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Re: [avr-gcc-list] Using X and Z register in global variables

From: Joerg Wunsch
Subject: Re: [avr-gcc-list] Using X and Z register in global variables
Date: Sun, 4 Sep 2005 21:00:39 +0200
User-agent: Mutt/

As User Tomdean wrote:

> This is warning about using Z and X, but, not Y.

Maybe you could really use Y as a global reg variable, but I'd rather
avoid that.  It severely restricts the compilers freedom of choice to
generate decent code for the remaining program.  If you're linking
against avr-libc, you're also *heavily* at risk that some library code
(not knowing about your choice of a global register variable) clobbers

> But, I could not get gcc to use Z+.

I think nobody taught GCC to use it, except perhaps in a few
fixed-pattern situations.

cheers, J"org               .-.-.   --... ...--   -.. .  DL8DTL

http://www.sax.de/~joerg/                        NIC: JW11-RIPE
Never trust an operating system you don't have sources for. ;-)

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