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 (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21 22 /* 23 * Copyright 2011 Nexenta Systems, Inc. All rights reserved. 24 */ 25 /* 26 * Copyright 2006 Sun Microsystems, Inc. All rights reserved. 27 * Use is subject to license terms. 28 */ 29 30 #pragma weak __exp2l = exp2l 31 32 #include "libm.h" 33 #include "longdouble.h" 34 35 /* 36 * exp2l(x) = 2**x = 2**((x-anint(x))+anint(x)) 37 * = 2**anint(x)*2**(x-anint(x)) 38 * = 2**anint(x)*exp((x-anint(x))*ln2) 39 */ 40 41 #define TINY 1.0e-20L /* single: 1e-5, double: 1e-10, quad: 1e-20 */ 42 #define OVFLEXP 16400 /* single: 130, double 1030, quad: 16400 */ 43 #define UNFLEXP -16520 /* single:-155, double -1080, quad:-16520 */ 44 45 static const long double 46 zero = 0.0L, 47 tiny = TINY * TINY, 48 half = 0.5L, 49 ln2 = 6.931471805599453094172321214581765680755e-0001L, 50 one = 1.0L; 51 52 static const int 53 ovflexp = OVFLEXP, 54 unflexp = UNFLEXP; 55 56 long double 57 exp2l(long double x) { 58 long double t; 59 60 if (!finitel(x)) { 61 if (isnanl(x) || x > zero) 62 return (x + x); 63 else 64 return (zero); 65 } 66 t = fabsl(x); 67 if (t < half) { 68 if (t < tiny) 69 return (one + x); 70 else 71 return (expl(ln2 * x)); 72 } 73 t = anintl(x); 74 if (t < ovflexp) { 75 if (t >= unflexp) 76 return (scalbnl(expl(ln2 * (x - t)), (int) t)); 77 else 78 return (scalbnl(one, unflexp)); /* underflow */ 79 } else 80 return (scalbnl(one, ovflexp)); /* overflow */ 81 } 82