On Fri, 2005-07-15 at 20:37 -0700, Andrew Warren wrote:

> Oops, we don't need to copy REGA, so it can be done even faster:
>
>     ; Find median of REGA, REGB, REGC.
>
>     MOVF    REGB,W    ;TEMP2 = REGB.
>     MOVWF   TEMP2     ;
>     MOVF    REGC,W    ;MEDIAN = REGC.
>     MOVWF   MEDIAN    ;
>
>     SUBWF   TEMP2,W   ;TEMP2 >= MEDIAN?
>     BC      $+3       ;If so, skip ahead.
>     ADDWF   MEDIAN    ;Otherwise, swap MEDIAN and
>     SUBWF   TEMP2     ;TEMP2.
>
>     MOVF    REGA,W   ;MEDIAN >= REGA?
>     SUBWF   MEDIAN,W  ;
>     SKPC              ;If so, skip ahead.
>     SUBWF   MEDIAN    ;Otherwise, MEDIAN = TEMP1.
>
>     MOVF    MEDIAN,W  ;TEMP2 >= MEDIAN?
>     SUBWF   TEMP2,W   ;
>     SKPC              ;If so, skip ahead.
>     ADDWF   MEDIAN    ;Otherwise, MEDIAN = TEMP2.
>
> 17 words, 16 or 17 cycles.

Looks good to me. There's away to make it 17-instructions and 17-cycles,
but it's not too interesting. I don't know what I was thinking earlier - I
guess I've been smoking too many virtual functions here lately!

Scott
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