swap:	pushl %ebx
        mrmovl 8(%esp),%eax	# param pa=&a
	mrmovl 12(%esp),%ebx	# param pb=&b
	mrmovl (%eax),%ecx	# valeur a=*pa
	mrmovl (%ebx),%edx	# valeur b=*pb
	rmmovl %ecx,(%ebx)	# swap *pb = a	
	rmmovl %edx,(%eax)	# swap *pa = b	
        popl %ebx
	ret