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 * Copyright 2011 Nexenta Systems, Inc. All rights reserved. 23*25c28e83SPiotr Jasiukajtis */ 24*25c28e83SPiotr Jasiukajtis /* 25*25c28e83SPiotr Jasiukajtis * Copyright 2006 Sun Microsystems, Inc. All rights reserved. 26*25c28e83SPiotr Jasiukajtis * Use is subject to license terms. 27*25c28e83SPiotr Jasiukajtis */ 28*25c28e83SPiotr Jasiukajtis 29*25c28e83SPiotr Jasiukajtis #pragma weak exp2 = __exp2 30*25c28e83SPiotr Jasiukajtis 31*25c28e83SPiotr Jasiukajtis /* INDENT OFF */ 32*25c28e83SPiotr Jasiukajtis /* 33*25c28e83SPiotr Jasiukajtis * exp2(x) 34*25c28e83SPiotr Jasiukajtis * Code by K.C. Ng for SUN 4.0 libm. 35*25c28e83SPiotr Jasiukajtis * Method : 36*25c28e83SPiotr Jasiukajtis * exp2(x) = 2**x = 2**((x-anint(x))+anint(x)) 37*25c28e83SPiotr Jasiukajtis * = 2**anint(x)*2**(x-anint(x)) 38*25c28e83SPiotr Jasiukajtis * = 2**anint(x)*exp((x-anint(x))*ln2) 39*25c28e83SPiotr Jasiukajtis */ 40*25c28e83SPiotr Jasiukajtis /* INDENT ON */ 41*25c28e83SPiotr Jasiukajtis 42*25c28e83SPiotr Jasiukajtis #include "libm.h" 43*25c28e83SPiotr Jasiukajtis 44*25c28e83SPiotr Jasiukajtis static const double C[] = { 45*25c28e83SPiotr Jasiukajtis 0.0, 46*25c28e83SPiotr Jasiukajtis 1.0, 47*25c28e83SPiotr Jasiukajtis 0.5, 48*25c28e83SPiotr Jasiukajtis 6.93147180559945286227e-01, 49*25c28e83SPiotr Jasiukajtis 1.0e300, 50*25c28e83SPiotr Jasiukajtis 1.0e-300, 51*25c28e83SPiotr Jasiukajtis }; 52*25c28e83SPiotr Jasiukajtis 53*25c28e83SPiotr Jasiukajtis #define zero C[0] 54*25c28e83SPiotr Jasiukajtis #define one C[1] 55*25c28e83SPiotr Jasiukajtis #define half C[2] 56*25c28e83SPiotr Jasiukajtis #define ln2 C[3] 57*25c28e83SPiotr Jasiukajtis #define huge C[4] 58*25c28e83SPiotr Jasiukajtis #define tiny C[5] 59*25c28e83SPiotr Jasiukajtis 60*25c28e83SPiotr Jasiukajtis double 61*25c28e83SPiotr Jasiukajtis exp2(double x) { 62*25c28e83SPiotr Jasiukajtis int ix, hx, k; 63*25c28e83SPiotr Jasiukajtis double t; 64*25c28e83SPiotr Jasiukajtis 65*25c28e83SPiotr Jasiukajtis ix = ((int *)&x)[HIWORD]; 66*25c28e83SPiotr Jasiukajtis hx = ix & ~0x80000000; 67*25c28e83SPiotr Jasiukajtis 68*25c28e83SPiotr Jasiukajtis if (hx >= 0x4090e000) { /* |x| >= 1080 or x is nan */ 69*25c28e83SPiotr Jasiukajtis if (hx >= 0x7ff00000) { /* x is inf or nan */ 70*25c28e83SPiotr Jasiukajtis if (ix == 0xfff00000 && ((int *)&x)[LOWORD] == 0) 71*25c28e83SPiotr Jasiukajtis return (zero); 72*25c28e83SPiotr Jasiukajtis return (x * x); 73*25c28e83SPiotr Jasiukajtis } 74*25c28e83SPiotr Jasiukajtis t = (ix < 0)? tiny : huge; 75*25c28e83SPiotr Jasiukajtis return (t * t); 76*25c28e83SPiotr Jasiukajtis } 77*25c28e83SPiotr Jasiukajtis 78*25c28e83SPiotr Jasiukajtis if (hx < 0x3fe00000) { /* |x| < 0.5 */ 79*25c28e83SPiotr Jasiukajtis if (hx < 0x3c000000) 80*25c28e83SPiotr Jasiukajtis return (one + x); 81*25c28e83SPiotr Jasiukajtis return (exp(ln2 * x)); 82*25c28e83SPiotr Jasiukajtis } 83*25c28e83SPiotr Jasiukajtis 84*25c28e83SPiotr Jasiukajtis k = (int)x; 85*25c28e83SPiotr Jasiukajtis if (x != (double)k) 86*25c28e83SPiotr Jasiukajtis k = (int)((ix < 0)? x - half : x + half); 87*25c28e83SPiotr Jasiukajtis return (scalbn(exp(ln2 * (x - (double)k)), k)); 88*25c28e83SPiotr Jasiukajtis } 89