From 51af35ffc632f7979fecc609445af8378466d405 Mon Sep 17 00:00:00 2001
From: Christian Cunningham <cc@localhost>
Date: Sat, 4 Dec 2021 18:00:23 -0700
Subject: Created basic Mutex

---
 src/util/mutex.c | 20 ++++++++++++++++++++
 src/util/mutex.h | 15 +++++++++++++++
 2 files changed, 35 insertions(+)
 create mode 100644 src/util/mutex.c
 create mode 100644 src/util/mutex.h

(limited to 'src/util')

diff --git a/src/util/mutex.c b/src/util/mutex.c
new file mode 100644
index 0000000..86ffcf5
--- /dev/null
+++ b/src/util/mutex.c
@@ -0,0 +1,20 @@
+#include "../util/mutex.h"
+
+unsigned char lock_mutex(struct Mutex* m, unsigned long pid) {
+	if (m->pid == NULL_PID) {
+		m->pid = pid;
+		return 0;
+	}
+	return 1;
+}
+
+// Eventually, there will need to be a hook into the scheduling mechanism
+//  that checks the currently running process and check that against the
+//  mutex's pid lock
+unsigned char release_mutex(struct Mutex* m, unsigned long pid) {
+	if (m->pid == pid) {
+		m->pid = NULL_PID;
+		return 0;
+	}
+	return 1;
+}
diff --git a/src/util/mutex.h b/src/util/mutex.h
new file mode 100644
index 0000000..8c9a097
--- /dev/null
+++ b/src/util/mutex.h
@@ -0,0 +1,15 @@
+#ifndef SYS_MUTEX_H
+#define SYS_MUTEX_H
+
+#define NULL_PID 0
+#define SCHED_PID 1
+
+struct Mutex {
+	unsigned long* addr;
+	unsigned long pid;
+};
+
+unsigned char lock_mutex(struct Mutex*, unsigned long);
+unsigned char release_mutex(struct Mutex*, unsigned long);
+
+#endif
-- 
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