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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.

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This commit is contained in:
adamdunkels 2008-08-15 19:16:09 +00:00
parent 86b835dd2c
commit 9324dc1e7d
2 changed files with 37 additions and 28 deletions
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13
core/sys/clock.h
View File

@ -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.

4
core/sys/timer.c
View File

@ -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);
}
/*---------------------------------------------------------------------------*/