Graham North <PICLIST@MITVMA.MIT.EDU> wrote:

> I am reading two 16 bit 2's comp numbers from an A2D. I know one
> will be greater than the other. My question is how do I compare
> them?

    Wasn't this JUST discussed here on the list?  One easy way is to
    invert the most-significant bit of each number (by XORLWing the
    high byte with 0x80), then do a straight subtraction:

    If (A ^ 0x8000) - (B ^ 0x8000) > 0, then A > B.

    Inverting the high bit is equivalent to adding 0x8000 (or
    subtracting 0x8000, if you want to think of 0x8000 as a negative
    number).  In any case, it remaps your [-32768 to 32767] range to
    [0 to 65535].

    -Andy


=== Andrew Warren - fastfwd@ix.netcom.com
=== Fast Forward Engineering - San Diego, California
=== http://www.geocities.com/SiliconValley/2499

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