Re: How to move two valuables to x86 CPU register ebx, ecx by using AT&A inline asm.

[Johnny Hung <johnny.hacking@gmail.com>]

Thank you. I got error because the valuable I actually pass is a
member of structure point. ex.

       __asm__ volatile ("movl (%0), %%ebx\n"
         "movl (%1), %%ecx\n"
         : : "r"(ptr->cnt), "r"(ptr->blk) );

I reassigned ptr->cnt and ptr->blk to local unsigned int valuable and
compile successfully. BTW, the first ':' is mean output operands,
second ':' is mean input operands but how about third ':'. Does it
mean which registers had been changed in inline asm code? So, does gcc
do push and pop to retain these registers in the front and end of asm
code?
    I have tried to compile inline asm in user space application and
use gcc -S flag to translate c code to asm code. How do I translate
kernel driver to asm code without compile to obj file?

Thank your help
BR, H. Johnny

2009/11/19 Viral Mehta <viral.mehta@einfochips.com>:
> [root@viral temp_c_files]# gcc foo.c
> [root@viral temp_c_files]# cat foo.c
> #include <stdio.h>
> int main()
> {
>       unsigned int val = 10;
>       unsigned int tmp = 5;
>
>       __asm__ volatile ("movl (%0), %%ebx\n"
>         "movl (%1), %%ecx\n"
>         : : "r"(val), "r"(tmp) );
> }
>
> [root@viral temp_c_files]#
> Thanks,
> Viral Mehta,
> Embedded Software Engineer,
> Tel. No. 91 79 26563705, Ext. 423
> www.einfochips.com <http://www.einfochips.com>
> Prepare and Prevent rather than Repair and Repent
>
>
> Johnny Hung wrote:
>>
>> It doesn't works. :(
>>
>> 2009/11/19 Viral Mehta <viral.mehta@einfochips.com>:
>>
>>>
>>> How about putting \n at the end ?
>>>
>>> Just try out,
>>>
>>> __asm__ volatile ("movl %0, %%ebx\n"
>>>        "movl %1, %%ecx\n"
>>>
>>>
>>>
>>>
>>> Thanks,
>>> Viral Mehta,
>>> Embedded Software Engineer,
>>> Tel. No. 91 79 26563705, Ext. 423
>>> www.einfochips.com <http://www.einfochips.com>
>>> Prepare and Prevent rather than Repair and Repent
>>>
>>>
>>> Johnny Hung wrote:
>>>
>>>>
>>>> Hi All:
>>>>   I want to move two local valuables to x86 arch CPU ebx, ecx
>>>> register and do outb cpu instruction by using AT&A inline asm in
>>>> kernel driver.  The following code was I wrote but gcc report syntax
>>>> error:
>>>> ==
>>>>   unsigned int val = 10;
>>>>   unsigned int tmp = 5;
>>>>   ....
>>>>   __asm__ volatile ("movl %0, %%ebx"
>>>>         "movl %1, %%ecx"
>>>>         "outb $0x27, $0xb2"
>>>>         :
>>>>         :"r"(val), "r"(tmp)
>>>>         :"%ebx", "%ecx"
>>>>  );
>>>>
>>>> Does anyone can point me out. Any reply is appreciated.
>>>>
>>>> BRs, H. Johnny
>>>>
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