ASM Check number of binary 1s

#include "stdafx.h"
#include <iostream>
using namespace std;


int main() {
    int a, b, cat, rest;
    a = 5;

    _asm {
        mov eax, a
        mov ecx, 0
        _while:
            cmp eax, 0
            je _endwhile
            mov ebx, eax
            and ebx, 1
            add ecx, ebx
            shr eax, 1
            jmp _while
        _endwhile:
        mov b, ecx;
        /* shl eax, 2*/
        /* shr eax, 2*/
        /* rol eax, 2*/
        /* ror eax, 2*/
        /* mul cx === ax * cx */
        /* div b == dxax / b = ax rest dx */
    };

    cout << b;
    cout << endl;

}