Re: [f-cpu] GCC and jmpz vs. jmpl

[Michael Riepe <michael@stud.uni-hannover.de>]

On Wed, Jan 08, 2003 at 03:01:23AM +0100, Yann Guidon wrote:
[...]
> Just one question : is GCC bound to this "1/0" scheme ?

AFAIK, gcc expects the result of a compare instruction to be either +1
or negative (that is, it can use the LSB or the MSB directly). This is
NOT true for an ordinary `xor'.

> F-CPU is based on "0 / not 0", so in some cases we can drop the andi :-)

Only if the unused high bits are zeroed.

> Or, if the result is not used in a computation or mask, the LSB 
> condition can
> be used.

Yep.

-- 
 Michael "Tired" Riepe <Michael.Riepe@stud.uni-hannover.de>
 "All I wanna do is have a little fun before I die"
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