1*25c28e83SPiotr Jasiukajtis /* 2*25c28e83SPiotr Jasiukajtis * CDDL HEADER START 3*25c28e83SPiotr Jasiukajtis * 4*25c28e83SPiotr Jasiukajtis * The contents of this file are subject to the terms of the 5*25c28e83SPiotr Jasiukajtis * Common Development and Distribution License (the "License"). 6*25c28e83SPiotr Jasiukajtis * You may not use this file except in compliance with the License. 7*25c28e83SPiotr Jasiukajtis * 8*25c28e83SPiotr Jasiukajtis * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9*25c28e83SPiotr Jasiukajtis * or http://www.opensolaris.org/os/licensing. 10*25c28e83SPiotr Jasiukajtis * See the License for the specific language governing permissions 11*25c28e83SPiotr Jasiukajtis * and limitations under the License. 12*25c28e83SPiotr Jasiukajtis * 13*25c28e83SPiotr Jasiukajtis * When distributing Covered Code, include this CDDL HEADER in each 14*25c28e83SPiotr Jasiukajtis * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15*25c28e83SPiotr Jasiukajtis * If applicable, add the following below this CDDL HEADER, with the 16*25c28e83SPiotr Jasiukajtis * fields enclosed by brackets "[]" replaced with your own identifying 17*25c28e83SPiotr Jasiukajtis * information: Portions Copyright [yyyy] [name of copyright owner] 18*25c28e83SPiotr Jasiukajtis * 19*25c28e83SPiotr Jasiukajtis * CDDL HEADER END 20*25c28e83SPiotr Jasiukajtis */ 21*25c28e83SPiotr Jasiukajtis 22*25c28e83SPiotr Jasiukajtis /* 23*25c28e83SPiotr Jasiukajtis * Copyright 2011 Nexenta Systems, Inc. All rights reserved. 24*25c28e83SPiotr Jasiukajtis */ 25*25c28e83SPiotr Jasiukajtis /* 26*25c28e83SPiotr Jasiukajtis * Copyright 2006 Sun Microsystems, Inc. All rights reserved. 27*25c28e83SPiotr Jasiukajtis * Use is subject to license terms. 28*25c28e83SPiotr Jasiukajtis */ 29*25c28e83SPiotr Jasiukajtis 30*25c28e83SPiotr Jasiukajtis #pragma weak frexp = __frexp 31*25c28e83SPiotr Jasiukajtis 32*25c28e83SPiotr Jasiukajtis /* 33*25c28e83SPiotr Jasiukajtis * frexp(x, exp) returns the normalized significand of x and sets 34*25c28e83SPiotr Jasiukajtis * *exp so that x = r*2^(*exp) where r is the return value. If x 35*25c28e83SPiotr Jasiukajtis * is finite and nonzero, 1/2 <= |r| < 1. 36*25c28e83SPiotr Jasiukajtis * 37*25c28e83SPiotr Jasiukajtis * If x is zero, infinite or NaN, frexp returns x and sets *exp = 0. 38*25c28e83SPiotr Jasiukajtis * (The relevant standards do not specify *exp when x is infinite or 39*25c28e83SPiotr Jasiukajtis * NaN, but this code sets it anyway.) 40*25c28e83SPiotr Jasiukajtis * 41*25c28e83SPiotr Jasiukajtis * If x is a signaling NaN, this code returns x without attempting 42*25c28e83SPiotr Jasiukajtis * to raise the invalid operation exception. If x is subnormal, 43*25c28e83SPiotr Jasiukajtis * this code treats it as nonzero regardless of nonstandard mode. 44*25c28e83SPiotr Jasiukajtis */ 45*25c28e83SPiotr Jasiukajtis 46*25c28e83SPiotr Jasiukajtis #include "libm.h" 47*25c28e83SPiotr Jasiukajtis 48*25c28e83SPiotr Jasiukajtis double 49*25c28e83SPiotr Jasiukajtis __frexp(double x, int *exp) { 50*25c28e83SPiotr Jasiukajtis union { 51*25c28e83SPiotr Jasiukajtis unsigned i[2]; 52*25c28e83SPiotr Jasiukajtis double d; 53*25c28e83SPiotr Jasiukajtis } xx, yy; 54*25c28e83SPiotr Jasiukajtis double t; 55*25c28e83SPiotr Jasiukajtis unsigned hx; 56*25c28e83SPiotr Jasiukajtis int e; 57*25c28e83SPiotr Jasiukajtis 58*25c28e83SPiotr Jasiukajtis xx.d = x; 59*25c28e83SPiotr Jasiukajtis hx = xx.i[HIWORD] & ~0x80000000; 60*25c28e83SPiotr Jasiukajtis 61*25c28e83SPiotr Jasiukajtis if (hx >= 0x7ff00000) { /* x is infinite or NaN */ 62*25c28e83SPiotr Jasiukajtis *exp = 0; 63*25c28e83SPiotr Jasiukajtis return (x); 64*25c28e83SPiotr Jasiukajtis } 65*25c28e83SPiotr Jasiukajtis 66*25c28e83SPiotr Jasiukajtis e = 0; 67*25c28e83SPiotr Jasiukajtis if (hx < 0x00100000) { /* x is subnormal or zero */ 68*25c28e83SPiotr Jasiukajtis if ((hx | xx.i[LOWORD]) == 0) { 69*25c28e83SPiotr Jasiukajtis *exp = 0; 70*25c28e83SPiotr Jasiukajtis return (x); 71*25c28e83SPiotr Jasiukajtis } 72*25c28e83SPiotr Jasiukajtis 73*25c28e83SPiotr Jasiukajtis /* 74*25c28e83SPiotr Jasiukajtis * normalize x by regarding it as an integer 75*25c28e83SPiotr Jasiukajtis * 76*25c28e83SPiotr Jasiukajtis * Here we use 32-bit integer arithmetic to avoid trapping 77*25c28e83SPiotr Jasiukajtis * or emulating 64-bit arithmetic. If 64-bit arithmetic is 78*25c28e83SPiotr Jasiukajtis * available (e.g., in SPARC V9), do this instead: 79*25c28e83SPiotr Jasiukajtis * 80*25c28e83SPiotr Jasiukajtis * long lx = ((long) hx << 32) | xx.i[LOWORD]; 81*25c28e83SPiotr Jasiukajtis * xx.d = (xx.i[HIWORD] < 0)? -lx : lx; 82*25c28e83SPiotr Jasiukajtis * 83*25c28e83SPiotr Jasiukajtis * If subnormal arithmetic doesn't trap, just multiply x by 84*25c28e83SPiotr Jasiukajtis * a power of two. 85*25c28e83SPiotr Jasiukajtis */ 86*25c28e83SPiotr Jasiukajtis yy.i[HIWORD] = 0x43300000 | hx; 87*25c28e83SPiotr Jasiukajtis yy.i[LOWORD] = xx.i[LOWORD]; 88*25c28e83SPiotr Jasiukajtis t = yy.d; 89*25c28e83SPiotr Jasiukajtis yy.i[HIWORD] = 0x43300000; 90*25c28e83SPiotr Jasiukajtis yy.i[LOWORD] = 0; 91*25c28e83SPiotr Jasiukajtis t -= yy.d; /* t = |x| scaled */ 92*25c28e83SPiotr Jasiukajtis xx.d = ((int)xx.i[HIWORD] < 0)? -t : t; 93*25c28e83SPiotr Jasiukajtis hx = xx.i[HIWORD] & ~0x80000000; 94*25c28e83SPiotr Jasiukajtis e = -1074; 95*25c28e83SPiotr Jasiukajtis } 96*25c28e83SPiotr Jasiukajtis 97*25c28e83SPiotr Jasiukajtis /* now xx.d is normal */ 98*25c28e83SPiotr Jasiukajtis xx.i[HIWORD] = (xx.i[HIWORD] & ~0x7ff00000) | 0x3fe00000; 99*25c28e83SPiotr Jasiukajtis *exp = e + (hx >> 20) - 0x3fe; 100*25c28e83SPiotr Jasiukajtis return (xx.d); 101*25c28e83SPiotr Jasiukajtis } 102