#include <stdio.h>

/* double, double -> double
 * function fpu_add adds 2 double FP numbers
 */
double fpu_add(double a, double b);
double fpu_div(double a, double b);

/* -> unsigned short (2B)
 * function get_fpu reads the FPU control word and returns it's value
 */
unsigned short get_fpu();

void set_fpu(unsigned short int);

/*
 *
 */
int main(int argc, char * argv[])
{
    unsigned short int fpucw = 0x1234;
    double dbls[3] = {123.45, 0.123, 0.0};
    double dblx[3] = {123.45, 0.0, 0.0};
    /* generate double constants */
    unsigned long dbl = 0x4000000000000000;
    double * wsk = &dbl;
    //dbls[1] = *wsk;
    printf("unsigned long: %lx\n", dbl);
    printf("unsigned long: %lf\n", *wsk);

    /* add two numbers */
    dbls[2] = fpu_add(dbls[0], dbls[1]);
    printf("default: %lf + %lf = %lf\n", dbls[0], dbls[1], dbls[2]);
fpucw = get_fpu();

    set_fpu(0xc7f); //changing precission
    /* add the same numbers as earlier to see difference */
    dbls[2] = fpu_add(dbls[0], dbls[1]);
    printf("default: %lf + %lf = %lf\n", dbls[0], dbls[1], dbls[2]);
fpucw = get_fpu();

    set_fpu(0x7f); //changing exceptions
    /* add the same numbers as earlier to see difference */
    dblx[2] = fpu_div(dblx[0], dblx[1]);
    printf("dividing: %lf / %lf = %lf\n", dblx[0], dblx[1], dblx[2]);

    /* print FPU control word */
    fpucw = get_fpu();
    printf("FPU CW: %04hx\n", fpucw);

    /* Return 0 if exiting normally.
     */
    return 0;
}