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对于有热心的小伙伴在微博上私信我，说我的uC/OS-II 一些函数简介篇幅有些过于长应该分开介绍。应小伙伴的要求，特此将文章分开进行讲解。上文主要介绍了任务相关的函数，本文介绍时间相关的函数：OSTimeDly()延时节拍函数，OSTimeDlyHMSM()系统延时函数，OSTimeDlyResume()延时恢复函数
OSTimeDly()延时节拍函数
1、主要作用：调用该函数的任务将自己延时一段时间并执行一次任务调度，一旦规定的延时时间完成或有其它的任务通过调用OSTimeDlyResume()取消了延时，调用OSTimeDly()函数的任务马上进入就绪状态（前提是先将任务调度后执行的任务执行到程序尾，且调用OSTimeDly的任务此时优先级最高）。
2、函数原型：void OSTimeDly (INT16U ticks);
3、参数说明：ticks为需要延时的时钟节拍数；
4、返回值：无
5、函数主体在os_time.c中
OSTimeDlyHMSM()系统延时函数
1、主要作用：函数是以小时(H)、分(M)、秒(S)和毫秒(m)四个参数来定义延时时间的，函数在内部把这些参数转换为时钟节拍，再通过单次或多次调用OSTimeDly()进行延时和任务调度，所以延时原理和调用延时函数OSTimeDly()是一样的。调用 OSTimeDlyHMSM() 后，如果延时时间不为0，系统将立即进行任务调度。
2、函数原型：INT8U OSTimeDlyHMSM (INT8U hours，INT8U minutes，INT8U seconds，INT16U milli);
3、参数说明：
hours 为延时小时数，范围从0-255。
minutes 为延时分钟数，范围从0-59
seconds 为延时秒数，范围从0-59
milli 为延时毫秒数，范围从0-999
4、返回值说明：
OS_NO_ERR：函数调用成功。
OS_TIME_INVALID_MINUTES：参数错误，分钟数大于59。
OS_TIME_INVALID_SECONDS：参数错误，秒数大于59。
OS_TIME_INVALID_MILLI：参数错误，毫秒数大于999。
OS_TIME_ZERO_DLY：四个参数全为0。
5、函数主体在os_time.c中
OSTimeDlyResume()延时恢复函数
1、主要作用：任务在延时之后，进入阻塞态。当延时时间到了就从阻塞态恢复到就绪态，可以被操作系统调度执行。但是，并非回到就绪态就只有这么一种可能，因为即便任务的延时时间没到，还是可以通过函数OSTimeDlyResume恢复该任务到就绪态的。另外，OSTimeDlyResume也不仅仅能恢复使用OSTimeDly或OSTimeDlyHMSM而延时的任务。对于因等待事件发生而阻塞的，并且设置了超时（timeout）时间的任务，也可以使用OSTimeDlyResume来恢复。对这些任务使用了OSTimeDlyResume，就好像已经等待超时了一样。但是，对于采用OSTaskSuspend挂起的任务，是不允许采用OSTimeDlyResume来恢复的。
2、函数原型：INT8U OSTimeDlyResume (INT8U prio)
3.参数说明：prio 被恢复任务的优先级
4、返回值：
OS_ERR_TASK_NOT_EXIST：任务优先级指针表中没有此任务
OS_NO_ERR：函数调用成功。
OS_ERR_PRIO_INVALID：参数指定的优先级大于或等于OS_LOWEST_PRIO。
OS_ERR_TIME_NOT_DLY：任务没有被延时阻塞
5、函数主体在os_time.c中
附os_time.c代码
/*
*********************************************************************************************************
* uC/OS-II
* The Real-Time Kernel
* TIME MANAGEMENT
*
* (c) Copyright 1992-2013, Micrium, Weston, FL
* All Rights Reserved
*
* File : OS_TIME.C
* By : Jean J. Labrosse
* Version : V2.92.08
*
* LICENSING TERMS:
* ---------------
* uC/OS-II is provided in source form for FREE evaluation, for educational use or for peaceful research.
* If you plan on using uC/OS-II in a commercial product you need to contact Micrium to properly license
* its use in your product. We provide ALL the source code for your convenience and to help you experience
* uC/OS-II. The fact that the source is provided does NOT mean that you can use it without paying a
* licensing fee.
*********************************************************************************************************
*/
#define MICRIUM_SOURCE
#ifndef OS_MASTER_FILE
#include <ucos_ii.h>
#endif
/*
*********************************************************************************************************
* DELAY TASK 'n' TICKS
*
* Description: This function is called to delay execution of the currently running task until the
* specified number of system ticks expires. This, of course, directly equates to delaying
* the current task for some time to expire. No delay will result If the specified delay is
* 0. If the specified delay is greater than 0 then, a context switch will result.
*
* Arguments : ticks is the time delay that the task will be suspended in number of clock 'ticks'.
* Note that by specifying 0, the task will not be delayed.
*
* Returns : none
*********************************************************************************************************
*/
void OSTimeDly (INT32U ticks)
{
INT8U y;
#if OS_CRITICAL_METHOD == 3u /* Allocate storage for CPU status register */
OS_CPU_SR cpu_sr = 0u;
#endif
if (OSIntNesting > 0u) { /* See if trying to call from an ISR */
return;
}
if (OSLockNesting > 0u) { /* See if called with scheduler locked */
return;
}
if (ticks > 0u) { /* 0 means no delay! */
OS_ENTER_CRITICAL();
y = OSTCBCur->OSTCBY; /* Delay current task */
OSRdyTbl[y] &= (OS_PRIO)~OSTCBCur->OSTCBBitX;
if (OSRdyTbl[y] == 0u) {
OSRdyGrp &= (OS_PRIO)~OSTCBCur->OSTCBBitY;
}
OSTCBCur->OSTCBDly = ticks; /* Load ticks in TCB */
OS_EXIT_CRITICAL();
OS_Sched(); /* Find next task to run! */
}
}
/*$PAGE*/
/*
*********************************************************************************************************
* DELAY TASK FOR SPECIFIED TIME
*
* Description: This function is called to delay execution of the currently running task until some time
* expires. This call allows you to specify the delay time in HOURS, MINUTES, SECONDS and
* MILLISECONDS instead of ticks.
*
* Arguments : hours specifies the number of hours that the task will be delayed (max. is 255)
* minutes specifies the number of minutes (max. 59)
* seconds specifies the number of seconds (max. 59)
* ms specifies the number of milliseconds (max. 999)
*
* Returns : OS_ERR_NONE
* OS_ERR_TIME_INVALID_MINUTES
* OS_ERR_TIME_INVALID_SECONDS
* OS_ERR_TIME_INVALID_MS
* OS_ERR_TIME_ZERO_DLY
* OS_ERR_TIME_DLY_ISR
*
* Note(s) : The resolution on the milliseconds depends on the tick rate. For example, you can't do
* a 10 mS delay if the ticker interrupts every 100 mS. In this case, the delay would be
* set to 0. The actual delay is rounded to the nearest tick.
*********************************************************************************************************
*/
#if OS_TIME_DLY_HMSM_EN > 0u
INT8U OSTimeDlyHMSM (INT8U hours,
INT8U minutes,
INT8U seconds,
INT16U ms)
{
INT32U ticks;
if (OSIntNesting > 0u) { /* See if trying to call from an ISR */
return (OS_ERR_TIME_DLY_ISR);
}
if (OSLockNesting > 0u) { /* See if called with scheduler locked */
return (OS_ERR_SCHED_LOCKED);
}
#if OS_ARG_CHK_EN > 0u
if (hours == 0u) {
if (minutes == 0u) {
if (seconds == 0u) {
if (ms == 0u) {
return (OS_ERR_TIME_ZERO_DLY);
}
}
}
}
if (minutes > 59u) {
return (OS_ERR_TIME_INVALID_MINUTES); /* Validate arguments to be within range */
}
if (seconds > 59u) {
return (OS_ERR_TIME_INVALID_SECONDS);
}
if (ms > 999u) {
return (OS_ERR_TIME_INVALID_MS);
}
#endif
/* Compute the total number of clock ticks required.. */
/* .. (rounded to the nearest tick) */
ticks = ((INT32U)hours * 3600uL + (INT32U)minutes * 60uL + (INT32U)seconds) * OS_TICKS_PER_SEC
+ OS_TICKS_PER_SEC * ((INT32U)ms + 500uL / OS_TICKS_PER_SEC) / 1000uL;
OSTimeDly(ticks);
return (OS_ERR_NONE);
}
#endif
/*$PAGE*/
/*
*********************************************************************************************************
* RESUME A DELAYED TASK
*
* Description: This function is used resume a task that has been delayed through a call to either
* OSTimeDly() or OSTimeDlyHMSM(). Note that you can call this function to resume a
* task that is waiting for an event with timeout. This would make the task look
* like a timeout occurred.
*
* Arguments : prio specifies the priority of the task to resume
*
* Returns : OS_ERR_NONE Task has been resumed
* OS_ERR_PRIO_INVALID if the priority you specify is higher that the maximum allowed
* (i.e. >= OS_LOWEST_PRIO)
* OS_ERR_TIME_NOT_DLY Task is not waiting for time to expire
* OS_ERR_TASK_NOT_EXIST The desired task has not been created or has been assigned to a Mutex.
*********************************************************************************************************
*/
#if OS_TIME_DLY_RESUME_EN > 0u
INT8U OSTimeDlyResume (INT8U prio)
{
OS_TCB *ptcb;
#if OS_CRITICAL_METHOD == 3u /* Storage for CPU status register */
OS_CPU_SR cpu_sr = 0u;
#endif
if (prio >= OS_LOWEST_PRIO) {
return (OS_ERR_PRIO_INVALID);
}
OS_ENTER_CRITICAL();
ptcb = OSTCBPrioTbl[prio]; /* Make sure that task exist */
if (ptcb == (OS_TCB *)0) {
OS_EXIT_CRITICAL();
return (OS_ERR_TASK_NOT_EXIST); /* The task does not exist */
}
if (ptcb == OS_TCB_RESERVED) {
OS_EXIT_CRITICAL();
return (OS_ERR_TASK_NOT_EXIST); /* The task does not exist */
}
if (ptcb->OSTCBDly == 0u) { /* See if task is delayed */
OS_EXIT_CRITICAL();
return (OS_ERR_TIME_NOT_DLY); /* Indicate that task was not delayed */
}
ptcb->OSTCBDly = 0u; /* Clear the time delay */
if ((ptcb->OSTCBStat & OS_STAT_PEND_ANY) != OS_STAT_RDY) {
ptcb->OSTCBStat &= ~OS_STAT_PEND_ANY; /* Yes, Clear status flag */
ptcb->OSTCBStatPend = OS_STAT_PEND_TO; /* Indicate PEND timeout */
} else {
ptcb->OSTCBStatPend = OS_STAT_PEND_OK;
}
if ((ptcb->OSTCBStat & OS_STAT_SUSPEND) == OS_STAT_RDY) { /* Is task suspended? */
OSRdyGrp |= ptcb->OSTCBBitY; /* No, Make ready */
OSRdyTbl[ptcb->OSTCBY] |= ptcb->OSTCBBitX;
OS_EXIT_CRITICAL();
OS_Sched(); /* See if this is new highest priority */
} else {
OS_EXIT_CRITICAL(); /* Task may be suspended */
}
return (OS_ERR_NONE);
}
#endif
/*$PAGE*/
/*
*********************************************************************************************************
* GET CURRENT SYSTEM TIME
*
* Description: This function is used by your application to obtain the current value of the 32-bit
* counter which keeps track of the number of clock ticks.
*
* Arguments : none
*
* Returns : The current value of OSTime
*********************************************************************************************************
*/
#if OS_TIME_GET_SET_EN > 0u
INT32U OSTimeGet (void)
{
INT32U ticks;
#if OS_CRITICAL_METHOD == 3u /* Allocate storage for CPU status register */
OS_CPU_SR cpu_sr = 0u;
#endif
OS_ENTER_CRITICAL();
ticks = OSTime;
OS_EXIT_CRITICAL();
return (ticks);
}
#endif
/*
*********************************************************************************************************
* SET SYSTEM CLOCK
*
* Description: This function sets the 32-bit counter which keeps track of the number of clock ticks.
*
* Arguments : ticks specifies the new value that OSTime needs to take.
*
* Returns : none
*********************************************************************************************************
*/
#if OS_TIME_GET_SET_EN > 0u
void OSTimeSet (INT32U ticks)
{
#if OS_CRITICAL_METHOD == 3u /* Allocate storage for CPU status register */
OS_CPU_SR cpu_sr = 0u;
#endif
OS_ENTER_CRITICAL();
OSTime = ticks;
OS_EXIT_CRITICAL();
}
#endif