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-barriers.h>
26#include <math_private.h>
27#include <fenv_private.h>
28#include <libm-alias-double.h>
29
30static const double
31TWO52[2]={
32 4.50359962737049600000e+15, /* 0x43300000, 0x00000000 */
33 -4.50359962737049600000e+15, /* 0xC3300000, 0x00000000 */
34};
35
36double
37__nearbyint(double x)
38{
39 fenv_t env;
40 int64_t i0,sx;
41 int32_t j0;
42 EXTRACT_WORDS64(i0,x);
43 sx = (i0>>63)&1;
44 j0 = ((i0>>52)&0x7ff)-0x3ff;
45 if(__builtin_expect(j0<52, 1)) {
46 if(j0<0) {
47 libc_feholdexcept (&env);
48 double w = TWO52[sx] + math_opt_barrier (x);
49 double t = w-TWO52[sx];
50 math_force_eval (t);
51 libc_fesetenv (&env);
52 return copysign (t, x);
53 }
54 } else {
55 if(j0==0x400) return x+x; /* inf or NaN */
56 else return x; /* x is integral */
57 }
58 libc_feholdexcept (&env);
59 double w = TWO52[sx] + math_opt_barrier (x);
60 double t = w-TWO52[sx];
61 math_force_eval (t);
62 libc_fesetenv (&env);
63 return t;
64}
65libm_alias_double (__nearbyint, nearbyint)
66