src/thread/sem_trywait.c

   1 #include <semaphore.h>
   2 #include <limits.h>
   3 #include "pthread_impl.h"
   4
   5 int sem_trywait(sem_t *sem)
   6 {
   7         int val;
   8         while ((val=sem->__val[0]) & SEM_VALUE_MAX) {
   9                 if (a_cas(sem->__val, val, val-1)==val) return 0;
  10         }
  11         errno = EAGAIN;
  12         return -1;
  13 }