old uncommited changes commited

2 files changed, 38 insertions, 0 deletions

diff --git a/src/kernel/lib/mutex.c b/src/kernel/lib/mutex.c
new file mode 100644
index 0000000..f3ed11f
--- /dev/null
+++ b/src/kernel/lib/mutex.c
@@ -0,0 +1,23 @@
+#include "mutex.h"
+#include <task/task.h>
+
+static uint32_t atomic_exchange(uint32_t* ptr, uint32_t newval) {
+	uint32_t r;
+	asm volatile("xchg (%%ecx), %%eax" : "=a"(r) : "c"(ptr), "a"(newval));
+	return r;
+}
+
+void mutex_lock(uint32_t* mutex) {
+	while (atomic_exchange(mutex, MUTEX_LOCKED) == MUTEX_LOCKED) {
+		thread_sleep(1);
+	}
+}
+
+int mutex_lockE(uint32_t* mutex) {
+	if (atomic_exchange(mutex, MUTEX_LOCKED) == MUTEX_LOCKED) return 0;
+	return 1;
+}
+
+void mutex_unlock(uint32_t* mutex) {
+	*mutex = MUTEX_UNLOCKED;
+}
diff --git a/src/kernel/lib/mutex.h b/src/kernel/lib/mutex.h
new file mode 100644
index 0000000..2687b30
--- /dev/null
+++ b/src/kernel/lib/mutex.h
@@ -0,0 +1,15 @@
+#ifndef DEF_MUTEX_H
+#define DEF_MUTEX_H
+
+#include <types.h>
+
+#define MUTEX_LOCKED 1
+#define MUTEX_UNLOCKED 0
+
+//A mutex is just an uint32_t
+
+void mutex_lock(uint32_t* mutex);	//wait for mutex to be free
+int mutex_lockE(uint32_t* mutex);	//lock mutex only if free, returns !0 if locked, 0 if was busy
+void mutex_unlock(uint32_t* mutex);
+
+#endif