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/* $OpenBSD: fpu.c,v 1.2 2020/10/19 08:50:35 kettenis Exp $ */
#include <err.h>
#include <fenv.h>
#include <stdlib.h>
int
main(int argc, char *argv[])
{
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);
/* Set the FPU exception flags. */
flag = FE_OVERFLOW;
rv = fesetexceptflag(&flag, FE_ALL_EXCEPT);
if (rv != 0)
errx(2, "fesetexceptflag returned %d", rv);
/* Schedule another process, to check if kernel preserves state. */
rv = system("true");
if (rv == -1)
err(2, "system");
if (rv != 0)
errx(2, "true: %d", rv);
/* 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__)
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);
}
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