RTEMS 4.7.1 On-Line Library

Clock Manager CLOCK_GET - Get system date and time information

RTEMS Ada User's Guide

7.4.2: CLOCK_GET - Get system date and time information

CALLING SEQUENCE:

procedure Clock_Get (
   Option      : in     RTEMS.Clock_Get_Options;
   Time_Buffer : in     RTEMS.Address;
   Result      :    out RTEMS.Status_Codes
);

DIRECTIVE STATUS CODES:

RTEMS.SUCCESSFUL - current time obtained successfully
RTEMS.NOT_DEFINED - system date and time is not set
RTEMS.INVALID_ADDRESS - time_buffer is NULL

DESCRIPTION:

This directive obtains the system date and time. If the caller is attempting to obtain the date and time (i.e. option is set to either RTEMS.CLOCK_GET_SECONDS_SINCE_EPOCH, RTEMS.CLOCK_GET_TOD, or RTEMS.CLOCK_GET_TIME_VALUE) and the date and time has not been set with a previous call to rtems.clock_set, then the RTEMS.NOT_DEFINED status code is returned. The caller can always obtain the number of ticks per second (option is RTEMS.CLOCK_GET_TICKS_PER_SECOND) and the number of ticks since the executive was initialized option is RTEMS.CLOCK_GET_TICKS_SINCE_BOOT).

The option argument may taken on any value of the enumerated type rtems_clock_get_options. The data type expected for time_buffer is based on the value of option as indicated below:

RTEMS.CLOCK_GET_TOD - Address of an variable of type RTEMS.Time_Of_Day
RTEMS.CLOCK_GET_TIME_VALUE - Address of an variable of type RTEMS.Clock_Time_Value
RTEMS.CLOCK_GET_TICKS_SINCE_BOOT - Address of an variable of type RTEMS.Interval
RTEMS.CLOCK_GET_SECONDS_SINCE_EPOCH - Address of an variable of type RTEMS.Interval
RTEMS.CLOCK_GET_TICKS_PER_SECOND - Address of an variable of type RTEMS.Interval

NOTES:

This directive is callable from an ISR.

This directive will not cause the running task to be preempted. Re-initializing RTEMS causes the system date and time to be reset to an uninitialized state. Another call to rtems.clock_set is required to re-initialize the system date and time to application specific specifications.

RTEMS Ada User's Guide