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 /*
28 * On SPARC V8, _Q_cplx_mul(v, z, w) sets *v = *z * *w with infinities
29 * handled according to C99.
30 *
31 * On SPARC V9, _Q_cplx_mul(z, w) returns *z * *w with infinities
32 * handled according to C99.
33 *
34 * If z and w are both finite, _Q_cplx_mul delivers the complex
35 * product according to the usual formula: let a = Re(z), b = Im(z),
36 * c = Re(w), and d = Im(w); then _Q_cplx_mul delivers x + I * y
37 * where x = a * c - b * d and y = a * d + b * c. Note that if both
38 * ac and bd overflow, then at least one of ad or bc must also over-
39 * flow, and vice versa, so that if one component of the product is
40 * NaN, the other is infinite. (Such a value is considered infinite
41 * according to C99.)
42 *
43 * If one of z or w is infinite and the other is either finite nonzero
44 * or infinite, _Q_cplx_mul delivers an infinite result. If one factor
45 * is infinite and the other is zero, _Q_cplx_mul delivers NaN + I * NaN.
46 * C99 doesn't specify the latter case.
47 *
48 * C99 also doesn't specify what should happen if either z or w is a
49 * complex NaN (i.e., neither finite nor infinite). This implementation
50 * delivers NaN + I * NaN in this case.
51 *
52 * This implementation can raise spurious underflow, overflow, invalid
53 * operation, and inexact exceptions. C99 allows this.
54 */
55
56 #if !defined(sparc) && !defined(__sparc)
57 #error This code is for SPARC only
58 #endif
59
60 static union {
61 int i[4];
62 long double q;
63 } inf = {
64 0x7fff0000, 0, 0, 0
65 };
66
67 /*
68 * Return +1 if x is +Inf, -1 if x is -Inf, and 0 otherwise
69 */
70 static int
testinfl(long double x)71 testinfl(long double x)
72 {
73 union {
74 int i[4];
75 long double q;
76 } xx;
77
78 xx.q = x;
79 return (((((xx.i[0] << 1) - 0xfffe0000) | xx.i[1] | xx.i[2] | xx.i[3])
80 == 0)? (1 | (xx.i[0] >> 31)) : 0);
81 }
82
83 #ifdef __sparcv9
84 long double _Complex
_Q_cplx_mul(const long double _Complex * z,const long double _Complex * w)85 _Q_cplx_mul(const long double _Complex *z, const long double _Complex *w)
86 {
87 long double _Complex v = 0;
88 #else
89 void
90 _Q_cplx_mul(long double _Complex *v, const long double _Complex *z,
91 const long double _Complex *w)
92 {
93 #endif
94 long double a, b, c, d, x, y;
95 int recalc, i, j;
96
97 /*
98 * The following is equivalent to
99 *
100 * a = creall(*z); b = cimagl(*z);
101 * c = creall(*w); d = cimagl(*w);
102 */
103 a = ((long double *)z)[0];
104 b = ((long double *)z)[1];
105 c = ((long double *)w)[0];
106 d = ((long double *)w)[1];
107
108 x = a * c - b * d;
109 y = a * d + b * c;
110
111 if (x != x && y != y) {
112 /*
113 * Both x and y are NaN, so z and w can't both be finite.
114 * If at least one of z or w is a complex NaN, and neither
115 * is infinite, then we might as well deliver NaN + I * NaN.
116 * So the only cases to check are when one of z or w is
117 * infinite.
118 */
119 recalc = 0;
120 i = testinfl(a);
121 j = testinfl(b);
122 if (i | j) { /* z is infinite */
123 /* "factor out" infinity */
124 a = i;
125 b = j;
126 recalc = 1;
127 }
128 i = testinfl(c);
129 j = testinfl(d);
130 if (i | j) { /* w is infinite */
131 /* "factor out" infinity */
132 c = i;
133 d = j;
134 recalc = 1;
135 }
136 if (recalc) {
137 x = inf.q * (a * c - b * d);
138 y = inf.q * (a * d + b * c);
139 }
140 }
141
142 #ifdef __sparcv9
143 ((long double *)&v)[0] = x;
144 ((long double *)&v)[1] = y;
145 return (v);
146 #else
147 ((long double *)v)[0] = x;
148 ((long double *)v)[1] = y;
149 #endif
150 }
151