Using gcc to compiler assembly

Using gcc to compiler assembly

[Andrew Haydon]

[-- Attachment #1: Type: text/plain, Size: 495 bytes --]

Gurus,

How to use GCC compiling assembly codes? I attached my example code and 
tried gcc -c -o foo.o foo.S. This line "typedef foo_bar_t int;" choked. I 
read the Makefiles for linux kernel and still could not understand how these 
assebmly codes were compiled by GCC.

Thanks in advance,

Andrew




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[-- Attachment #2: foo.h --]
[-- Type: application/octet-stream, Size: 80 bytes --]

#ifndef FOO_H
#define FOO_H

typedef foo_bar_t int;
#define FOO_BAR 100

#endif

[-- Attachment #3: foo.S --]
[-- Type: application/octet-stream, Size: 47 bytes --]

#include "foo.h"

.text
	movl	$ FOO_BAR, %eax

Re: Using gcc to compiler assembly

[Maciej Hrebien]

Andrew Haydon wrote:
> 
> How to use GCC compiling assembly codes? I attached my example code and
> tried gcc -c -o foo.o foo.S. This line "typedef foo_bar_t int;" choked.

Yes, "typedef" isn't assembly directive nor asm instruction.

> I
> read the Makefiles for linux kernel and still could not understand how these
> assebmly codes were compiled by GCC.

Some of them are only preporcessed by gcc (-E flag) and then send to the
assembler, linker... Maybe asm code is passed to gcc streight, i don't
remember, but notice that the code isn't mixed in form Your example is.

If You mix C & assembly code try C's asm keyword, ie:

void foo()
{
   double a;

   /* ... */

   asm("fsin" : "=st" (a));
}

For details on how to pass arguments to asm() see gcc's man page.

It's the first solution. The second one is to separate Your asm and C
code in their own files. Assemble Your low level code to *.o and then
pass it to the C compiler. I think it's better solution but of course
it's Your code.

Regards,

-- 
Maciej Hrebien

RE: Using gcc to compiler assembly

[Joseph D. Wagner]

What you've got isn't pure Assembly; it's some strange jumble of C and
Assembly.

To include Assembly in C, use
asm {
	;	// Assembly Code Here
}

or 

__asm {
	;	// Assembly Code Here
}

depending on the compiler.

To program in pure Assembly, ditch GCC.  Go with NASM.
http://sourceforge.net/projects/nasm

And based on your lack of distinction between C and Assembly, I also
recommend:
http://www.amazon.com/exec/obidos/tg/detail/-/0130910139/

Joseph Wagner

-----Original Message-----
From: linux-assembly-owner@vger.kernel.org
[mailto:linux-assembly-owner@vger.kernel.org] On Behalf Of Andrew Haydon
Sent: Saturday, November 02, 2002 5:09 PM
To: linux-assembly@vger.kernel.org
Subject: Using gcc to compiler assembly

Gurus,

How to use GCC compiling assembly codes? I attached my example code and 
tried gcc -c -o foo.o foo.S. This line "typedef foo_bar_t int;" choked.
I 
read the Makefiles for linux kernel and still could not understand how
these 
assebmly codes were compiled by GCC.

Thanks in advance,

Andrew




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Unlimited Internet access -- and 2 months free!  Try MSN. 
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