1 files changed, 37 insertions, 0 deletions
diff --git a/libcr_ipc/mutex.c b/libcr_ipc/mutex.c
new file mode 100644
index 0000000..c5cea96
--- /dev/null
+++ b/libcr_ipc/mutex.c
@@ -0,0 +1,37 @@
+/* libcr_ipc/mutex.c - Simple mutexes for libcr (implementation file)
+ *
+ * Copyright (C) 2024  Luke T. Shumaker <lukeshu@lukeshu.com>
+ * SPDX-Licence-Identifier: AGPL-3.0-or-later
+ */
+
+#include <libcr_ipc/mutex.h>
+
+void cr_mutex_lock(cr_mutex_t *mu) {
+	assert(mu);
+	if (!mu->tail)
+		mu->tail = &mu->head;
+	if (!mu->locked) {
+		mu->locked = true;
+		return;
+	}
+	struct _cr_mutex_cid_list self = {
+		.val = cr_getcid(),
+		.next = NULL,
+	};
+	*(mu->tail) = &self;
+	mu->tail = &(self.next);
+	cr_pause_and_yield();
+}
+
+void cr_mutex_unlock(cr_mutex_t *mu) {
+	assert(mu);
+	assert(mu->tail);
+	assert(mu->locked);
+	if (mu->head) {
+		cr_unpause(mu->head->val);
+		mu->head = mu->head->next;
+		if (!mu->head)
+			mu->tail = &mu->head;
+	} else
+		mu->locked = false;
+}