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_mul(v, z, w) sets *v = *z * *w with infinities 31 * handled according to C99. 32 * 33 * On SPARC V9, _Q_cplx_mul(z, w) returns *z * *w with infinities 34 * handled according to C99. 35 * 36 * If z and w are both finite, _Q_cplx_mul delivers the complex 37 * product according to the usual formula: let a = Re(z), b = Im(z), 38 * c = Re(w), and d = Im(w); then _Q_cplx_mul delivers x + I * y 39 * where x = a * c - b * d and y = a * d + b * c. Note that if both 40 * ac and bd overflow, then at least one of ad or bc must also over- 41 * flow, and vice versa, so that if one component of the product is 42 * NaN, the other is infinite. (Such a value is considered infinite 43 * according to C99.) 44 * 45 * If one of z or w is infinite and the other is either finite nonzero 46 * or infinite, _Q_cplx_mul delivers an infinite result. If one factor 47 * is infinite and the other is zero, _Q_cplx_mul delivers NaN + I * NaN. 48 * C99 doesn't specify the latter case. 49 * 50 * C99 also doesn't specify what should happen if either z or w is a 51 * complex NaN (i.e., neither finite nor infinite). This implementation 52 * delivers NaN + I * NaN in this case. 53 * 54 * This implementation can raise spurious underflow, overflow, invalid 55 * operation, and inexact exceptions. C99 allows this. 56 */ 57 58 #if !defined(sparc) && !defined(__sparc) 59 #error This code is for SPARC only 60 #endif 61 62 static union { 63 int i[4]; 64 long double q; 65 } inf = { 66 0x7fff0000, 0, 0, 0 67 }; 68 69 /* 70 * Return +1 if x is +Inf, -1 if x is -Inf, and 0 otherwise 71 */ 72 static int 73 testinfl(long double x) 74 { 75 union { 76 int i[4]; 77 long double q; 78 } xx; 79 80 xx.q = x; 81 return (((((xx.i[0] << 1) - 0xfffe0000) | xx.i[1] | xx.i[2] | xx.i[3]) 82 == 0)? (1 | (xx.i[0] >> 31)) : 0); 83 } 84 85 #ifdef __sparcv9 86 long double _Complex 87 _Q_cplx_mul(const long double _Complex *z, const long double _Complex *w) 88 { 89 long double _Complex v; 90 #else 91 void 92 _Q_cplx_mul(long double _Complex *v, const long double _Complex *z, 93 const long double _Complex *w) 94 { 95 #endif 96 long double a, b, c, d, x, y; 97 int recalc, i, j; 98 99 /* 100 * The following is equivalent to 101 * 102 * a = creall(*z); b = cimagl(*z); 103 * c = creall(*w); d = cimagl(*w); 104 */ 105 a = ((long double *)z)[0]; 106 b = ((long double *)z)[1]; 107 c = ((long double *)w)[0]; 108 d = ((long double *)w)[1]; 109 110 x = a * c - b * d; 111 y = a * d + b * c; 112 113 if (x != x && y != y) { 114 /* 115 * Both x and y are NaN, so z and w can't both be finite. 116 * If at least one of z or w is a complex NaN, and neither 117 * is infinite, then we might as well deliver NaN + I * NaN. 118 * So the only cases to check are when one of z or w is 119 * infinite. 120 */ 121 recalc = 0; 122 i = testinfl(a); 123 j = testinfl(b); 124 if (i | j) { /* z is infinite */ 125 /* "factor out" infinity */ 126 a = i; 127 b = j; 128 recalc = 1; 129 } 130 i = testinfl(c); 131 j = testinfl(d); 132 if (i | j) { /* w is infinite */ 133 /* "factor out" infinity */ 134 c = i; 135 d = j; 136 recalc = 1; 137 } 138 if (recalc) { 139 x = inf.q * (a * c - b * d); 140 y = inf.q * (a * d + b * c); 141 } 142 } 143 144 #ifdef __sparcv9 145 ((long double *)&v)[0] = x; 146 ((long double *)&v)[1] = y; 147 return (v); 148 #else 149 ((long double *)v)[0] = x; 150 ((long double *)v)[1] = y; 151 #endif 152 } 153