Not getting expected output using cmpxchg8b for unsigned long

Question

I am trying to write a simple compare and swap inline assembly code. Here is my code

#include 
#include 
#include 

        

Answer 1

Sorry for not answering your question directly, but my question is: why not use C11's or C++11's ? It's a lot less error-prone than writing your own functions and has the advantage that you're not targeting a specific hardware architecture or compiler.

In your case you should either be using atomic_compare_exchange_weak() or atomic_compare_exchange_strong().