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#include "libm.h" // for FORCE_EVAL
#include <float.h> // for DBL_EPSILON, FLT_EVAL_METHOD
#include <math.h> // for double_t, round
#include <stdint.h> // for uint64_t
#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 round(double x)
{
union {
double f;
uint64_t i;
} u = { x };
int e = u.i >> 52 & 0x7ff;
double_t y;
if (e >= 0x3ff + 52)
return x;
if (u.i >> 63)
x = -x;
if (e < 0x3ff - 1) {
/* raise inexact if x!=0 */
FORCE_EVAL(x + toint);
return 0 * u.f;
}
y = x + toint - toint - x;
if (y > 0.5)
y = y + x - 1;
else if (y <= -0.5)
y = y + x + 1;
else
y = y + x;
if (u.i >> 63)
y = -y;
return y;
}
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