Hardy Griech's timer bugfix: avoid direct comparison for timer values since they may wrap. Instead, use the CLOCK_LT() that works correctly even for wrapped timers.

core/sys/clock.h

@@ -53,14 +53,23 @@
  *
  * Author: Adam Dunkels <adam@sics.se>
  *
- * $Id: clock.h,v 1.6 2008/07/10 17:09:32 adamdunkels Exp $
+ * $Id: clock.h,v 1.7 2008/08/15 19:16:09 adamdunkels Exp $
  */
 #ifndef __CLOCK_H__
 #define __CLOCK_H__
 
 #include "contiki-conf.h"
 
-#define CLOCK_LT(a,b)     ((signed short)((a)-(b)) < 0)
+/**
+ * Check if a clock time value is less than another clock time value.
+ *
+ * This macro checks if a clock time value is less than another clock
+ * time value. This macro is needed to correctly handle wrap-around of
+ * clock time values.
+ *
+ */
+#define CLOCK_LT(a, b) ((clock_time_t)((a) - (b)) < \
+                       ((clock_time_t)(~((clock_time_t)0)) >> 1))
 
 /**
  * Initialize the clock library.

core/sys/timer.c

@@ -42,7 +42,7 @@
  *
  * Author: Adam Dunkels <adam@sics.se>
  *
- * $Id: timer.c,v 1.2 2007/05/27 11:11:28 oliverschmidt Exp $
+ * $Id: timer.c,v 1.3 2008/08/15 19:16:09 adamdunkels Exp $
  */
 
 #include "contiki-conf.h"
@@ -121,7 +121,7 @@ timer_restart(struct timer *t)
 int
 timer_expired(struct timer *t)
 {
-  return (clock_time_t)(clock_time() - t->start) >= (clock_time_t)t->interval;
+  return CLOCK_LT(clock_time(), t->start + t->interval);
 }
 /*---------------------------------------------------------------------------*/