1 files changed, 17 insertions, 0 deletions
diff --git a/libc-top-half/musl/src/thread/sem_post.c b/libc-top-half/musl/src/thread/sem_post.c
new file mode 100644
index 0000000..31e3293
--- /dev/null
+++ b/libc-top-half/musl/src/thread/sem_post.c
@@ -0,0 +1,17 @@
+#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;
+}