/* ----------------------------------------------------------------------------
 * Copyright (c) Huawei Technologies Co., Ltd. 2018-2019. All rights reserved.
 * Description: Scheduler Private HeadFile
 * Author: Huawei LiteOS Team
 * Create: 2018-09-10
 * 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.
 * --------------------------------------------------------------------------- */
//这个头文件定义了调度器相关的一些结构体和函数声明
#ifndef _LOS_SCHED_PRI_H
#define _LOS_SCHED_PRI_H

#include "los_percpu_pri.h"
#include "los_hwi.h"

#ifdef __cplusplus
#if __cplusplus
extern "C" {
#endif /* __cplusplus */
#endif /* __cplusplus */
//表示任务调度标志位，每个位代表一个核心，用于防止在OSStartToRun之前进行内核调度
extern UINT32 g_taskScheduled;

/*
 * Schedule flag, one bit represents one core.
 * This flag is used to prevent kernel scheduling before OSStartToRun.
 */
//设置对应核心的调度标志位
#define OS_SCHEDULER_SET(cpuid) do {     \
    g_taskScheduled |= (1U << (cpuid));  \
} while (0);
//清除对应核心的调度标志位
#define OS_SCHEDULER_CLR(cpuid) do {     \
    g_taskScheduled &= ~(1U << (cpuid)); \
} while (0);
//判断当前核心的调度标志位是否激活
#define OS_SCHEDULER_ACTIVE (g_taskScheduled & (1U << ArchCurrCpuid()))

typedef enum {
    INT_NO_RESCH = 0,   /* no needs to schedule */
    INT_PEND_RESCH,     /* pending schedule flag */
} SchedFlag;

/* Check if preemptable with counter flag */
//用于判断当前任务是否可以被抢占
STATIC INLINE BOOL OsPreemptable(VOID)
{
    /*
     * Unlike OsPreemptableInSched, the int may be not disabled when OsPreemptable
     * is called, needs manually disable interrupt, to prevent current task from
     * being migrated to another core, and get the wrong preemptable status.
     */
    UINT32 intSave = LOS_IntLock();
    BOOL preemptable = (OsPercpuGet()->taskLockCnt == 0);
    if (!preemptable) {
        /* Set schedule flag if preemption is disabled */
        OsPercpuGet()->schedFlag = INT_PEND_RESCH;
    }
    LOS_IntRestore(intSave);
    return preemptable;
}
//用于判断当前任务是否可以在调度过程中被抢占
STATIC INLINE BOOL OsPreemptableInSched(VOID)
{
    BOOL preemptable = FALSE;

#ifdef LOSCFG_KERNEL_SMP
    /*
     * For smp systems, schedule must hold the task spinlock, and this counter
     * will increase by 1 in that case.
     */
    preemptable = (OsPercpuGet()->taskLockCnt == 1);

#else
    preemptable = (OsPercpuGet()->taskLockCnt == 0);
#endif
    if (!preemptable) {
        /* Set schedule flag if preemption is disabled */
        OsPercpuGet()->schedFlag = INT_PEND_RESCH;
    }

    return preemptable;
}

/*
 * This function simply picks the next task and switches to it.
 * Current task needs to already be in the right state or the right
 * queues it needs to be in.
 */
//选择下一个任务并切换到它
extern VOID OsSchedResched(VOID);

/*
 * This function put the current task back to the ready queue and
 * try to do the schedule. However, the schedule won't be definitely
 * taken place while there're no other higher priority tasks or locked.
 */
//将当前任务放回就绪队列，并尝试进行调度
extern VOID OsSchedPreempt(VOID);

/*
 * Just like OsSchedPreempt, except this function will do the OS_INT_ACTIVE
 * check, in case the schedule taken place in the middle of an interrupt.
 */
//触发调度，如果在中断中则设置调度标志位
STATIC INLINE VOID LOS_Schedule(VOID)
{
    if (OS_INT_ACTIVE) {
        OsPercpuGet()->schedFlag = INT_PEND_RESCH;
        return;
    }

    /*
     * trigger schedule in task will also do the slice check
     * if necessary, it will give up the timeslice more in time.
     * otherwise, there's no other side effects.
     */
    OsSchedPreempt();
}

#ifdef LOSCFG_BASE_CORE_TIMESLICE
/**
 * @ingroup los_sched
 * This API is used to check time slices. If the number of Ticks equals to the time for task switch,
 * tasks are switched. Otherwise, the Tick counting continues.
 */
//检查时间片，如果满足任务切换的条件则进行切换
extern VOID OsTimesliceCheck(VOID);
#endif

#ifdef __cplusplus
#if __cplusplus
}
#endif /* __cplusplus */
#endif /* __cplusplus */

#endif /* _LOS_SCHED_PRI_H */
