36 lines
597 B
C
36 lines
597 B
C
|
#include "libm.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 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;
|
||
|
|
}
|