Module: xenomai-forge
Branch: next
Commit: 2fff60141c221f0065addab35e99e970dfb0e9cc
URL:
http://git.xenomai.org/?p=xenomai-forge.git;a=commit;h=2fff60141c221f0065addab35e99e970dfb0e9cc
Author: Philippe Gerum <r...@xenomai.org>
Date: Fri Feb 7 18:33:42 2014 +0100
copperplate/clockobj: add clockobj_get_distance()
This helper computes the distance between the current time and the
next shot from an interval timer.
---
include/copperplate/clockobj.h | 4 ++++
lib/copperplate/clockobj.c | 33 ++++++++++++++++++++++++++++-----
2 files changed, 32 insertions(+), 5 deletions(-)
diff --git a/include/copperplate/clockobj.h b/include/copperplate/clockobj.h
index bdba790..56d24b4 100644
--- a/include/copperplate/clockobj.h
+++ b/include/copperplate/clockobj.h
@@ -61,6 +61,10 @@ void clockobj_get_date(struct clockobj *clkobj, ticks_t
*pticks);
void clockobj_get_time(struct clockobj *clkobj,
ticks_t *pticks, ticks_t *ptsc);
+void clockobj_get_distance(struct clockobj *clkobj,
+ const struct itimerspec *itm,
+ struct timespec *delta);
+
ticks_t clockobj_get_tsc(void);
void clockobj_caltime_to_timeout(struct clockobj *clkobj, const struct tm *tm,
diff --git a/lib/copperplate/clockobj.c b/lib/copperplate/clockobj.c
index 3fda138..1a22ab2 100644
--- a/lib/copperplate/clockobj.c
+++ b/lib/copperplate/clockobj.c
@@ -25,6 +25,7 @@
#include <time.h>
#include <string.h>
#include "boilerplate/lock.h"
+#include "boilerplate/time.h"
#include "copperplate/clockobj.h"
#include "copperplate/debug.h"
#include "internal.h"
@@ -205,11 +206,12 @@ void clockobj_set_date(struct clockobj *clkobj, ticks_t
ticks)
}
/*
- * XXX: clockobj_set_resolution() should be called during the init
- * phase, not after. For performance reason, we want to run locklessly
- * for common time unit conversions, so the clockobj implementation
- * does assume that the clock resolution will not be updated
- * on-the-fly.
+ * CAUTION: clockobj_set_resolution() may be called during the init
+ * phase only, not after. IOW, the resolution is perceived as a
+ * constant when the application code executes. For performance
+ * reason, we want to run locklessly for common time unit conversions,
+ * so the clockobj implementation does assume that the clock
+ * resolution will NOT be updated after the init phase.
*/
int clockobj_set_resolution(struct clockobj *clkobj, unsigned int
resolution_ns)
{
@@ -354,6 +356,27 @@ void clockobj_convert_clocks(struct clockobj *clkobj,
timespec_add(out, &delta, &now);
}
+void clockobj_get_distance(struct clockobj *clkobj,
+ const struct itimerspec *itm,
+ struct timespec *delta)
+{
+ ticks_t now, start, interval, dist;
+
+ clockobj_get_time(clkobj, &now, NULL);
+ start = timespec_scalar(&itm->it_value);
+
+ if (start >= now)
+ /* Distance to first shot. */
+ dist = start - now;
+ else {
+ interval = timespec_scalar(&itm->it_interval);
+ /* Distance to next shot. */
+ dist = interval - ((now - start) % interval);
+ }
+
+ __clockobj_ticks_to_timespec(clkobj, dist, delta);
+}
+
int clockobj_init(struct clockobj *clkobj,
const char *name, unsigned int resolution_ns)
{
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