/*      $OpenBSD: fpsig.c,v 1.4 2022/10/28 16:06:54 miod Exp $  */

/*
 * Public domain.  2005, Otto Moerbeek
 *
 * Try to check if fp registers are properly saved and restored while
 * calling a signal hander.  This is not supposed to catch all that
 * can go wrong, but trashed fp registers will typically get caught.
 */
 
#include <err.h>
#include <signal.h>
#include <unistd.h>
#include <sys/time.h>

#define LIMIT   11.1

volatile sig_atomic_t count;

volatile double g1;
volatile double g2;

void
handler(int signo)
{
        double a, b, c = 0.0;

        for (a = 0.0; a < LIMIT; a += 1.1)
                for (b = 0.0; b < LIMIT; b += 1.1)
                        c += a * a + b * b;

        if (signo) {
                g1 = c;
                count++;
        } else
                g2 = c;
}

int
main()
{
        struct itimerval it = {
                .it_interval =  { .tv_sec = 0, .tv_usec = 10000 },
                .it_value =  { .tv_sec = 0, .tv_usec = 10000 }
        };

        /* initialize global vars */
        handler(0);
        handler(1);

        signal(SIGALRM, handler);
        setitimer(ITIMER_REAL, &it, NULL);
        
        while (count < 10000) {
                handler(0);

                double a, b, h1 = g1, h2 = g2;

                for (a = 0.0; a < LIMIT; a += 1.1)
                        for (b = 0.0; b < LIMIT; b += 1.1)
                                h1 += a * a + b * b;
                for (a = 0.0; a < LIMIT; a += 1.1)
                        for (b = 0.0; b < LIMIT; b += 1.1)
                                h2 += a * a + b * b;

                if (h1 != h2)
                        errx(1, "%f %f", g1, g2);
        }
        return (0);
}