From 4abab5ad6c8465a7528ccdd5f49367da05f78bbd Mon Sep 17 00:00:00 2001
From: Vladimir Azarov <avm@intermediate-node.net>
Date: Tue, 1 Oct 2024 15:47:05 +0200
Subject: Initial version

---
 src/thread/sem_trywait.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)
 create mode 100644 src/thread/sem_trywait.c

(limited to 'src/thread/sem_trywait.c')

diff --git a/src/thread/sem_trywait.c b/src/thread/sem_trywait.c
new file mode 100644
index 0000000..beb435d
--- /dev/null
+++ b/src/thread/sem_trywait.c
@@ -0,0 +1,13 @@
+#include <semaphore.h>
+#include <limits.h>
+#include "pthread_impl.h"
+
+int sem_trywait(sem_t *sem)
+{
+	int val;
+	while ((val=sem->__val[0]) & SEM_VALUE_MAX) {
+		if (a_cas(sem->__val, val, val-1)==val) return 0;
+	}
+	errno = EAGAIN;
+	return -1;
+}
-- 
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