1/* $NetBSD: s_ilogbl.c,v 1.4 2016/08/26 08:20:31 christos Exp $ */ 2 3/*- 4 * Copyright (c) 2011 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Joerg Sonnenberger. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 * POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32#include <sys/cdefs.h> 33__RCSID("$NetBSD: s_ilogbl.c,v 1.4 2016/08/26 08:20:31 christos Exp $"); 34 35#include "namespace.h" 36 37#include <float.h> 38#include <math.h> 39#define __TEST_FENV 40#include <fenv.h> 41#ifndef __HAVE_FENV 42#define feraiseexcept(a) 43#endif 44#include <machine/ieee.h> 45 46#ifdef __HAVE_LONG_DOUBLE 47 48#if LDBL_MANT_DIG == 64 49#define FROM_UNDERFLOW 0x1p65L 50#elif LDBL_MANT_DIG == 113 51#define FROM_UNDERFLOW 0x1p114L 52#else 53#error Unsupported long double format 54#endif 55 56int 57ilogbl(long double x) 58{ 59 union ieee_ext_u u; 60 61 if (x == 0.0L) { 62 feraiseexcept(FE_INVALID); 63 return FP_ILOGB0; /* ilogbl(0) = 0x80000001 */ 64 } 65 66 u.extu_ld = x; 67 68 if (u.extu_ext.ext_exp == EXT_EXP_INFNAN) { 69 feraiseexcept(FE_INVALID); 70 return isnan(x) ? FP_ILOGBNAN : INT_MAX; 71 } 72 73 if (u.extu_ext.ext_exp == 0) { 74 /* 75 * Scale denormalized numbers slightly, 76 * so that they are normal. 77 */ 78 u.extu_ld *= FROM_UNDERFLOW; 79 return u.extu_ext.ext_exp - EXT_EXP_BIAS - LDBL_MANT_DIG - 1; 80 } 81 return u.extu_ext.ext_exp - EXT_EXP_BIAS; 82 83} 84 85#endif 86