对os_tick.c进行源码注释与阅读
//作用：实现系统滴答定时器的功能，包括滴答列表的更新、滴答步长的动态调整等。用于管理自身主动延迟或在内核对象上被超时挂起的任务；
/*
*********************************************************************************************************
* uC/OS-III
* The Real-Time Kernel
*
* Copyright 2009-2022 Silicon Laboratories Inc. www.silabs.com
*
* SPDX-License-Identifier: APACHE-2.0
*
* This software is subject to an open source license and is distributed by
* Silicon Laboratories Inc. pursuant to the terms of the Apache License,
* Version 2.0 available at www.apache.org/licenses/LICENSE-2.0.
*
*********************************************************************************************************
*/
/*
*********************************************************************************************************
* TICK MANAGEMENT
*
* File : os_tick.c
* Version : V3.08.02
*********************************************************************************************************
*/
#define MICRIUM_SOURCE
#include "os.h"
#ifdef VSC_INCLUDE_SOURCE_FILE_NAMES
const CPU_CHAR *os_tick__c = "$Id: $";
#endif
#if (OS_CFG_TICK_EN > 0u)
/*
************************************************************************************************************************
* FUNCTION PROTOTYPES
************************************************************************************************************************
*/
static void OS_TickListUpdate (OS_TICK ticks);
/*
************************************************************************************************************************
* TICK INIT
*
* Description: This function initializes the variables related to the tick handler.
* The function is internal to uC/OS-III.
*
* Arguments : p_err is a pointer to a variable that will contain an error code returned by this function.
* -----
* OS_ERR_NONE the tick variables were initialized successfully
*
* Returns : none
*
* Note(s) : This function is INTERNAL to uC/OS-III and your application should not call it.
************************************************************************************************************************
*/
/**
* @brief 初始化操作系统滴答定时器
*
* 该函数用于初始化操作系统滴答定时器的相关参数，包括滴答计数器、滴答步长、以及滴答列表等。
*
* @param p_err 指向错误代码的指针，用于返回函数执行后的错误状态。
*/
void OS_TickInit (OS_ERR *p_err)
{
// 初始化错误代码为无错误
*p_err = OS_ERR_NONE;
// 清除滴答计数器
OSTickCtr = 0u; /* Clear the tick counter */
// 如果启用了动态滴答功能，则初始化滴答步长为0
#if (OS_CFG_DYN_TICK_EN > 0u)
OSTickCtrStep = 0u;
#endif
// 初始化滴答列表的TCB指针为NULL
OSTickList.TCB_Ptr = (OS_TCB *)0;
// 如果启用了调试功能，则初始化滴答列表的条目数和更新数为0
#if (OS_CFG_DBG_EN > 0u)
OSTickList.NbrEntries = 0u;
OSTickList.NbrUpdated = 0u;
#endif
}
/*
************************************************************************************************************************
* TICK UPDATE
*
* Description: This function updates the list of task either delayed pending with timeout.
* The function is internal to uC/OS-III.
*
* Arguments : ticks the number of ticks which have elapsed
* -----
*
* Returns : none
*
* Note(s) : This function is INTERNAL to uC/OS-III and your application should not call it.
************************************************************************************************************************
*/
// 更新系统滴答计数和相关时间戳
void OS_TickUpdate (OS_TICK ticks)
{
#if (OS_CFG_TS_EN > 0u)
CPU_TS ts_start;
#endif
//保存SR寄存器状态
CPU_SR_ALLOC();
//进入临界区
CPU_CRITICAL_ENTER();
// 累加滴答计数，用于跟踪系统时间
OSTickCtr += ticks;
// 跟踪滴答增量，用于调试和分析
OS_TRACE_TICK_INCREMENT(OSTickCtr);
#if (OS_CFG_TS_EN > 0u)
// 获取开始时间戳，用于计算滴答处理时间
ts_start = OS_TS_GET();
// 更新滴答列表，管理周期性任务
OS_TickListUpdate(ticks);
// 计算并更新滴答时间
OSTickTime = OS_TS_GET() - ts_start;
// 更新最大滴答时间，用于监控系统性能
if (OSTickTimeMax < OSTickTime) {
OSTickTimeMax = OSTickTime;
}
#else
// 更新滴答列表，即使没有时间戳功能也需管理周期性任务
OS_TickListUpdate(ticks);
#endif
#if (OS_CFG_DYN_TICK_EN > 0u)
// 动态滴答功能：根据当前任务调整滴答间隔
if (OSTickList.TCB_Ptr != (OS_TCB *)0) {
OSTickCtrStep = OSTickList.TCB_Ptr->TickRemain;
} else {
OSTickCtrStep = 0u;
}
// 设置动态滴答间隔
OS_DynTickSet(OSTickCtrStep);
#endif
// 退出临界区
CPU_CRITICAL_EXIT();
}
/*
************************************************************************************************************************
* INSERT
*
* Description: This task is internal to uC/OS-III and allows the insertion of a task in a tick list.
*
* Arguments : p_tcb is a pointer to the TCB to insert in the list
*
* elapsed is the number of elapsed ticks since the last tick interrupt
*
* tick_base is value of OSTickCtr from which time is offset
*
* time is the amount of time remaining (in ticks) for the task to become ready
*
* Returns : OS_TRUE if time is valid for the given tick base
*
* OS_FALSE if time is invalid (i.e. zero delay)
*
* Note(s) : 1) This function is INTERNAL to uC/OS-III and your application should not call it.
*
* 2) This function supports both Periodic Tick Mode (PTM) and Dynamic Tick Mode (DTM).
*
* 3) PTM should always call this function with elapsed == 0u.
************************************************************************************************************************
*/
/**
* @brief 插入任务控制块到滴答列表中
*
* 本函数负责将任务控制块(TCB)根据指定的时间插入到滴答列表中，用于任务的延迟调度
* 它计算任务到期所需的滴答数，并根据当前列表状态，将任务插入到正确的位置
*
* @param p_tcb 任务控制块指针，代表需要插入的任务
* @param elapsed 任务自上次调度以来经过的滴答数
* @param tick_base 任务开始延迟时的基准滴答数
* @param time 任务延迟的总时间
* @return CPU_BOOLEAN 插入结果，OS_TRUE表示成功插入，OS_FALSE表示立即到期（无需插入）
*/
CPU_BOOLEAN OS_TickListInsert (OS_TCB *p_tcb,
OS_TICK elapsed,
OS_TICK tick_base,
OS_TICK time)
{
OS_TCB *p_tcb1;
OS_TCB *p_tcb2;
OS_TICK_LIST *p_list;
OS_TICK delta;
OS_TICK remain;
// 计算任务到期还需多少滴答？
delta = (time + tick_base) - (OSTickCtr + elapsed);
// 如果任务立即到期，设置剩余滴答为0，并返回OS_FALSE
if (delta == 0u) {
p_tcb->TickRemain = 0u;
return (OS_FALSE);
}
// 跟踪任务延迟
OS_TRACE_TASK_DLY(delta);
// 获取滴答列表指针
p_list = &OSTickList;
// 如果列表为空，将任务直接插入
if (p_list->TCB_Ptr == (OS_TCB *)0) {
p_tcb->TickRemain = delta; // 存储到期时间到TCB
p_tcb->TickNextPtr = (OS_TCB *)0;
p_tcb->TickPrevPtr = (OS_TCB *)0;
p_list->TCB_Ptr = p_tcb; // 列表指向新插入的任务TCB
#if (OS_CFG_DYN_TICK_EN > 0u)
// 如果elapsed不为0，更新OSTickCtr
if (elapsed != 0u) {
OSTickCtr += elapsed;
OS_TRACE_TICK_INCREMENT(OSTickCtr);
}
// 设置新的滴答步长并更新动态滴答
OSTickCtrStep = delta;
OS_DynTickSet(OSTickCtrStep);
#endif
#if (OS_CFG_DBG_EN > 0u)
// 调试时更新列表条目数
p_list->NbrEntries = 1u;
#endif
return (OS_TRUE);
}
#if (OS_CFG_DBG_EN > 0u)
// 调试时增加列表条目计数
p_list->NbrEntries++;
#endif
// 从列表头开始遍历
p_tcb2 = p_list->TCB_Ptr;
remain = p_tcb2->TickRemain - elapsed; // 计算列表头任务剩余时间
// 如果当前任务应插入为新的列表头
if ((delta < remain) && (p_tcb2->TickPrevPtr == (OS_TCB *)0)) {
p_tcb->TickRemain = delta; // 设置当前任务的剩余时间为delta
p_tcb2->TickRemain = remain - delta; // 更新原列表头任务的剩余时间
p_tcb->TickPrevPtr = (OS_TCB *)0;
p_tcb->TickNextPtr = p_tcb2;
p_tcb2->TickPrevPtr = p_tcb;
p_list->TCB_Ptr = p_tcb;
#if (OS_CFG_DYN_TICK_EN > 0u)
// 更新OSTickCtr并设置新的滴答步长
if (elapsed != 0u) {
OSTickCtr += elapsed;
OS_TRACE_TICK_INCREMENT(OSTickCtr);
}
OSTickCtrStep = delta;
OS_DynTickSet(OSTickCtrStep);
#endif
return (OS_TRUE);
}
// 当前任务不在列表头插入，更新delta为相对于列表头的时间
delta -= remain;
p_tcb1 = p_tcb2;
p_tcb2 = p_tcb1->TickNextPtr;
// 寻找合适的插入位置
while ((p_tcb2 != (OS_TCB *)0) && (delta >= p_tcb2->TickRemain)) {
delta -= p_tcb2->TickRemain;
p_tcb1 = p_tcb2;
p_tcb2 = p_tcb2->TickNextPtr;
}
// 插入任务到列表中适当位置
if (p_tcb2 != (OS_TCB *)0) {
p_tcb1 = p_tcb2->TickPrevPtr;
p_tcb->TickRemain = delta;
p_tcb->TickPrevPtr = p_tcb1;
p_tcb->TickNextPtr = p_tcb2;
p_tcb2->TickRemain -= delta;
p_tcb2->TickPrevPtr = p_tcb;
p_tcb1->TickNextPtr = p_tcb;
} else {
// 如果任务插入到列表末尾
p_tcb->TickRemain = delta;
p_tcb->TickPrevPtr = p_tcb1;
p_tcb->TickNextPtr = (OS_TCB *)0;
p_tcb1->TickNextPtr = p_tcb;
}
return (OS_TRUE);
}
/*
************************************************************************************************************************
* ADD DELAYED TASK TO TICK LIST
*
* Description: This function is called to place a task in a list of task waiting for time to expire
*
* Arguments : p_tcb is a pointer to the OS_TCB of the task to add to the tick list
* -----
*
* time represents either the 'match' value of OSTickCtr or a relative time from the current
* system time as specified by the 'opt' argument..
*
* relative when 'opt' is set to OS_OPT_TIME_DLY
* relative when 'opt' is set to OS_OPT_TIME_TIMEOUT
* match when 'opt' is set to OS_OPT_TIME_MATCH
* periodic when 'opt' is set to OS_OPT_TIME_PERIODIC
*
* opt is an option specifying how to calculate time. The valid values are:
* ---
* OS_OPT_TIME_DLY
* OS_OPT_TIME_TIMEOUT
* OS_OPT_TIME_PERIODIC
* OS_OPT_TIME_MATCH
*
* p_err is a pointer to a variable that will contain an error code returned by this function.
* -----
* OS_ERR_NONE the call was successful and the time delay was scheduled.
* OS_ERR_TIME_ZERO_DLY if the effective delay is zero
*
* Returns : None
*
* Note(s) : 1) This function is INTERNAL to uC/OS-III and your application MUST NOT call it.
*
* 2) This function is assumed to be called with interrupts disabled.
************************************************************************************************************************
*/
/**
* @brief 插入任务到滴答列表中
*
* 本函数根据指定的时间和选项将任务控制块(p_tcb)插入到系统滴答列表中。
* 它处理绝对时间、周期性和相对时间延迟的选项，并更新任务的相应状态。
*
* @param p_tcb 指向任务控制块的指针，表示要插入列表的任务
* @param time 延迟的时间或周期时间
* @param opt 时间选项，决定时间计算的方式
* @param p_err 指向错误代码的指针，返回函数执行后的错误状态
*/
void OS_TickListInsertDly (OS_TCB *p_tcb,
OS_TICK time,
OS_OPT opt,
OS_ERR *p_err)
{
OS_TICK elapsed;
OS_TICK tick_base;
OS_TICK base_offset;
CPU_BOOLEAN valid_dly;
// 根据是否启用动态滴答配置，获取当前动态滴答数或初始化为0
#if (OS_CFG_DYN_TICK_EN > 0u)
elapsed = OS_DynTickGet();
#else
elapsed = 0u;
#endif
// 根据不同的时间选项处理任务的滴答基础值
if (opt == OS_OPT_TIME_MATCH) { /* MATCH to absolute tick ctr value mode */
tick_base = 0u; /* tick_base + time == time */
} else if (opt == OS_OPT_TIME_PERIODIC) { /* PERIODIC mode. */
if (time == 0u) {
*p_err = OS_ERR_TIME_ZERO_DLY; /* Infinite frequency is invalid. */
return;
}
tick_base = p_tcb->TickCtrPrev;
// 计算滴答基础值与当前系统时间的偏移量
#if (OS_CFG_DYN_TICK_EN > 0u)
base_offset = OSTickCtr + elapsed - tick_base;
#else
base_offset = OSTickCtr - tick_base;
#endif
// 如果任务错过了上一个周期，调整滴答基础值到下一个周期
if (base_offset >= time) {
tick_base += time * (base_offset / time);
if ((base_offset % time) != 0u) {
tick_base += time;
}
p_tcb->TickCtrPrev = tick_base;
}
p_tcb->TickCtrPrev += time;
} else { /* RELATIVE time delay mode */
// 根据当前系统时间计算滴答基础值
#if (OS_CFG_DYN_TICK_EN > 0u)
tick_base = OSTickCtr + elapsed;
#else
tick_base = OSTickCtr;
#endif
}
// 将任务插入到滴答列表中，并检查插入是否有效
valid_dly = OS_TickListInsert(p_tcb, elapsed, tick_base, time);
// 根据插入结果更新任务状态和错误代码
if (valid_dly == OS_TRUE) {
p_tcb->TaskState = OS_TASK_STATE_DLY;
*p_err = OS_ERR_NONE;
} else {
*p_err = OS_ERR_TIME_ZERO_DLY;
}
}
/*
************************************************************************************************************************
* REMOVE A TASK FROM THE TICK LIST
*
* Description: This function is called to remove a task from the tick list
*
* Arguments : p_tcb Is a pointer to the OS_TCB to remove.
* -----
*
* Returns : none
*
* Note(s) : 1) This function is INTERNAL to uC/OS-III and your application MUST NOT call it.
*
* 2) This function is assumed to be called with interrupts disabled.
************************************************************************************************************************
*/
/**
* 函数名称: OS_TickListRemove
* 功能描述: 从系统滴答列表中移除指定的任务控制块 (TCB)
* 参数:
* - p_tcb: 指向要移除的 TCB 的指针
*/
void OS_TickListRemove (OS_TCB *p_tcb)
{
OS_TCB *p_tcb1;
OS_TCB *p_tcb2;
OS_TICK_LIST *p_list;
#if (OS_CFG_DYN_TICK_EN > 0u)
OS_TICK elapsed;
#endif
#if (OS_CFG_DYN_TICK_EN > 0u)
// 获取动态滴答计数
elapsed = OS_DynTickGet();
#endif
// 获取当前 TCB 的前一个和后一个 TCB 指针
p_tcb1 = p_tcb->TickPrevPtr;
p_tcb2 = p_tcb->TickNextPtr;
p_list = &OSTickList;
// 检查当前 TCB 是否是列表中的唯一条目
if (p_tcb1 == (OS_TCB *)0) {
if (p_tcb2 == (OS_TCB *)0) { // 列表中只有一个条目
p_list->TCB_Ptr = (OS_TCB *)0;
#if (OS_CFG_DBG_EN > 0u)
p_list->NbrEntries = 0u;
#endif
p_tcb->TickRemain = 0u;
#if (OS_CFG_DYN_TICK_EN > 0u)
// 更新滴答计数器
if (elapsed != 0u) {
OSTickCtr += elapsed;
OS_TRACE_TICK_INCREMENT(OSTickCtr);
}
OSTickCtrStep = 0u;
OS_DynTickSet(OSTickCtrStep);
#endif
} else { // 列表中有多个条目，当前 TCB 是第一个
p_tcb2->TickPrevPtr = (OS_TCB *)0;
p_tcb2->TickRemain += p_tcb->TickRemain; // 将当前 TCB 的剩余滴答数加到下一个 TCB
p_list->TCB_Ptr = p_tcb2;
#if (OS_CFG_DBG_EN > 0u)
p_list->NbrEntries--;
#endif
#if (OS_CFG_DYN_TICK_EN > 0u)
// 更新滴答计数器
if (p_tcb2->TickRemain != p_tcb->TickRemain) {
if (elapsed != 0u) {
OSTickCtr += elapsed;
OS_TRACE_TICK_INCREMENT(OSTickCtr);
p_tcb2->TickRemain -= elapsed;
}
OSTickCtrStep = p_tcb2->TickRemain;
OS_DynTickSet(OSTickCtrStep);
}
#endif
p_tcb->TickNextPtr = (OS_TCB *)0;
p_tcb->TickRemain = 0u;
}
} else { // 当前 TCB 不是第一个
p_tcb1->TickNextPtr = p_tcb2;
if (p_tcb2 != (OS_TCB *)0) {
p_tcb2->TickPrevPtr = p_tcb1;
p_tcb2->TickRemain += p_tcb->TickRemain; // 将当前 TCB 的剩余滴答数加到下一个 TCB
}
p_tcb->TickPrevPtr = (OS_TCB *)0;
#if (OS_CFG_DBG_EN > 0u)
p_list->NbrEntries--;
#endif
p_tcb->TickNextPtr = (OS_TCB *)0;
p_tcb->TickRemain = 0u;
}
}
/*
************************************************************************************************************************
* UPDATE THE LIST OF TASKS DELAYED OR PENDING WITH TIMEOUT
*
* Description: This function updates the delta list which contains tasks that are delayed or pending with a timeout.
*
* Arguments : ticks the number of ticks which have elapsed.
*
* Returns : none
*
* Note(s) : 1) This function is INTERNAL to uC/OS-III and your application MUST NOT call it.
************************************************************************************************************************
*/
/**
* 更新系统滴答列表，减少列表中每个任务的剩余滴答数。
*
* @param ticks 需要减少的滴答数
*/
static void OS_TickListUpdate(OS_TICK ticks)
{
OS_TCB *p_tcb;
OS_TICK_LIST *p_list;
#if (OS_CFG_DBG_EN > 0u)
OS_OBJ_QTY nbr_updated;
#endif
#if (OS_CFG_MUTEX_EN > 0u)
OS_TCB *p_tcb_owner;
OS_PRIO prio_new;
#endif
#if (OS_CFG_DBG_EN > 0u)
nbr_updated = 0u; // 初始化更新的任务数量计数器
#endif
p_list = &OSTickList; // 获取滴答列表指针
p_tcb = p_list->TCB_Ptr; // 获取当前任务控制块指针
if (p_tcb != (OS_TCB *)0) {
if (p_tcb->TickRemain <= ticks) {
ticks = ticks - p_tcb->TickRemain;
p_tcb->TickRemain = 0u;
} else {
p_tcb->TickRemain -= ticks;
}
while (p_tcb->TickRemain == 0u) {
#if (OS_CFG_DBG_EN > 0u)
nbr_updated++; // 增加更新的任务数量计数器
#endif
switch (p_tcb->TaskState) {
case OS_TASK_STATE_DLY:
p_tcb->TaskState = OS_TASK_STATE_RDY;
OS_RdyListInsert(p_tcb); // 将任务插入就绪列表
break;
case OS_TASK_STATE_DLY_SUSPENDED:
p_tcb->TaskState = OS_TASK_STATE_SUSPENDED;
break;
default:
#if (OS_CFG_MUTEX_EN > 0u)
p_tcb_owner = (OS_TCB *)0;
if (p_tcb->PendOn == OS_TASK_PEND_ON_MUTEX) {
p_tcb_owner = (OS_TCB *)((OS_MUTEX *)((void *)p_tcb->PendObjPtr))->OwnerTCBPtr;
}
#endif
#if (OS_MSG_EN > 0u)
p_tcb->MsgPtr = (void *)0;
p_tcb->MsgSize = 0u;
#endif
#if (OS_CFG_TS_EN > 0u)
p_tcb->TS = OS_TS_GET();
#endif
OS_PendListRemove(p_tcb); // 从挂起列表中移除任务
switch (p_tcb->TaskState) {
case OS_TASK_STATE_PEND_TIMEOUT:
OS_RdyListInsert(p_tcb); // 将任务插入就绪列表
p_tcb->TaskState = OS_TASK_STATE_RDY;
break;
case OS_TASK_STATE_PEND_TIMEOUT_SUSPENDED:
p_tcb->TaskState = OS_TASK_STATE_SUSPENDED;
break;
default:
break;
}
p_tcb->PendStatus = OS_STATUS_PEND_TIMEOUT; // 标记挂起超时
p_tcb->PendOn = OS_TASK_PEND_ON_NOTHING; // 标记不再挂起
#if (OS_CFG_MUTEX_EN > 0u)
if (p_tcb_owner != (OS_TCB *)0) {
if ((p_tcb_owner->Prio != p_tcb_owner->BasePrio) &&
(p_tcb_owner->Prio == p_tcb->Prio)) { // 检查所有者是否继承了优先级
prio_new = OS_MutexGrpPrioFindHighest(p_tcb_owner);
prio_new = (prio_new > p_tcb_owner->BasePrio) ? p_tcb_owner->BasePrio : prio_new;
if (prio_new != p_tcb_owner->Prio) {
OS_TaskChangePrio(p_tcb_owner, prio_new);
OS_TRACE_MUTEX_TASK_PRIO_DISINHERIT(p_tcb_owner, p_tcb_owner->Prio);
}
}
}
#endif
break;
}
p_list->TCB_Ptr = p_tcb->TickNextPtr; // 获取下一个任务控制块指针
p_tcb = p_list->TCB_Ptr; // 重新获取 p_tcb 以继续循环
if (p_tcb == (OS_TCB *)0) {
#if (OS_CFG_DBG_EN > 0u)
p_list->NbrEntries = 0u; // 更新列表中的任务数量
#endif
break;
} else {
#if (OS_CFG_DBG_EN > 0u)
p_list->NbrEntries--; // 减少列表中的任务数量
#endif
p_tcb->TickPrevPtr = (OS_TCB *)0;
if (p_tcb->TickRemain <= ticks) {
ticks = ticks - p_tcb->TickRemain;
p_tcb->TickRemain = 0u;
} else {
p_tcb->TickRemain -= ticks;
}
}
}
}
#if (OS_CFG_DBG_EN > 0u)
p_list->NbrUpdated = nbr_updated; // 更新已处理的任务数量
#endif
}
#endif /* #if OS_CFG_TICK_EN */