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diff --git a/c-user/glossary.rst b/c-user/glossary.rst index 65e1fd7..8aa1266 100644 --- a/c-user/glossary.rst +++ b/c-user/glossary.rst @@ -121,6 +121,39 @@ Glossary of elements. It differs from an array in that it is not limited to a predefined size. + Clock Driver + The Clock Driver is a driver which provides the :term:`clock tick` and a + time counter. The time counter is used to drive the :term:`CLOCK_REALTIME` + and :term:`CLOCK_MONOTONIC`. The Clock Driver can be initialized by the + application with the :ref:`CONFIGURE_APPLICATION_NEEDS_CLOCK_DRIVER` and + :ref:`CONFIGURE_MICROSECONDS_PER_TICK` application configuration options. + + clock tick + The clock tick is a coarse time measure provided by RTEMS. The + :term:`Clock Driver` emits clock ticks at rate specified by the + :ref:`CONFIGURE_MICROSECONDS_PER_TICK` application configuration option. In + contrast to :term:`CLOCK_REALTIME` and :term:`CLOCK_MONOTONIC`, the clock + tick rate is not affected by incremental adjustments. + + CLOCK_MONOTONIC + The CLOCK_MONOTONIC is a clock provided by RTEMS which measures the time + since an unspecified starting point. In contrast to :term:`CLOCK_REALTIME`, + this clock cannot be set. It may be affected by incremental adjustments for + example carried out by the :term:`NTP` or the use of a :term:`PPS` signal. + See also :term:`CLOCK_REALTIME`, :term:`clock tick`, and + :term:`Clock Driver`. + + CLOCK_REALTIME + The CLOCK_REALTIME is a clock provided by RTEMS which measures the real time + (also known as wall-clock time). It is defined by :term:`POSIX`. In + particular, every day is treated as if it contains exactly 86400 seconds and + leap seconds are ignored. This clock can be set by the application which may + result in time jumps. It may be affected by incremental adjustments for + example carried out by the :term:`NTP` or the use of a :term:`PPS` signal. + 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. See also + :term:`CLOCK_MONOTONIC`, :term:`clock tick`, and :term:`Clock Driver`. + cluster We have clustered scheduling in case the set of processors of a system is partitioned into non-empty pairwise disjoint subsets. These subsets are @@ -458,6 +491,10 @@ Glossary non-existent The state occupied by an uncreated or deleted task. + NTP + This term is an acronym for + `Network Time Protocol <https://en.wikipedia.org/wiki/Network_Time_Protocol>`_. + NUMA This term is an acronym for Non-Uniform Memory Access. @@ -527,9 +564,17 @@ Glossary A term used to describe the ease with which software can be rehosted on another computer. + POSIX + This term is an acronym for + `Portable Operating System Interface <https://en.wikipedia.org/wiki/POSIX>`_. + posting The act of sending an event, message, semaphore, or signal to a task. + PPS + This term is an acronym for + `Pulse-Per-Second <https://en.wikipedia.org/wiki/Pulse-per-second_signal>`_. + preempt The act of forcing a task to relinquish the processor and dispatching to another task. @@ -650,6 +695,10 @@ Glossary RTEMS This term is an acronym for Real-Time Executive for Multiprocessor Systems. + RTEMS epoch + The RTEMS epoch is a point in time. It is 1988-01-01T00:00:00Z in + `ISO 8601 <https://en.wikipedia.org/wiki/ISO_8601>`_ time format. + running The state of a rate monotonic timer while it is being used to delineate a period. The timer exits this state by either expiring or being canceled. @@ -910,6 +959,10 @@ Glossary TTAS This term is an acronym for Test and Test-And-Set. + Unix epoch + The Unix epoch is a point in time. It is 1970-01-01T00:00:00Z in + `ISO 8601 <https://en.wikipedia.org/wiki/ISO_8601>`_ time format. + User Extension Table A table which contains the entry points for each user extensions. |