#include <stdio.h>

int
main(void)
{
	float x = 2.0;
	float y = 5.0;
	asm("fld %1\n\t"
	    "fld %2\n\t"
	    "fxch\n\t"       // swap
	    "fsubp\n\t"      // subtract and pop
	    "fstp %0\n"      // halt FPU and store result
	    : "=m"(x)        // output (%0)
	    : "m"(x), "m"(y) // input  (%1, %2)
	);
	fprintf(stderr, "%.4f\n", x);
}