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typedef void * xQueueHandle; and ansi c

Posted by GregK on January 31, 2009
Hi

I have trivial question (I hope), I do not understand something.

situation:

task:
//=======================================
extern xQueueHandle xQueue; //ours queue

while(xQueue == NULL) //wait on till queue will be created in other task
{
delay(10);
}

xQueueSendToBack(xQueue,...);
(...)
//========================================

So we creating a queue in other task, this task just waiting on when queue is created. xQueueHandle is defined:
typedef void * xQueueHandle;
My doubts are: is it safe if to declare handler to queue like non volatile pointer? General rule is that volatile type should be for example:
"Global variables accessed by multiple tasks within a multi-threaded application"
I understand this like:
typedef void * volatile xQueueHandle;

What are yours thoughts ?

Kind Regards
/Greg

RE: typedef void * xQueueHandle; and ansi c

Posted by Richard on January 31, 2009
I think technically you are correct, you may need a volatile on the definition, depending on the compiler and optimisation level used.

Regards.

RE: typedef void * xQueueHandle; and ansi c

Posted by GregK on February 2, 2009
I checked 2 another RTOS and non of them declare non volatile pointers. It seems that neither compiler use such optimization, because is really unlike that no one report bug yet.

Regards


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