#include "pthread_impl.h"

int pthread_rwlock_timedwrlock(pthread_rwlock_t* restrict rw,
                               const struct timespec* restrict at) {
  int r, t;

  r = pthread_rwlock_trywrlock(rw);
  if (r != EBUSY)
    return r;

  int spins = 100;
  while (spins-- && rw->_rw_lock && !rw->_rw_waiters)
    a_spin();

  while ((r = pthread_rwlock_trywrlock(rw)) == EBUSY) {
    if (!(r = rw->_rw_lock))
      continue;
    t = r | 0x80000000;
    a_inc(&rw->_rw_waiters);
    a_cas(&rw->_rw_lock, r, t);
    r = __timedwait(&rw->_rw_lock, t, CLOCK_REALTIME, at, rw->_rw_shared ^ 128);
    a_dec(&rw->_rw_waiters);
    if (r && r != EINTR)
      return r;
  }
  return r;
}