linux-kernel - macro _set_base - "do

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Date:	Wed, 2 Jan 2008 12:45:39 +0100
From:	Abdel <draconux@...il.com>
To:	linux-kernel@...r.kernel.org
Subject: macro _set_base - "do - while(0)" question

Hi,

In file include/asm-i386/system.h,  _set_base and _set_limit use an
useless do ... while(0)

Why is this needed ?

exemple with _set_base from linux-2.6.23

#define _set_base(addr,base) do { unsigned long __pr; \
__asm__ __volatile__ ("movw %%dx,%1\n\t" \
	"rorl $16,%%edx\n\t" \
	"movb %%dl,%2\n\t" \
	"movb %%dh,%3" \
	:"=&d" (__pr) \
	:"m" (*((addr)+2)), \
	 "m" (*((addr)+4)), \
	 "m" (*((addr)+7)), \
         "0" (base) \
        ); } while(0)


-- 
Abdel
http://draconux.free.fr/
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