linux-kernel - ARM assembly syntax (was Re: [patch 03/36] Hexagon: Add bitops support)

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Date:	Tue, 30 Aug 2011 16:14:49 -0500
From:	"Linas Vepstas (Code Aurora)" <linas@...eaurora.org>
To:	Pavel Machek <pavel@....cz>
Cc:	Richard Kuo <rkuo@...eaurora.org>, linux-kernel@...r.kernel.org,
	linux-hexagon@...r.kernel.org
Subject: ARM assembly syntax  (was Re: [patch 03/36] Hexagon: Add bitops
 support)

On Fri, Aug 26, 2011 at 10:34:10PM +0200, Pavel Machek wrote:
> Hi!
> 
> > +	__asm__ __volatile__ (
> > +	"	{R10 = %1; R11 = asr(%2,#5); }\n"
> > +	"	{R10 += asl(R11,#2); R11 = and(%2,#0x1f)}\n"
> > +	"1:	R12 = memw_locked(R10);\n"
> > +	"	{ P0 = tstbit(R12,R11); R12 = clrbit(R12,R11); }\n"
> > +	"	memw_locked(R10,P1) = R12;\n"
> > +	"	{if !P1 jump 1b; %0 = mux(P0,#1,#0);}\n"
> 
> Nice assembly syntax, btw. I can only wish architectures such as arm
> used something as readable...

Yes, I, too, was very pleasantly surprised when I first saw this.

Of course, one *could* alter binutils to accept something similar
for ARM, and then alter gcc to spit it out. Whether anyone would use
this isn't clear .. and I can already almost hear certain maintainers
telling us how much of a bad idea this is from the maintainership
point-of-view ....

--linas

-- 
Sent by an employee of the Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.
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