[rtems-docs commit] c-user: Document time of day constraints
Sebastian Huber
sebh at rtems.org
Mon Sep 6 10:27:15 UTC 2021
Module: rtems-docs
Branch: master
Commit: 081ec5d5e975c8295c768193af7f2e00129885d3
Changeset: http://git.rtems.org/rtems-docs/commit/?id=081ec5d5e975c8295c768193af7f2e00129885d3
Author: Sebastian Huber <sebastian.huber at embedded-brains.de>
Date: Fri Sep 3 15:28:50 2021 +0200
c-user: Document time of day constraints
Close #4338.
---
c-user/clock/directives.rst | 19 +++++++++++++++----
1 file changed, 15 insertions(+), 4 deletions(-)
diff --git a/c-user/clock/directives.rst b/c-user/clock/directives.rst
index e0f858a..1a65abf 100644
--- a/c-user/clock/directives.rst
+++ b/c-user/clock/directives.rst
@@ -70,10 +70,15 @@ Sets the :term:`CLOCK_REALTIME` to the time of day.
The date, time, and ticks specified by ``time_of_day`` are all range-checked,
and an error is returned if any one is out of its valid range.
-RTEMS can represent time points of this clock in nanoseconds ranging from
-1988-01-01T00:00:00.000000000Z to 2514-05-31T01:53:03.999999999Z. The future
-uptime of the system shall be in this range, otherwise the system behaviour is
-undefined.
+RTEMS can represent time points of the :term:`CLOCK_REALTIME` clock in
+nanoseconds ranging from 1988-01-01T00:00:00.000000000Z to
+2514-05-31T01:53:03.999999999Z. The future uptime of the system shall be in
+this range, otherwise the system behaviour is undefined. Due to implementation
+constraints, the time of day set by the directive shall be before
+2100-01-01:00:00.000000000Z. The latest valid time of day accepted by the
+POSIX `clock_settime()
+<https://pubs.opengroup.org/onlinepubs/9699919799/functions/clock_settime.html>`_
+is 2400-01-01T00:00:00.999999999Z.
The specified time is based on the configured :term:`clock tick` rate, see the
:ref:`CONFIGURE_MICROSECONDS_PER_TICK` application configuration option.
@@ -102,6 +107,12 @@ The following constraints apply to this directive:
* The directive may unblock a task. This may cause the calling task to be
preempted.
+* The time of day set by the directive shall be 1988-01-01T00:00:00.000000000Z
+ or later.
+
+* The time of day set by the directive shall be before
+ 2100-01-01T00:00:00.000000000Z.
+
.. Generated from spec:/rtems/clock/if/get-tod
.. raw:: latex
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