#include <float.h> | |
#include <math.h> | |
#include <stdint.h> | |
#if FLT_EVAL_METHOD == 0 || FLT_EVAL_METHOD == 1 | |
#define EPS DBL_EPSILON | |
#elif FLT_EVAL_METHOD == 2 | |
#define EPS LDBL_EPSILON | |
#endif | |
static const double_t toint = 1 / EPS; | |
double rint(double x) { | |
union { | |
double f; | |
uint64_t i; | |
} u = {x}; | |
int e = u.i >> 52 & 0x7ff; | |
int s = u.i >> 63; | |
double_t y; | |
if (e >= 0x3ff + 52) | |
return x; | |
if (s) | |
y = x - toint + toint; | |
else | |
y = x + toint - toint; | |
if (y == 0) | |
return s ? -0.0 : 0; | |
return y; | |
} |