src/thread/pthread_rwlock_tryrdlock.c

   1 #include "pthread_impl.h"
   2
   3 int __pthread_rwlock_tryrdlock(pthread_rwlock_t *rw)
   4 {
   5         int val, cnt;
   6         do {
   7                 val = rw->_rw_lock;
   8                 cnt = val & 0x7fffffff;
   9                 if (cnt == 0x7fffffff) return EBUSY;
  10                 if (cnt == 0x7ffffffe) return EAGAIN;
  11         } while (a_cas(&rw->_rw_lock, val, val+1) != val);
  12         return 0;
  13 }
  14
  15 weak_alias(__pthread_rwlock_tryrdlock, pthread_rwlock_tryrdlock);