From owner-freebsd-hackers@FreeBSD.ORG  Sun Apr 24 11:06:21 2005
Return-Path: <owner-freebsd-hackers@FreeBSD.ORG>
Delivered-To: freebsd-hackers@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP id 385D116A4CE
	for <freebsd-hackers@freebsd.org>;
	Sun, 24 Apr 2005 11:06:21 +0000 (GMT)
Received: from mailserv1.neuroflux.com (ns2.neuroflux.com [204.228.228.85])
	by mx1.FreeBSD.org (Postfix) with ESMTP id C0B8C43D2F
	for <freebsd-hackers@freebsd.org>;
	Sun, 24 Apr 2005 11:06:20 +0000 (GMT)
	(envelope-from ryans@gamersimpact.com)
Received: (qmail 32736 invoked by uid 1003); 24 Apr 2005 11:06:38 -0000
Received: from ryans@gamersimpact.com by mailserv1.neuroflux.com by uid 89
	with qmail-scanner-1.22 
	(clamscan: 0.65. spamassassin: 2.60.  Clear:RC:1(63.231.170.25):. 
	Processed in 1.268871 secs); 24 Apr 2005 11:06:38 -0000
Received: from unknown (HELO ?192.168.0.5?) (63.231.170.25)
  by mailserv1.neuroflux.com with SMTP; 24 Apr 2005 11:06:37 -0000
Message-ID: <426B7DAE.4080502@gamersimpact.com>
Date: Sun, 24 Apr 2005 06:06:22 -0500
From: Ryan Sommers <ryans@gamersimpact.com>
User-Agent: Mozilla Thunderbird 0.7.3 (Windows/20040803)
X-Accept-Language: en-us, en
MIME-Version: 1.0
To: "Tetsuji \"Maverick\" Rai" <maverick31337@vfemail.net>
References: <001601c548a5$bcdde6b0$6702a8c0@IBM6C6CDABCD41>
	<426B74C5.3090509@vfemail.net>
In-Reply-To: <426B74C5.3090509@vfemail.net>
Content-Type: text/plain; charset=us-ascii; format=flowed
Content-Transfer-Encoding: 7bit
cc: freebsd-hackers@freebsd.org
cc: HHCHANG <b8701143@tmu.edu.tw>
Subject: Re: about execute assembly exapmles under freebsd
X-BeenThere: freebsd-hackers@freebsd.org
X-Mailman-Version: 2.1.1
Precedence: list
List-Id: Technical Discussions relating to FreeBSD
	<freebsd-hackers.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-hackers>,
	<mailto:freebsd-hackers-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-hackers>
List-Post: <mailto:freebsd-hackers@freebsd.org>
List-Help: <mailto:freebsd-hackers-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-hackers>,
	<mailto:freebsd-hackers-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Sun, 24 Apr 2005 11:06:21 -0000

Something else than can be useful is to use inline assembly and the -S
switch for GCC (gcc -S sourcefile, produces sourcesfile.s which is the
assembly that would have been sent to gas if you had specified -o).

Inline assembly example:

(ryans@blue)~:cat test.c
int
main()
{
int input=0;
void *edx, *ebx, *ecx, *eax;
asm("cpuid" : "=a" (eax), "=b" (ebx), "=c" (ecx), "=d" (edx) : "a" (input));
printf("CPUid returned: EAX=%0.8x EBX=%0.8x ECX=%0.8x EDX=%0.8x\n", eax,
ebx, ecx, edx);
return 1;
}
(ryans@blue)~:./test
CPUid returned: EAX=0001 EBX=68747541 ECX=444d4163 EDX=69746e65
(ryans@blue)~:perl -e 'print
"\x41\x75\x74\x68\x65\x6e\x74\x69\x63\x41\x4d\x44\n";'
AuthenticAMD
(ryans@blue)~:

NOTE: If the order in the Perl command confused you, remember,
byte-ordering. :) Little-endian you have to reverse the bytes.

-- 
Ryan Sommers
ryans@gamersimpact.com