1/* Adapted for use as nearbyint by Ulrich Drepper <drepper@cygnus.com>. */
2/*
3 * ====================================================
4 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
5 *
6 * Developed at SunPro, a Sun Microsystems, Inc. business.
7 * Permission to use, copy, modify, and distribute this
8 * software is freely granted, provided that this notice
9 * is preserved.
10 * ====================================================
11 */
12
13/*
14 * rint(x)
15 * Return x rounded to integral value according to the prevailing
16 * rounding mode.
17 * Method:
18 * Using floating addition.
19 * Exception:
20 * Inexact flag raised if x not equal to rint(x).
21 */
22
23#include <fenv.h>
24#include <math.h>
25#include <math_private.h>
26
27static const double
28TWO52[2]={
29 4.50359962737049600000e+15, /* 0x43300000, 0x00000000 */
30 -4.50359962737049600000e+15, /* 0xC3300000, 0x00000000 */
31};
32
33double
34__nearbyint(double x)
35{
36 fenv_t env;
37 int64_t i0,sx;
38 int32_t j0;
39 EXTRACT_WORDS64(i0,x);
40 sx = (i0>>63)&1;
41 j0 = ((i0>>52)&0x7ff)-0x3ff;
42 if(__builtin_expect(j0<52, 1)) {
43 if(j0<0) {
44 libc_feholdexcept (&env);
45 double w = TWO52[sx]+x;
46 double t = w-TWO52[sx];
47 math_opt_barrier(t);
48 libc_fesetenv (&env);
49 return __copysign (t, x);
50 }
51 } else {
52 if(j0==0x400) return x+x; /* inf or NaN */
53 else return x; /* x is integral */
54 }
55 libc_feholdexcept (&env);
56 double w = TWO52[sx]+x;
57 double t = w-TWO52[sx];
58 math_opt_barrier (t);
59 libc_fesetenv (&env);
60 return t;
61}
62weak_alias (__nearbyint, nearbyint)
63#ifdef NO_LONG_DOUBLE
64strong_alias (__nearbyint, __nearbyintl)
65weak_alias (__nearbyint, nearbyintl)
66#endif
67