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 * Copyright 2011 Nexenta Systems, Inc. All rights reserved. 23 */ 24 /* 25 * Copyright 2006 Sun Microsystems, Inc. All rights reserved. 26 * Use is subject to license terms. 27 */ 28 29 #pragma weak exp10 = __exp10 30 31 /* INDENT OFF */ 32 /* 33 * exp10(x) 34 * Code by K.C. Ng for SUN 4.0 libm. 35 * Method : 36 * n = nint(x*(log10/log2)); 37 * exp10(x) = 10**x = exp(x*ln(10)) = exp(n*ln2+(x*ln10-n*ln2)) 38 * = 2**n*exp(ln10*(x-n*log2/log10))) 39 * If x is an integer < 23 then use repeat multiplication. For 40 * 10**22 is the largest representable integer. 41 */ 42 /* INDENT ON */ 43 44 #include "libm.h" 45 46 static const double C[] = { 47 3.3219280948736234787, /* log(10)/log(2) */ 48 2.3025850929940456840, /* log(10) */ 49 3.0102999565860955045E-1, /* log(2)/log(10) high */ 50 5.3716447674669983622E-12, /* log(2)/log(10) low */ 51 0.0, 52 0.5, 53 1.0, 54 10.0, 55 1.0e300, 56 1.0e-300, 57 }; 58 59 #define lg10 C[0] 60 #define ln10 C[1] 61 #define logt2hi C[2] 62 #define logt2lo C[3] 63 #define zero C[4] 64 #define half C[5] 65 #define one C[6] 66 #define ten C[7] 67 #define huge C[8] 68 #define tiny C[9] 69 70 double 71 exp10(double x) { 72 double t, pt; 73 int ix, hx, k; 74 75 ix = ((int *)&x)[HIWORD]; 76 hx = ix & ~0x80000000; 77 78 if (hx >= 0x4074a000) { /* |x| >= 330 or x is nan */ 79 if (hx >= 0x7ff00000) { /* x is inf or nan */ 80 if (ix == 0xfff00000 && ((int *)&x)[LOWORD] == 0) 81 return (zero); 82 return (x * x); 83 } 84 t = (ix < 0)? tiny : huge; 85 return (t * t); 86 } 87 88 if (hx < 0x3c000000) 89 return (one + x); 90 91 k = (int)x; 92 if (0 <= k && k < 23 && (double)k == x) { 93 /* x is a small positive integer */ 94 t = one; 95 pt = ten; 96 if (k & 1) 97 t = ten; 98 k >>= 1; 99 while (k) { 100 pt *= pt; 101 if (k & 1) 102 t *= pt; 103 k >>= 1; 104 } 105 return (t); 106 } 107 t = x * lg10; 108 k = (int)((ix < 0)? t - half : t + half); 109 return (scalbn(exp(ln10 * ((x - k * logt2hi) - k * logt2lo)), k)); 110 } 111