what's wrong with my inline assembly program

roMoon · 03-14-2011, 12:41 AM

hi all, I am trying to use inline assembly code in my program, but the mov instruction does not work.
my code:

Quote:

#include "stdio.h"
int main( int argc, char* argv[])
{
int cpu_iid;

__asm__ __volatile__(
"mov %0, 1\n"
:"=m"(cpu_iid)
:
);
}

and the error:

Quote:

$gcc test.c -o a.out
test.c: Assembler messages:
test.c:6: Error: too many memory references for `mov'

Thank you for your help.

Sylvester Ink · 03-14-2011, 02:26 AM

What assembly language are you using? X86?

[EDIT]Here, read this:
http://www.ibiblio.org/gferg/ldp/GCC...-HOWTO.html#s2
Seems to me you're missing a \t

roMoon · 03-15-2011, 04:32 AM

Quote:

Originally Posted by Sylvester Ink

What assembly language are you using? X86?

[EDIT]Here, read this:
http://www.ibiblio.org/gferg/ldp/GCC...-HOWTO.html#s2
Seems to me you're missing a \t

thank you Sylvester,
I have fix it with this:

Code:

#define CPU_ID(cpu_iid)                   \
       __asm__ __volatile__ (             \
       "mov $0, %0\n"                     \
       :"=r"(cpu_iid)                     \
       :                                  \
       );

but when I try to use memory another fault occurs

Code:

#define CPU_ID_R(cpu_iid)                 \
       __asm__ __volatile__ (             \
       "mov $0, %%eax\n\t"                \
       "mov %%eax, %0\n\t"                \
       :"=m"(cpu_iid)                     \
       :                                  \
       :"%eax"                            \
       );

error: unknown register name '%eax' in 'asm'

Sylvester Ink · 03-15-2011, 11:30 PM

I haven't used inline assembly in some time, but if I recall correctly, #defining stuff like that isn't such a hot idea, as preprocessor directives bypass the error and syntax checking of the compiler. All it's really doing is copy-pasting the macro into the locations where it's being called. Probably safer to write it into its own method. As for the error itself, I'd take a closer look at your syntax. Try using the Intel style. The code is cleaner and it's easier to find errors. See the following link for an example:
http://www.cplusplus.com/forum/beginner/3280/

Beyond that, I couldn't say.
Hopefully there's someone else better versed in assembly here. Otherwise, I'd ask on the cplusplus.com forums, or one of the many assembly forums out there . . .

paulsm4 · 03-15-2011, 11:40 PM

In your other thread, you suggested you were compiling for an Alpha.

Q: (also asked above):

Quote:

What assembly language are you using? X86?