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CRITICAL and return

Posted by Nobody/Anonymous on January 17, 2006
Sorry - this maybe a repost - I'm not sure my first atempt made it through my ADSL which is playing up this morning...

The question is, is it okay to return a global variable inside a critical section :-

inline unsigned short MessagesToSend( void )
{
taskENTER_CRITICAL();
return m_MessagesToSend;
taskEXIT_CRITICAL();
}

rather than the more secure, but slower :-

inline unsigned short MessagesToSend( void )
{
unsigned short Val;
taskENTER_CRITICAL();
Val = m_MessagesToSend;
taskEXIT_CRITICAL();
return Val;
}

TIA

Tim (@vaquita.co.uk)

RE: CRITICAL and return

Posted by Nobody/Anonymous on January 17, 2006
Unfortunately not. This could/would (depending on the port) exit the function with interrupts disabled, leave the stack incorrect and thus not return correctly.

RE: CRITICAL and return

Posted by Nobody/Anonymous on January 17, 2006
Also note the inline request. I assume that if the compiler does inline it, it will be fine. Maybe not though. I'm just not convinced what will happen if it doesn't.

Basically, will the EXIT_CRITICAL bit get called, or will the compiler do what I'm telling it to, and just skip to the end of the routine ?

:
:

Okay, I think I've answered my question. If the compiler is more clever than I think, and fix my dumb errors, then let me know...

Tim


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