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 #if defined(ELFOBJ) 31 #pragma weak ilogbl = __ilogbl 32 #endif 33 34 #include "libm.h" 35 #include "xpg6.h" /* __xpg6 */ 36 37 #if defined(__sparc) 38 #define ISNORMALL(k, x) (k != 0x7fff) /* assuming k != 0 */ 39 #define X86PDNRM(k, x) 40 #define XSCALE_OFFSET 0x406f /* 0x3fff + 112 */ 41 static const long double xscale = 5192296858534827628530496329220096.0L; 42 /* 2^112 */ 43 #elif defined(__x86) 44 /* 45 * if pseudo-denormal, replace by the equivalent normal 46 */ 47 #define X86PDNRM(k, x) if (k == 0 && (((int *) &x)[1] & 0x80000000) != 0) \ 48 ((int *) &x)[2] |= k = 1 49 #if defined(HANDLE_UNSUPPORTED) /* assuming k != 0 */ 50 #define ISNORMALL(k, x) (k != 0x7fff && (((int *) &x)[1] & 0x80000000) != 0) 51 #else 52 #define ISNORMALL(k, x) (k != 0x7fff) 53 #endif 54 #define XSCALE_OFFSET 0x403e /* 0x3fff + 63 */ 55 static const long double xscale = 9223372036854775808.0L; /* 2^63 */ 56 #endif 57 58 static int 59 raise_invalid(int v) { /* SUSv3 requires ilogbl(0,+/-Inf,NaN) raise invalid */ 60 #ifndef lint 61 if ((__xpg6 & _C99SUSv3_ilogb_0InfNaN_raises_invalid) != 0) { 62 static const double zero = 0.0; 63 volatile double dummy; 64 65 dummy = zero / zero; 66 } 67 #endif 68 return (v); 69 } 70 71 int 72 ilogbl(long double x) { 73 int k = XBIASED_EXP(x); 74 75 X86PDNRM(k, x); 76 if (k == 0) { 77 if (ISZEROL(x)) 78 return (raise_invalid(0x80000001)); 79 else { 80 x *= xscale; /* scale up by 2^112 or 2^63 */ 81 return (XBIASED_EXP(x) - XSCALE_OFFSET); 82 } 83 } else if (ISNORMALL(k, x)) 84 return (k - 0x3fff); 85 else 86 return (raise_invalid(0x7fffffff)); 87 } 88