path: root/ecos/packages/kernel/current/include/mboxt.inl

#ifndef CYGONCE_KERNEL_MBOXT_INL
#define CYGONCE_KERNEL_MBOXT_INL
//==========================================================================
//
//      mboxt.inl
//
//      Mboxt mbox template class implementation
//
//==========================================================================
// ####ECOSGPLCOPYRIGHTBEGIN####                                            
// -------------------------------------------                              
// This file is part of eCos, the Embedded Configurable Operating System.   
// Copyright (C) 1998, 1999, 2000, 2001, 2002, 2006 Free Software Foundation, 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     
// Software Foundation; either version 2 or (at your option) any later      
// version.                                                                 
//
// eCos 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 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.,    
// 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, 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 v2.                                               
//
// This exception does not invalidate any other reasons why a work based    
// on this file might be covered by the GNU General Public License.         
// -------------------------------------------                              
// ####ECOSGPLCOPYRIGHTEND####                                              
//==========================================================================
//#####DESCRIPTIONBEGIN####
//
// Author(s):   hmt
// Contributors:        hmt
// Date:        1998-02-10
// Purpose:     Mboxt template implementation
// Description: This file contains the implementations of the mboxt
//              template 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/mboxt.hxx>        // our header

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

// -------------------------------------------------------------------------
// inline function for awakening waiting threads

template <class T, cyg_count32 QUEUE_SIZE>
inline void
Cyg_Mboxt<T,QUEUE_SIZE>::wakeup_waiter( Cyg_ThreadQueue &q )
{
    if( !q.empty() ) {
        // The queue is non-empty, so grab the next thread and wake it up.
        Cyg_Thread *thread = q.dequeue();

        CYG_ASSERTCLASS( thread, "Bad thread pointer");

        thread->set_wake_reason( Cyg_Thread::DONE );
        thread->wake();
        CYG_INSTRUMENT_MBOXT(WAKE, this, thread);        
    }
}

// -------------------------------------------------------------------------
// Constructor

template <class T, cyg_count32 QUEUE_SIZE>
Cyg_Mboxt<T,QUEUE_SIZE>::Cyg_Mboxt()
{
    CYG_REPORT_FUNCTION();
    base = 0;
    count = 0;
}

// -------------------------------------------------------------------------
// Destructor

template <class T, cyg_count32 QUEUE_SIZE>
Cyg_Mboxt<T,QUEUE_SIZE>::~Cyg_Mboxt()
{
    CYG_REPORT_FUNCTION();
    CYG_ASSERT( 0 == count, "Deleting mboxt with messages");
    CYG_ASSERT( get_threadq.empty(), "Deleting mboxt with threads waiting to get");
#ifdef CYGMFN_KERNEL_SYNCH_MBOXT_PUT_CAN_WAIT
    CYG_ASSERT( put_threadq.empty(), "Deleting mboxt with threads waiting to put");
#endif
}

// -------------------------------------------------------------------------
// debugging/assert function

#ifdef CYGDBG_USE_ASSERTS

template <class T, cyg_count32 QUEUE_SIZE>
cyg_bool 
Cyg_Mboxt<T,QUEUE_SIZE>::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 ) return false;

#if 0 // thread queues do not have checking funcs.
    if ( ! get_threadq.check_this( zeal ) ) return false;
#ifdef CYGMFN_KERNEL_SYNCH_MBOXT_PUT_CAN_WAIT
    if ( ! put_threadq.check_this( zeal ) ) return false;
#endif
#endif

    switch( zeal )
    {
    case cyg_system_test:
    case cyg_extreme:
    case cyg_thorough:
    case cyg_quick:
    case cyg_trivial:
        // plenty of scope for fencepost problems here
        if ( size < count ) return false;
        if ( size <= base ) return false;
        if ( 0 > count ) return false;
        if ( 0 > base  ) return false;
      
        // there was initially a test of the form
        //    (0 < count && count < size) && ! threadqueue.empty()
        // here - ie. there should only be people waiting if the Q is full
        // or empty.  This is bogus, anyone else might run between a waiter
        // being awoken, so there can be a 2nd waiter in the Q and a free
        // slot (say) simultaneously.

        // Further, we need 2 queues; imagine a 10-slot itemqueue with 25
        // attempts to put to it, so 15 sleep.  10 other threads get,
        // awakening 10 of the 15 put-sleepers.  Another one gets, and
        // can't because there is no data there _yet_; it sleeps, and the
        // 10 awakened threads cycle through the run queue, each putting,
        // the first awakens the get-sleeper, which in turn awakens a
        // further put-sleeper.

        // This requirement for 2 queue only holds if Ngetters > 2 * Nslots
        // or Nputters > 2 * Nslots; if these are both false, one queue
        // will suffice.  This could be an optimisation for the future -
        // wow, 4 bytes.

    case cyg_none:
    default:
        break;
    };

    return true;
}

#endif


// -------------------------------------------------------------------------
// From here downwards, these are the major functions of the template; if
// being genuinely used as a template they should probably not be inlined.
// If being used to construct a specific class, with explicit functions,
// then they should be.  This is controlled by:

#ifdef CYGIMP_MBOXT_INLINE
#define CYG_MBOXT_INLINE inline
#else
#define CYG_MBOXT_INLINE
#endif

// -------------------------------------------------------------------------
// Get an item, or wait for one to arrive

template <class T, cyg_count32 QUEUE_SIZE>
CYG_MBOXT_INLINE cyg_bool
Cyg_Mboxt<T,QUEUE_SIZE>::get( T &ritem )
{
    CYG_REPORT_FUNCTION();
    cyg_bool result = true;
        
    Cyg_Thread *self = Cyg_Thread::self();
    
    // Prevent preemption
    Cyg_Scheduler::lock();

    CYG_ASSERTCLASS( this, "Bad this pointer");
    
    CYG_INSTRUMENT_MBOXT(GET, this, count);

    // Loop while the mboxt is empty, sleeping each time around
    // the loop. This copes with the possibility of a higher priority
    // thread grabbing the message between the wakeup in unlock() and
    // this thread actually starting.
    
    while( result && (0 == count) ) {
        self->set_sleep_reason( Cyg_Thread::WAIT );
        self->sleep();
        get_threadq.enqueue( self );

        CYG_INSTRUMENT_MBOXT(WAIT, this, count);
        
        CYG_ASSERTCLASS( this, "Bad this pointer");        

        // Allow other threads to run
        Cyg_Scheduler::reschedule();

        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 ) {
        CYG_INSTRUMENT_MBOXT(GOT, this, count);
    
        ritem = itemqueue[ (count--, base++) ];
        CYG_ASSERT( 0 <= count, "Count went -ve" );
        CYG_ASSERT( size >= base, "Base overflow" );

        if ( size <= base )
            base = 0;

#ifdef CYGMFN_KERNEL_SYNCH_MBOXT_PUT_CAN_WAIT
        wakeup_waiter( put_threadq );
#endif
    }

    CYG_ASSERTCLASS( this, "Bad this pointer");

    // Unlock the scheduler and maybe switch threads
    Cyg_Scheduler::unlock();

    CYG_REPORT_RETVAL( result );
    return result;
}


// -------------------------------------------------------------------------
// Try to get an item with an absolute timeout and return success.

#ifdef CYGFUN_KERNEL_THREADS_TIMER
template <class T, cyg_count32 QUEUE_SIZE>
CYG_MBOXT_INLINE cyg_bool
Cyg_Mboxt<T,QUEUE_SIZE>::get( T &ritem, cyg_tick_count abs_timeout )
{
    CYG_REPORT_FUNCTION();
    cyg_bool result = true;
        
    Cyg_Thread *self = Cyg_Thread::self();
    
    // Prevent preemption
    Cyg_Scheduler::lock();

    CYG_ASSERTCLASS( this, "Bad this pointer");
    
    CYG_INSTRUMENT_MBOXT(GET, this, count);

    // Set the timer _once_ outside the loop.
    self->set_timer( abs_timeout, Cyg_Thread::TIMEOUT  );

    // If the timeout is in the past, the wake reason will have been
    // set to something other than NONE already. Set the result false
    // to force an immediate return.
    
    if( self->get_wake_reason() != Cyg_Thread::NONE )
        result = false;
                
    // Loop while the mboxt is empty, sleeping each time around the loop.
    // This copes with the possibility of a higher priority thread grabbing
    // the message between the wakeup in put()&c and this thread actually
    // starting.
    while ( result && (0 == count) ) {
        // must reset the sleep reason every time
        self->set_sleep_reason( Cyg_Thread::TIMEOUT );
        self->sleep();
        get_threadq.enqueue( self );

        CYG_INSTRUMENT_MBOXT(WAIT, this, count);

        // Allow other threads to run
        Cyg_Scheduler::reschedule();

        CYG_ASSERTCLASS( this, "Bad this pointer");        

        switch( self->get_wake_reason() )
        {
        case Cyg_Thread::TIMEOUT:
            result = false;
            CYG_INSTRUMENT_MBOXT(TIMEOUT, this, count);
            break;
            
        case Cyg_Thread::DESTRUCT:
        case Cyg_Thread::BREAK:
            result = false;
            break;
            
        case Cyg_Thread::EXIT:            
            self->exit();
            break;

        default:
            break;
        }
    }

    // clear the timer; if it actually fired, no worries.
    self->clear_timer();

    if ( result ) {

        CYG_INSTRUMENT_MBOXT(GOT, this, count);
    
        ritem = itemqueue[ (count--, base++) ];
        CYG_ASSERT( 0 <= count, "Count went -ve" );
        CYG_ASSERT( size >= base, "Base overflow" );

        if ( size <= base )
            base = 0;

#ifdef CYGMFN_KERNEL_SYNCH_MBOXT_PUT_CAN_WAIT
        wakeup_waiter( put_threadq );
#endif
    }

    CYG_ASSERTCLASS( this, "Bad this pointer");

    // Unlock the scheduler and maybe switch threads
    Cyg_Scheduler::unlock();

    CYG_REPORT_RETVAL( result );
    return result;
}
#endif // CYGFUN_KERNEL_THREADS_TIMER

// -------------------------------------------------------------------------
// Try to get an item and return success.

template <class T, cyg_count32 QUEUE_SIZE>
CYG_MBOXT_INLINE cyg_bool
Cyg_Mboxt<T,QUEUE_SIZE>::tryget( T &ritem )
{
    CYG_REPORT_FUNCTION();
        
    // Prevent preemption
    Cyg_Scheduler::lock();

    CYG_ASSERTCLASS( this, "Bad this pointer");
    
    CYG_INSTRUMENT_MBOXT(TRY, this, count);
    
    cyg_bool result = ( 0 < count );
    // If the mboxt is not empty, grab an item and return it.
    if ( result ) {
        ritem = itemqueue[ (count--, base++) ];
        CYG_ASSERT( 0 <= count, "Count went -ve" );
        CYG_ASSERT( size >= base, "Base overflow" );
        if ( size <= base )
            base = 0;

#ifdef CYGMFN_KERNEL_SYNCH_MBOXT_PUT_CAN_WAIT
        wakeup_waiter( put_threadq );
#endif
    }

    // Unlock the scheduler and maybe switch threads
    Cyg_Scheduler::unlock();
    
    return result;    
}

// -------------------------------------------------------------------------
// get next item without removing it
template <class T, cyg_count32 QUEUE_SIZE>
CYG_MBOXT_INLINE cyg_bool
Cyg_Mboxt<T,QUEUE_SIZE>::peek_item( T &ritem )
{
    CYG_REPORT_FUNCTION();
        
    // Prevent preemption
    Cyg_Scheduler::lock();

    CYG_ASSERTCLASS( this, "Bad this pointer");
    
    CYG_INSTRUMENT_MBOXT(TRY, this, count);
    
    cyg_bool result = ( 0 < count );
    // If the mboxt is not empty, grab an item and return it.
    if ( result )
        ritem = itemqueue[ base ];

    // Unlock the scheduler and maybe switch threads
    Cyg_Scheduler::unlock();
    
    return result;    
}

// -------------------------------------------------------------------------
// Put an item in the queue; wait if full.

#ifdef CYGMFN_KERNEL_SYNCH_MBOXT_PUT_CAN_WAIT
template <class T, cyg_count32 QUEUE_SIZE>
CYG_MBOXT_INLINE cyg_bool
Cyg_Mboxt<T,QUEUE_SIZE>::put( const T item )
{
    CYG_REPORT_FUNCTION();
    cyg_bool result = true;

    Cyg_Thread *self = Cyg_Thread::self();

    // Prevent preemption
    Cyg_Scheduler::lock();

    CYG_INSTRUMENT_MBOXT(PUT, this, count);
    CYG_ASSERTCLASS( this, "Bad this pointer");

    while ( result && (size == count) ) {
        self->set_sleep_reason( Cyg_Thread::WAIT );
        self->sleep();
        put_threadq.enqueue( self );

        CYG_INSTRUMENT_MBOXT(WAIT, this, count);

        // 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 ) {
        cyg_count32 in = base + (count++);
        if ( size <= in )
            in -= size;

        CYG_ASSERT( size > in, "in overflow" );
        CYG_ASSERT( 0 <= in, "in overflow" );
        CYG_ASSERT( size >= count, "count overflow" );

        itemqueue[ in ] = item;

        wakeup_waiter( get_threadq );
    }
    CYG_ASSERTCLASS( this, "Bad this pointer");    
    
    // Unlock the scheduler and maybe switch threads
    Cyg_Scheduler::unlock();
    CYG_REPORT_RETVAL( result );
    return result;
}

// -------------------------------------------------------------------------
// Put an item in the queue; wait if full, with an absolute timeout;
// return success.

#ifdef CYGFUN_KERNEL_THREADS_TIMER
template <class T, cyg_count32 QUEUE_SIZE>
CYG_MBOXT_INLINE cyg_bool
Cyg_Mboxt<T,QUEUE_SIZE>::put( const T item, cyg_tick_count abs_timeout )
{
    CYG_REPORT_FUNCTION();
    cyg_bool result = true;

    Cyg_Thread *self = Cyg_Thread::self();

    // Prevent preemption
    Cyg_Scheduler::lock();

    CYG_INSTRUMENT_MBOXT(PUT, this, count);
    CYG_ASSERTCLASS( this, "Bad this pointer");

    // Set the timer _once_ outside the loop.
    self->set_timer( abs_timeout, Cyg_Thread::TIMEOUT );

    // If the timeout is in the past, the wake reason will have been
    // set to something other than NONE already. Set the result false
    // to force an immediate return.
    
    if( self->get_wake_reason() != Cyg_Thread::NONE )
        result = false;
    
    // Loop while the mboxt is full, sleeping each time around the loop.
    // This copes with the possibility of a higher priority thread filling
    // the empty slot between the wakeup in get()&c and this thread
    // actually starting.
    while ( result && (size == count) ) {
        // must reset the sleep reason every time
        self->set_sleep_reason( Cyg_Thread::TIMEOUT );
        self->sleep();
        put_threadq.enqueue( self );

        CYG_INSTRUMENT_MBOXT(WAIT, this, count);

        // Allow other threads to run
        Cyg_Scheduler::reschedule();

        CYG_ASSERTCLASS( this, "Bad this pointer");        

        switch( self->get_wake_reason() )
        {
        case Cyg_Thread::TIMEOUT:
            result = false;
            CYG_INSTRUMENT_MBOXT(TIMEOUT, this, count);
            break;
            
        case Cyg_Thread::DESTRUCT:
        case Cyg_Thread::BREAK:
            result = false;
            break;
            
        case Cyg_Thread::EXIT:            
            self->exit();
            break;

        default:
            break;
        }
    }

    // clear the timer; if it actually fired, no worries.
    self->clear_timer();

    if ( result ) {
        cyg_count32 in = base + (count++);
        if ( size <= in )
            in -= size;

        CYG_ASSERT( size > in, "in overflow" );
        CYG_ASSERT( 0 <= in, "in overflow" );
        CYG_ASSERT( size >= count, "count overflow" );

        itemqueue[ in ] = item;

        wakeup_waiter( get_threadq );
    }
    CYG_ASSERTCLASS( this, "Bad this pointer");    
    
    // Unlock the scheduler and maybe switch threads
    Cyg_Scheduler::unlock();
    CYG_REPORT_RETVAL( result );
    return result;
}
#endif // CYGFUN_KERNEL_THREADS_TIMER
#endif // CYGMFN_KERNEL_SYNCH_MBOXT_PUT_CAN_WAIT

// -------------------------------------------------------------------------
// Try to put an item in the queue and return success; queue may be full.

template <class T, cyg_count32 QUEUE_SIZE>
CYG_MBOXT_INLINE cyg_bool
Cyg_Mboxt<T,QUEUE_SIZE>::tryput( const T item )
{
    CYG_REPORT_FUNCTION();
        
    // Prevent preemption
    Cyg_Scheduler::lock();

    CYG_INSTRUMENT_MBOXT(PUT, this, count);
    CYG_ASSERTCLASS( this, "Bad this pointer");

    if ( size == count ) {
        Cyg_Scheduler::unlock();        // unlock, maybe switch threads
        return false;                   // the mboxt is full
    }

    cyg_count32 in = base + (count++);
    if ( size <= in )
        in -= size;

    CYG_ASSERT( size > in, "in overflow" );
    CYG_ASSERT( 0 <= in, "in overflow" );
    CYG_ASSERT( size >= count, "count overflow" );

    itemqueue[ in ] = item;

    CYG_ASSERTCLASS( this, "Bad this pointer");    

    wakeup_waiter( get_threadq );
    
    // Unlock the scheduler and maybe switch threads
    Cyg_Scheduler::unlock();

    return true;
}


// -------------------------------------------------------------------------
#endif // ifndef CYGONCE_KERNEL_MBOXT_INL
// EOF mboxt.inl