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#include <semaphore.h> #include "pthread_impl.h" int sem_post(sem_t *sem) { int val, waiters; do { val = sem->__val[0]; waiters = sem->__val[1]; } while (a_cas(sem->__val, val, val+1+(val<0)) != val); if (val<0 || waiters) __wake(sem->__val, 1, 0); return 0; }