

        thread->set_wake_reason( Cyg_Thread::DESTRUCT );

        thread->wake();

    }

    // Unlock the scheduler and maybe switch threads

    Cyg_Scheduler::unlock();

    CYG_REPORT_RETURN();

}

// -------------------------------------------------------------------------

// debugging/assert function

#ifdef CYGDBG_USE_ASSERTS

cyg_bool

Cyg_Flag::check_this(cyg_assert_class_zeal zeal) const

{

    CYG_REPORT_FUNCTION();

    if ( Cyg_Thread::DESTRUCT == Cyg_Thread::self()->get_wake_reason() )

        // then the whole thing is invalid, and we know it.

        // so return OK, since this check should NOT make an error.

        return true;

    // check that we have a non-NULL pointer first

    if( this == NULL ) {

        CYG_REPORT_RETVAL( false );

        return false;

    }

    // there ain't a lot to check here.

    CYG_REPORT_RETVAL( true );

    return true;

}

#endif

// -------------------------------------------------------------------------

// now the members themselves:

// clear some bits in the value (all of them by default) by ANDing with the

// argument.  This cannot make a wait condition become true, so there's not

// much to it.

void

Cyg_Flag::maskbits( Cyg_FlagValue arg )

{

    CYG_REPORT_FUNCTION();

    // Prevent preemption

    Cyg_Scheduler::lock();

    value &= arg;

    // no need to wake anyone up; no waiter can become valid in

    // consequence of this operation.

    // Unlock scheduler and allow other threads to run

    Cyg_Scheduler::unlock();

    CYG_REPORT_RETURN();

}

// -------------------------------------------------------------------------

// set some bits in the value (all of them by default) and wake up any

// affected waiting threads; we do the decision making here so as to get

// atomicity wrt the other threads waking up - the value might have changed

// by the time they get to run.

void

Cyg_Flag::setbits( Cyg_FlagValue arg )

{

    CYG_REPORT_FUNCTION();

    CYG_ASSERTCLASS( this, "Bad this pointer");

    // Prevent preemption

    Cyg_Scheduler::lock();

    // OR in the argument to get a new flag value.

    value |= arg;

    // anyone waiting?

    if ( !(queue.empty()) ) {

        FlagWaitInfo   *p;

        Cyg_Thread     *thread;

        Cyg_ThreadQueue holding;

        do {

            thread = queue.dequeue();

            p = (FlagWaitInfo *)(thread->get_wait_info());

            CYG_ASSERT( (p->allmask == 0) != (p->anymask == 0),

                        "Both masks set" );

            CYG_ASSERT( 0 == p->value_out, "Thread already awoken?" );

            if ( ((p->allmask != 0) && (p->allmask & value) == p->allmask) ||

                 ((p->anymask & value) != 0 ) ) {

                // success!  awaken the thread

                thread->set_wake_reason( Cyg_Thread::DONE );

                thread->wake();

                // return the successful value to it

                p->value_out = value;

                // do we clear the value; is this the end?

                if ( p->do_clear ) {

                    // we can break here but need to preserve ordering

                    value = 0;

                    // so let it cycle the whole queue regardless

                }

            }

            else {

                // preserve the entry on the holding queue

                holding.enqueue( thread );

            }

        } while ( !(queue.empty()) );

        // Now re-queue the unaffected threads back into the flag queue

        while ( !(holding.empty()) ) {

            queue.enqueue( holding.dequeue() );

        }

    }

    // Unlock scheduler and allow other threads to run

    Cyg_Scheduler::unlock();

    CYG_REPORT_RETURN();

}

// -------------------------------------------------------------------------

// Wait for a match on our pattern, according to the flags given.

// Return the matching value.

Cyg_FlagValue

Cyg_Flag::wait( Cyg_FlagValue pattern, WaitMode mode )

{

    CYG_REPORT_FUNCTION();

    CYG_ASSERTCLASS( this, "Bad this pointer");

    CYG_ASSERT( Cyg_Flag::MASK >= mode, "Bad mode" );

    Cyg_FlagValue result;

    // Prevent preemption so that we compare atomically

    Cyg_Scheduler::lock();

    // try the current value

    result = poll( pattern, mode );

    if ( 0 != result ) {

        Cyg_Scheduler::unlock();

        CYG_REPORT_RETVAL( result );

        return result;                  // all done

    }

    // we have to wait until we are awoken

    Cyg_Thread *self = Cyg_Thread::self();

    FlagWaitInfo saveme;

    saveme.allmask = (Cyg_Flag::OR & mode) ? 0 : pattern;

    saveme.anymask = (Cyg_Flag::OR & mode) ? pattern : 0;

    saveme.do_clear = (0 != (Cyg_Flag::CLR & mode));

    self->set_wait_info( (CYG_ADDRWORD)&saveme );

    result = true; // just being used as an early-out flag now

    // this loop allows us to deal correctly with spurious wakeups

    while ( result && (0 == saveme.value_out) ) {

        self->set_sleep_reason( Cyg_Thread::WAIT );

        self->sleep();

        // keep track of myself on the queue of waiting threads

        queue.enqueue( self );

        // Allow other threads to run

        Cyg_Scheduler::reschedule();

        CYG_ASSERT( ((CYG_ADDRWORD)&saveme) ==

                    Cyg_Thread::self()->get_wait_info(),

                    "Wait info lost" );

        switch( self->get_wake_reason() )

        {

        case Cyg_Thread::DESTRUCT:

        case Cyg_Thread::BREAK:

            result = false;

            break;

        case Cyg_Thread::EXIT:

            self->exit();

            break;

        default:

            break;

        }

    }

    CYG_ASSERT( (false == result) ^ (0 != saveme.value_out),

                "Break out but also good result!" );

    // Unlock scheduler and allow other threads to run

    Cyg_Scheduler::unlock();

    CYG_REPORT_RETVAL( saveme.value_out );

    return saveme.value_out;

}

// -------------------------------------------------------------------------

// Wait for a match on our pattern, with a timeout.

// Return the matching value, or zero if timed out.

// (zero cannot match any pattern).

#ifdef CYGFUN_KERNEL_THREADS_TIMER

Cyg_FlagValue

Cyg_Flag::wait( Cyg_FlagValue pattern, WaitMode mode,

                cyg_tick_count abs_timeout )

{

    CYG_REPORT_FUNCTION();

    CYG_ASSERTCLASS( this, "Bad this pointer");

    CYG_ASSERT( Cyg_Flag::MASK >= mode, "Bad mode" );

    Cyg_FlagValue result;

    // Prevent preemption so that we compare atomically

    Cyg_Scheduler::lock();

    // try the current value

    result = poll( pattern, mode );

    if ( 0 != result ) {

        Cyg_Scheduler::unlock();

        CYG_REPORT_RETVAL( result );

        return result;                  // all done

    }

    // we have to wait until we are awoken

    Cyg_Thread *self = Cyg_Thread::self();

    FlagWaitInfo saveme;

    saveme.allmask = (Cyg_Flag::OR & mode) ? 0 : pattern;

    saveme.anymask = (Cyg_Flag::OR & mode) ? pattern : 0;

    saveme.do_clear = (0 != (Cyg_Flag::CLR & mode));

    self->set_wait_info( (CYG_ADDRWORD)&saveme );

    // Set the timer _once_ outside the loop.

    self->set_timer( abs_timeout, Cyg_Thread::TIMEOUT );

    // If the timeout was in the past, it will have changed the value

    // of wake_reason, so avoid going into the loop.

    if( self->get_wake_reason() != Cyg_Thread::NONE )

        result = false;

    else result = true;

    // Result is just being used as an early-out flag now. This loop

    // allows us to deal correctly with spurious wakeups.

    while ( result && (0 == saveme.value_out) ) {

        self->set_sleep_reason( Cyg_Thread::TIMEOUT );

        self->sleep();

        // keep track of myself on the queue of waiting threads

        queue.enqueue( self );

        // Allow other threads to run

        Cyg_Scheduler::reschedule();

        CYG_ASSERT( ((CYG_ADDRWORD)&saveme) ==

                    Cyg_Thread::self()->get_wait_info(),

                    "Wait info lost" );

        switch( self->get_wake_reason() )

        {

        case Cyg_Thread::TIMEOUT:

            result = false;

            break;

        case Cyg_Thread::DESTRUCT:

        case Cyg_Thread::BREAK:

            result = false;

            break;

        case Cyg_Thread::EXIT:

            self->exit();

            break;

        default:

            break;

        }

    }

    CYG_ASSERT( (false == result) ^ (0 != saveme.value_out),

                "Break out but also good result!" );

    // clear the timer; if it actually fired, no worries.

    self->clear_timer();

    // Unlock scheduler and allow other threads to run

    Cyg_Scheduler::unlock();

    // in this version, value_out might be zero meaning timed out.

    CYG_REPORT_RETVAL( saveme.value_out );

    return saveme.value_out;

}

#endif // CYGFUN_KERNEL_THREADS_TIMER

// -------------------------------------------------------------------------

// Test for a match on our pattern, according to the flags given.

// Return the matching value if success, else zero.

Cyg_FlagValue

Cyg_Flag::poll( Cyg_FlagValue pattern, WaitMode mode )

{

    CYG_REPORT_FUNCTION();

    CYG_ASSERTCLASS( this, "Bad this pointer");

    CYG_ASSERT( Cyg_Flag::MASK >= mode, "Bad mode" );

    // Prevent preemption so that we compare atomically

    Cyg_Scheduler::lock();

    Cyg_FlagValue result = 0;

    if ( Cyg_Flag::OR & mode ) {

        if ( 0 != (value & pattern) )

            result = value;

    }

    else { // Cyg_Flag::AND - all must be set

        if ( (pattern != 0) && (pattern == (value & pattern)) )

            result = value;

    }

    // result != 0 <=> test passed

    if ( result && (Cyg_Flag::CLR & mode) )

        value = 0;

    Cyg_Scheduler::unlock();

    CYG_REPORT_RETVAL( result );

    return result;

}

// -------------------------------------------------------------------------

// EOF flag.cxx