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Date: Fri, 06 Dec 2002 12:38:13 -0500 (EST)
From: John Baldwin <jhb@FreeBSD.org>
To: kai ouyang <oykai@msn.com>
Subject: RE: One GNU ASM syntax problem
Cc: hackers@FreeBSD.org
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On 06-Dec-2002 kai ouyang wrote:
> Hi,everybody,
> 
>   I have one question about GNU ASM syntax. 
> As I know:
> __asm __volatile(
>    "instructions"
>    :output
>    :input
>    :exception);
> In Linux, the restriction of output are "=m","=a", etc.
> But I found in FreeBSD, there are "=m" and "+m".
> I do not know the difference between "+" and "=". why?
> Thank you!

Check the info pages for gcc.  = conotes an output-only operand
and + conotes an input and output operand.

-- 

John Baldwin <jhb@FreeBSD.org>  <><  http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve!"  -  http://www.FreeBSD.org/

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