一、rtimer概述
The Contiki rtimer library provides scheduling and execution of real-time tasks (with predictable execution times)
数据结构:
struct rtimer { rtimer_clock_t time; rtimer_callback_t func; void *ptr; };
typedef void (* rtimer_callback_t)(struct rtimer *t, void *ptr);
1、rtimer_init
void rtimer_init(void) { rtimer_arch_init(); }
rtimer_arch_init是跟平台相关的，rtimer_arch_init() is called by the rtimer library to initialize the rtimer architecture code.
2、rtimer_set
int rtimer_set(struct rtimer *rtimer, rtimer_clock_t time, rtimer_clock_t duration, rtimer_callback_t func, void *ptr) { int first = 0; PRINTF("rtimer_set time %d ", time); if(next_rtimer == NULL) {//空，first置1 first = 1; } rtimer->func = func;//设置回调函数 rtimer->ptr = ptr;//回调函数第一个参数 rtimer->time = time;//设置 next_rtimer = rtimer;//设置next_rtimer if(first == 1) {//如果是1 rtimer_arch_schedule(time); } }
rtimer用来设置rtimer，即在特定的时间（time）执行特定的回调函数（func）。
其中rtimer_arch_schedule函数是跟平台相关的，被底层用来确定调用rtimer_run_next的时间，rtimer_run_next会在特定的时间执行回调函数。
3、rtimer_run_next
void rtimer_run_next(void) { struct rtimer *t; if(next_rtimer == NULL) { return; } t = next_rtimer; next_rtimer = NULL;//重新设置为NULL t->func(t, t->ptr);//执行回调函数 if(next_rtimer != NULL) {//在执行回调函数期间有rtimer set，在调用一次rtimer_arch_schedule rtimer_arch_schedule(next_rtimer->time); } return; }
rtimer_run_next会调用特定的next_rtimer的回调函数。
rtimer_run_next是在底层被调用的。
直观的流程：
rtimer_set（设置rtimer） ---> rtimer_arch_schedule(通知底层在特定时间) ------> rtimer_run_next（在特定时间执行回调函数） -------> rtimer_set
注：RTIMER_NOW() RTIMER_SECOND rtimer_arch_init() rtimer_arch_now() rtimer_arch_schedule()等都是跟平台有关的。