1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License, Version 1.0 only
6 * (the "License"). You may not use this file except in compliance
7 * with the License.
8 *
9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10 * or http://www.opensolaris.org/os/licensing.
11 * See the License for the specific language governing permissions
12 * and limitations under the License.
13 *
14 * When distributing Covered Code, include this CDDL HEADER in each
15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16 * If applicable, add the following below this CDDL HEADER, with the
17 * fields enclosed by brackets "[]" replaced with your own identifying
18 * information: Portions Copyright [yyyy] [name of copyright owner]
19 *
20 * CDDL HEADER END
21 */
22 /*
23 * Copyright 2003 Sun Microsystems, Inc. All rights reserved.
24 * Use is subject to license terms.
25 */
26
27 #if !defined(sparc) && !defined(__sparc)
28 #error This code is for SPARC only
29 #endif
30
31 /*
32 * _Q_scl(x, n) sets *x = *x * 2^n.
33 *
34 * This routine tacitly assumes the result will be either zero
35 * or normal, so there is no need to raise any exceptions.
36 */
37 void
_Q_scl(long double * x,int n)38 _Q_scl(long double *x, int n)
39 {
40 union {
41 unsigned int i[4];
42 long double q;
43 } xx;
44 int hx;
45
46 xx.q = *x;
47 hx = xx.i[0] & ~0x80000000;
48
49 if (hx < 0x10000) { /* x is zero or subnormal */
50 if ((hx | xx.i[1] | xx.i[2] | xx.i[3]) == 0)
51 return;
52
53 /* normalize x */
54 while (hx == 0 && xx.i[1] < 0x10000) {
55 hx = xx.i[1];
56 xx.i[1] = xx.i[2];
57 xx.i[2] = xx.i[3];
58 xx.i[3] = 0;
59 n -= 32;
60 }
61 while (hx < 0x10000) {
62 hx = (hx << 1) | (xx.i[1] >> 31);
63 xx.i[1] = (xx.i[1] << 1) | (xx.i[2] >> 31);
64 xx.i[2] = (xx.i[2] << 1) | (xx.i[3] >> 31);
65 xx.i[3] <<= 1;
66 n--;
67 }
68 xx.i[0] = hx | (xx.i[0] & 0x80000000);
69 }
70
71 if ((hx >> 16) + n < 1) {
72 /* for subnormal result, just deliver zero */
73 xx.i[0] = xx.i[0] & 0x80000000;
74 xx.i[1] = xx.i[2] = xx.i[3] = 0;
75 } else
76 xx.i[0] += (n << 16);
77 *x = xx.q;
78 }
79
80 static const union {
81 int i[4];
82 long double q;
83 } consts[2] = {
84 { 0x7ffe0000, 0, 0, 0 },
85 { 0x00010000, 0, 0, 0 }
86 };
87
88 /*
89 * _Q_scle(x, n) sets *x = *x * 2^n, raising overflow or underflow
90 * as appropriate.
91 *
92 * This routine tacitly assumes the argument is either zero or normal.
93 */
94 void
_Q_scle(long double * x,int n)95 _Q_scle(long double *x, int n)
96 {
97 union {
98 unsigned int i[4];
99 long double q;
100 } xx;
101 int hx;
102
103 xx.q = *x;
104 hx = (xx.i[0] >> 16) & 0x7fff;
105
106 if (hx == 0) /* x must be zero */
107 return;
108
109 hx += n;
110 if (hx >= 0x7fff) { /* overflow */
111 xx.i[0] = 0x7ffe0000 | (xx.i[0] & 0x80000000);
112 xx.i[1] = xx.i[2] = xx.i[3] = 0;
113 xx.q *= consts[0].q;
114 } else if (hx < 1) { /* possible underflow */
115 if (hx < -112) {
116 xx.i[0] = 0x00010000 | (xx.i[0] & 0x80000000);
117 xx.i[1] = xx.i[2] = xx.i[3] = 0;
118 } else {
119 xx.i[0] = (0x3ffe0000 + (hx << 16)) |
120 (xx.i[0] & 0x8000ffff);
121 }
122 xx.q *= consts[1].q;
123 } else
124 xx.i[0] += (n << 16);
125
126 *x = xx.q;
127 }
128