...
determines the type of post performed.
OS_OPT_POST_1
Post and ready only the highest-priority task waiting on the semaphore.
OS_OPT_POST_ALL
Post to all tasks waiting on the semaphore. You should only use this option if the semaphore is used as a signaling mechanism and never when the semaphore is used to guard a shared resource. It does not make sense to tell all tasks that are sharing a resource that they can all access the resource.
OS_OPT_POST_NO_SCHED
This option indicates that the caller does not want the scheduler to be called after the post. This option can be used in combination with one of the two previous options.
You should use this option if the task (or ISR) calling OSSemPost() will be doing additional posting and, the user does not want to reschedule until all done, and multiple posts are to take effect simultaneously.
p_err
is a pointer to a variable that holds an error code:
...
The current value of the semaphore count
Notes/Warnings
- Semaphores must be created before they are used.
- You can also post to a semaphore from an ISR but the semaphore must be used as a signaling mechanism and not to protect a shared resource.