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/* Small test program for probing how various math functions
* with specific operands set floating point exceptions
*/
#define _ISOC99_SOURCE 1
#define _GNU_SOURCE 1
#include <stdint.h>
#include <math.h>
#include <fenv.h>
#include <stdio.h>
int main(int argc, char **argv)
{
float largest, small, t, inf_float;
largest = small = 1;
while (1) {
t = largest + small;
/* optimizations may make plain "t == largest" unreliable */
if (memcmp(&t, &largest, sizeof(float)) == 0)
break;
if (isfinite(t)) {
largest = t;
small *= 2;
continue;
}
small /= 2;
}
inf_float = largest + largest;
//printf("%.40g ", largest);
//printf("[%llx]\n", (long long) (*(uint32_t *)&largest));
feclearexcept(FE_ALL_EXCEPT);
//t = 1.0 / 0.0; // simple test: FE_DIVBYZERO
//t = nextafterf(largest, 1); // glibc 2.8: no math exceptions raised
//t = nextafterf(largest, largest); // glibc 2.8: no math exceptions raised
//t = nextafterf(largest, inf_float); // glibc 2.8: FE_INEXACT FE_OVERFLOW
#define PREX(ex) do { if (fetestexcept(ex)) printf(#ex " "); } while(0)
#ifdef FE_INEXACT
PREX(FE_INEXACT);
#endif
#ifdef FE_DIVBYZERO
PREX(FE_DIVBYZERO);
#endif
#ifdef FE_UNDERFLOW
PREX(FE_UNDERFLOW);
#endif
#ifdef FE_OVERFLOW
PREX(FE_OVERFLOW);
#endif
#ifdef FE_INVALID
PREX(FE_INVALID);
#endif
if (fetestexcept(FE_ALL_EXCEPT))
printf("\n");
else
printf("no math exceptions raised\n");
printf("%.40g\n", t);
return 0;
}
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