mart/ex08/ex08a.c

   1 #include <stdio.h>
   2 #include <signal.h>
   3 #include <unistd.h>
   4 #include <sys/mman.h>
   5
   6 #include <native/task.h>
   7 #include <native/timer.h>
   8 #include <native/sem.h>
   9
  10 #include <rtdk.h>
  11
  12 static RT_TASK tl;
  13 static RT_TASK tm;
  14 static RT_TASK th;
  15 RTIME timeblock = 1e7;
  16 RT_SEM sem;
  17
  18 int global = 0;
  19
  20 void t_low(void *arg)
  21 {
  22         int i;
  23         for(i = 0; i<3; i++){
  24                 rt_sem_p(&sem, TM_INFINITE);
  25                 rt_printf("Low priority task locks semaphore\n");
  26                 rt_task_sleep(timeblock*3);
  27                 rt_printf("Low priority task unlocks semaphore\n");
  28                 rt_sem_v(&sem);
  29         }
  30         rt_printf(".....Low priority task ends\n");
  31 }
  32
  33 void t_med(void *arg)
  34 {
  35         rt_task_sleep(timeblock*2);
  36         int i;
  37         for(i = 0; i<10; i++){
  38                 rt_printf("Medium task running\n");
  39                 rt_timer_spin(timeblock);
  40         }
  41         rt_printf(".....Medium priority task ends\n");
  42 }
  43
  44 void t_high(void *arg)
  45 {
  46         rt_task_sleep(timeblock*3);
  47         int i;
  48         for(i = 0; i<3; i++){
  49                 rt_printf("High priority task tries to locks semaphore\n");
  50                 rt_sem_p(&sem, TM_INFINITE);
  51                 rt_printf("High priority task locks semaphore\n");
  52                 rt_timer_spin(timeblock*3);
  53                 rt_printf("High priority task unlocks semaphore\n");
  54                 rt_sem_v(&sem);
  55         }
  56         rt_printf(".....High priority task ends\n");
  57 }
  58
  59 int main(int argc, char* argv[])
  60 {
  61         /* Perform auto-init of rt_print buffers if the task doesn't do so */
  62         rt_print_auto_init(1);
  63
  64         /* Avoids memory swapping for this program */
  65         mlockall(MCL_CURRENT | MCL_FUTURE);
  66
  67         /* create the two tasks */
  68         rt_task_create(&tl, "t_low", 0, 49, 0);
  69         rt_task_create(&tm, "t_med", 0, 50, 0);
  70         rt_task_create(&th, "t_high", 0, 51, 0);
  71
  72         /* create semaphore and start in blocked mode */
  73         rt_sem_create(&sem, "sem", 1, S_PRIO);
  74
  75         /* start the two tasks */
  76         rt_task_start(&tl, &t_low, 0);
  77         rt_task_start(&tm, &t_med, 0);
  78         rt_task_start(&th, &t_high, 0);
  79
  80         pause();
  81 }