1/*
2 * ====================================================
3 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
4 *
5 * Developed at SunPro, a Sun Microsystems, Inc. business.
6 * Permission to use, copy, modify, and distribute this
7 * software is freely granted, provided that this notice
8 * is preserved.
9 * ====================================================
10 */
11
12/*
13 * rint(x)
14 * Return x rounded to integral value according to the prevailing
15 * rounding mode.
16 * Method:
17 * Using floating addition.
18 * Exception:
19 * Inexact flag raised if x not equal to rint(x).
20 */
21
22#include <math.h>
23#include <math_private.h>
24#include <libm-alias-double.h>
25
26static const double
27TWO52[2]={
28 4.50359962737049600000e+15, /* 0x43300000, 0x00000000 */
29 -4.50359962737049600000e+15, /* 0xC3300000, 0x00000000 */
30};
31
32double
33__rint(double x)
34{
35 int64_t i0,sx;
36 int32_t j0;
37 EXTRACT_WORDS64(i0,x);
38 sx = (i0>>63)&1;
39 j0 = ((i0>>52)&0x7ff)-0x3ff;
40 if(j0<52) {
41 if(j0<0) {
42 double w = TWO52[sx]+x;
43 double t = w-TWO52[sx];
44 EXTRACT_WORDS64(i0,t);
45 INSERT_WORDS64(t,(i0&UINT64_C(0x7fffffffffffffff))|(sx<<63));
46 return t;
47 }
48 } else {
49 if(j0==0x400) return x+x; /* inf or NaN */
50 else return x; /* x is integral */
51 }
52 double w = TWO52[sx]+x;
53 return w-TWO52[sx];
54}
55#ifndef __rint
56libm_alias_double (__rint, rint)
57#endif
58