Inline Assembly, MOV, and Memory Operand Constraint

[Georg-Johann Lay]

Jeffrey Walton schrieb:
> Hi All,
> 
> I have a question on inline assembly. For my first experiment, I'm
> trying to read the flags register. Intuitively, I'm trying to perform
> the following:
>     mov %eax, result
> 
> The assembler does not take the simple syntax (see [1], [2]), andI'm
> having trouble getting the statement right. I've tried lots of
> variations on the following, but have yet to find success.
>     unsigned int result;
>     ...
>     asm volatile("mov %eax, result" : "=m(result)");
> 
> What's the trick to move from a register to memory (C variable)?

Something like

asm volatile("mov %%eax, %[result]" : [result] "=m" (result) :: "memory");

> Jeff
> 
> [1]
> [2] http://www.ibiblio.org/gferg/ldp/GCC-Inline-Assembly-HOWTO.html
>