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From: Chris Friesen <cfriesen@nortel.com>
To: Kumar Gala <kumar.gala@freescale.com>
Cc: linuxppc-dev@ozlabs.org
Subject: Re: question on inline assembly and long long values
Date: Wed, 06 Apr 2005 14:01:20 -0600	[thread overview]
Message-ID: <42544010.4020105@nortel.com> (raw)
In-Reply-To: <2b5cd7aefbd800842537d00be729d169@freescale.com>

Kumar Gala wrote:
> I'm having a similar need (for a different purpose), this post might be 
> useful:
> 
> http://gcc.gnu.org/ml/gcc/2005-04/msg00283.html

Sweet!  My new code is now shorter *and* more efficient:

static inline unsigned long long getmsr()
{
	unsigned long long val;
         asm volatile( \
                 "mfmsr  %L0               \n\t" \
                 "rldicl %0,%L0,32,32       \n\t" \
                 "rldicl %L0,%L0,0,32        \n\t" \
                 : "=r" (val));
	return val;
}

This results in

unsigned long long a = asdf3();
unsigned long long b = asdf3();

being compiled to

	mfmsr  6
	rldicl 5,6,32,32
	rldicl 6,6,0,32
	
	mfmsr  8
	rldicl 7,8,32,32
	rldicl 8,8,0,32

Which is about as good as it gets...

Thanks!

Chris

  reply	other threads:[~2005-04-06 20:01 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-04-06 18:26 question on inline assembly and long long values Chris Friesen
2005-04-06 19:16 ` Kumar Gala
2005-04-06 20:01   ` Chris Friesen [this message]
2005-04-06 21:18     ` Gabriel Paubert
2005-04-06 21:37       ` Chris Friesen
2005-04-06 23:19 ` Benjamin Herrenschmidt
2005-04-06 23:30   ` Chris Friesen
2005-04-06 23:49     ` Benjamin Herrenschmidt
2005-04-06 23:56       ` Chris Friesen
2005-04-06 23:57         ` Benjamin Herrenschmidt
2005-04-07  0:09           ` Chris Friesen

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