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标题: 请问调用rt_thread_create（）创建线程，初始化定时器有何用处 [打印本页]

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作者: choose521    时间: 2022-7-13 13:13
标题: 请问调用rt_thread_create（）创建线程，初始化定时器有何用处
调用rt_thread_create（）创建线程的时候，调用了下面的代码，作用是什么？
1 l' @% r& U( G/ |- W
. W* b1 E6 ~9 o0 F( J3 s, }1 X+ K6 Y9 T/* initialize thread timer */
rt_timer_init(&(thread->thread_timer),thread->name,rt_thread_timeout,thread,0,RT_TIMER_FLAG_ONE_SHOT);
为什么要创建这个定时器？

在系统时钟中断回调函数里面，已经调用了下面的代码
: b& n3 k. j) N  V7 Y
8 U3 V$ l$ a2 \2 pvoid rt_tick_increase(void)
' }0 d# Z" @+ @3 N+ F2 p' E{
struct rt_thread thread;
& _7 b4 ?" f0 N% E8 `, o( s1 A( ?/ increase the global tick /
++ rt_tick;
) u/ W' G$ ]  }+ N8 e+ J& c/ check time slice /
thread = rt_thread_self();
-- thread->remaining_tick;
if (thread->remaining_tick == 0)
{
5 _; V8 Q% g6 \1 B/ change to initialized tick /
thread->remaining_tick = thread->init_tick;
, w. e, R  j) ?/ yield /
$ I0 J! [" V: yrt_thread_yield();
}
8 U* e: s0 J7 G4 D/ _! q/ check timer */
. j+ C- Z( ^0 A! L% |' ]rt_timer_check();
}
上面的代码已经会去判断remaining_tick，这个为0就执行让出cpu操作了。

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作者: opipo    时间: 2022-7-13 13:51
用来控制挂起时间的。例如你主动调用delay或者阻塞于获取信号量等都会用到这个定时器。截取了一段信号量获取函数中的源码：
' I* X! ]2 C, D* j, [`
/ start /
) _8 r( q7 D& F, vrt_ipc_list_suspend(&(sem->parent.suspend_thread),
thread,
sem->parent.parent.flag);
" T: Y6 W1 f/ d  o; z7 {
/* has waiting time, start thread timer */
& }4 M" X, b  s7 t9 W, A* S' ]if (time > 0)
& z- W+ A6 N8 K+ Z{
RT_DEBUG_LOG(RT_DEBUG_IPC, ("set thread:%s to timer list\n",
thread->name));
/* reset the timeout of thread timer and start it */
rt_timer_control(&(thread->thread_timer),
# p2 _6 _- h/ _, C1 LRT_TIMER_CTRL_SET_TIME,
&time);
rt_timer_start(&(thread->thread_timer));
5 \; _$ F7 C' t& Y2 w* f}
/* enable interrupt */
rt_hw_interrupt_enable(temp);
8 Y/ k: k% w- p, y( e8 v# ^9 S/* do schedule */
rt_schedule(); rt_ipc_list_suspend(&(sem->parent.suspend_thread),
* m- S# f" O2 f" K: lthread,
sem->parent.parent.flag);
0 l# U# U4 h: `) E4 j' g/* has waiting time, start thread timer */
if (time > 0)
# r8 _6 }, I' s/ {! X{
RT_DEBUG_LOG(RT_DEBUG_IPC, ("set thread:%s to timer list\n",
thread->name));
/* reset the timeout of thread timer and start it */
* f- R% V# j: ~rt_timer_control(&(thread->thread_timer),
% X2 r+ w/ j1 |8 q% U, `RT_TIMER_CTRL_SET_TIME,
" N( v/ ~0 _3 d' G+ p) B2 [&time);
/ a8 g% f$ p1 _9 g) x3 Y: @rt_timer_start(&(thread->thread_timer));
}
3 T% k3 R! |8 V1 T* M/* enable interrupt */
+ C, v2 F1 k' i/ N7 U0 Z1 urt_hw_interrupt_enable(temp);
/* do schedule */
" d# M; y/ m5 }/ J1 x9 K2 K, \rt_schedule();`

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作者: Blah    时间: 2022-7-13 14:50
楼上说的很不错的

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作者: land    时间: 2022-7-13 15:23
可以试试一楼的方法

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