/*      $OpenBSD: infinity.c,v 1.2 2004/01/16 19:34:37 miod Exp $       */
/*
 * Written by Miodrag Vallat, 2004 - Public Domain
 * Inspired from Perl's t/op/arith test #134
 */

#include <math.h>
#include <signal.h>
#include <unistd.h>

void
sigfpe(int signum)
{
        /* looks like we don't handle fp overflow correctly... */
        _exit(1);
}

int
main(int argc, char *argv[])
{
        int opt;
        double d, two;
        int i;
        char method = 'a';

        while ((opt = getopt(argc, argv, "amnp")) != -1)
                method = (char)opt;

        signal(SIGFPE, sigfpe);

        switch (method) {
        case 'a':
                /* try to produce +Inf through addition */
                d = 1.0;
                for (i = 2000; i != 0; i--) {
                        d = d + d;
                }
                /* result should be _positive_ infinity */
                if (!isinf(d) || copysign(1.0, d) < 0.0)
                        return (1);
                break;
        case 'm':
                /* try to produce +Inf through multiplication */
                d = 1.0;
                two = 2.0;
                for (i = 2000; i != 0; i--) {
                        d = d * two;
                }
                /* result should be _positive_ infinity */
                if (!isinf(d) || copysign(1.0, d) < 0.0)
                        return (1);
                break;
        case 'n':
                /* try to produce -Inf through subtraction */
                d = -1.0;
                for (i = 2000; i != 0; i--) {
                        d = d + d;
                }
                /* result should be _negative_ infinity */
                if (!isinf(d) || copysign(1.0, d) > 0.0)
                        return (1);
                break;
        case 'p':
                /* try to produce -Inf through multiplication */
                d = -1.0;
                two = 2.0;
                for (i = 2000; i != 0; i--) {
                        d = d * two;
                }
                /* result should be _negative_ infinity */
                if (!isinf(d) || copysign(1.0, d) > 0.0)
                        return (1);
                break;
        }

        return (0);
}