sys/xtimer: add xtimer_set_timeout_flag()

sys/include/xtimer.h

@@ -439,6 +439,17 @@ static inline bool xtimer_less64(xtimer_ticks64_t a, xtimer_ticks64_t b);
  */
 int xtimer_mutex_lock_timeout(mutex_t *mutex, uint64_t us);
 
+/**
+ * @brief    Set timeout thread flag after @p timeout
+ *
+ * This function will set THREAD_FLAG_TIMEOUT on the current thread after @p
+ * timeout usec have passed.
+ *
+ * @param[in]   t       timer struct to use
+ * @param[in]   timeout timeout in usec
+ */
+void xtimer_set_timeout_flag(xtimer_t *t, uint32_t timeout);
+
 /**
  * @brief xtimer backoff value
  *

sys/xtimer/xtimer.c

@@ -30,6 +30,10 @@
 
 #include "timex.h"
 
+#ifdef MODULE_CORE_THREAD_FLAGS
+#include "thread_flags.h"
+#endif
+
 #define ENABLE_DEBUG 0
 #include "debug.h"
 
@@ -257,3 +261,18 @@ int xtimer_mutex_lock_timeout(mutex_t *mutex, uint64_t timeout)
     xtimer_remove(&t);
     return -mt.timeout;
 }
+
+#ifdef MODULE_CORE_THREAD_FLAGS
+static void _set_timeout_flag_callback(void* arg)
+{
+    thread_flags_set(arg, THREAD_FLAG_TIMEOUT);
+}
+
+void xtimer_set_timeout_flag(xtimer_t *t, uint32_t timeout)
+{
+    t->callback = _set_timeout_flag_callback;
+    t->arg = (thread_t *)sched_active_thread;
+    thread_flags_clear(THREAD_FLAG_TIMEOUT);
+    xtimer_set(t, timeout);
+}
+#endif