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circuitpython/lib/libm_dbl/rint.c

29 lines
489 B

#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;
}