/*  IBM_PROLOG_BEGIN_TAG
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 *  $Source: src/kernel/scheduler.C $
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 *  IBM CONFIDENTIAL
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 *  COPYRIGHT International Business Machines Corp. 2010-2012
 *
 *  p1
 *
 *  Object Code Only (OCO) source materials
 *  Licensed Internal Code Source Materials
 *  IBM HostBoot Licensed Internal Code
 *
 *  The source code for this program is not published or other-
 *  wise divested of its trade secrets, irrespective of what has
 *  been deposited with the U.S. Copyright Office.
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 *  Origin: 30
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 *  IBM_PROLOG_END_TAG
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#include <kernel/task.H>
#include <kernel/scheduler.H>
#include <kernel/taskmgr.H>
#include <kernel/cpu.H>
#include <kernel/cpumgr.H>
#include <kernel/console.H>
#include <kernel/timemgr.H>
#include <util/lockfree/atomic_construct.H>

void Scheduler::addTask(task_t* t)
{
    t->state = TASK_STATE_READY;

    if (t->cpu->idle_task != t)
    {
        // If task is pinned to this CPU, add to the per-CPU queue.
        if (0 != t->affinity_pinned)
        {
            // Allocate a per-CPU queue if this is the first pinning to CPU.
            Util::Lockfree::atomic_construct
                (reinterpret_cast<Runqueue_t**>(&t->cpu->scheduler_extra));

            // Insert into queue.
            static_cast<Runqueue_t*>(t->cpu->scheduler_extra)->insert(t);
        }
        // Not pinned, add to global run-queue.
        else
        {
            iv_taskList.insert(t);
        }
    }
}

void Scheduler::addTaskMasterCPU(task_t* t)
{
    t->state = TASK_STATE_READY;

    if (t->cpu->idle_task != t)
    {
        cpu_t* master = CpuManager::getMasterCPU();

        // Allocate a per-CPU queue if this is the first pinning to CPU.
        Util::Lockfree::atomic_construct(
                reinterpret_cast<Runqueue_t**>(&master->scheduler_extra));

        // Insert into queue.
        static_cast<Runqueue_t*>(master->scheduler_extra)->insert(t);

    }
}

void Scheduler::returnRunnable()
{
    this->addTask(TaskManager::getCurrentTask());
}

void Scheduler::setNextRunnable()
{
    task_t* t = NULL;
    cpu_t* cpu = CpuManager::getCurrentCPU();

    // Check for ready task in local run-queue, if it exists.
    if (NULL != cpu->scheduler_extra)
    {
        t = static_cast<Runqueue_t*>(cpu->scheduler_extra)->remove();
    }

    // Check for ready task in global run-queue.
    if (NULL == t)
    {
        t = iv_taskList.remove();
    }

    // Choose idle task if no other ready task is available.
    if (NULL == t)
    {
        t = cpu->idle_task;
        setDEC(TimeManager::getIdleTimeSliceCount());
    }
    else // Set normal timeslice to decrementer.
    {
        setDEC(TimeManager::getTimeSliceCount());
    }

    TaskManager::setCurrentTask(t);
}