Eric Smith wrote:

> > Test if a value is in a certain range
> >
> > W = value
> >
> > addlw 255 - Hi
> > addlw (Hi - Lo) + 1
> >
> > Carry is set if W is in range Lo - Hi
>
> That can't possibly work!  There aren't enough instructions!  And I refuse
> to try it out to see if it works, since I know I'm right!
>

Let's see :-)


Lower = 50
Upper = 60

addlw 255 - Hi equates to addlw 195
addlw (Hi - Lo) + 1 equates to addlw 11

W = 50          ; lower limit

addlw 195       ; w = 245
addlw 11        ; w = 0, C = 1, result = OK

W = 55          ; in range

addlw 195       ; w = 250
addlw 11        ; w = 5, C = 1, result = OK

W = 60          ; upper limit

addlw 195       ; w = 255
addlw 11        ; w = 11, C = 1, result = OK

W = 49          ; under minimum

addlw 195       ; w = 244
addlw 11        ; w = 255, C = 0, result = Not OK

W = 61          ; over maximum

addlw 195       ; w = 0
addlw 11        ; w = 11, C = 0, result = Not OK


--
Best regards

Tony

'The Engine' - Design your own programmer.

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