inline assembly in gcc

gursev · 02-25-2005, 08:53 AM

Hi All,

I am trying to compile the following the inline assmebly code in linux. But it gives error. Your help will be very useful to me.

void main()
{
__asm__(
"movl %esi, 0x8(%esi)"
"movb $0x0, 0x7(%esi) "
"movl $0x0, 0xc(%esi) "
);

}

These are the errors

/tmp/cc42yoOW.s: Assembler messages:
/tmp/cc42yoOW.s:12: Error: ignoring junk `(%esi)movb $0x0' after expression
/tmp/cc42yoOW.s:12: Error: too many memory references for `mov'
bash-2.04$

Thanks in advance,
Gursev

teval · 03-01-2005, 07:27 PM

You forgot semicolons.
"movl %esi, 0x8(%esi);"
"movb $0x0, 0x7(%esi);"
"movl $0x0, 0xc(%esi);"

Multi instruction asm statements are translated into 1 long line by gcc. So without the ; the assembler doesn't know where a instruction ends.

If you get more trouble of this sort, gcc -S is you friend.
It will print out the asm code right before linking. If you were to look at that in your case you'll see what I mean by the 1 long line.

gursev · 03-04-2005, 02:17 AM

Thanks a lot teval !!!