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 #pragma ident "%Z%%M% %I% %E% SMI"
28
29 /*
30 * On SPARC V8, _Q_cplx_div_ix(v, b, w) sets *v = (I * *b / *w) with
31 * infinities handling according to C99.
32 *
33 * On SPARC V9, _Q_cplx_div_ix(b, w) returns (I * *b) / *w with in-
34 * finities handled according to C99.
35 *
36 * If b and w are both finite and w is nonzero, _Q_cplx_div_ix de-
37 * livers the complex quotient q according to the usual formula: let
38 * c = Re(w), and d = Im(w); then q = x + I * y where x = (b * d) / r
39 * and y = (-b * d) / r with r = c * c + d * d. This implementation
40 * scales to avoid premature underflow or overflow.
41 *
42 * If b is neither NaN nor zero and w is zero, or if b is infinite
43 * and w is finite and nonzero, _Q_cplx_div_ix delivers an infinite
44 * result. If b is finite and w is infinite, _Q_cplx_div_ix delivers
45 * a zero result.
46 *
47 * If b and w are both zero or both infinite, or if either b or w is
48 * NaN, _Q_cplx_div_ix delivers NaN + I * NaN. C99 doesn't specify
49 * these cases.
50 *
51 * This implementation can raise spurious underflow, overflow, in-
52 * valid operation, inexact, and division-by-zero exceptions. C99
53 * allows this.
54 */
55
56 #if !defined(sparc) && !defined(__sparc)
57 #error This code is for SPARC only
58 #endif
59
60 extern void _Q_scl(long double *, int);
61 extern void _Q_scle(long double *, int);
62
63 /*
64 * Return +1 if x is +Inf, -1 if x is -Inf, and 0 otherwise
65 */
66 static int
testinfl(long double x)67 testinfl(long double x)
68 {
69 union {
70 int i[4];
71 long double q;
72 } xx;
73
74 xx.q = x;
75 return (((((xx.i[0] << 1) - 0xfffe0000) | xx.i[1] | xx.i[2] | xx.i[3])
76 == 0)? (1 | (xx.i[0] >> 31)) : 0);
77 }
78
79 #ifdef __sparcv9
80 long double _Complex
_Q_cplx_div_ix(const long double * pb,const long double _Complex * w)81 _Q_cplx_div_ix(const long double *pb, const long double _Complex *w)
82 {
83 long double _Complex v;
84 #else
85 void
86 _Q_cplx_div_ix(long double _Complex *v, const long double *pb,
87 const long double _Complex *w)
88 {
89 #endif
90 union {
91 int i[4];
92 long double q;
93 } bb, cc, dd;
94 long double b, c, d, sc, sd, r;
95 int hb, hc, hd, hw, i, j;
96
97 b = *pb;
98
99 /*
100 * The following is equivalent to
101 *
102 * c = creall(*w); d = cimagl(*w);
103 */
104 c = ((long double *)w)[0];
105 d = ((long double *)w)[1];
106
107 /* extract high-order words to estimate |b| and |w| */
108 bb.q = b;
109 hb = bb.i[0] & ~0x80000000;
110
111 cc.q = c;
112 dd.q = d;
113 hc = cc.i[0] & ~0x80000000;
114 hd = dd.i[0] & ~0x80000000;
115 hw = (hc > hd)? hc : hd;
116
117 /* check for special cases */
118 if (hw >= 0x7fff0000) { /* w is inf or nan */
119 i = testinfl(c);
120 j = testinfl(d);
121 if (i | j) { /* w is infinite */
122 c = (cc.i[0] < 0)? -0.0l : 0.0l;
123 d = (dd.i[0] < 0)? -0.0l : 0.0l;
124 } else /* w is nan */
125 b += c + d;
126 c *= b;
127 d *= b;
128 goto done;
129 }
130
131 if (hw == 0 && (cc.i[1] | cc.i[2] | cc.i[3] |
132 dd.i[1] | dd.i[2] | dd.i[3]) == 0) {
133 /* w is zero; multiply b by 1/Re(w) - I * Im(w) */
134 c = 1.0l / c;
135 j = testinfl(b);
136 if (j) { /* b is infinite */
137 b = j;
138 }
139 c *= b;
140 d = (b == 0.0l)? c : b * d;
141 goto done;
142 }
143
144 if (hb >= 0x7fff0000) { /* a is inf or nan */
145 c *= b;
146 d *= b;
147 goto done;
148 }
149
150 /*
151 * Compute the real and imaginary parts of the quotient,
152 * scaling to avoid overflow or underflow.
153 */
154 hw = (hw - 0x3fff0000) >> 16;
155 sc = c;
156 sd = d;
157 _Q_scl(&sc, -hw);
158 _Q_scl(&sd, -hw);
159 r = sc * sc + sd * sd;
160
161 hb = (hb - 0x3fff0000) >> 16;
162 _Q_scl(&b, -hb);
163 b /= r;
164 hb -= (hw + hw);
165
166 hc = (hc - 0x3fff0000) >> 16;
167 _Q_scl(&c, -hc);
168 c *= b;
169 hc += hb;
170
171 hd = (hd - 0x3fff0000) >> 16;
172 _Q_scl(&d, -hd);
173 d *= b;
174 hd += hb;
175
176 /* compensate for scaling */
177 _Q_scle(&c, hc);
178 _Q_scle(&d, hd);
179
180 done:
181 #ifdef __sparcv9
182 ((long double *)&v)[0] = d;
183 ((long double *)&v)[1] = c;
184 return (v);
185 #else
186 ((long double *)v)[0] = d;
187 ((long double *)v)[1] = c;
188 #endif
189 }
190