From mboxrd@z Thu Jan  1 00:00:00 1970
From: j.neuschaefer@gmx.net (Jonathan =?utf-8?Q?Neusch=C3=A4fer?=)
Date: Wed, 29 May 2013 17:33:59 +0200
Subject: hi about C and asm
In-Reply-To: <CA+5jrf=B1OpTbGNTU_aShBWg8_Qb25vyhn-vLZy2siYght5xPg@mail.gmail.com>
References: <CA+5jrf=B1OpTbGNTU_aShBWg8_Qb25vyhn-vLZy2siYght5xPg@mail.gmail.com>
Message-ID: <20130529153359.GA3135@debian.debian>
To: kernelnewbies@lists.kernelnewbies.org
List-Id: kernelnewbies.lists.kernelnewbies.org

On Wed, May 29, 2013 at 09:02:22AM +0800, lx wrote:
> hi all:
>      They are some asm codes in the kernel like:
> 
> #define set_bit(nr,addr) ({\
> register int res __asm__("ax"); \
> __asm__ __volatile__("btsl %2,%3\n\tsetb %%al": \
> "=a" (res):"0" (0),"r" (nr),"m" (*(addr))); \
> res;})
> 
> 
> But, almost I can't understand this. So I want to understand asm in C,
> which book or website I should learn ?

Google "asm in c", first link is:
http://www.ibiblio.org/gferg/ldp/GCC-Inline-Assembly-HOWTO.html


HTH,
Jonathan Neusch?fer