How to access local variable from asm insert?

Question

C++ / C#

I am writing a program in C, and it so happened that assembler inserts are required (because the code is very small), the main problem is that from the asm insert I need to access a local variable, I tried to implement access to this variable through the frame pointer (rsp), but it didn't work for me. Here is an example of how I did it:

...
int a = 0;
asm("movq $5, (%rsp)\n");
...

I would be grateful for help.

Answer 1

asm("mov $5, %0" : "=r" (a));