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 __logbl = logbl 31 32 #include "libm.h" 33 #include "xpg6.h" /* __xpg6 */ 34 #define _C99SUSv3_logb _C99SUSv3_logb_subnormal_is_like_ilogb 35 36 #if defined(__sparc) 37 #define ISNORMALL(k, x) (k != 0x7fff) /* assuming k != 0 */ 38 #define X86PDNRM(k, x) 39 #define XSCALE_OFFSET 0x406f /* 0x3fff + 112 */ 40 static const long double xscale = 5192296858534827628530496329220096.0L; 41 /* 2^112 */ 42 #elif defined(__x86) 43 /* 44 * if pseudo-denormal, replace by the equivalent normal 45 */ 46 #define X86PDNRM(k, x) if (k == 0 && (((int *) &x)[1] & 0x80000000) != 0) \ 47 ((int *) &x)[2] |= k = 1 48 #if defined(HANDLE_UNSUPPORTED) /* assuming k != 0 */ 49 #define ISNORMALL(k, x) (k != 0x7fff && (((int *) &x)[1] & 0x80000000) != 0) 50 #else 51 #define ISNORMALL(k, x) (k != 0x7fff) 52 #endif 53 #define XSCALE_OFFSET 0x403e /* 0x3fff + 63 */ 54 static const long double xscale = 9223372036854775808.0L; /* 2^63 */ 55 #endif 56 57 static long double 58 raise_division(long double v) { 59 #pragma STDC FENV_ACCESS ON 60 static const long double zero = 0.0L; 61 return (v / zero); 62 } 63 64 long double 65 logbl(long double x) { 66 int k = XBIASED_EXP(x); 67 68 X86PDNRM(k, x); 69 if (k == 0) { 70 if (ISZEROL(x)) 71 return (raise_division(-1.0L)); 72 else if ((__xpg6 & _C99SUSv3_logb) != 0) { 73 x *= xscale; /* scale up by 2^112 or 2^63 */ 74 return (long double) (XBIASED_EXP(x) - XSCALE_OFFSET); 75 } else 76 return ((long double) (-16382)); 77 } else if (ISNORMALL(k, x)) 78 return ((long double) (k - 0x3fff)); 79 else 80 return (x * x); 81 } 82