[ae68ff0] | 1 | @c |
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[bf6d03d] | 2 | @c COPYRIGHT (c) 1988-2008 |
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[ae68ff0] | 3 | @c On-Line Applications Research Corporation (OAR). |
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| 4 | @c All rights reserved. |
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| 5 | |
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| 6 | @chapter Clock Manager |
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[20515fc] | 7 | |
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[169502e] | 8 | @cindex clock |
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| 9 | |
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[ae68ff0] | 10 | @section Introduction |
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| 11 | |
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| 12 | The clock manager provides support for time of day |
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| 13 | and other time related capabilities. The directives provided by |
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| 14 | the clock manager are: |
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| 15 | |
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| 16 | @itemize @bullet |
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[bf6d03d] | 17 | @item @code{@value{DIRPREFIX}clock_set} - Set date and time |
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| 18 | @item @code{@value{DIRPREFIX}clock_get} - Get date and time information |
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| 19 | @item @code{@value{DIRPREFIX}clock_get_tod} - Get date and time in TOD format |
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| 20 | @item @code{@value{DIRPREFIX}clock_get_tod_timeval} - Get date and time in timeval format |
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[2d1bdc8] | 21 | @item @code{@value{DIRPREFIX}clock_get_seconds_since_epoch} - Get seconds since epoch |
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[bf6d03d] | 22 | @item @code{@value{DIRPREFIX}clock_get_ticks_per_second} - Get ticks per second |
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[f553c6e] | 23 | @item @code{@value{DIRPREFIX}clock_get_ticks_since_boot} - Get current ticks counter value |
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[96ec8ee8] | 24 | @item @code{@value{DIRPREFIX}clock_tick_later} - Get tick value in the future |
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| 25 | @item @code{@value{DIRPREFIX}clock_tick_later_usec} - Get tick value in the future in microseconds |
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| 26 | @item @code{@value{DIRPREFIX}clock_tick_before} - Is tick value is before a point in time |
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[bf4d016] | 27 | @item @code{@value{DIRPREFIX}clock_get_uptime} - Get time since boot |
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[bfddb047] | 28 | @item @code{@value{DIRPREFIX}clock_get_uptime_timeval} - Get time since boot in timeval format |
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[90733a86] | 29 | @item @code{@value{DIRPREFIX}clock_get_uptime_seconds} - Get seconds since boot |
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[2d1bdc8] | 30 | @item @code{@value{DIRPREFIX}clock_get_uptime_nanoseconds} - Get nanoseconds since boot |
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[a91cc06] | 31 | @item @code{@value{DIRPREFIX}clock_set_nanoseconds_extension} - Install the nanoseconds since last tick handler |
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[4fa4ea65] | 32 | @item @code{@value{DIRPREFIX}clock_tick} - Announce a clock tick |
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[ae68ff0] | 33 | @end itemize |
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| 34 | |
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| 35 | @section Background |
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[20515fc] | 36 | |
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[ae68ff0] | 37 | @subsection Required Support |
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| 38 | |
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| 39 | For the features provided by the clock manager to be |
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| 40 | utilized, periodic timer interrupts are required. Therefore, a |
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| 41 | real-time clock or hardware timer is necessary to create the |
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[75e22db] | 42 | timer interrupts. The @code{@value{DIRPREFIX}clock_tick} |
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| 43 | directive is normally called |
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[ae68ff0] | 44 | by the timer ISR to announce to RTEMS that a system clock tick |
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| 45 | has occurred. Elapsed time is measured in ticks. A tick is |
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| 46 | defined to be an integral number of microseconds which is |
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| 47 | specified by the user in the Configuration Table. |
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| 48 | |
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| 49 | @subsection Time and Date Data Structures |
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| 50 | |
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| 51 | The clock facilities of the clock manager operate |
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| 52 | upon calendar time. These directives utilize the following date |
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[7e8a1fc] | 53 | and time @value{STRUCTURE} for the native time and date format: |
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[ae68ff0] | 54 | |
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[adee5979] | 55 | |
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[61389eac] | 56 | @ifset is-C |
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[adee5979] | 57 | @findex rtems_time_of_day |
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[ae68ff0] | 58 | @example |
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| 59 | struct rtems_tod_control @{ |
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[ae10dbd] | 60 | uint32_t year; /* greater than 1987 */ |
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| 61 | uint32_t month; /* 1 - 12 */ |
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| 62 | uint32_t day; /* 1 - 31 */ |
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| 63 | uint32_t hour; /* 0 - 23 */ |
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| 64 | uint32_t minute; /* 0 - 59 */ |
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| 65 | uint32_t second; /* 0 - 59 */ |
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| 66 | uint32_t ticks; /* elapsed between seconds */ |
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[ae68ff0] | 67 | @}; |
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| 68 | |
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| 69 | typedef struct rtems_tod_control rtems_time_of_day; |
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| 70 | @end example |
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[61389eac] | 71 | @end ifset |
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| 72 | |
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| 73 | @ifset is-Ada |
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| 74 | @example |
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| 75 | type Time_Of_Day is |
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| 76 | record |
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| 77 | Year : RTEMS.Unsigned32; -- year, A.D. |
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| 78 | Month : RTEMS.Unsigned32; -- month, 1 .. 12 |
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| 79 | Day : RTEMS.Unsigned32; -- day, 1 .. 31 |
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| 80 | Hour : RTEMS.Unsigned32; -- hour, 0 .. 23 |
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| 81 | Minute : RTEMS.Unsigned32; -- minute, 0 .. 59 |
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| 82 | Second : RTEMS.Unsigned32; -- second, 0 .. 59 |
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| 83 | Ticks : RTEMS.Unsigned32; -- elapsed ticks between seconds |
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| 84 | end record; |
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| 85 | @end example |
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| 86 | @end ifset |
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[ae68ff0] | 87 | |
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| 88 | |
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| 89 | The native date and time format is the only format |
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| 90 | supported when setting the system date and time using the |
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[3372dc8] | 91 | @code{@value{DIRPREFIX}clock_set} directive. Some applications |
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[2d1bdc8] | 92 | expect to operate on a "UNIX-style" date and time data structure. The |
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[3372dc8] | 93 | @code{@value{DIRPREFIX}clock_get_tod_timeval} always returns |
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[2d1bdc8] | 94 | the date and time in @code{struct timeval} format. The |
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[75e22db] | 95 | @code{@value{DIRPREFIX}clock_get} directive can optionally return |
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[2d1bdc8] | 96 | the current date and time in this format. |
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[ae68ff0] | 97 | |
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[3372dc8] | 98 | The @code{struct timeval} data structure has two fields: @code{tv_sec} |
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| 99 | and @code{tv_usec} which are seconds and microseconds, respectively. |
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| 100 | The @code{tv_sec} field in this data structure is the number of seconds |
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[638a9195] | 101 | since the POSIX epoch of January 1, 1970 but will never be prior to |
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| 102 | the RTEMS epoch of January 1, 1988. |
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[ae68ff0] | 103 | |
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| 104 | @subsection Clock Tick and Timeslicing |
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| 105 | |
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[adee5979] | 106 | @cindex timeslicing |
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| 107 | |
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[ae68ff0] | 108 | Timeslicing is a task scheduling discipline in which |
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| 109 | tasks of equal priority are executed for a specific period of |
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| 110 | time before control of the CPU is passed to another task. It is |
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| 111 | also sometimes referred to as the automatic round-robin |
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| 112 | scheduling algorithm. The length of time allocated to each task |
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| 113 | is known as the quantum or timeslice. |
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| 114 | |
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| 115 | The system's timeslice is defined as an integral |
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| 116 | number of ticks, and is specified in the Configuration Table. |
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| 117 | The timeslice is defined for the entire system of tasks, but |
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| 118 | timeslicing is enabled and disabled on a per task basis. |
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| 119 | |
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[75e22db] | 120 | The @code{@value{DIRPREFIX}clock_tick} |
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| 121 | directive implements timeslicing by |
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[ae68ff0] | 122 | decrementing the running task's time-remaining counter when both |
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| 123 | timeslicing and preemption are enabled. If the task's timeslice |
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| 124 | has expired, then that task will be preempted if there exists a |
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| 125 | ready task of equal priority. |
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| 126 | |
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| 127 | @subsection Delays |
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| 128 | |
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[adee5979] | 129 | @cindex delays |
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| 130 | |
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[ae68ff0] | 131 | A sleep timer allows a task to delay for a given |
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| 132 | interval or up until a given time, and then wake and continue |
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| 133 | execution. This type of timer is created automatically by the |
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[75e22db] | 134 | @code{@value{DIRPREFIX}task_wake_after} |
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| 135 | and @code{@value{DIRPREFIX}task_wake_when} directives and, as a result, |
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[ae68ff0] | 136 | does not have an RTEMS ID. Once activated, a sleep timer cannot |
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| 137 | be explicitly deleted. Each task may activate one and only one |
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| 138 | sleep timer at a time. |
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| 139 | |
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| 140 | @subsection Timeouts |
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| 141 | |
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[adee5979] | 142 | @cindex timeouts |
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| 143 | |
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[ae68ff0] | 144 | Timeouts are a special type of timer automatically |
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| 145 | created when the timeout option is used on the |
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[75e22db] | 146 | @code{@value{DIRPREFIX}message_queue_receive}, |
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| 147 | @code{@value{DIRPREFIX}event_receive}, |
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| 148 | @code{@value{DIRPREFIX}semaphore_obtain} and |
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[2d1bdc8] | 149 | @code{@value{DIRPREFIX}region_get_segment} directives. |
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| 150 | Each task may have one and only one timeout active at a time. |
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[75e22db] | 151 | When a timeout expires, it unblocks the task with a timeout status code. |
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[ae68ff0] | 152 | |
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| 153 | @section Operations |
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[20515fc] | 154 | |
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[ae68ff0] | 155 | @subsection Announcing a Tick |
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| 156 | |
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[75e22db] | 157 | RTEMS provides the @code{@value{DIRPREFIX}clock_tick} directive which is |
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[ae68ff0] | 158 | called from the user's real-time clock ISR to inform RTEMS that |
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| 159 | a tick has elapsed. The tick frequency value, defined in |
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| 160 | microseconds, is a configuration parameter found in the |
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| 161 | Configuration Table. RTEMS divides one million microseconds |
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| 162 | (one second) by the number of microseconds per tick to determine |
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[75e22db] | 163 | the number of calls to the |
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| 164 | @code{@value{DIRPREFIX}clock_tick} directive per second. The |
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| 165 | frequency of @code{@value{DIRPREFIX}clock_tick} |
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| 166 | calls determines the resolution |
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[ae68ff0] | 167 | (granularity) for all time dependent RTEMS actions. For |
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[75e22db] | 168 | example, calling @code{@value{DIRPREFIX}clock_tick} |
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| 169 | ten times per second yields a higher |
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| 170 | resolution than calling @code{@value{DIRPREFIX}clock_tick} |
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| 171 | two times per second. The @code{@value{DIRPREFIX}clock_tick} |
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| 172 | directive is responsible for maintaining both |
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[ae68ff0] | 173 | calendar time and the dynamic set of timers. |
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| 174 | |
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| 175 | @subsection Setting the Time |
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| 176 | |
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[75e22db] | 177 | The @code{@value{DIRPREFIX}clock_set} directive allows a task or an ISR to |
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[ae68ff0] | 178 | set the date and time maintained by RTEMS. If setting the date |
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| 179 | and time causes any outstanding timers to pass their deadline, |
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| 180 | then the expired timers will be fired during the invocation of |
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[75e22db] | 181 | the @code{@value{DIRPREFIX}clock_set} directive. |
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[ae68ff0] | 182 | |
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| 183 | @subsection Obtaining the Time |
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| 184 | |
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[75e22db] | 185 | The @code{@value{DIRPREFIX}clock_get} directive allows a task or an ISR to |
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[ae68ff0] | 186 | obtain the current date and time or date and time related |
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| 187 | information. The current date and time can be returned in |
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| 188 | either native or UNIX-style format. Additionally, the |
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| 189 | application can obtain date and time related information such as |
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| 190 | the number of seconds since the RTEMS epoch, the number of ticks |
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| 191 | since the executive was initialized, and the number of ticks per |
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[75e22db] | 192 | second. The information returned by the |
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| 193 | @code{@value{DIRPREFIX}clock_get} directive is |
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[adee5979] | 194 | dependent on the option selected by the caller. This |
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| 195 | is specified using one of the following constants |
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| 196 | associated with the enumerated type |
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| 197 | @code{@value{DIRPREFIX}clock_get_options}: |
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| 198 | |
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[2d1bdc8] | 199 | @findex rtems_clock_get_options |
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[ae68ff0] | 200 | |
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| 201 | @itemize @bullet |
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[4fa4ea65] | 202 | @item @code{@value{RPREFIX}CLOCK_GET_TOD} - obtain native style date and time |
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[a94c5a5d] | 203 | |
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[75e22db] | 204 | @item @code{@value{RPREFIX}CLOCK_GET_TIME_VALUE} - obtain UNIX-style |
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| 205 | date and time |
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[a94c5a5d] | 206 | |
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[4fa4ea65] | 207 | @item @code{@value{RPREFIX}CLOCK_GET_TICKS_SINCE_BOOT} - obtain number of ticks |
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[a94c5a5d] | 208 | since RTEMS was initialized |
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| 209 | |
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[75e22db] | 210 | @item @code{@value{RPREFIX}CLOCK_GET_SECONDS_SINCE_EPOCH} - obtain number |
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| 211 | of seconds since RTEMS epoch |
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[a94c5a5d] | 212 | |
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[75e22db] | 213 | @item @code{@value{RPREFIX}CLOCK_GET_TICKS_PER_SECOND} - obtain number of clock |
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| 214 | ticks per second |
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[a94c5a5d] | 215 | |
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[ae68ff0] | 216 | @end itemize |
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| 217 | |
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| 218 | Calendar time operations will return an error code if |
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| 219 | invoked before the date and time have been set. |
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| 220 | |
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| 221 | @section Directives |
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| 222 | |
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| 223 | This section details the clock manager's directives. |
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| 224 | A subsection is dedicated to each of this manager's directives |
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| 225 | and describes the calling sequence, related constants, usage, |
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| 226 | and status codes. |
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| 227 | |
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[169502e] | 228 | @c |
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| 229 | @c |
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| 230 | @c |
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[ae68ff0] | 231 | @page |
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[bf6d03d] | 232 | @subsection CLOCK_SET - Set date and time |
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[ae68ff0] | 233 | |
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| 234 | @subheading CALLING SEQUENCE: |
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| 235 | |
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[169502e] | 236 | @cindex set the time of day |
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| 237 | |
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[61389eac] | 238 | @ifset is-C |
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[169502e] | 239 | @findex rtems_clock_set |
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[ae68ff0] | 240 | @example |
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| 241 | rtems_status_code rtems_clock_set( |
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| 242 | rtems_time_of_day *time_buffer |
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| 243 | ); |
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| 244 | @end example |
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[61389eac] | 245 | @end ifset |
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| 246 | |
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| 247 | @ifset is-Ada |
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| 248 | @example |
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| 249 | procedure Clock_Set ( |
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| 250 | Time_Buffer : in RTEMS.Time_Of_Day; |
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| 251 | Result : out RTEMS.Status_Codes |
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| 252 | ); |
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| 253 | @end example |
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| 254 | @end ifset |
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[ae68ff0] | 255 | |
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| 256 | @subheading DIRECTIVE STATUS CODES: |
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[4fa4ea65] | 257 | @code{@value{RPREFIX}SUCCESSFUL} - date and time set successfully@* |
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[f8892c9] | 258 | @code{@value{RPREFIX}INVALID_ADDRESS} - @code{time_buffer} is NULL@* |
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[4dc6a46] | 259 | @code{@value{RPREFIX}INVALID_CLOCK} - invalid time of day |
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[ae68ff0] | 260 | |
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| 261 | @subheading DESCRIPTION: |
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| 262 | |
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| 263 | This directive sets the system date and time. The |
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[7e8a1fc] | 264 | date, time, and ticks in the time_buffer @value{STRUCTURE} are all |
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[ae68ff0] | 265 | range-checked, and an error is returned if any one is out of its |
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| 266 | valid range. |
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| 267 | |
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| 268 | @subheading NOTES: |
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| 269 | |
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| 270 | Years before 1988 are invalid. |
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| 271 | |
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| 272 | The system date and time are based on the configured |
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| 273 | tick rate (number of microseconds in a tick). |
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| 274 | |
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| 275 | Setting the time forward may cause a higher priority |
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| 276 | task, blocked waiting on a specific time, to be made ready. In |
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| 277 | this case, the calling task will be preempted after the next |
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| 278 | clock tick. |
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| 279 | |
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| 280 | Re-initializing RTEMS causes the system date and time |
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| 281 | to be reset to an uninitialized state. Another call to |
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[75e22db] | 282 | @code{@value{DIRPREFIX}clock_set} is required to re-initialize |
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| 283 | the system date and time to application specific specifications. |
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[ae68ff0] | 284 | |
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[169502e] | 285 | @c |
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| 286 | @c |
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| 287 | @c |
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[ae68ff0] | 288 | @page |
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[bf6d03d] | 289 | @subsection CLOCK_GET - Get date and time information |
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[ae68ff0] | 290 | |
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[169502e] | 291 | @cindex obtain the time of day |
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| 292 | |
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[ae68ff0] | 293 | @subheading CALLING SEQUENCE: |
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| 294 | |
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[61389eac] | 295 | @ifset is-C |
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[169502e] | 296 | @findex rtems_clock_get |
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[ae68ff0] | 297 | @example |
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| 298 | rtems_status_code rtems_clock_get( |
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| 299 | rtems_clock_get_options option, |
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| 300 | void *time_buffer |
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| 301 | ); |
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| 302 | @end example |
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[61389eac] | 303 | @end ifset |
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| 304 | |
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| 305 | @ifset is-Ada |
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| 306 | @example |
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| 307 | procedure Clock_Get ( |
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| 308 | Option : in RTEMS.Clock_Get_Options; |
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| 309 | Time_Buffer : in RTEMS.Address; |
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| 310 | Result : out RTEMS.Status_Codes |
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| 311 | ); |
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| 312 | @end example |
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| 313 | @end ifset |
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[ae68ff0] | 314 | |
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| 315 | @subheading DIRECTIVE STATUS CODES: |
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[4fa4ea65] | 316 | @code{@value{RPREFIX}SUCCESSFUL} - current time obtained successfully@* |
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[f8892c9] | 317 | @code{@value{RPREFIX}NOT_DEFINED} - system date and time is not set@* |
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| 318 | @code{@value{RPREFIX}INVALID_ADDRESS} - @code{time_buffer} is NULL |
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[ae68ff0] | 319 | |
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| 320 | @subheading DESCRIPTION: |
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| 321 | |
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| 322 | This directive obtains the system date and time. If |
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| 323 | the caller is attempting to obtain the date and time (i.e. |
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[4fa4ea65] | 324 | option is set to either @code{@value{RPREFIX}CLOCK_GET_SECONDS_SINCE_EPOCH}, |
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[75e22db] | 325 | @code{@value{RPREFIX}CLOCK_GET_TOD}, or |
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| 326 | @code{@value{RPREFIX}CLOCK_GET_TIME_VALUE}) and the date and time |
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| 327 | has not been set with a previous call to |
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| 328 | @code{@value{DIRPREFIX}clock_set}, then the |
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[2d1bdc8] | 329 | @code{@value{RPREFIX}NOT_DEFINED} status code is returned. |
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[75e22db] | 330 | The caller can always obtain the number of ticks per second (option is |
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| 331 | @code{@value{RPREFIX}CLOCK_GET_TICKS_PER_SECOND}) and the number of |
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| 332 | ticks since the executive was initialized option is |
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| 333 | @code{@value{RPREFIX}CLOCK_GET_TICKS_SINCE_BOOT}). |
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[ae68ff0] | 334 | |
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[adee5979] | 335 | The @code{option} argument may taken on any value of the enumerated |
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| 336 | type @code{rtems_clock_get_options}. The data type expected for |
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| 337 | @code{time_buffer} is based on the value of @code{option} as |
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| 338 | indicated below: |
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[c3fec1c] | 339 | |
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[2d1bdc8] | 340 | @findex rtems_clock_get_options |
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[c3fec1c] | 341 | @ifset is-C |
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| 342 | @itemize @bullet |
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[4fa4ea65] | 343 | @item @code{@value{RPREFIX}CLOCK_GET_TOD} - (rtems_time_of_day *) |
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[c3fec1c] | 344 | |
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[4ffbc49] | 345 | @item @code{@value{RPREFIX}CLOCK_GET_SECONDS_SINCE_EPOCH} - (rtems_interval *) |
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[c3fec1c] | 346 | |
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[4fa4ea65] | 347 | @item @code{@value{RPREFIX}CLOCK_GET_TICKS_SINCE_BOOT} - (rtems_interval *) |
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[c3fec1c] | 348 | |
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[4fa4ea65] | 349 | @item @code{@value{RPREFIX}CLOCK_GET_TICKS_PER_SECOND} - (rtems_interval *) |
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[c3fec1c] | 350 | |
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[c0640a2] | 351 | @item @code{@value{RPREFIX}CLOCK_GET_TIME_VALUE} - (struct timeval *) |
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[4ffbc49] | 352 | |
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[c3fec1c] | 353 | @end itemize |
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| 354 | @end ifset |
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| 355 | |
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| 356 | @ifset is-Ada |
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| 357 | @itemize @bullet |
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[4ffbc49] | 358 | @item @code{@value{RPREFIX}Clock_Get_TOD} - Address of an variable of |
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[75e22db] | 359 | type RTEMS.Time_Of_Day |
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[c3fec1c] | 360 | |
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[4ffbc49] | 361 | @item @code{@value{RPREFIX}Clock_Get_Seconds_Since_Epoch} - Address of an |
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[75e22db] | 362 | variable of type RTEMS.Interval |
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[c3fec1c] | 363 | |
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[4ffbc49] | 364 | @item @code{@value{RPREFIX}Clock_Get_Ticks_Since_Boot} - Address of an |
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[75e22db] | 365 | variable of type RTEMS.Interval |
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[c3fec1c] | 366 | |
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[4ffbc49] | 367 | @item @code{@value{RPREFIX}Clock_Get_Ticks_Per_Second} - Address of an |
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[75e22db] | 368 | variable of type RTEMS.Interval |
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[c3fec1c] | 369 | |
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[4ffbc49] | 370 | @item @code{@value{RPREFIX}Clock_Get_Time_Value} - Address of an variable of |
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| 371 | type RTEMS.Clock_Time_Value |
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| 372 | |
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[c3fec1c] | 373 | @end itemize |
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| 374 | @end ifset |
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| 375 | |
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[ae68ff0] | 376 | @subheading NOTES: |
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| 377 | |
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| 378 | This directive is callable from an ISR. |
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| 379 | |
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| 380 | This directive will not cause the running task to be |
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| 381 | preempted. Re-initializing RTEMS causes the system date and |
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| 382 | time to be reset to an uninitialized state. Another call to |
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[75e22db] | 383 | @code{@value{DIRPREFIX}clock_set} is required to re-initialize the |
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| 384 | system date and time to application specific specifications. |
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[ae68ff0] | 385 | |
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[a91cc06] | 386 | @c |
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| 387 | @c |
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| 388 | @c |
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| 389 | @page |
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[bf6d03d] | 390 | @subsection CLOCK_GET_TOD - Get date and time in TOD format |
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[a91cc06] | 391 | |
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[bf6d03d] | 392 | @cindex obtain the time of day |
---|
[a91cc06] | 393 | |
---|
| 394 | @subheading CALLING SEQUENCE: |
---|
| 395 | |
---|
| 396 | @ifset is-C |
---|
[bf6d03d] | 397 | @findex rtems_clock_get_tod |
---|
[a91cc06] | 398 | @example |
---|
[bf6d03d] | 399 | rtems_status_code rtems_clock_get_tod( |
---|
| 400 | rtems_time_of_day *time_buffer |
---|
[a91cc06] | 401 | ); |
---|
| 402 | @end example |
---|
| 403 | @end ifset |
---|
| 404 | |
---|
| 405 | @ifset is-Ada |
---|
| 406 | @example |
---|
[bf6d03d] | 407 | procedure Clock_Get_TOD ( |
---|
| 408 | Time_Buffer : in RTEMS.Time_Of_Day; |
---|
| 409 | Result : out RTEMS.Status_Codes |
---|
| 410 | ); |
---|
[a91cc06] | 411 | @end example |
---|
| 412 | @end ifset |
---|
| 413 | |
---|
| 414 | @subheading DIRECTIVE STATUS CODES: |
---|
[bf6d03d] | 415 | @code{@value{RPREFIX}SUCCESSFUL} - current time obtained successfully@* |
---|
| 416 | @code{@value{RPREFIX}NOT_DEFINED} - system date and time is not set@* |
---|
[a91cc06] | 417 | @code{@value{RPREFIX}INVALID_ADDRESS} - @code{time_buffer} is NULL |
---|
| 418 | |
---|
| 419 | @subheading DESCRIPTION: |
---|
| 420 | |
---|
[bf6d03d] | 421 | This directive obtains the system date and time. If the date and time |
---|
| 422 | has not been set with a previous call to |
---|
| 423 | @code{@value{DIRPREFIX}clock_set}, then the |
---|
[2d1bdc8] | 424 | @code{@value{RPREFIX}NOT_DEFINED} status code is returned. |
---|
[a91cc06] | 425 | |
---|
[bf6d03d] | 426 | @subheading NOTES: |
---|
| 427 | |
---|
| 428 | This directive is callable from an ISR. |
---|
| 429 | |
---|
| 430 | This directive will not cause the running task to be |
---|
| 431 | preempted. Re-initializing RTEMS causes the system date and |
---|
| 432 | time to be reset to an uninitialized state. Another call to |
---|
| 433 | @code{@value{DIRPREFIX}clock_set} is required to re-initialize the |
---|
| 434 | system date and time to application specific specifications. |
---|
| 435 | |
---|
| 436 | @c |
---|
| 437 | @c |
---|
| 438 | @c |
---|
| 439 | @page |
---|
| 440 | @subsection CLOCK_GET_TOD_TIMEVAL - Get date and time in timeval format |
---|
| 441 | |
---|
| 442 | @cindex obtain the time of day |
---|
| 443 | |
---|
| 444 | @subheading CALLING SEQUENCE: |
---|
| 445 | |
---|
| 446 | @ifset is-C |
---|
| 447 | @findex rtems_clock_get_tod_timeval |
---|
| 448 | @example |
---|
| 449 | rtems_status_code rtems_clock_get_tod( |
---|
| 450 | struct timeval *time |
---|
| 451 | ); |
---|
| 452 | @end example |
---|
| 453 | @end ifset |
---|
| 454 | |
---|
| 455 | @ifset is-Ada |
---|
| 456 | @example |
---|
| 457 | procedure Clock_Get_TOD_Timeval ( |
---|
| 458 | Time : in RTEMS.Timeval; |
---|
| 459 | Result : out RTEMS.Status_Codes |
---|
| 460 | ); |
---|
| 461 | @end example |
---|
| 462 | @end ifset |
---|
| 463 | |
---|
| 464 | @subheading DIRECTIVE STATUS CODES: |
---|
| 465 | @code{@value{RPREFIX}SUCCESSFUL} - current time obtained successfully@* |
---|
| 466 | @code{@value{RPREFIX}NOT_DEFINED} - system date and time is not set@* |
---|
| 467 | @code{@value{RPREFIX}INVALID_ADDRESS} - @code{time} is NULL |
---|
| 468 | |
---|
| 469 | @subheading DESCRIPTION: |
---|
| 470 | |
---|
| 471 | This directive obtains the system date and time in POSIX |
---|
| 472 | @code{struct timeval} format. If the date and time |
---|
| 473 | has not been set with a previous call to |
---|
| 474 | @code{@value{DIRPREFIX}clock_set}, then the |
---|
[2d1bdc8] | 475 | @code{@value{RPREFIX}NOT_DEFINED} status code is returned. |
---|
[a91cc06] | 476 | |
---|
| 477 | @subheading NOTES: |
---|
| 478 | |
---|
[bf6d03d] | 479 | This directive is callable from an ISR. |
---|
[a91cc06] | 480 | |
---|
[bf6d03d] | 481 | This directive will not cause the running task to be |
---|
| 482 | preempted. Re-initializing RTEMS causes the system date and |
---|
| 483 | time to be reset to an uninitialized state. Another call to |
---|
| 484 | @code{@value{DIRPREFIX}clock_set} is required to re-initialize the |
---|
| 485 | system date and time to application specific specifications. |
---|
| 486 | |
---|
| 487 | @c |
---|
| 488 | @c |
---|
| 489 | @c |
---|
| 490 | @page |
---|
| 491 | @subsection CLOCK_GET_SECONDS_SINCE_EPOCH - Get seconds since epoch |
---|
| 492 | |
---|
| 493 | @cindex obtain seconds since epoch |
---|
| 494 | |
---|
| 495 | @subheading CALLING SEQUENCE: |
---|
| 496 | |
---|
| 497 | @ifset is-C |
---|
| 498 | @findex rtems_clock_get_seconds_since_epoch |
---|
| 499 | @example |
---|
| 500 | rtems_status_code rtems_clock_get_seconds_since_epoch( |
---|
| 501 | rtems_interval *the_interval |
---|
| 502 | ); |
---|
| 503 | @end example |
---|
| 504 | @end ifset |
---|
| 505 | |
---|
| 506 | @ifset is-Ada |
---|
| 507 | @example |
---|
| 508 | procedure Clock_Get_Seconds_Since_Epoch( |
---|
| 509 | The_Interval : out RTEMS.Interval; |
---|
| 510 | Result : out RTEMS.Status_Codes |
---|
| 511 | ); |
---|
| 512 | @end example |
---|
| 513 | @end ifset |
---|
| 514 | |
---|
| 515 | @subheading DIRECTIVE STATUS CODES: |
---|
| 516 | @code{@value{RPREFIX}SUCCESSFUL} - current time obtained successfully@* |
---|
| 517 | @code{@value{RPREFIX}NOT_DEFINED} - system date and time is not set@* |
---|
| 518 | @code{@value{RPREFIX}INVALID_ADDRESS} - @code{the_interval} is NULL |
---|
| 519 | |
---|
| 520 | @subheading DESCRIPTION: |
---|
| 521 | |
---|
| 522 | This directive returns the number of seconds since the RTEMS |
---|
| 523 | epoch and the current system date and time. If the date and time |
---|
| 524 | has not been set with a previous call to |
---|
| 525 | @code{@value{DIRPREFIX}clock_set}, then the |
---|
[2d1bdc8] | 526 | @code{@value{RPREFIX}NOT_DEFINED} status code is returned. |
---|
[bf6d03d] | 527 | |
---|
| 528 | @subheading NOTES: |
---|
| 529 | |
---|
| 530 | This directive is callable from an ISR. |
---|
| 531 | |
---|
| 532 | This directive will not cause the running task to be |
---|
| 533 | preempted. Re-initializing RTEMS causes the system date and |
---|
| 534 | time to be reset to an uninitialized state. Another call to |
---|
| 535 | @code{@value{DIRPREFIX}clock_set} is required to re-initialize the |
---|
| 536 | system date and time to application specific specifications. |
---|
| 537 | |
---|
| 538 | @c |
---|
| 539 | @c |
---|
| 540 | @c |
---|
| 541 | @page |
---|
| 542 | @subsection CLOCK_GET_TICKS_PER_SECOND - Get ticks per second |
---|
| 543 | |
---|
| 544 | @cindex obtain seconds since epoch |
---|
| 545 | |
---|
| 546 | @subheading CALLING SEQUENCE: |
---|
| 547 | |
---|
| 548 | @ifset is-C |
---|
| 549 | @findex rtems_clock_get_ticks_per_second |
---|
| 550 | @example |
---|
[29a3d72c] | 551 | rtems_interval rtems_clock_get_ticks_per_second(void); |
---|
[bf6d03d] | 552 | @end example |
---|
| 553 | @end ifset |
---|
| 554 | |
---|
| 555 | @ifset is-Ada |
---|
| 556 | @example |
---|
| 557 | function Clock_Get_Ticks_Per_Seconds |
---|
| 558 | return RTEMS.Interval; |
---|
| 559 | @end example |
---|
| 560 | @end ifset |
---|
| 561 | |
---|
| 562 | @subheading DIRECTIVE STATUS CODES: |
---|
| 563 | NONE |
---|
| 564 | |
---|
| 565 | @subheading DESCRIPTION: |
---|
| 566 | |
---|
| 567 | This directive returns the number of clock ticks per second. This |
---|
| 568 | is strictly based upon the microseconds per clock tick that the |
---|
| 569 | application has configured. |
---|
| 570 | |
---|
| 571 | @subheading NOTES: |
---|
| 572 | |
---|
| 573 | This directive is callable from an ISR. |
---|
| 574 | |
---|
[f553c6e] | 575 | This directive will not cause the running task to be preempted. |
---|
[bf6d03d] | 576 | |
---|
| 577 | @c |
---|
| 578 | @c |
---|
| 579 | @c |
---|
| 580 | @page |
---|
[f553c6e] | 581 | @subsection CLOCK_GET_TICKS_SINCE_BOOT - Get current ticks counter value |
---|
[bf6d03d] | 582 | |
---|
| 583 | @cindex obtain ticks since boot |
---|
[f553c6e] | 584 | @cindex get current ticks counter value |
---|
[bf6d03d] | 585 | |
---|
| 586 | @subheading CALLING SEQUENCE: |
---|
| 587 | |
---|
| 588 | @ifset is-C |
---|
| 589 | @findex rtems_clock_get_ticks_since_boot |
---|
| 590 | @example |
---|
| 591 | rtems_interval rtems_clock_get_ticks_since_boot(void); |
---|
| 592 | @end example |
---|
| 593 | @end ifset |
---|
| 594 | |
---|
| 595 | @ifset is-Ada |
---|
| 596 | @example |
---|
| 597 | function Clock_Get_Ticks_Since_Boot |
---|
| 598 | return RTEMS.Interval; |
---|
| 599 | @end example |
---|
| 600 | @end ifset |
---|
| 601 | |
---|
| 602 | @subheading DIRECTIVE STATUS CODES: |
---|
| 603 | NONE |
---|
| 604 | |
---|
| 605 | @subheading DESCRIPTION: |
---|
| 606 | |
---|
[f553c6e] | 607 | This directive returns the current tick counter value. With a 1ms clock tick, |
---|
| 608 | this counter overflows after 50 days since boot. This is the historical |
---|
| 609 | measure of uptime in an RTEMS system. The newer service |
---|
| 610 | @code{@value{DIRPREFIX}clock_get_uptime} is another and potentially more |
---|
| 611 | accurate way of obtaining similar information. |
---|
[bf6d03d] | 612 | |
---|
| 613 | @subheading NOTES: |
---|
| 614 | |
---|
| 615 | This directive is callable from an ISR. |
---|
| 616 | |
---|
[f553c6e] | 617 | This directive will not cause the running task to be preempted. |
---|
[a91cc06] | 618 | |
---|
[96ec8ee8] | 619 | @c |
---|
| 620 | @c |
---|
| 621 | @c |
---|
| 622 | @page |
---|
| 623 | @subsection CLOCK_TICK_LATER - Get tick value in the future |
---|
| 624 | |
---|
| 625 | @subheading CALLING SEQUENCE: |
---|
| 626 | |
---|
| 627 | @ifset is-C |
---|
| 628 | @findex rtems_clock_tick_later |
---|
| 629 | @example |
---|
| 630 | rtems_interval rtems_clock_tick_later( |
---|
| 631 | rtems_interval delta |
---|
| 632 | ); |
---|
| 633 | @end example |
---|
| 634 | @end ifset |
---|
| 635 | |
---|
| 636 | @subheading DESCRIPTION: |
---|
| 637 | |
---|
| 638 | Returns the ticks counter value delta ticks in the future. |
---|
| 639 | |
---|
| 640 | @subheading NOTES: |
---|
| 641 | |
---|
| 642 | This directive is callable from an ISR. |
---|
| 643 | |
---|
| 644 | This directive will not cause the running task to be preempted. |
---|
| 645 | |
---|
| 646 | @c |
---|
| 647 | @c |
---|
| 648 | @c |
---|
| 649 | @page |
---|
| 650 | @subsection CLOCK_TICK_LATER_USEC - Get tick value in the future in microseconds |
---|
| 651 | |
---|
| 652 | @subheading CALLING SEQUENCE: |
---|
| 653 | |
---|
| 654 | @ifset is-C |
---|
| 655 | @findex rtems_clock_tick_later_usec |
---|
| 656 | @example |
---|
| 657 | rtems_interval rtems_clock_tick_later_usec( |
---|
| 658 | rtems_interval delta_in_usec |
---|
| 659 | ); |
---|
| 660 | @end example |
---|
| 661 | @end ifset |
---|
| 662 | |
---|
| 663 | @subheading DESCRIPTION: |
---|
| 664 | |
---|
| 665 | Returns the ticks counter value at least delta microseconds in the future. |
---|
| 666 | |
---|
| 667 | @subheading NOTES: |
---|
| 668 | |
---|
| 669 | This directive is callable from an ISR. |
---|
| 670 | |
---|
| 671 | This directive will not cause the running task to be preempted. |
---|
| 672 | |
---|
| 673 | @c |
---|
| 674 | @c |
---|
| 675 | @c |
---|
| 676 | @page |
---|
| 677 | @subsection CLOCK_TICK_BEFORE - Is tick value is before a point in time |
---|
| 678 | |
---|
| 679 | @subheading CALLING SEQUENCE: |
---|
| 680 | |
---|
| 681 | @ifset is-C |
---|
| 682 | @findex rtems_clock_tick_before |
---|
| 683 | @example |
---|
| 684 | rtems_interval rtems_clock_tick_before( |
---|
| 685 | rtems_interval tick |
---|
| 686 | ); |
---|
| 687 | @end example |
---|
| 688 | @end ifset |
---|
| 689 | |
---|
| 690 | @subheading DESCRIPTION: |
---|
| 691 | |
---|
| 692 | Returns true if the current ticks counter value indicates a time before the |
---|
| 693 | time specified by the tick value and false otherwise. |
---|
| 694 | |
---|
| 695 | @subheading NOTES: |
---|
| 696 | |
---|
| 697 | This directive is callable from an ISR. |
---|
| 698 | |
---|
| 699 | This directive will not cause the running task to be preempted. |
---|
| 700 | |
---|
| 701 | @subheading EXAMPLE: |
---|
| 702 | |
---|
| 703 | @example |
---|
| 704 | @group |
---|
| 705 | status busy( void ) |
---|
| 706 | @{ |
---|
| 707 | rtems_interval timeout = rtems_clock_tick_later_usec( 10000 ); |
---|
| 708 | |
---|
| 709 | do @{ |
---|
| 710 | if ( ok() ) @{ |
---|
| 711 | return success; |
---|
| 712 | @} |
---|
| 713 | @} while ( rtems_clock_tick_before( timeout ) ); |
---|
| 714 | |
---|
| 715 | return timeout; |
---|
| 716 | @} |
---|
| 717 | @end group |
---|
| 718 | @end example |
---|
| 719 | |
---|
[bf4d016] | 720 | @c |
---|
| 721 | @c |
---|
| 722 | @c |
---|
| 723 | @page |
---|
[4ffbc49] | 724 | @subsection CLOCK_GET_UPTIME - Get the time since boot |
---|
[bf4d016] | 725 | |
---|
| 726 | @cindex clock get uptime |
---|
| 727 | @cindex uptime |
---|
| 728 | |
---|
| 729 | @subheading CALLING SEQUENCE: |
---|
| 730 | |
---|
| 731 | @ifset is-C |
---|
| 732 | @findex rtems_clock_get_uptime |
---|
| 733 | @example |
---|
| 734 | rtems_status_code rtems_clock_get_uptime( |
---|
| 735 | struct timespec *uptime |
---|
| 736 | ); |
---|
| 737 | @end example |
---|
| 738 | @end ifset |
---|
| 739 | |
---|
| 740 | @ifset is-Ada |
---|
| 741 | @example |
---|
[4ffbc49] | 742 | procedure Clock_Get_Uptime ( |
---|
| 743 | Uptime : out RTEMS.Timespec; |
---|
| 744 | Result : out RTEMS.Status_Codes |
---|
| 745 | ); |
---|
[bf4d016] | 746 | @end example |
---|
| 747 | @end ifset |
---|
| 748 | |
---|
| 749 | @subheading DIRECTIVE STATUS CODES: |
---|
| 750 | @code{@value{RPREFIX}SUCCESSFUL} - clock tick processed successfully@* |
---|
| 751 | @code{@value{RPREFIX}INVALID_ADDRESS} - @code{time_buffer} is NULL |
---|
| 752 | |
---|
| 753 | @subheading DESCRIPTION: |
---|
| 754 | |
---|
| 755 | This directive returns the seconds and nanoseconds since the |
---|
| 756 | system was booted. If the BSP supports nanosecond clock |
---|
| 757 | accuracy, the time reported will probably be different on every |
---|
| 758 | call. |
---|
| 759 | |
---|
| 760 | @subheading NOTES: |
---|
| 761 | |
---|
| 762 | This directive may be called from an ISR. |
---|
| 763 | |
---|
[bfddb047] | 764 | @c |
---|
| 765 | @c |
---|
| 766 | @c |
---|
| 767 | @page |
---|
| 768 | @subsection CLOCK_GET_UPTIME_TIMEVAL - Get the time since boot in timeval format |
---|
| 769 | |
---|
| 770 | @cindex clock get uptime |
---|
| 771 | @cindex uptime |
---|
| 772 | |
---|
| 773 | @subheading CALLING SEQUENCE: |
---|
| 774 | |
---|
| 775 | @ifset is-C |
---|
| 776 | @findex rtems_clock_get_uptime_timeval |
---|
| 777 | @example |
---|
| 778 | void rtems_clock_get_uptime_timeval( |
---|
| 779 | struct timeval *uptime |
---|
| 780 | ); |
---|
| 781 | @end example |
---|
| 782 | @end ifset |
---|
| 783 | |
---|
| 784 | @subheading DIRECTIVE STATUS CODES: |
---|
| 785 | |
---|
| 786 | NONE |
---|
| 787 | |
---|
| 788 | @subheading DESCRIPTION: |
---|
| 789 | |
---|
| 790 | This directive returns the seconds and microseconds since the |
---|
| 791 | system was booted. If the BSP supports nanosecond clock |
---|
| 792 | accuracy, the time reported will probably be different on every |
---|
| 793 | call. |
---|
| 794 | |
---|
| 795 | @subheading NOTES: |
---|
| 796 | |
---|
| 797 | This directive may be called from an ISR. |
---|
[bf6d03d] | 798 | |
---|
[90733a86] | 799 | @c |
---|
| 800 | @c |
---|
| 801 | @c |
---|
| 802 | @page |
---|
| 803 | @subsection CLOCK_GET_UPTIME_SECONDS - Get the seconds since boot |
---|
| 804 | |
---|
| 805 | @cindex clock get uptime |
---|
| 806 | @cindex uptime |
---|
| 807 | |
---|
| 808 | @subheading CALLING SEQUENCE: |
---|
| 809 | |
---|
| 810 | @ifset is-C |
---|
| 811 | @findex rtems_clock_get_uptime_seconds |
---|
| 812 | @example |
---|
| 813 | time_t rtems_clock_get_uptime_seconds(void); |
---|
| 814 | @end example |
---|
| 815 | @end ifset |
---|
| 816 | |
---|
| 817 | @subheading DIRECTIVE STATUS CODES: |
---|
| 818 | |
---|
| 819 | The system uptime in seconds. |
---|
| 820 | |
---|
| 821 | @subheading DESCRIPTION: |
---|
| 822 | |
---|
| 823 | This directive returns the seconds since the system was booted. |
---|
| 824 | |
---|
| 825 | @subheading NOTES: |
---|
| 826 | |
---|
| 827 | This directive may be called from an ISR. |
---|
| 828 | |
---|
[2d1bdc8] | 829 | @c |
---|
| 830 | @c |
---|
| 831 | @c |
---|
| 832 | @page |
---|
| 833 | @subsection CLOCK_GET_UPTIME_NANOSECONDS - Get the nanoseconds since boot |
---|
| 834 | |
---|
| 835 | @cindex clock get nanoseconds uptime |
---|
| 836 | @cindex uptime |
---|
| 837 | |
---|
| 838 | @subheading CALLING SEQUENCE: |
---|
| 839 | |
---|
| 840 | @ifset is-C |
---|
| 841 | @findex rtems_clock_get_uptime_nanoseconds |
---|
| 842 | @example |
---|
| 843 | uint64_t rtems_clock_get_uptime_nanoseconds(void); |
---|
| 844 | @end example |
---|
| 845 | @end ifset |
---|
| 846 | |
---|
| 847 | @subheading DIRECTIVE STATUS CODES: |
---|
| 848 | |
---|
| 849 | The system uptime in nanoseconds. |
---|
| 850 | |
---|
| 851 | @subheading DESCRIPTION: |
---|
| 852 | |
---|
| 853 | This directive returns the nanoseconds since the system was booted. |
---|
| 854 | |
---|
| 855 | @subheading NOTES: |
---|
| 856 | |
---|
| 857 | This directive may be called from an ISR. |
---|
| 858 | |
---|
[bf6d03d] | 859 | @c |
---|
| 860 | @c |
---|
| 861 | @c |
---|
| 862 | @page |
---|
| 863 | @subsection CLOCK_SET_NANOSECONDS_EXTENSION - Install the nanoseconds since last tick handler |
---|
| 864 | |
---|
| 865 | @cindex clock set nanoseconds extension |
---|
| 866 | @cindex nanoseconds extension |
---|
| 867 | @cindex nanoseconds time accuracy |
---|
| 868 | |
---|
| 869 | @subheading CALLING SEQUENCE: |
---|
| 870 | |
---|
| 871 | @ifset is-C |
---|
| 872 | @findex rtems_clock_set_nanoseconds_extension |
---|
| 873 | @example |
---|
| 874 | rtems_status_code rtems_clock_set_nanoseconds_extension( |
---|
| 875 | rtems_nanoseconds_extension_routine routine |
---|
| 876 | ); |
---|
| 877 | @end example |
---|
| 878 | @end ifset |
---|
| 879 | |
---|
| 880 | @ifset is-Ada |
---|
| 881 | @example |
---|
| 882 | NOT SUPPORTED FROM Ada BINDING |
---|
| 883 | @end example |
---|
| 884 | @end ifset |
---|
| 885 | |
---|
| 886 | @subheading DIRECTIVE STATUS CODES: |
---|
| 887 | @code{@value{RPREFIX}SUCCESSFUL} - clock tick processed successfully@* |
---|
| 888 | @code{@value{RPREFIX}INVALID_ADDRESS} - @code{time_buffer} is NULL |
---|
| 889 | |
---|
| 890 | @subheading DESCRIPTION: |
---|
| 891 | |
---|
[2d1bdc8] | 892 | This directive is used by the Clock device driver to install the |
---|
[bf6d03d] | 893 | @code{routine} which will be invoked by the internal RTEMS method used to |
---|
| 894 | obtain a highly accurate time of day. It is usually called during |
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| 895 | the initialization of the driver. |
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| 896 | |
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| 897 | When the @code{routine} is invoked, it will determine the number of |
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| 898 | nanoseconds which have elapsed since the last invocation of |
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| 899 | the @code{@value{DIRPREFIX}clock_tick} directive. It should do |
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| 900 | this as quickly as possible with as little impact as possible |
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| 901 | on the device used as a clock source. |
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| 902 | |
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| 903 | @subheading NOTES: |
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| 904 | |
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| 905 | This directive may be called from an ISR. |
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| 906 | |
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[2d1bdc8] | 907 | This directive is called as part of every service to obtain the |
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[bf6d03d] | 908 | current date and time as well as timestamps. |
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| 909 | |
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[169502e] | 910 | @c |
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| 911 | @c |
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| 912 | @c |
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[ae68ff0] | 913 | @page |
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| 914 | @subsection CLOCK_TICK - Announce a clock tick |
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| 915 | |
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[169502e] | 916 | @cindex clock tick |
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| 917 | |
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[ae68ff0] | 918 | @subheading CALLING SEQUENCE: |
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| 919 | |
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[61389eac] | 920 | @ifset is-C |
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[169502e] | 921 | @findex rtems_clock_tick |
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[ae68ff0] | 922 | @example |
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| 923 | rtems_status_code rtems_clock_tick( void ); |
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| 924 | @end example |
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[61389eac] | 925 | @end ifset |
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| 926 | |
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| 927 | @ifset is-Ada |
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| 928 | @example |
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[4ffbc49] | 929 | procedure Clock_Tick ( |
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| 930 | Result : out RTEMS.Status_Codes |
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| 931 | ); |
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[61389eac] | 932 | @end example |
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| 933 | @end ifset |
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[ae68ff0] | 934 | |
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| 935 | @subheading DIRECTIVE STATUS CODES: |
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[f8892c9] | 936 | @code{@value{RPREFIX}SUCCESSFUL} - clock tick processed successfully |
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[ae68ff0] | 937 | |
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| 938 | @subheading DESCRIPTION: |
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| 939 | |
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| 940 | This directive announces to RTEMS that a system clock |
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| 941 | tick has occurred. The directive is usually called from the |
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| 942 | timer interrupt ISR of the local processor. This directive |
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| 943 | maintains the system date and time, decrements timers for |
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| 944 | delayed tasks, timeouts, rate monotonic periods, and implements |
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| 945 | timeslicing. |
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| 946 | |
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| 947 | @subheading NOTES: |
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| 948 | |
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| 949 | This directive is typically called from an ISR. |
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| 950 | |
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[a91cc06] | 951 | The @code{microseconds_per_tick} and @code{ticks_per_timeslice} |
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[ae68ff0] | 952 | parameters in the Configuration Table contain the number of |
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| 953 | microseconds per tick and number of ticks per timeslice, |
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| 954 | respectively. |
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