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#include <assert.h>
#include <stdbool.h>
#include <fenv.h>
#include <float.h>
#include <math.h>
#define NO_OPTIMIZE(x) asm volatile("" :: "r,m" (x) : "memory")
static void div_by_zero() {
volatile float zero = 0.0f;
NO_OPTIMIZE(69.0f / zero);
}
static bool float_cmp(float a, float b) {
return a == b || fabs(a - b) < (fabs(a) + fabs(b)) * FLT_EPSILON;
}
static void test_rounding(float expectation1, float expectation2) {
float x;
volatile float f = 1.968750f;
volatile float m = 0x1.0p23f;
NO_OPTIMIZE(x = f + m);
assert(float_cmp(expectation1, x));
NO_OPTIMIZE(x = x - m);
assert(x == expectation2);
}
void test0() {
// test whether the divide-by-zero exception is raised
feclearexcept(FE_ALL_EXCEPT);
assert(fetestexcept(FE_ALL_EXCEPT) == 0);
div_by_zero();
int raised = fetestexcept(FE_DIVBYZERO);
assert((raised & FE_DIVBYZERO));
}
void test1() {
// test various rounding modes
feclearexcept(FE_DIVBYZERO);
assert(fetestexcept(FE_ALL_EXCEPT) == 0);
fesetround(FE_UPWARD);
assert(fegetround() == FE_UPWARD);
test_rounding(8388610.0f, 2.0f);
fesetround(FE_DOWNWARD);
assert(fegetround() == FE_DOWNWARD);
test_rounding(8388609.0f, 1.0f);
fesetround(FE_TONEAREST);
assert(fegetround() == FE_TONEAREST);
test_rounding(8388610.0f, 2.0f);
fesetround(FE_TOWARDZERO);
assert(fegetround() == FE_TOWARDZERO);
test_rounding(8388609.0f, 1.0f);
}
void test2() {
// test feraiseexcept
feclearexcept(FE_ALL_EXCEPT);
assert(fetestexcept(FE_ALL_EXCEPT) == 0);
assert(feraiseexcept(FE_DIVBYZERO | FE_OVERFLOW) == 0);
assert(fetestexcept(FE_ALL_EXCEPT) == (FE_DIVBYZERO | FE_OVERFLOW));
}
void test3() {
// test fe{get,set}env
feclearexcept(FE_ALL_EXCEPT);
assert(fetestexcept(FE_ALL_EXCEPT) == 0);
assert(feraiseexcept(FE_OVERFLOW) == 0);
fenv_t state;
assert(fegetenv(&state) == 0);
assert(fetestexcept(FE_ALL_EXCEPT) == FE_OVERFLOW);
div_by_zero();
assert(fetestexcept(FE_ALL_EXCEPT) == (FE_DIVBYZERO | FE_OVERFLOW));
assert(fesetenv(&state) == 0);
assert(fetestexcept(FE_ALL_EXCEPT) == FE_OVERFLOW);
}
int main() {
test0();
test1();
test2();
test3();
}
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