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 frexp = __frexp
31*25c28e83SPiotr Jasiukajtis
32*25c28e83SPiotr Jasiukajtis /*
33*25c28e83SPiotr Jasiukajtis * frexp(x, exp) returns the normalized significand of x and sets
34*25c28e83SPiotr Jasiukajtis * *exp so that x = r*2^(*exp) where r is the return value. If x
35*25c28e83SPiotr Jasiukajtis * is finite and nonzero, 1/2 <= |r| < 1.
36*25c28e83SPiotr Jasiukajtis *
37*25c28e83SPiotr Jasiukajtis * If x is zero, infinite or NaN, frexp returns x and sets *exp = 0.
38*25c28e83SPiotr Jasiukajtis * (The relevant standards do not specify *exp when x is infinite or
39*25c28e83SPiotr Jasiukajtis * NaN, but this code sets it anyway.)
40*25c28e83SPiotr Jasiukajtis *
41*25c28e83SPiotr Jasiukajtis * If x is a signaling NaN, this code returns x without attempting
42*25c28e83SPiotr Jasiukajtis * to raise the invalid operation exception. If x is subnormal,
43*25c28e83SPiotr Jasiukajtis * this code treats it as nonzero regardless of nonstandard mode.
44*25c28e83SPiotr Jasiukajtis */
45*25c28e83SPiotr Jasiukajtis
46*25c28e83SPiotr Jasiukajtis #include "libm.h"
47*25c28e83SPiotr Jasiukajtis
48*25c28e83SPiotr Jasiukajtis double
__frexp(double x,int * exp)49*25c28e83SPiotr Jasiukajtis __frexp(double x, int *exp) {
50*25c28e83SPiotr Jasiukajtis union {
51*25c28e83SPiotr Jasiukajtis unsigned i[2];
52*25c28e83SPiotr Jasiukajtis double d;
53*25c28e83SPiotr Jasiukajtis } xx, yy;
54*25c28e83SPiotr Jasiukajtis double t;
55*25c28e83SPiotr Jasiukajtis unsigned hx;
56*25c28e83SPiotr Jasiukajtis int e;
57*25c28e83SPiotr Jasiukajtis
58*25c28e83SPiotr Jasiukajtis xx.d = x;
59*25c28e83SPiotr Jasiukajtis hx = xx.i[HIWORD] & ~0x80000000;
60*25c28e83SPiotr Jasiukajtis
61*25c28e83SPiotr Jasiukajtis if (hx >= 0x7ff00000) { /* x is infinite or NaN */
62*25c28e83SPiotr Jasiukajtis *exp = 0;
63*25c28e83SPiotr Jasiukajtis return (x);
64*25c28e83SPiotr Jasiukajtis }
65*25c28e83SPiotr Jasiukajtis
66*25c28e83SPiotr Jasiukajtis e = 0;
67*25c28e83SPiotr Jasiukajtis if (hx < 0x00100000) { /* x is subnormal or zero */
68*25c28e83SPiotr Jasiukajtis if ((hx | xx.i[LOWORD]) == 0) {
69*25c28e83SPiotr Jasiukajtis *exp = 0;
70*25c28e83SPiotr Jasiukajtis return (x);
71*25c28e83SPiotr Jasiukajtis }
72*25c28e83SPiotr Jasiukajtis
73*25c28e83SPiotr Jasiukajtis /*
74*25c28e83SPiotr Jasiukajtis * normalize x by regarding it as an integer
75*25c28e83SPiotr Jasiukajtis *
76*25c28e83SPiotr Jasiukajtis * Here we use 32-bit integer arithmetic to avoid trapping
77*25c28e83SPiotr Jasiukajtis * or emulating 64-bit arithmetic. If 64-bit arithmetic is
78*25c28e83SPiotr Jasiukajtis * available (e.g., in SPARC V9), do this instead:
79*25c28e83SPiotr Jasiukajtis *
80*25c28e83SPiotr Jasiukajtis * long lx = ((long) hx << 32) | xx.i[LOWORD];
81*25c28e83SPiotr Jasiukajtis * xx.d = (xx.i[HIWORD] < 0)? -lx : lx;
82*25c28e83SPiotr Jasiukajtis *
83*25c28e83SPiotr Jasiukajtis * If subnormal arithmetic doesn't trap, just multiply x by
84*25c28e83SPiotr Jasiukajtis * a power of two.
85*25c28e83SPiotr Jasiukajtis */
86*25c28e83SPiotr Jasiukajtis yy.i[HIWORD] = 0x43300000 | hx;
87*25c28e83SPiotr Jasiukajtis yy.i[LOWORD] = xx.i[LOWORD];
88*25c28e83SPiotr Jasiukajtis t = yy.d;
89*25c28e83SPiotr Jasiukajtis yy.i[HIWORD] = 0x43300000;
90*25c28e83SPiotr Jasiukajtis yy.i[LOWORD] = 0;
91*25c28e83SPiotr Jasiukajtis t -= yy.d; /* t = |x| scaled */
92*25c28e83SPiotr Jasiukajtis xx.d = ((int)xx.i[HIWORD] < 0)? -t : t;
93*25c28e83SPiotr Jasiukajtis hx = xx.i[HIWORD] & ~0x80000000;
94*25c28e83SPiotr Jasiukajtis e = -1074;
95*25c28e83SPiotr Jasiukajtis }
96*25c28e83SPiotr Jasiukajtis
97*25c28e83SPiotr Jasiukajtis /* now xx.d is normal */
98*25c28e83SPiotr Jasiukajtis xx.i[HIWORD] = (xx.i[HIWORD] & ~0x7ff00000) | 0x3fe00000;
99*25c28e83SPiotr Jasiukajtis *exp = e + (hx >> 20) - 0x3fe;
100*25c28e83SPiotr Jasiukajtis return (xx.d);
101*25c28e83SPiotr Jasiukajtis }
102