Since timers are a limited resource, the use of two timers could be an issue on some systems.
- The job could be done with a single timer if, for example, the single timer were kept in a free-running at all times. Some timer/counters have the capability to generate a compare interrupt when the timer matches a comparison value but also to continue counting without stopping. If your hardware supports such counters, one might used the CONFIG_SCHED_TICKLESS_ALARM option and be able to simply set the comparison count at the value of the free running timer PLUS the desired delay. Then you could have both with a single timer: An alarm and a free-running counter with the same timer!
+ The job could be done with a single timer if, for example, the single timer were kept in a free-running at all times. Some timer/counters have the capability to generate a compare interrupt when the timer matches a comparison value but also to continue counting without stopping. If your hardware supports such counters, one might used the CONFIG_SCHED_TICKLESS_ALARM option and be able to simply set the comparison count at the value of the free running timer PLUS the desired delay. Then you could have both with a single timer: An alarm and a free-running counter with the same timer!
In addition to these imported interfaces, the RTOS will export the following interfaces for use by the platform-specific interval timer implementation: @@ -3041,7 +3041,7 @@ VxWorks provides the following comparable interface:
up_addrenv_select()Function Prototype:
int up_addrenv_select(group_addrenv_t addrenv, hw_addrenv_t *oldenv);
+ int up_addrenv_select(group_addrenv_t addrenv, save_addrenv_t *oldenv);
Description:
oldenv:
The address environment that was in place before up_addrenv_select() was called.
This may be used with up_addrenv_restore() to restore the original address environment that was in place before up_addrenv_select() was called.
- Note that this may be a task agnostic, hardware representation that is different from group_addrenv_t.
+ Note that this may be a task agnostic, platform-specific representation that may or may not be different from group_addrenv_t.
Returned Value:
@@ -3065,7 +3065,7 @@ VxWorks provides the following comparable interface:up_addrenv_restore()Function Prototype:
int up_addrenv_restore(hw_addrenv_t oldenv);
+ int up_addrenv_restore(save_addrenv_t oldenv);
Description:
Input Parameters:
oldenv: The hardware representation of the address environment previously returned by up_addrenv_select().oldenv: The platform-specific representation of the address environment previously returned by up_addrenv_select().Returned Value: