C ++内联汇编：如何处理引用？

Question

How to deal with references in function from inline assembler? I'm trying this

void foo(int& x)
{
    __asm mov x, 10
}

int main()
{
    int x = 0;
    foo(x);
    std::cout << x << std::endl;
}

but x is still 0 after function execution, however this one works fine

int x = 0;
__asm mov x, 10
std::cout << x << std::endl;

How to solve that?

Thanks.

Answer 1

A reference is a pointer with value semantics - in assembly language these semantics are irrelevant, so you are left with a pointer:

void foo(int& x)
{
    __asm { 
        mov eax, x
        mov DWORD PTR [eax], 10
    }
}

(Of course, YMMV depending on the compiler, version, optimisations, etc. all the usual stuff when using inline assembly.)

Answer 2

Reference is essentially a pointer, an address of the value, not the value itself. So this works for example:

void foo(int& x)
{
    __asm mov eax, x
    __asm mov dword ptr [eax], 10
}

Output:

10