Subversion Repositories openrisc_me

#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 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

// 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.,

// 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):   hmt

// Contributors:        hmt

// Date:        1998-02-10

// Purpose:     Mboxt template implementation

// Description: This file contains the implementations of the mboxt

//              template classes.

//

//####DESCRIPTIONEND####

//

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

#include 

#include          // base kernel types

#include         // tracing macros

#include          // assertion macros

#include        // instrumentation

#include         // our header

#include        // thread inlines

#include         // scheduler inlines

#include         // clock inlines

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

// inline function for awakening waiting threads

template 

inline void

Cyg_Mboxt::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 

Cyg_Mboxt::Cyg_Mboxt()

{

    CYG_REPORT_FUNCTION();

    base = 0;

    count = 0;

}

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

// Destructor

template 

Cyg_Mboxt::~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 

cyg_bool

Cyg_Mboxt::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 

CYG_MBOXT_INLINE cyg_bool

Cyg_Mboxt::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);

        // 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_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

    }

    // Unlock the scheduler and maybe switch threads

    Cyg_Scheduler::unlock();

    CYG_ASSERTCLASS( this, "Bad this pointer");

    CYG_REPORT_RETVAL( result );

    return result;

}

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

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

#ifdef CYGFUN_KERNEL_THREADS_TIMER

template 

CYG_MBOXT_INLINE cyg_bool

Cyg_Mboxt::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

    }

    // Unlock the scheduler and maybe switch threads

    Cyg_Scheduler::unlock();

    CYG_ASSERTCLASS( this, "Bad this pointer");

    CYG_REPORT_RETVAL( result );

    return result;

}

#endif // CYGFUN_KERNEL_THREADS_TIMER

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

// Try to get an item and return success.

template 

CYG_MBOXT_INLINE cyg_bool

Cyg_Mboxt::tryget( T &ritem )

{

    CYG_REPORT_FUNCTION();

    CYG_ASSERTCLASS( this, "Bad this pointer");

    // Prevent preemption

    Cyg_Scheduler::lock();

    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 

CYG_MBOXT_INLINE cyg_bool

Cyg_Mboxt::peek_item( T &ritem )

{

    CYG_REPORT_FUNCTION();

    CYG_ASSERTCLASS( this, "Bad this pointer");

    // Prevent preemption

    Cyg_Scheduler::lock();

    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 

CYG_MBOXT_INLINE cyg_bool

Cyg_Mboxt::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 

CYG_MBOXT_INLINE cyg_bool

Cyg_Mboxt::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 

CYG_MBOXT_INLINE cyg_bool

Cyg_Mboxt::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