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//==========================================================================
//
//      sync/mutex.cxx
//
//      Mutex and condition variable 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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//
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// WARRANTY; without even the implied warranty of MERCHANTABILITY or
// 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
// in accordance with section (3) of the GNU General Public License.
//
// This exception does not invalidate any other reasons why a work based on
// this file might be covered by the GNU General Public License.
//
// Alternative licenses for eCos may be arranged by contacting Red Hat, Inc.
// at http://sources.redhat.com/ecos/ecos-license/
// -------------------------------------------
//####ECOSGPLCOPYRIGHTEND####
//==========================================================================
//#####DESCRIPTIONBEGIN####
//
// Author(s):    nickg
// Contributors: nickg, jlarmour
// Date:         1999-02-17
// Purpose:      Mutex implementation
// Description:  This file contains the implementations of the mutex
//               and condition variable classes.
//
//####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/mutex.hxx>        // our header
 
#include <cyg/kernel/thread.inl>       // thread inlines
#include <cyg/kernel/sched.inl>        // scheduler inlines
#include <cyg/kernel/clock.inl>        // clock inlines
 
// -------------------------------------------------------------------------
// Mutex protocol test macros.
// If the dynamic protocol option is enabled, then these generate appropriate
// tests on the protocol field. If there is no dynamic choice then they simply
// result in empty statements.
 
#ifdef CYGSEM_KERNEL_SYNCH_MUTEX_PRIORITY_INVERSION_PROTOCOL_DYNAMIC
 
#define IF_PROTOCOL_INHERIT if( protocol == INHERIT )
#define IF_PROTOCOL_CEILING if( protocol == CEILING )
#define IF_PROTOCOL_ACTIVE  if( protocol != NONE )
 
#else
 
#define IF_PROTOCOL_INHERIT
#define IF_PROTOCOL_CEILING
#define IF_PROTOCOL_ACTIVE
 
#endif
 
// -------------------------------------------------------------------------
// Constructor
 
Cyg_Mutex::Cyg_Mutex()
{
    CYG_REPORT_FUNCTION();
 
    locked      = false;
    owner       = NULL;
 
#if defined(CYGSEM_KERNEL_SYNCH_MUTEX_PRIORITY_INVERSION_PROTOCOL_DEFAULT) && \
    defined(CYGSEM_KERNEL_SYNCH_MUTEX_PRIORITY_INVERSION_PROTOCOL_DYNAMIC)
 
#ifdef CYGSEM_KERNEL_SYNCH_MUTEX_PRIORITY_INVERSION_PROTOCOL_DEFAULT_INHERIT
    protocol    = INHERIT;
#endif    
#ifdef CYGSEM_KERNEL_SYNCH_MUTEX_PRIORITY_INVERSION_PROTOCOL_DEFAULT_CEILING
    protocol    = CEILING;
    ceiling     = CYGSEM_KERNEL_SYNCH_MUTEX_PRIORITY_INVERSION_PROTOCOL_DEFAULT_PRIORITY;
#endif    
#ifdef CYGSEM_KERNEL_SYNCH_MUTEX_PRIORITY_INVERSION_PROTOCOL_DEFAULT_NONE
    protocol    = NONE;
#endif
 
#else // not (DYNAMIC and DEFAULT defined)
 
#ifdef CYGSEM_KERNEL_SYNCH_MUTEX_PRIORITY_INVERSION_PROTOCOL_CEILING    
#ifdef CYGSEM_KERNEL_SYNCH_MUTEX_PRIORITY_INVERSION_PROTOCOL_DEFAULT_PRIORITY
 
    // if there is a default priority ceiling defined, use that to initialize
    // the ceiling.
    ceiling = CYGSEM_KERNEL_SYNCH_MUTEX_PRIORITY_INVERSION_PROTOCOL_DEFAULT_PRIORITY;    
 
#else
 
    // Otherwise set it to zero.
    ceiling = 0;
 
#endif    
#endif
 
#endif // DYNAMIC and DEFAULT defined
 
    CYG_REPORT_RETURN();
}
 
// -------------------------------------------------------------------------
// Construct with defined protocol
 
#ifdef CYGSEM_KERNEL_SYNCH_MUTEX_PRIORITY_INVERSION_PROTOCOL_DYNAMIC
 
Cyg_Mutex::Cyg_Mutex( cyg_protcol protocol_arg )
{
    CYG_REPORT_FUNCTION();
 
    locked      = false;
    owner       = NULL;
 
    protocol    = protocol_arg;
 
#ifdef CYGSEM_KERNEL_SYNCH_MUTEX_PRIORITY_INVERSION_PROTOCOL_CEILING    
#ifdef CYGSEM_KERNEL_SYNCH_MUTEX_PRIORITY_INVERSION_PROTOCOL_DEFAULT_PRIORITY
 
    // if there is a default priority ceiling defined, use that to initialize
    // the ceiling.
    ceiling = CYGSEM_KERNEL_SYNCH_MUTEX_PRIORITY_INVERSION_PROTOCOL_DEFAULT_PRIORITY;    
 
#else
 
    // Otherwise set it to zero.
    ceiling = 0;
 
#endif    
#endif
 
    CYG_REPORT_RETURN();
}
 
#endif
 
// -------------------------------------------------------------------------
// Destructor
 
Cyg_Mutex::~Cyg_Mutex()
{
    CYG_REPORT_FUNCTION();
 
    CYG_ASSERT( owner == NULL, "Deleting mutex with owner");
    CYG_ASSERT( queue.empty(), "Deleting mutex with waiting threads");
    CYG_REPORT_RETURN();
}
 
// -------------------------------------------------------------------------
 
#ifdef CYGDBG_USE_ASSERTS
 
cyg_bool
Cyg_Mutex::check_this( cyg_assert_class_zeal zeal) const
{
//    CYG_REPORT_FUNCTION();
 
    // check that we have a non-NULL pointer first
    if( this == NULL ) return false;
 
    switch( zeal )
    {
    case cyg_system_test:
    case cyg_extreme:
    case cyg_thorough:
    case cyg_quick:
    case cyg_trivial:
        if(  locked && owner == NULL ) return false;
        if( !locked && owner != NULL ) return false;        
    case cyg_none:
    default:
        break;
    };
 
    return true;
}
 
#endif
 
// -------------------------------------------------------------------------
// Lock and/or wait
 
cyg_bool
Cyg_Mutex::lock(void)
{
    CYG_REPORT_FUNCTYPE("returning %d");
 
    cyg_bool result = true;
    Cyg_Thread *self = Cyg_Thread::self();
 
    // Prevent preemption
    Cyg_Scheduler::lock();
 
    CYG_ASSERTCLASS( this, "Bad this pointer");
 
    CYG_INSTRUMENT_MUTEX(LOCK, this, 0);
 
    // Loop while the mutex is locked, sleeping each time around
    // the loop. This copes with the possibility of a higher priority
    // thread grabbing the mutex between the wakeup in unlock() and
    // this thread actually starting.
 
#ifdef CYGSEM_KERNEL_SYNCH_MUTEX_PRIORITY_INVERSION_PROTOCOL
 
    IF_PROTOCOL_ACTIVE
	self->count_mutex();
 
#endif
 
#ifdef CYGSEM_KERNEL_SYNCH_MUTEX_PRIORITY_INVERSION_PROTOCOL_CEILING
 
    IF_PROTOCOL_CEILING
        self->set_priority_ceiling(ceiling);
 
#endif        
 
    while( locked && result )
    {
        CYG_ASSERT( self != owner, "Locking mutex I already own");
 
        self->set_sleep_reason( Cyg_Thread::WAIT );
 
        self->sleep();
 
        queue.enqueue( self );
 
#ifdef CYGSEM_KERNEL_SYNCH_MUTEX_PRIORITY_INVERSION_PROTOCOL_INHERIT
 
        IF_PROTOCOL_INHERIT
            owner->inherit_priority(self);
 
#endif
 
        CYG_INSTRUMENT_MUTEX(WAIT, this, 0);
 
        // Allow other threads to run
        Cyg_Scheduler::reschedule();
 
        CYG_ASSERTCLASS( this, "Bad this pointer");
 
        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;
        }
 
    }
 
    if( result )
    {
        locked      = true;
        owner       = self;
 
        CYG_INSTRUMENT_MUTEX(LOCKED, this, 0);
    }
    else
    {
#ifdef CYGSEM_KERNEL_SYNCH_MUTEX_PRIORITY_INVERSION_PROTOCOL
 
       IF_PROTOCOL_ACTIVE
           self->uncount_mutex();
 
#endif    
#ifdef CYGSEM_KERNEL_SYNCH_MUTEX_PRIORITY_INVERSION_PROTOCOL_INHERIT
 
        IF_PROTOCOL_INHERIT
            self->disinherit_priority();
 
#endif
#ifdef CYGSEM_KERNEL_SYNCH_MUTEX_PRIORITY_INVERSION_PROTOCOL_CEILING
 
        IF_PROTOCOL_CEILING
            self->clear_priority_ceiling();
 
#endif
    }
 
    // Unlock the scheduler and maybe switch threads
    Cyg_Scheduler::unlock();
 
    CYG_ASSERTCLASS( this, "Bad this pointer");    
 
    CYG_REPORT_RETVAL(result);
 
    return result;
}
 
// -------------------------------------------------------------------------
// Try to lock and return success
 
cyg_bool
Cyg_Mutex::trylock(void)
{
    CYG_REPORT_FUNCTYPE("returning %d");
 
    CYG_ASSERTCLASS( this, "Bad this pointer");
 
    cyg_bool result = true;
 
    // Prevent preemption
    Cyg_Scheduler::lock();
 
    // If the mutex is not locked, grab it
    // for ourself. Otherwise return failure.
    if( !locked )
    {
        Cyg_Thread *self = Cyg_Thread::self();
 
        locked  = true;
        owner   = self;
 
#ifdef CYGSEM_KERNEL_SYNCH_MUTEX_PRIORITY_INVERSION_PROTOCOL
 
       IF_PROTOCOL_ACTIVE
            self->count_mutex();
 
#endif
#ifdef CYGSEM_KERNEL_SYNCH_MUTEX_PRIORITY_INVERSION_PROTOCOL_CEILING
 
        IF_PROTOCOL_CEILING
            self->set_priority_ceiling(ceiling);
 
#endif        
 
    }
    else result = false;
 
    CYG_INSTRUMENT_MUTEX(TRY, this, result);
 
    // Unlock the scheduler and maybe switch threads
    Cyg_Scheduler::unlock();
 
    CYG_REPORT_RETVAL(result);
    return result;    
}
 
// -------------------------------------------------------------------------
// unlock
 
void
Cyg_Mutex::unlock(void)
{
    CYG_REPORT_FUNCTION();
 
    // Prevent preemption
    Cyg_Scheduler::lock();
 
    CYG_INSTRUMENT_MUTEX(UNLOCK, this, 0);
 
    CYG_ASSERTCLASS( this, "Bad this pointer");
    CYG_ASSERT( locked, "Unlock mutex that is not locked");
    CYG_ASSERT( owner == Cyg_Thread::self(), "Unlock mutex I do not own");
 
    if( !queue.empty() ) {
 
        // The queue is non-empty, so grab the next
        // thread from it and wake it up.
 
        Cyg_Thread *thread = queue.dequeue();
 
        CYG_ASSERTCLASS( thread, "Bad thread pointer");
 
#ifdef CYGSEM_KERNEL_SYNCH_MUTEX_PRIORITY_INVERSION_PROTOCOL_INHERIT
 
        // Give the owner-to-be a chance to inherit from the remaining
        // queue or the relinquishing thread:
 
        IF_PROTOCOL_INHERIT
            thread->relay_priority(owner, &queue);
 
#endif
 
        thread->set_wake_reason( Cyg_Thread::DONE );
 
        thread->wake();
 
        CYG_INSTRUMENT_MUTEX(WAKE, this, thread);
 
    }
 
#ifdef CYGSEM_KERNEL_SYNCH_MUTEX_PRIORITY_INVERSION_PROTOCOL
 
    IF_PROTOCOL_ACTIVE
	owner->uncount_mutex();
 
#endif    
#ifdef CYGSEM_KERNEL_SYNCH_MUTEX_PRIORITY_INVERSION_PROTOCOL_INHERIT
 
    IF_PROTOCOL_INHERIT
        owner->disinherit_priority();
 
#endif
#ifdef CYGSEM_KERNEL_SYNCH_MUTEX_PRIORITY_INVERSION_PROTOCOL_CEILING
 
    IF_PROTOCOL_CEILING
        owner->clear_priority_ceiling();
 
#endif
 
    locked      = false;
    owner       = NULL;
 
    CYG_ASSERTCLASS( this, "Bad this pointer");    
 
    // Unlock the scheduler and maybe switch threads
    Cyg_Scheduler::unlock();
 
    CYG_REPORT_RETURN();
}
 
// -------------------------------------------------------------------------
// Release all waiting threads.
 
void Cyg_Mutex::release()
{
    CYG_REPORT_FUNCTION();
 
    // Prevent preemption
    Cyg_Scheduler::lock();
 
    CYG_INSTRUMENT_MUTEX(RELEASE, this, 0);
 
    CYG_ASSERTCLASS( this, "Bad this pointer");
 
    while( !queue.empty() )
    {
        // The queue is non-empty, so grab each
        // thread from it and release it.
 
        Cyg_Thread *thread = queue.dequeue();
 
        CYG_ASSERTCLASS( thread, "Bad thread pointer");
 
        thread->release();
 
        CYG_INSTRUMENT_MUTEX(RELEASED, this, thread);
 
    }
 
    CYG_ASSERTCLASS( this, "Bad this pointer");    
 
    // Unlock the scheduler and maybe switch threads
    Cyg_Scheduler::unlock();
 
    CYG_REPORT_RETURN();
}
 
// -------------------------------------------------------------------------
// Set ceiling priority for priority ceiling protocol
 
#ifdef CYGSEM_KERNEL_SYNCH_MUTEX_PRIORITY_INVERSION_PROTOCOL_CEILING
 
void Cyg_Mutex::set_ceiling( cyg_priority priority )
{
    CYG_REPORT_FUNCTION();
 
//    CYG_ASSERT( priority >=  CYG_THREAD_MAX_PRIORITY, "Priority out of range");
//    CYG_ASSERT( priority <=  CYG_THREAD_MIN_PRIORITY, "Priority out of range");
 
    // Prevent preemption
    Cyg_Scheduler::lock();
 
    ceiling = priority;
 
    // Unlock the scheduler
    Cyg_Scheduler::unlock();
 
    CYG_REPORT_RETURN();    
}
 
#endif
 
// -------------------------------------------------------------------------
// Set priority inversion protocol
 
#ifdef CYGSEM_KERNEL_SYNCH_MUTEX_PRIORITY_INVERSION_PROTOCOL_DYNAMIC
void Cyg_Mutex::set_protocol( cyg_protcol new_protocol )
{
    CYG_REPORT_FUNCTION();
 
    // Prevent preemption
    Cyg_Scheduler::lock();
 
    protocol = new_protocol;
 
    // Unlock the scheduler
    Cyg_Scheduler::unlock();
 
    CYG_REPORT_RETURN();    
}
 
#endif
 
 
//==========================================================================
// Condition variables
 
Cyg_Condition_Variable::Cyg_Condition_Variable(
    Cyg_Mutex   &mx                // linked mutex
    )
{
    CYG_REPORT_FUNCTION();
 
    mutex       = &mx;
 
    CYG_ASSERTCLASS( mutex, "Invalid mutex argument");
 
    CYG_REPORT_RETURN();
}
 
Cyg_Condition_Variable::Cyg_Condition_Variable()
{
    CYG_REPORT_FUNCTION();
 
    mutex       = NULL;
 
    CYG_REPORT_RETURN();
}
 
// -------------------------------------------------------------------------
// Destructor
 
Cyg_Condition_Variable::~Cyg_Condition_Variable()
{
    CYG_REPORT_FUNCTION();
 
    CYG_ASSERT( queue.empty(), "Deleting condvar with waiting threads");
 
    CYG_REPORT_RETURN();
}
 
// -------------------------------------------------------------------------
 
#ifdef CYGDBG_USE_ASSERTS
 
cyg_bool
Cyg_Condition_Variable::check_this( cyg_assert_class_zeal zeal) const
{
    bool result = true;
 
    CYG_REPORT_FUNCTYPE("returning %d");
    CYG_REPORT_FUNCARG1("zeal = %d", zeal);
 
    // check that we have a non-NULL pointer first
    if( this == NULL )
        result = false;
    else {
 
        switch( zeal )
        {
        case cyg_system_test:
        case cyg_extreme:
        case cyg_thorough:
            if( mutex != NULL && !mutex->check_this(zeal) )
                result = false;
        case cyg_quick:
        case cyg_trivial:
        case cyg_none:
        default:
            break;
        }
    }
 
    CYG_REPORT_RETVAL(result);
    return result;
}
 
#endif
 
// -------------------------------------------------------------------------
// Wait for condition to be true    
// Note: if this function is entered with the scheduler locked (e.g. to
// suspend DSR processing) then there is no need to take the lock.  Also
// in this case, exit with the scheduler locked, which allows this function
// to be used in a totally thread-safe manner.
 
cyg_bool
Cyg_Condition_Variable::wait_inner( Cyg_Mutex *mx )
{
    CYG_REPORT_FUNCTION();
 
    cyg_bool result = true;
    Cyg_Thread *self = Cyg_Thread::self();
 
    Cyg_Scheduler::lock();
 
    CYG_ASSERTCLASS( this, "Bad this pointer");
    CYG_ASSERTCLASS( mx, "Corrupt mutex");
    CYG_ASSERTCLASS( self, "Bad self thread");
 
    CYG_INSTRUMENT_CONDVAR(WAIT, this, 0);
 
    mx->unlock();
 
    self->set_sleep_reason( Cyg_Thread::WAIT );
 
    self->sleep();
 
    queue.enqueue( self );
 
    // Avoid calling ASRs during the following unlock.
    self->set_asr_inhibit();
 
    // Unlock the scheduler and switch threads
    Cyg_Scheduler::unlock_reschedule();
 
    // Allow ASRs again
    self->clear_asr_inhibit();
 
    CYG_INSTRUMENT_CONDVAR(WOKE, this, self->get_wake_reason());
 
    CYG_ASSERTCLASS( this, "Bad this pointer");
    CYG_ASSERTCLASS( mx, "Corrupt mutex");
 
    switch( self->get_wake_reason() )
    {
    case Cyg_Thread::DESTRUCT:          // which, the cv or the mutex?
    case Cyg_Thread::BREAK:
        result = false;
        break;
 
    case Cyg_Thread::EXIT:            
        self->exit();
        break;
 
    default:
        break;
    }
 
    // When we awake, we must re-acquire the mutex.  Note that while
    // it is essential to release the mutex and queue on the CV
    // atomically relative to other threads, to avoid races, it is not
    // necessary for us to re-acquire the mutex in the same atomic
    // action. Hence we can do it after unlocking the scheduler.
    // We need to loop here in case the thread is released while waiting
    // for the mutex. It is essential that we exit this function with the
    // mutex claimed.
 
    while ( !mx->lock() )
        continue;
 
    CYG_ASSERTCLASS( this, "Bad this pointer");
    CYG_ASSERTCLASS( mx, "Corrupt mutex");
    CYG_ASSERT( mx->owner == self, "Not mutex owner");
 
    CYG_REPORT_RETURN();
 
    return result;
}
 
// -------------------------------------------------------------------------
// Wake one thread
 
void
Cyg_Condition_Variable::signal(void)
{
    CYG_REPORT_FUNCTION();
 
    CYG_ASSERTCLASS( this, "Bad this pointer");
 
    // Prevent preemption
    Cyg_Scheduler::lock();
 
    CYG_INSTRUMENT_CONDVAR(SIGNAL, this, 0);
 
    if( !queue.empty() )
    {
        // The queue is non-empty, so grab the next
        // thread from it and wake it up.
 
        Cyg_Thread *thread = queue.dequeue();
 
        CYG_ASSERTCLASS( thread, "Bad thread pointer");
 
        thread->set_wake_reason( Cyg_Thread::DONE );
 
        thread->wake();
 
        CYG_INSTRUMENT_CONDVAR(WAKE, this, thread);
 
    }
 
    CYG_ASSERTCLASS( this, "Bad this pointer");
 
    // Unlock the scheduler and maybe switch threads
    Cyg_Scheduler::unlock();
 
    CYG_REPORT_RETURN();
}
 
// -------------------------------------------------------------------------
// Set cond true, wake all threads
 
void
Cyg_Condition_Variable::broadcast(void)
{
    CYG_REPORT_FUNCTION();
 
    CYG_ASSERTCLASS( this, "Bad this pointer");
 
    // Prevent preemption
    Cyg_Scheduler::lock();
 
    CYG_INSTRUMENT_CONDVAR(BROADCAST, this, 0);
 
    // Grab all the threads from the queue and let them
    // go.
 
    while( !queue.empty() )
    {
        Cyg_Thread *thread = queue.dequeue();
 
        CYG_ASSERTCLASS( thread, "Bad thread pointer");
 
        thread->set_wake_reason( Cyg_Thread::DONE );
 
        thread->wake();
 
        CYG_INSTRUMENT_CONDVAR(WAKE, this, thread);        
    }
 
    CYG_ASSERTCLASS( this, "Bad this pointer");
 
    // Unlock the scheduler and maybe switch threads
    Cyg_Scheduler::unlock();    
 
    CYG_REPORT_RETURN();
}
 
// -------------------------------------------------------------------------
// Optional timed wait on a CV
 
#if defined(CYGMFN_KERNEL_SYNCH_CONDVAR_TIMED_WAIT)
 
cyg_bool
Cyg_Condition_Variable::wait_inner( Cyg_Mutex *mx, cyg_tick_count timeout )
{
    CYG_REPORT_FUNCTYPE("returning %d");
    CYG_REPORT_FUNCARG1("timeout = %d", timeout);
 
    CYG_ASSERTCLASS( this, "Bad this pointer");
    CYG_ASSERTCLASS( mx, "Corrupt mutex");
 
    cyg_bool result = true;
 
    Cyg_Thread *self = Cyg_Thread::self();
 
    CYG_ASSERTCLASS( self, "Bad self thread");
 
    // Prevent preemption
    Cyg_Scheduler::lock();
 
    CYG_INSTRUMENT_CONDVAR(TIMED_WAIT, this, 0 );
 
    mx->unlock();
 
    // The ordering of sleep() and set_timer() here are
    // important. If the timeout is in the past, the thread
    // will be woken up immediately and will not sleep.
 
    self->sleep();
 
    // Set the timer and sleep reason
    self->set_timer( timeout, Cyg_Thread::TIMEOUT );
 
    // Only enqueue if the timeout has not already fired.
    if( self->get_wake_reason() == Cyg_Thread::NONE )
        queue.enqueue( self );
 
    // Avoid calling ASRs during the following unlock.
    self->set_asr_inhibit();
 
    // Unlock the scheduler and switch threads
    Cyg_Scheduler::unlock_reschedule();
 
    // Allow ASRs again
    self->clear_asr_inhibit();
 
    CYG_ASSERTCLASS( this, "Bad this pointer");
    CYG_ASSERTCLASS( mx, "Corrupt mutex");
 
    self->clear_timer();
 
    CYG_INSTRUMENT_CONDVAR(WOKE, this, self->get_wake_reason());
 
    switch( self->get_wake_reason() )
    {
    case Cyg_Thread::TIMEOUT:            
    case Cyg_Thread::DESTRUCT:          // which, the cv or the mutex?
    case Cyg_Thread::BREAK:
        result = false;
        break;
 
    case Cyg_Thread::EXIT:            
        self->exit();
        break;
 
    default:
        break;
    }
 
 
    // When we awake, we must re-acquire the mutex.  Note that while
    // it is essential to release the mutex and queue on the CV
    // atomically relative to other threads, to avoid races, it is not
    // necessary for us to re-acquire the mutex in the same atomic
    // action. Hence we can do it after unlocking the scheduler.
 
    while ( !mx->lock() )
        continue;
 
    CYG_ASSERTCLASS( this, "Bad this pointer");
    CYG_ASSERTCLASS( mx, "Corrupt mutex");
 
    CYG_REPORT_RETVAL(result);
 
    return result;
}
 
#endif
 
 
// -------------------------------------------------------------------------
// EOF sync/mutex.cxx