Re: [LIP] syscall simulation!

hey arun,
> main()
> {
>     char hello[]="hello world\n";
>     __asm__ __volatile(
>          "movl $4,%%eax\n\t"      /*$4 SYS_write*/
>          "movl $1,%%ebx\n\t"      /*$1 fd for
> stdout*/
>          "movl $12,%%edx\n\t"     /*strlength*/
>          "int $0x80\n\t"
>          :: "c" (hello)
>     );

I tried my code with the modified constraint "m"
instead of "g" (xor's removed) and found that it
worked properly,
see the code below
main()
{
    char hello[]="hello world\n";
    __asm__ __volatile(
         "movl $4,%%eax\n\t"      /*$4 SYS_write*/
         "movl $1,%%ebx\n\t"      /*$1 fd for stdout*/
         "movl %0,%%ecx\n\t"
         "movl $12,%%edx\n\t"     /*strlength*/
         "int $0x80\n\t"
         :: "m" (hello)
    );
        printf("\n");
}
but,while compiling, gcc gave a warning
warning: use of memory input without lvalue in asm
operand 0 is deprecated (why??)

Refering to ur code, isn't specifying constraint "c"
(ie use ecx to hold a variable) same as moving
argument %0 into ecx (which I was doing explicitly by
using constraint "g") ? 

What exactly is happening when we are executing
movl %0,%%ecx 
Is it moving the memory location of "hello world\n"
using  disp(base,index,scale)?

-sanjay



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