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//==========================================================================
//
//      sched/bitmap.cxx
//
//      Bitmap scheduler class implementation
//
//==========================================================================
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//==========================================================================
//#####DESCRIPTIONBEGIN####
//
// Author(s):   nickg
// Contributors:        nickg
// Date:        1997-09-16
// Purpose:     Bitmap scheduler class implementation
// Description: This file contains the implementations of
//              Cyg_Scheduler_Implementation and Cyg_SchedThread_Implementation.
//              
//
//####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/sched.hxx>            // our header
 
#include <cyg/hal/hal_arch.h>           // Architecture specific definitions
 
#include <cyg/kernel/thread.inl>           // thread inlines
#include <cyg/kernel/sched.inl>            // scheduler inlines
 
#ifdef CYGSEM_KERNEL_SCHED_BITMAP
 
//==========================================================================
// Cyg_Scheduler_Implementation class members
 
// -------------------------------------------------------------------------
// Constructor.
 
Cyg_Scheduler_Implementation::Cyg_Scheduler_Implementation()
{
    CYG_REPORT_FUNCTION();
 
    // At present we cannot init run_queue here because the absence of
    // ordering of static constructors means that we could do this
    // after the static idle thread has been created. (Guess how I
    // found this out!)    
//    run_queue = 0;
 
}
 
// -------------------------------------------------------------------------
// Choose the best thread to run next
 
Cyg_Thread *Cyg_Scheduler_Implementation::schedule()
{
    CYG_REPORT_FUNCTION();
 
    // The run queue may _never_ be empty, there is always
    // an idle thread at the lowest priority.
 
    CYG_ASSERT(run_queue != 0, "Run queue empty");
 
    cyg_uint32 index;
 
    HAL_LSBIT_INDEX(index, run_queue);
 
    CYG_INSTRUMENT_BITMAP(SCHEDULE, thread_table[index], index);
 
    return thread_table[index];
}
 
// -------------------------------------------------------------------------
 
void Cyg_Scheduler_Implementation::add_thread(Cyg_Thread *thread)
{
    CYG_REPORT_FUNCTION();
 
    CYG_INSTRUMENT_BITMAP(ADD, thread, thread->priority);
 
    CYG_ASSERT((CYG_THREAD_MIN_PRIORITY >= thread->priority) 
               && (CYG_THREAD_MAX_PRIORITY <= thread->priority),
               "Priority out of range!");
 
    CYG_ASSERT( thread_table[thread->priority] == NULL ||
                thread_table[thread->priority] == thread,
                "Duplicate thread priorities" );
 
    CYG_ASSERT( (run_queue & (1<<thread->priority)) == 0,
                "Run queue bit already set" );
 
    // If the thread is on some other queue, remove it
    // here.
    if( thread->queue != NULL )
    {
        thread->queue->remove(thread);
        thread->queue = NULL;
    }
 
    run_queue |= 1<<thread->priority;
 
    // If the new thread is higher priority than the
    // current thread, request a reschedule.
 
    if( thread->priority < Cyg_Scheduler::get_current_thread()->priority )
        set_need_reschedule();
}
 
// -------------------------------------------------------------------------
 
void Cyg_Scheduler_Implementation::rem_thread(Cyg_Thread *thread)
{
    CYG_REPORT_FUNCTION();
 
    CYG_INSTRUMENT_BITMAP(REM, thread, thread->priority);
 
    CYG_ASSERT( thread_table[thread->priority] == thread,
                "Invalid thread priority" );
 
    CYG_ASSERT( (run_queue & (1<<thread->priority)) != 0,
                "Run queue bit not set" );
 
    run_queue &= ~(1<<thread->priority);
 
    if( thread == Cyg_Scheduler::get_current_thread() )
        set_need_reschedule();
}
 
// -------------------------------------------------------------------------
// Set up initial idle thread
 
void Cyg_Scheduler_Implementation::set_idle_thread( Cyg_Thread *thread, HAL_SMP_CPU_TYPE cpu )
{
    CYG_REPORT_FUNCTION();
 
    // Make the thread the current thread for this CPU.
 
    current_thread[cpu] = thread;
 
    // This will insert the thread in the run queues and make it
    // available to execute.
    thread->resume();
}
 
// -------------------------------------------------------------------------
// register thread with scheduler
 
void Cyg_Scheduler_Implementation::register_thread(Cyg_Thread *thread)
{
    CYG_REPORT_FUNCTION();
 
    thread_table[thread->priority] = thread;
}
 
// -------------------------------------------------------------------------
 
// deregister thread
void Cyg_Scheduler_Implementation::deregister_thread(Cyg_Thread *thread)
{
    CYG_REPORT_FUNCTION();
 
    thread_table[thread->priority] = NULL;
}
 
// -------------------------------------------------------------------------
// Test the given priority for uniqueness
 
cyg_bool Cyg_Scheduler_Implementation::unique( cyg_priority priority)
{
    CYG_REPORT_FUNCTION();
 
    return thread_table[priority] == NULL;
}
 
 
//==========================================================================
// Cyg_Cyg_SchedThread_Implementation class members
 
Cyg_SchedThread_Implementation::Cyg_SchedThread_Implementation
(
    CYG_ADDRWORD sched_info
)
{
    CYG_REPORT_FUNCTION();
 
#if 1
    // Assign this thread's priority to the supplied sched_info
    // or the next highest priority available.
 
    priority = cyg_priority(sched_info);
 
    while( !Cyg_Scheduler::scheduler.unique(priority) )
        priority++;
 
#else    
    // Assign initial priorities to threads in descending order of
    // creation.
 
    static cyg_priority init_priority = 0;
 
    priority = init_priority++;
#endif
 
}
 
// -------------------------------------------------------------------------
 
void Cyg_SchedThread_Implementation::yield()
{
    CYG_REPORT_FUNCTION();
 
    // We cannot yield in this scheduler
}
 
//==========================================================================
// Cyg_ThreadQueue_Implementation class members
 
Cyg_ThreadQueue_Implementation::Cyg_ThreadQueue_Implementation()
{
    CYG_REPORT_FUNCTION();
 
    wait_queue = 0;                       // empty queue
 
    CYG_REPORT_RETURN();
}
 
 
void Cyg_ThreadQueue_Implementation::enqueue(Cyg_Thread *thread)
{
    CYG_REPORT_FUNCTION();
 
    CYG_INSTRUMENT_BITMAP(ENQUEUE, this, thread);
 
    wait_queue |= 1<<thread->priority;
    thread->queue = CYG_CLASSFROMBASE(Cyg_ThreadQueue,
                                      Cyg_ThreadQueue_Implementation,
                                      this);
}
 
// -------------------------------------------------------------------------
 
Cyg_Thread *Cyg_ThreadQueue_Implementation::dequeue()
{
    CYG_REPORT_FUNCTION();
 
    // Isolate ls bit in run_queue.
    cyg_sched_bitmap next_thread = wait_queue & -wait_queue;
 
    if( next_thread == 0 )
    {
        CYG_INSTRUMENT_BITMAP(DEQUEUE, this, NULL);
        return NULL;
    }
 
    wait_queue &= ~next_thread;
 
    cyg_uint32 index;
 
    HAL_LSBIT_INDEX(index, next_thread);
 
    Cyg_Thread *thread = Cyg_Scheduler::scheduler.thread_table[index];
 
    CYG_INSTRUMENT_BITMAP(DEQUEUE, this, thread);
 
    thread->queue = NULL;
 
    return thread;
}
 
// -------------------------------------------------------------------------
 
Cyg_Thread *Cyg_ThreadQueue_Implementation::highpri()
{
    CYG_REPORT_FUNCTION();
 
    // Isolate ls bit in run_queue.
    cyg_sched_bitmap next_thread = wait_queue & -wait_queue;
 
    if( next_thread == 0 ) return NULL;
 
    cyg_uint32 index;
 
    HAL_LSBIT_INDEX(index, next_thread);
 
    return Cyg_Scheduler::scheduler.thread_table[index];
}
 
// -------------------------------------------------------------------------
 
void Cyg_ThreadQueue_Implementation::remove(Cyg_Thread *thread)
{
    CYG_REPORT_FUNCTION();
 
    CYG_INSTRUMENT_BITMAP(REMOVE, this, thread);
 
    wait_queue &= ~(1<<thread->priority);
    thread->queue = NULL;
}
 
#endif
 
// -------------------------------------------------------------------------
// EOF sched/bitmap.cxx