On Thu, Sep 18, 1997 at 05:19:56PM -0500, John Payson wrote:

> Doesn't "movf _i,w" trash Z?  Perhaps you mistyped that?

Yeah, I was being (too) clever. I looked at the compiler output and thought
I could improve on it.

It should have read:

 ;x.c: 6: if(i <= j)
         movf    _j+1,w          ;get the most significant byte
         xorlw   128             ;make it an unsigned number
         movwf   btemp           ;save
         movf    _i+1,w          ;ditto the other operand
         xorlw   128
         subwf   btemp,w         ;subtract to compare
         btfss   3,2             ;if hi bytes not equal, we're done
         goto    u15
         movf    _i,w            ;get ready to compare low bytes
         subwf   _j,w
u15
         btfss   3,0             ;now C bit is set if i <= j

Of course when comparing with a constant, the temp location is not
required.
>
>
> Hmm... my attempt:
>

Interesting - same number of instructions, but avoids using the temp
location, but does require the known-zero, which not all PICs have.

Clyde

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