1 files changed, 61 insertions, 0 deletions

diff --git a/src/kernel_iface.c b/src/kernel_iface.c
new file mode 100644
index 0000000..5751ca6
--- /dev/null
+++ b/src/kernel_iface.c
@@ -0,0 +1,61 @@
+#include <stdio.h>
+
+#include "litmus.h"
+#include "internal.h"
+
+struct np_flag {
+        #define RT_PREEMPTIVE           0x2050 /* = NP */
+        #define RT_NON_PREEMPTIVE       0x4e50 /* =  P */
+        unsigned short preemptivity;
+
+        #define RT_EXIT_NP_REQUESTED    0x5251 /* = RQ */
+        unsigned short request;
+
+        unsigned int ctr;
+};
+
+int register_np_flag(struct np_flag* flag);
+int signal_exit_np(void);
+
+
+
+static struct np_flag np_flag;
+
+
+int init_kernel_iface(void)
+{
+        int ret;
+        np_flag.preemptivity = RT_PREEMPTIVE;
+        np_flag.ctr = 0;
+        ret = register_np_flag(&np_flag);
+        check("register_np_flag()");  
+        return ret;
+}
+
+static inline void barrier(void)
+{
+        __asm__ __volatile__("sfence": : :"memory");
+}
+
+void enter_np(void)
+{
+        if (++np_flag.ctr == 1)
+        {
+                np_flag.request = 0;
+                barrier();
+                np_flag.preemptivity = RT_NON_PREEMPTIVE;
+        }
+}
+
+
+void exit_np(void)
+{
+        if (--np_flag.ctr == 0)
+        {
+                np_flag.preemptivity = RT_PREEMPTIVE;
+                barrier();
+                if (np_flag.request == RT_EXIT_NP_REQUESTED)
+                        signal_exit_np();
+        }
+}
+