From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jerry Van Baren <gerald.vanbaren@smiths-aerospace.com>
Date: Fri, 06 Jan 2006 10:36:44 -0500
Subject: [U-Boot-Users] need PPC asm. help. for 83xx watchdog
In-Reply-To: <43BE8B32.1060507@cray.com>
References: <43BE8B32.1060507@cray.com>
Message-ID: <43BE8E8C.3060501@smiths-aerospace.com>
List-Id: <u-boot.lists.denx.de>
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
To: u-boot@lists.denx.de

David Updegraff wrote:
> Hi.
> 
> Attempting to enable&use watchdog in 8343; but run into Assembler
> (v.2.15) problem in cpu/mpc83xx/start.S:424
> ....
> /* and reset it */
> 	li	r4, 0x556C
> 	sth	r4, SWSRR at l(r3)
> 	li	r4, 0xAA39    <-------- gas barks here, 0xAA39 > 0x8000
> 	sth	r4, SWSRR at l(r3)
> 
> which I do not understand, since I thought 'li' was an UNsigned 16bit
> load. I can work around it in a kludgey way with.
> 
> 	lis	r4, 0
> 	ori	r4, r4, 0xAA39
> 	sth	r4, SWSRR at l(r3)
> 
> but wonder if one you PowerPC assembler gurus could offer better suggestion.
> 
> Thanx.
> 
> -dbu.

"li" is a simplified mnemonic which is actually "addi" (which 
sign-extends the immediate value) according to  the "PowerPC 
Microprocessor Family: The Programming Environments" Appendix F (p. F-15).

Why gas barks, I'm not quite sure.  Probably because it suspects you 
wanted it unsigned (which actually is the case - I hate it when tools 
are smarter than me).

gvb