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c-user: Document time of day constraints

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Close #4338.
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Sebastian Huber 2021-09-03 15:28:50 +02:00
parent 8edb899da5
commit 081ec5d5e9
1 changed files with 15 additions and 4 deletions
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c-user/clock/directives.rst
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@ -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, 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. 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 RTEMS can represent time points of the :term:`CLOCK_REALTIME` clock in
1988-01-01T00:00:00.000000000Z to 2514-05-31T01:53:03.999999999Z. The future nanoseconds ranging from 1988-01-01T00:00:00.000000000Z to
uptime of the system shall be in this range, otherwise the system behaviour is 2514-05-31T01:53:03.999999999Z. The future uptime of the system shall be in
undefined. 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 The specified time is based on the configured :term:`clock tick` rate, see the
:ref:`CONFIGURE_MICROSECONDS_PER_TICK` application configuration option. :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 * The directive may unblock a task. This may cause the calling task to be
preempted. 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 .. Generated from spec:/rtems/clock/if/get-tod
.. raw:: latex .. raw:: latex