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void  OSSemDel (OS_SEM  *p_sem,

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                OS_OPT   opt,

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                OS_ERR  *p_err)

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File
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Called from
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Code enabled by
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os_sem.c
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Task only
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OS_CFG_SEM_EN and OS_CFG_SEM_DEL_EN
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OSSemDel() is used to delete a semaphore. This function should be used with care as multiple tasks may rely on the presence of the semaphore. Generally speaking, before deleting a semaphore, first delete all the tasks that access the semaphore. As a rule, it is highly recommended to not delete kernel objects at run time. Anchor10031231003123
Deleting the semaphore will not de-allocate the object. In other words, storage for the variable will still remain at the same location unless the semaphore is allocated dynamically from the heap. The dynamic allocation of objects has its own set of problems. Specifically, it is not recommended for embedded systems to allocate (and de-allocate) objects from the heap given the high likelihood of fragmentation. Anchor10031271003127
Arguments
 Anchor10031281003128p_sem Anchor10031301003130
is a pointer to the semaphore.
 Anchor10031311003131opt Anchor10031321003132
specifies one of two options: OS_OPT_DEL_NO_PEND or OS_OPT_DEL_ALWAYS.
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OS_OPT_DEL_NO_PEND specifies to delete the semaphore only if no task is waiting on the semaphore. Because no task is “currently” waiting on the semaphore does not mean that a task will not attempt to wait for the semaphore later. How would such a task handle the situation waiting for a semaphore that was deleted? The application code will have to deal with this eventuality.
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OS_OPT_DEL_ALWAYS specifies deleting the semaphore, regardless of whether tasks are waiting on the semaphore or not. If there are tasks waiting on the semaphore, these tasks will be made ready-to-run and informed (through an appropriate error code) that the reason the task is readied is that the semaphore it was waiting on was deleted. The same reasoning applies with the other option, how will the tasks handle the fact that the semaphore they want to wait for is no longer available?
 Anchor10031451003145p_err Anchor10031461003146
is a pointer to a variable used to hold an error code. The error code may be one of the following:
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OS_ERR_NONE
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class
WebWorks_Indent_2
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if the call is successful and the semaphore has been deleted.
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class
WebWorks_Indent_1
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OS_ERR_DEL_ISR
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if OS_CFG_CALLED_FROM_ISR_CHK_EN set to 1 in os_cfg.h: if attempting to delete the semaphore from an ISR.
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class
WebWorks_Indent_1
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OS_ERR_OBJ_PTR_NULL
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class
WebWorks_Indent_2
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if OS_CFG_ARG_CHK_EN is set to 1 in os_cfg.h: if p_sem is a NULL pointer.
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OS_ERR_OBJ_TYPE
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class
WebWorks_Indent_2
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if OS_CFG_OBJ_TYPE_CHK_EN is set to 1 in os_cfg.h: if p_sem is not pointing to a semaphore.
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OS_ERR_OPT_INVALID
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if OS_CFG_ARG_CHK_EN is set to 1 in os_cfg.h: if one of the two options mentioned in the opt argument is not specified.
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class
WebWorks_Indent_1
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OS_ERR_TASK_WAITING
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class
WebWorks_Indent_2
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if one or more tasks are waiting on the semaphore.
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Returned Value
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1003164None Anchor10031651003165
Notes/Warnings
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Use this call with care because other tasks might expect the presence of the semaphore. Anchor10032201003220
Example
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rowspan
16
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