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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 // 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: 1998-02-11 // 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
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