// myMutex.c++
// $ g++ -Wall -c myMutex.c++
#include "myMutex.h"

void myMutexInit(int &lock){
     lock = 0;
}

void myMutexLock(int *lockP){
     __asm__ __volatile__ (
        "movl $1, %%eax \n\t"
        ".MyLbl1:     \n\t"
        "lock         \n\t"
        "xchgl %%eax, 0(%%rbx) \n\t"
        "cmpl $0, %%eax \n\t"
        "jne .MyLbl1     \n\t"
        :
        :"b"(lockP)
        :"%eax"
    );
}

void myMutexUnlock(int &lock){
     lock = 0;
}