// code based on https://www.cs.uaf.edu/courses/cs301/2014-fall/notes/inline-assembly/
// this is the 32-bit version
//
// fastcall convention: first (word) arg in ecx, second in edx, remainder on stack
// caller pops from stack, result in %eax
//  - see  https://gcc.gnu.org/onlinedocs/gcc/x86-Function-Attributes.html
//

extern "C" long add100(long in); /* Prototype */

__asm__( /* Assembly function body */
"add100:\n"
"  mov %ecx,%eax\n"
"  add $100,%eax\n"
// 64-bit version:
//"  mov %rdi,%rax\n"
//"  add $100,%rax\n"
"  ret\n"
);

#include <iostream>
using namespace std;

int main() {
  cout << "Enter a number: ";
  long num;
  cin >> num;
  long num_plus_100 = add100(num);
  cout << "Number plus 100: " << num_plus_100 << endl;
  return 0;
}