ON 20051028@12:53:51 PM at page:
http://www.piclist.com/microchip/math/scale/index.htm#38653.4612152778
James Newton[JMN-EFP-786] published post 38653.4612152778

<A TITLE="P-212.105.8.155" NAME="38653.4612152778">
</A> 
<PRE>8-bit value scaled by n-bit fraction

I have a lookup table with 4-bit numbers m=0..15. A value t should be scaled according to theese numbers, so that

s = t * m/16

Rather than using 16-bit multiplication followed by s&gt;&gt;4, I found a much faster code. As can be seen, the code can be carried out for e.g. 7-bit m-values as well. 

--------------------
	clrf s
	movf t, W

	bcf STATUS, C
	btfsc m, 0
	addwf s, F
	rrf s, F

	bcf STATUS, C
	btfsc m, 1
	addwf s, F
	rrf s, F

	bcf STATUS, C
	btfsc m, 2
	addwf s, F
	rrf s, F

	bcf STATUS, C
	btfsc m, 3
	addwf s, F
	rrf s, F

	btfsc STATUS, C
	incf s, F		;nearest value
-----------------------

Regards,
Anders Jansson

</PRE>
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ON 20051030@9:24:26 AM at page:
http://www.piclist.com/microchip/math/scale/index.htm#38655.0651041667
James Newton[JMN-EFP-786] published post 38655.0651041667

<A TITLE="P-212.105.9.68" NAME="38655.0651041667">
</A> 
OK, I realize now that my scaling algorithm is very similar to the 8x8bit mult by Warren. /A.J
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