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Re: question about isr function signature (profiling)
- From: Andrew Lunn <andrew at lunn dot ch>
- To: Yuxin Jiang <yjiang at matrics dot com>
- Cc: Ecos-Discuss <ecos-discuss at sources dot redhat dot com>
- Date: Sat, 27 Mar 2004 19:28:41 +0100
- Subject: Re: [ECOS] question about isr function signature (profiling)
- References: <LIEGIBEMFCHIDNLFFKKEAEIJCGAA.yjiang@matrics.com>
On Fri, Mar 26, 2004 at 05:30:25PM -0500, Yuxin Jiang wrote:
>
> For ARM7TDMI core, I want to define a ISR service routine, as following:
>
> // ISR.
> static cyg_uint32
> timer_isr(CYG_ADDRWORD vector, CYG_ADDRWORD data, HAL_SavedRegisters *regs)
> {
>
> HAL_INTERRUPT_ACKNOWLEDGE (CYGNUM_HAL_INTERRUPT_PROFILE_TIMER);
> __profile_hit(regs->pc);
>
> return CYG_ISR_HANDLED;
> }
>
>
> My question is: is the signature for the timer_isr correct?
It looks correct.
> To be specific, is it correct to declare that there is a third parameter for
> a isr, and this third parameter is a pointer to the HAL_SavedRegisters
> structure, and the structure has correct (updated) context registers value
> at the moment the interrupt occurs?
>
> As you can see, I am trying to do profiling. But I am not sure I actually
> get the correct pc value passed into the __profile_hit() function call.
For ARM the PC will be for the next instruction to be executed, not
the interrupted instruction. It could also be wrong when the
instruction just executed was a branch.
Andrew
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