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 * _F_cplx_mul(z, w) returns z * w with infinities handled according 31 * to C99. 32 * 33 * If z and w are both finite, _F_cplx_mul(z, w) delivers the complex 34 * product according to the usual formula: let a = Re(z), b = Im(z), 35 * c = Re(w), and d = Im(w); then _F_cplx_mul(z, w) delivers x + I * y 36 * where x = a * c - b * d and y = a * d + b * c. This implementation 37 * uses double precision to form these expressions, so none of the 38 * intermediate products can overflow. 39 * 40 * If one of z or w is infinite and the other is either finite nonzero 41 * or infinite, _F_cplx_mul delivers an infinite result. If one factor 42 * is infinite and the other is zero, _F_cplx_mul delivers NaN + I * NaN. 43 * C99 doesn't specify the latter case. 44 * 45 * C99 also doesn't specify what should happen if either z or w is a 46 * complex NaN (i.e., neither finite nor infinite). This implementation 47 * delivers NaN + I * NaN in this case. 48 * 49 * This implementation can raise spurious invalid operation and inexact 50 * exceptions. C99 allows this. 51 */ 52 53 #if !defined(sparc) && !defined(__sparc) 54 #error This code is for SPARC only 55 #endif 56 57 static union { 58 int i[2]; 59 double d; 60 } inf = { 61 0x7ff00000, 0 62 }; 63 64 /* 65 * Return +1 if x is +Inf, -1 if x is -Inf, and 0 otherwise 66 */ 67 static int 68 testinff(float x) 69 { 70 union { 71 int i; 72 float f; 73 } xx; 74 75 xx.f = x; 76 return ((((xx.i << 1) - 0xff000000) == 0)? (1 | (xx.i >> 31)) : 0); 77 } 78 79 float _Complex 80 _F_cplx_mul(float _Complex z, float _Complex w) 81 { 82 float _Complex v; 83 float a, b, c, d; 84 double x, y; 85 int recalc, i, j; 86 87 /* 88 * The following is equivalent to 89 * 90 * a = crealf(z); b = cimagf(z); 91 * c = crealf(w); d = cimagf(w); 92 */ 93 a = ((float *)&z)[0]; 94 b = ((float *)&z)[1]; 95 c = ((float *)&w)[0]; 96 d = ((float *)&w)[1]; 97 98 x = (double)a * c - (double)b * d; 99 y = (double)a * d + (double)b * c; 100 101 if (x != x && y != y) { 102 /* 103 * Both x and y are NaN, so z and w can't both be finite. 104 * If at least one of z or w is a complex NaN, and neither 105 * is infinite, then we might as well deliver NaN + I * NaN. 106 * So the only cases to check are when one of z or w is 107 * infinite. 108 */ 109 recalc = 0; 110 i = testinff(a); 111 j = testinff(b); 112 if (i | j) { /* z is infinite */ 113 /* "factor out" infinity */ 114 a = i; 115 b = j; 116 recalc = 1; 117 } 118 i = testinff(c); 119 j = testinff(d); 120 if (i | j) { /* w is infinite */ 121 /* "factor out" infinity */ 122 c = i; 123 d = j; 124 recalc = 1; 125 } 126 if (recalc) { 127 x = inf.d * ((double)a * c - (double)b * d); 128 y = inf.d * ((double)a * d + (double)b * c); 129 } 130 } 131 132 /* 133 * The following is equivalent to 134 * 135 * return x + I * y; 136 */ 137 ((float *)&v)[0] = (float)x; 138 ((float *)&v)[1] = (float)y; 139 return (v); 140 } 141