/*      $OpenBSD: setjmp-fpu.c,v 1.7 2021/06/17 12:55:38 kettenis Exp $ */

#include <err.h>
#include <fenv.h>
#include <setjmp.h>

int
TEST_SETJMP(void)
{
        JMP_BUF env;
        fexcept_t flag;
        int rv;

        /* Set up the FPU control word register. */
        rv = fesetround(FE_UPWARD);
        if (rv != 0)
                errx(2, "fesetround FE_UPWARD returned %d", rv);
        fedisableexcept(FE_ALL_EXCEPT);
        feenableexcept(FE_DIVBYZERO);

        rv = SETJMP(env, 0);

        switch(rv) {
        case 0: {
                /* Mess with the FPU control word. */
                rv = fesetround(FE_DOWNWARD);
                if (rv != 0)
                        errx(2, "fesetround FE_DOWNWARD returned %d", rv);
                fedisableexcept(FE_DIVBYZERO);

                /* Set the FPU exception flags. */
                flag = FE_OVERFLOW;
                rv = fesetexceptflag(&flag, FE_ALL_EXCEPT);
                if (rv != 0)
                        errx(2, "fesetexceptflag returned %d", rv);

                LONGJMP(env, 1);
                errx(2, "longjmp returned");
        }
        case 1: {
                /* Verify that the FPU control word is preserved. */
                rv = fegetround();
                if (rv != FE_UPWARD)
                        errx(1, "fegetround returned %d, not FE_UPWARD", rv);
#if !defined(__arm__) && !defined(__aarch64__) && !defined(__riscv)
                rv = fegetexcept();
                if (rv != FE_DIVBYZERO)
                        errx(1, "fegetexcept returned %d, not FE_DIVBYZERO",
                            rv);
#endif

                /* Verify that the FPU exception flags weren't clobbered. */
                flag = 0;
                rv = fegetexceptflag(&flag, FE_ALL_EXCEPT);
                if (rv != 0)
                        errx(2, "fegetexceptflag returned %d", rv);
                if (flag != FE_OVERFLOW)
                        errx(1, "except flag is %d, no FE_OVERFLOW", rv);

                return (0);
        }
        default:
                errx(2, "setjmp returned %d", rv);
        }
}