On 2010-02-19 21:28, Josh Koffman wrote:
> Hi all.
>
> I've just come across a problem that I've never had happen before.
> Likely that was due to luck. Now I'm not sure what the best way to
> solve it is.
>
> At the start of my ISR, I save WREG, STATUS, and BSR (this is a
> PIC18F) to temporary registers.

How are these "temporary register" allocated ?
Should be via UDATA_ACS, are thay ?

> I then restore them on exit. I've been
> tracking a bug that seems to be manifesting itself due to incorrect
> bank selection. Here's why I think this is happening, look at the
> addresses of the following registers:
>
> W_Temp     0x080
> PORTA       0xF80
>
> The other registers have similar overlapping low byte addresses.
> So...going into my ISR I might not be in the correct bank.

Does not matter a bit, since the temp regs are in the access bank anyway.
Or at least should be.

> But if I
> change the bank, I've upset the current state and things won't get
> restored correctly.
>
> I'm not really sure what to do on this one.

Simple. Just make sure your temp-regs are in the access bank !

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