/* ----------------------------------------------------------------------------
 * Copyright (c) Huawei Technologies Co., Ltd. 2018-2019. All rights reserved.
 * Description: Scheduler
 * Author: Huawei LiteOS Team
 * Create: 2018-08-29
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 * 1. Redistributions of source code must retain the above copyright notice, this list of
 * conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice, this list
 * of conditions and the following disclaimer in the documentation and/or other materials
 * provided with the distribution.
 * 3. Neither the name of the copyright holder nor the names of its contributors may be used
 * to endorse or promote products derived from this software without specific prior written
 * permission.
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * --------------------------------------------------------------------------- */

#include "los_base.h"
#include "los_trace.h"
#include "los_task_pri.h"
#include "los_priqueue_pri.h"
#include "los_percpu_pri.h"
#include "los_task_pri.h"
#include "los_mux_debug_pri.h"
#ifdef LOSCFG_KERNEL_CPUP
#include "los_cpup_pri.h"
#endif

#ifdef __cplusplus
#if __cplusplus
extern "C" {
#endif /* __cplusplus */
#endif /* __cplusplus */

VOID OsSchedResched(VOID)
{
    LosTaskCB *runTask = NULL;
    LosTaskCB *newTask = NULL;

    LOS_ASSERT(LOS_SpinHeld(&g_taskSpin));

    if (!OsPreemptableInSched()) {
        return;
    }

    runTask = OsCurrTaskGet();
    newTask = OsGetTopTask();

    /* always be able to get one task */
    LOS_ASSERT(newTask != NULL);

    newTask->taskStatus &= ~OS_TASK_STATUS_READY;

    if (runTask == newTask) {
        return;
    }

    runTask->taskStatus &= ~OS_TASK_STATUS_RUNNING;
    newTask->taskStatus |= OS_TASK_STATUS_RUNNING;

#ifdef LOSCFG_KERNEL_SMP
    /* mask new running task's owner processor */
    runTask->currCpu = OS_TASK_INVALID_CPUID;
    newTask->currCpu = ArchCurrCpuid();
#endif

    OsTaskTimeUpdateHook(runTask->taskId, LOS_TickCountGet());

#ifdef LOSCFG_KERNEL_CPUP
    OsTaskCycleEndStart(newTask);
#endif

#ifdef LOSCFG_BASE_CORE_TSK_MONITOR
    OsTaskSwitchCheck(runTask, newTask);
#endif

    LOS_TRACE(TASK_SWITCH, newTask->taskId, runTask->priority, runTask->taskStatus, newTask->priority,
        newTask->taskStatus);

#ifdef LOSCFG_DEBUG_SCHED_STATISTICS
    OsSchedStatistics(runTask, newTask);
#endif

#ifdef LOSCFG_BASE_CORE_TIMESLICE
    if (newTask->timeSlice == 0) {
        newTask->timeSlice = KERNEL_TIMESLICE_TIMEOUT;
    }
#endif

    OsCurrTaskSet((VOID*)newTask);

    /* do the task context switch */
    OsTaskSchedule(newTask, runTask);
}
/*这段代码实现了操作系统的任务调度功能，根据任务的优先级和状态来选择合适的任务进行切换，并更新任务状态及相关信息，最终实现任务的切换和调度*/
VOID OsSchedPreempt(VOID)
{
    LosTaskCB *runTask = NULL;
    UINT32 intSave;

    if (!OsPreemptable()) {
        return;
    }

    SCHEDULER_LOCK(intSave);

    /* add run task back to ready queue */
    runTask = OsCurrTaskGet();
    runTask->taskStatus |= OS_TASK_STATUS_READY;

#ifdef LOSCFG_BASE_CORE_TIMESLICE
    if (runTask->timeSlice == 0) {
        OsPriQueueEnqueue(&runTask->pendList, runTask->priority);
    } else {
#endif
        OsPriQueueEnqueueHead(&runTask->pendList, runTask->priority);
#ifdef LOSCFG_BASE_CORE_TIMESLICE
    }
#endif

    /* reschedule to new thread */
    OsSchedResched();

    SCHEDULER_UNLOCK(intSave);
}
/*这段代码实现了在需要进行任务抢占时，将当前任务标记为就绪状态并重新加入就绪队列，然后触发任务重新调度，以实现任务的抢占和切换。*/
#ifdef LOSCFG_BASE_CORE_TIMESLICE
LITE_OS_SEC_TEXT VOID OsTimesliceCheck(VOID)
{
    LosTaskCB *runTask = OsCurrTaskGet();
    if (runTask->timeSlice != 0) {
        runTask->timeSlice--;
        if (runTask->timeSlice == 0) {
            LOS_Schedule();
        }
    }
}
#endif
/*这段代码实现了时间片轮转调度算法中的时间片检查和调度触发功能，当任务时间片用尽时，会自动触发调度，让其他可运行任务有机会获得 CPU 时间片并进行执行。*/
#ifdef __cplusplus
#if __cplusplus
}
#endif /* __cplusplus */
#endif /* __cplusplus */