----- Original Message -----
From: <piclist@xargs.com>
To: Microcontroller discussion list - Public. <piclist@mit.edu>
Sent: Friday, October 08, 2004 4:58 PM
Subject: Re: [PIC] new optimisation in XCSB


> On Fri, 8 Oct 2004, Sergio Masci wrote:
>
> > > > An insteresting question is what does you favourite PIC C compiler make
of
> > > >
> > > >         if ((A == B) == 0)
>
> > That's very good. I've seen some really inefficient code generated for this
in
> > the past. Which compiler is this?
>
> Hi-Tech PICC.
>

Thanks for the info.

> > Are A and B defined as global or local here?
>
> They were global to make the assembly listing more readable.  When
> local, it looks like this:
>
>   00000A  50E1                movf    fsr1l,w,c
>   00000C  18D9                xorwf   fsr2l,w,c
>   00000E  A4D8                btfss   status,2,c
>   000010  8880                bsf 3968,4,c    ;volatile
>
> since no RAM is allocated for A and B.

But this is only part of the code, you still need to include the code that
calculates the addresses of A and B at run time and prepares fsr1l and fsr2l.

Regards
Sergio Masci

http://www.xcprod.com/titan/XCSB - optimising PIC compiler



_______________________________________________
http://www.piclist.com
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist