Oh my...
>    I'm trying to see if the input number is EQUAL
>    to 3.
>
>    Here's how it works:
>
>    First, I check for divisibility by 3.  If the number passes that
>    test, I then make sure that it's not also divisible by 2.  After
>    that, I use Eric Smith's routine for checking whether a number's
>    within a certain range... I start with a range of [0-255], then
>    progressively narrow the range, one step at a time, to [2-4].
>
>    At this point, if the input number's passed all those tests, I'm
>    pretty sure that it may be equal to 3.  To make ABSOLUTELY sure,
>    though, I check bits 2-7 of the number individually, verifying
>    that each is clear, then I check bits 0 and 1 and verify
>    that they're both set.
>
>    Since this is a very critical aplication, though, even THIS
>    isn't enough.  To get that last little bit of certainty, I
>    divide 4,294,967,296 by the input number.  If the answer's
>    1,431,655,765, (with no remainder), I asume that the input
>    number was indeed equal to 3.
>
>    Finally, I double-check my assumption using the following code:
>
>        XORLW   3
>        BZ      ITS_EQUAL_TO_3
>
>    -Andy

Andy:

You forgot to subtract three from the original input value and then check
the zero flag.
Only then can you ABSOLUTELY sure.

Todd Peterson

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