source: azure_iot_hub/trunk/musl-1.1.18/src/thread/sem_post.c@ 388

#include <semaphore.h>
#include "pthread_impl.h"

int sem_post(sem_t *sem)
{
        int val, waiters, priv = sem->__val[2];
        do {
                val = sem->__val[0];
                waiters = sem->__val[1];
                if (val == SEM_VALUE_MAX) {
                        errno = EOVERFLOW;
                        return -1;
                }
        } while (a_cas(sem->__val, val, val+1+(val<0)) != val);
        if (val<0 || waiters) __wake(sem->__val, 1, priv);
        return 0;
}