X-Git-Url: https://scm.lunaixsky.com/lunaix-os.git/blobdiff_plain/baca54322c66983205edecd2ebb00d997878be50..270869139db617e29a35bb9ded41087bb702f9ac:/lunaix-os/includes/lunaix/switch.h

diff --git a/lunaix-os/includes/lunaix/switch.h b/lunaix-os/includes/lunaix/switch.h
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+++ b/lunaix-os/includes/lunaix/switch.h
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+#ifndef __LUNAIX_SWITCH_H
+#define __LUNAIX_SWITCH_H
+
+#define SWITCH_MODE_NORMAL   0
+#define SWITCH_MODE_FAST     1
+#define SWITCH_MODE_GIVEUP   2
+
+#ifndef __ASM__
+
+#include <lunaix/types.h>
+
+struct signpost_result
+{
+    int mode;
+    ptr_t stack;
+};
+
+/**
+ * @brief Decide how current thread should perform the context switch
+ *        back to it's previously saved context. 
+ * 
+ *        Return a user stack pointer perform a temporary fast redirected 
+ *        context switch. 
+ *        No redirection is required if such pointer is null.
+ * 
+ *        This function might never return if the decision is made to give up
+ *        this switching.
+ * 
+ *        NOTE: This function might have side effects, it can only be
+ *         called within the twilight zone of context restore. (after entering
+ *         do_switch and before returning from exception)
+ * 
+ * @return ptr_t
+ */
+ptr_t
+switch_signposting();
+
+static inline void
+redirect_switch(struct signpost_result* res, ptr_t stack)
+{
+    res->mode  = SWITCH_MODE_FAST;
+    res->stack = stack;
+}
+
+static inline void
+continue_switch(struct signpost_result* res)
+{
+    res->mode  = SWITCH_MODE_NORMAL;
+    res->stack = 0;
+}
+
+static inline void
+giveup_switch(struct signpost_result* res)
+{
+    res->mode  = SWITCH_MODE_GIVEUP;
+    res->stack = 0;
+}
+
+#endif
+#endif /* __LUNAIX_SWITCH_H */