RTEMS 4.5.0 On-Line Library

Clock Manager CLOCK_GET - Get system date and time information

RTEMS C User's Guide

7.4.2: CLOCK_GET - Get system date and time information

CALLING SEQUENCE:

rtems_status_code rtems_clock_get(
  rtems_clock_get_options  option,
  void                    *time_buffer
);

DIRECTIVE STATUS CODES:

RTEMS_SUCCESSFUL - current time obtained successfully
RTEMS_NOT_DEFINED - system date and time is not set

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 - (rtems_time_of_day *)
RTEMS_CLOCK_GET_TIME_VALUE - (rtems_clock_time_value *)
RTEMS_CLOCK_GET_TICKS_SINCE_BOOT - (rtems_interval *)
RTEMS_CLOCK_GET_SECONDS_SINCE_EPOCH - (rtems_interval *)
RTEMS_CLOCK_GET_TICKS_PER_SECOND - (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 C User's Guide