1 files changed, 65 insertions, 0 deletions
diff --git a/lib/libc_r/uthread/uthread_spinlock.c b/lib/libc_r/uthread/uthread_spinlock.c
new file mode 100644
index 0000000..b2fe269
--- /dev/null
+++ b/lib/libc_r/uthread/uthread_spinlock.c
@@ -0,0 +1,65 @@
+/*
+ * Copyright (c) 1997 John Birrell <jb@cimlogic.com.au>.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *	This product includes software developed by John Birrell.
+ * 4. Neither the name of the author nor the names of any co-contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $Id$
+ *
+ */
+
+#include <stdio.h>
+#include <sched.h>
+#include <unistd.h>
+#include <pthread.h>
+#include "spinlock.h"
+#include "pthread_private.h"
+
+/*
+ * Lock a location for the running thread. Yield to allow other
+ * threads to run if this thread is blocked because the lock is
+ * not available. Note that this function does not sleep. It
+ * assumes that the lock will be available very soon.
+ */
+void
+_spinlock(long *lck)
+{
+	do {
+		/*
+		 * Allow other threads to run if the lock is not
+		 * available:
+		 */
+		while (*lck != 0)
+			sched_yield();
+
+	/*
+	 * Try to grab the lock and loop if another thread grabs
+	 * it before we do.
+	 */
+	} while(_atomic_lock(lck,(long) _thread_run));
+}