Re: Least significant bit?

[buyer1342@saladlove.com]

On Wed, 26 Jul 2000, Lionel Pinkhard wrote:

> I've been thinking of doing this with some kind of AND/OR/XOR mask,
> but I think that would get way too complex (after all, I'm only trying
> to read in ONE BIT!)
> Kind regards,
> Lionel Pinkhard

Hmm... assuming you mean you're programming in asm or similar... you
should be able to do a byte/word ROR or ROL and check to see if the
overflow flag was triggered. (Or was that a SHL/SHR?)

Ie, depending on the architecture, I think the fastes way to check was to
do that. You rotate the register where the bit of the word/byte in
question is stored. Since you are, by shifting the bits towards the least
sig/bit, you force that bit to land in one of the state flags. By checking
the flag after the register has been shifted/rotated will achive what you
want. I think that's like what? 2-3 instructions.

In C/C++, there is a library you can use to check it, but I forget what
it's called and it is slower than a shift+flag check.

Hope that helps some.

Wing.

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