1*25c28e83SPiotr Jasiukajtis /*
2*25c28e83SPiotr Jasiukajtis * CDDL HEADER START
3*25c28e83SPiotr Jasiukajtis *
4*25c28e83SPiotr Jasiukajtis * The contents of this file are subject to the terms of the
5*25c28e83SPiotr Jasiukajtis * Common Development and Distribution License (the "License").
6*25c28e83SPiotr Jasiukajtis * You may not use this file except in compliance with the License.
7*25c28e83SPiotr Jasiukajtis *
8*25c28e83SPiotr Jasiukajtis * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9*25c28e83SPiotr Jasiukajtis * or http://www.opensolaris.org/os/licensing.
10*25c28e83SPiotr Jasiukajtis * See the License for the specific language governing permissions
11*25c28e83SPiotr Jasiukajtis * and limitations under the License.
12*25c28e83SPiotr Jasiukajtis *
13*25c28e83SPiotr Jasiukajtis * When distributing Covered Code, include this CDDL HEADER in each
14*25c28e83SPiotr Jasiukajtis * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15*25c28e83SPiotr Jasiukajtis * If applicable, add the following below this CDDL HEADER, with the
16*25c28e83SPiotr Jasiukajtis * fields enclosed by brackets "[]" replaced with your own identifying
17*25c28e83SPiotr Jasiukajtis * information: Portions Copyright [yyyy] [name of copyright owner]
18*25c28e83SPiotr Jasiukajtis *
19*25c28e83SPiotr Jasiukajtis * CDDL HEADER END
20*25c28e83SPiotr Jasiukajtis */
21*25c28e83SPiotr Jasiukajtis
22*25c28e83SPiotr Jasiukajtis /*
23*25c28e83SPiotr Jasiukajtis * Copyright 2011 Nexenta Systems, Inc. All rights reserved.
24*25c28e83SPiotr Jasiukajtis */
25*25c28e83SPiotr Jasiukajtis /*
26*25c28e83SPiotr Jasiukajtis * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
27*25c28e83SPiotr Jasiukajtis * Use is subject to license terms.
28*25c28e83SPiotr Jasiukajtis */
29*25c28e83SPiotr Jasiukajtis
30*25c28e83SPiotr Jasiukajtis #pragma weak nearbyint = __nearbyint
31*25c28e83SPiotr Jasiukajtis
32*25c28e83SPiotr Jasiukajtis /*
33*25c28e83SPiotr Jasiukajtis * nearbyint(x) returns the nearest fp integer to x in the direction
34*25c28e83SPiotr Jasiukajtis * corresponding to the current rounding direction without raising
35*25c28e83SPiotr Jasiukajtis * the inexact exception.
36*25c28e83SPiotr Jasiukajtis *
37*25c28e83SPiotr Jasiukajtis * nearbyint(x) is x unchanged if x is +/-0 or +/-inf. If x is NaN,
38*25c28e83SPiotr Jasiukajtis * nearbyint(x) is also NaN.
39*25c28e83SPiotr Jasiukajtis */
40*25c28e83SPiotr Jasiukajtis
41*25c28e83SPiotr Jasiukajtis #include "libm.h"
42*25c28e83SPiotr Jasiukajtis #include <fenv.h>
43*25c28e83SPiotr Jasiukajtis
44*25c28e83SPiotr Jasiukajtis double
__nearbyint(double x)45*25c28e83SPiotr Jasiukajtis __nearbyint(double x) {
46*25c28e83SPiotr Jasiukajtis union {
47*25c28e83SPiotr Jasiukajtis unsigned i[2];
48*25c28e83SPiotr Jasiukajtis double d;
49*25c28e83SPiotr Jasiukajtis } xx;
50*25c28e83SPiotr Jasiukajtis unsigned hx, sx, i, frac;
51*25c28e83SPiotr Jasiukajtis int rm, j;
52*25c28e83SPiotr Jasiukajtis
53*25c28e83SPiotr Jasiukajtis xx.d = x;
54*25c28e83SPiotr Jasiukajtis sx = xx.i[HIWORD] & 0x80000000;
55*25c28e83SPiotr Jasiukajtis hx = xx.i[HIWORD] & ~0x80000000;
56*25c28e83SPiotr Jasiukajtis
57*25c28e83SPiotr Jasiukajtis /* handle trivial cases */
58*25c28e83SPiotr Jasiukajtis if (hx >= 0x43300000) { /* x is nan, inf, or already integral */
59*25c28e83SPiotr Jasiukajtis if (hx >= 0x7ff00000) /* x is inf or nan */
60*25c28e83SPiotr Jasiukajtis #if defined(FPADD_TRAPS_INCOMPLETE_ON_NAN)
61*25c28e83SPiotr Jasiukajtis return (hx >= 0x7ff80000 ? x : x + x);
62*25c28e83SPiotr Jasiukajtis /* assumes sparc-like QNaN */
63*25c28e83SPiotr Jasiukajtis #else
64*25c28e83SPiotr Jasiukajtis return (x + x);
65*25c28e83SPiotr Jasiukajtis #endif
66*25c28e83SPiotr Jasiukajtis return (x);
67*25c28e83SPiotr Jasiukajtis } else if ((hx | xx.i[LOWORD]) == 0) /* x is zero */
68*25c28e83SPiotr Jasiukajtis return (x);
69*25c28e83SPiotr Jasiukajtis
70*25c28e83SPiotr Jasiukajtis /* get the rounding mode */
71*25c28e83SPiotr Jasiukajtis rm = fegetround();
72*25c28e83SPiotr Jasiukajtis
73*25c28e83SPiotr Jasiukajtis /* flip the sense of directed roundings if x is negative */
74*25c28e83SPiotr Jasiukajtis if (sx && (rm == FE_UPWARD || rm == FE_DOWNWARD))
75*25c28e83SPiotr Jasiukajtis rm = (FE_UPWARD + FE_DOWNWARD) - rm;
76*25c28e83SPiotr Jasiukajtis
77*25c28e83SPiotr Jasiukajtis /* handle |x| < 1 */
78*25c28e83SPiotr Jasiukajtis if (hx < 0x3ff00000) {
79*25c28e83SPiotr Jasiukajtis if (rm == FE_UPWARD || (rm == FE_TONEAREST &&
80*25c28e83SPiotr Jasiukajtis (hx >= 0x3fe00000 && ((hx & 0xfffff) | xx.i[LOWORD]))))
81*25c28e83SPiotr Jasiukajtis xx.i[HIWORD] = sx | 0x3ff00000;
82*25c28e83SPiotr Jasiukajtis else
83*25c28e83SPiotr Jasiukajtis xx.i[HIWORD] = sx;
84*25c28e83SPiotr Jasiukajtis xx.i[LOWORD] = 0;
85*25c28e83SPiotr Jasiukajtis return (xx.d);
86*25c28e83SPiotr Jasiukajtis }
87*25c28e83SPiotr Jasiukajtis
88*25c28e83SPiotr Jasiukajtis /* round x at the integer bit */
89*25c28e83SPiotr Jasiukajtis j = 0x433 - (hx >> 20);
90*25c28e83SPiotr Jasiukajtis if (j >= 32) {
91*25c28e83SPiotr Jasiukajtis i = 1 << (j - 32);
92*25c28e83SPiotr Jasiukajtis frac = ((xx.i[HIWORD] << 1) << (63 - j)) |
93*25c28e83SPiotr Jasiukajtis (xx.i[LOWORD] >> (j - 32));
94*25c28e83SPiotr Jasiukajtis if (xx.i[LOWORD] & (i - 1))
95*25c28e83SPiotr Jasiukajtis frac |= 1;
96*25c28e83SPiotr Jasiukajtis if (!frac)
97*25c28e83SPiotr Jasiukajtis return (x);
98*25c28e83SPiotr Jasiukajtis xx.i[LOWORD] = 0;
99*25c28e83SPiotr Jasiukajtis xx.i[HIWORD] &= ~(i - 1);
100*25c28e83SPiotr Jasiukajtis if ((rm == FE_UPWARD) || ((rm == FE_TONEAREST) &&
101*25c28e83SPiotr Jasiukajtis ((frac > 0x80000000u) || ((frac == 0x80000000) &&
102*25c28e83SPiotr Jasiukajtis (xx.i[HIWORD] & i)))))
103*25c28e83SPiotr Jasiukajtis xx.i[HIWORD] += i;
104*25c28e83SPiotr Jasiukajtis } else {
105*25c28e83SPiotr Jasiukajtis i = 1 << j;
106*25c28e83SPiotr Jasiukajtis frac = (xx.i[LOWORD] << 1) << (31 - j);
107*25c28e83SPiotr Jasiukajtis if (!frac)
108*25c28e83SPiotr Jasiukajtis return (x);
109*25c28e83SPiotr Jasiukajtis xx.i[LOWORD] &= ~(i - 1);
110*25c28e83SPiotr Jasiukajtis if ((rm == FE_UPWARD) || ((rm == FE_TONEAREST) &&
111*25c28e83SPiotr Jasiukajtis (frac > 0x80000000u || ((frac == 0x80000000) &&
112*25c28e83SPiotr Jasiukajtis (xx.i[LOWORD] & i))))) {
113*25c28e83SPiotr Jasiukajtis xx.i[LOWORD] += i;
114*25c28e83SPiotr Jasiukajtis if (xx.i[LOWORD] == 0)
115*25c28e83SPiotr Jasiukajtis xx.i[HIWORD]++;
116*25c28e83SPiotr Jasiukajtis }
117*25c28e83SPiotr Jasiukajtis }
118*25c28e83SPiotr Jasiukajtis return (xx.d);
119*25c28e83SPiotr Jasiukajtis }
120