Jason Harper says:
Assuming that code space is also a concern, try this: it's a bit shorter than the other solutions I've seen posted. Note that it actually calculates input * 102 / 256, but due to roundoff errors it produces 100 for an input of 255, so it should do the job for you.
percentify
; input in W, output in temp
movwf temp
bcf status,c
rrf temp,f ;temp = input * 128 / 256
addwf temp,f ;carry/temp = input * 384 / 256
rrf temp,f ;temp = input * 192 / 256
bcf status,c
rrf temp,f ;temp = input * 96 / 256
swapf temp,w
andlw 0x0F ;w = input * 6 / 256
addwf temp,f ;temp = input * 102 / 256
;or: addwf temp,w for result in w
return
| file: /techref/microchip/math/scale/8bxperfast.htm, 1KB, , updated: 2000/2/25 10:58, local time: 2008/12/1 19:46,
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