Xenbus implementation ported from Linux to Mini-os, simple thread support introduced

to simplify the porting. 64 bit version of Mini-os now compiles, but does not work
because of the pagetables and some bits of scheduler not being written.

Signed-off-by: Grzegorz Milos <gm281@cam.ac.uk>

1 files changed, 46 insertions, 0 deletions

diff --git a/extras/mini-os/include/semaphore.h b/extras/mini-os/include/semaphore.h
new file mode 100644
index 0000000000..d30c81e674
--- /dev/null
+++ b/extras/mini-os/include/semaphore.h
@@ -0,0 +1,46 @@
+#ifndef _SEMAPHORE_H_
+#define _SEMAPHORE_H_
+
+#include <wait.h>
+
+/*
+ * Implementation of semaphore in Mini-os is simple, because 
+ * there are no preemptive threads, the atomicity is guaranteed.
+ */
+
+struct semaphore
+{
+	int count;
+	struct wait_queue_head wait;
+};
+
+
+#define __SEMAPHORE_INITIALIZER(name, n)                            \
+{                                                                   \
+    .count    = n,                                                  \
+    .wait           = __WAIT_QUEUE_HEAD_INITIALIZER((name).wait)    \
+}
+
+#define __MUTEX_INITIALIZER(name) \
+    __SEMAPHORE_INITIALIZER(name,1)
+                           
+#define __DECLARE_SEMAPHORE_GENERIC(name,count) \
+    struct semaphore name = __SEMAPHORE_INITIALIZER(name,count)
+    
+#define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1)
+
+#define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name,0)
+
+static void inline down(struct semaphore *sem)
+{
+    wait_event(sem->wait, sem->count > 0);
+    sem->count--;
+}
+
+static void inline up(struct semaphore *sem)
+{
+    sem->count++;
+    wake_up(&sem->wait);
+}
+
+#endif /* _SEMAPHORE_H */