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 <fenv.h>
23#include <math.h>
24#include <math-barriers.h>
25#include <math_private.h>
26#include <fenv_private.h>
27#include <libm-alias-double.h>
28#include <math-use-builtins.h>
29
30double
31__nearbyint (double x)
32{
33#if USE_NEARBYINT_BUILTIN
34 return __builtin_nearbyint (x);
35#else
36 /* Use generic implementation. */
37 static const double
38 TWO52[2] = {
39 4.50359962737049600000e+15, /* 0x43300000, 0x00000000 */
40 -4.50359962737049600000e+15, /* 0xC3300000, 0x00000000 */
41 };
42 fenv_t env;
43 int64_t i0, sx;
44 int32_t j0;
45 EXTRACT_WORDS64 (i0, x);
46 sx = (i0 >> 63) & 1;
47 j0 = ((i0 >> 52) & 0x7ff) - 0x3ff;
48 if (__glibc_likely (j0 < 52))
49 {
50 if (j0 < 0)
51 {
52 libc_feholdexcept (&env);
53 double w = TWO52[sx] + math_opt_barrier (x);
54 double t = w - TWO52[sx];
55 math_force_eval (t);
56 libc_fesetenv (&env);
57 return copysign (t, x);
58 }
59 }
60 else
61 {
62 if (j0 == 0x400)
63 return x + x; /* inf or NaN */
64 else
65 return x; /* x is integral */
66 }
67 libc_feholdexcept (&env);
68 double w = TWO52[sx] + math_opt_barrier (x);
69 double t = w - TWO52[sx];
70 math_force_eval (t);
71 libc_fesetenv (&env);
72 return t;
73#endif /* ! USE_NEARBYINT_BUILTIN */
74}
75libm_alias_double (__nearbyint, nearbyint)
76