third_party/ulib/musl/pthread/pthread_rwlock_tryrdlock.c

#include "threads_impl.h"

int pthread_rwlock_tryrdlock(pthread_rwlock_t* rw) {
    int val, cnt;
    do {
        val = atomic_load(&rw->_rw_lock);
        cnt = val & 0x7fffffff;
        if (cnt == 0x7fffffff)
            return EBUSY;
        if (cnt == 0x7ffffffe)
            return EAGAIN;
    } while (a_cas_shim(&rw->_rw_lock, val, val + 1) != val);
    return 0;
}