initial check-in, version 0.5.0v0.5.0

1 files changed, 31 insertions, 0 deletions

diff --git a/src/thread/pthread_barrier_wait.c b/src/thread/pthread_barrier_wait.c
new file mode 100644
index 00000000..02c252ad
--- /dev/null
+++ b/src/thread/pthread_barrier_wait.c
@@ -0,0 +1,31 @@
+#include "pthread_impl.h"
+
+int pthread_barrier_wait(pthread_barrier_t *b)
+{
+	int cur;
+
+	/* Trivial case: count was set at 1 */
+	if (!b->__limit) return PTHREAD_BARRIER_SERIAL_THREAD;
+
+	/* Wait for anyone still suspended at previous use of barrier */
+	while ((cur=b->__left))
+		__wait(&b->__left, &b->__waiters, cur, 0);
+
+	/* If we are the last to reach barrier, reset it and wake others */
+	if (a_fetch_add(&b->__count, 1) == b->__limit) {
+		b->__left = b->__limit;
+		b->__count = 0;
+		__wake(&b->__count, -1, 0);
+		return PTHREAD_BARRIER_SERIAL_THREAD;
+	}
+
+	/* Wait for our peers to reach the barrier */
+	while ((cur=b->__count))
+		__wait(&b->__count, 0, cur, 0);
+
+	/* If we're the last to wake up and barrier is awaiting reuse */
+	if (a_fetch_add(&b->__left, -1) == 1 && b->__waiters)
+		__wake(&b->__left, -1, 0);
+
+	return 0;
+}