1136385Sstefanf/* 2136385Sstefanf * From: @(#)s_ilogb.c 5.1 93/09/24 3136385Sstefanf * ==================================================== 4136385Sstefanf * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. 5136385Sstefanf * 6136385Sstefanf * Developed at SunPro, a Sun Microsystems, Inc. business. 7136385Sstefanf * Permission to use, copy, modify, and distribute this 8136385Sstefanf * software is freely granted, provided that this notice 9136385Sstefanf * is preserved. 10136385Sstefanf * ==================================================== 11136385Sstefanf */ 12136385Sstefanf 13176451Sdas#include <sys/cdefs.h> 14176451Sdas__FBSDID("$FreeBSD$"); 15136385Sstefanf 16136385Sstefanf#include <float.h> 17136385Sstefanf#include <limits.h> 18136385Sstefanf#include <math.h> 19136385Sstefanf 20136385Sstefanf#include "fpmath.h" 21136385Sstefanf 22136385Sstefanfint 23136385Sstefanfilogbl(long double x) 24136385Sstefanf{ 25136385Sstefanf union IEEEl2bits u; 26136385Sstefanf unsigned long m; 27136385Sstefanf int b; 28136385Sstefanf 29136385Sstefanf u.e = x; 30136385Sstefanf if (u.bits.exp == 0) { 31136385Sstefanf if ((u.bits.manl | u.bits.manh) == 0) 32136385Sstefanf return (FP_ILOGB0); 33136385Sstefanf /* denormalized */ 34136385Sstefanf if (u.bits.manh == 0) { 35136385Sstefanf m = 1lu << (LDBL_MANL_SIZE - 1); 36136385Sstefanf for (b = LDBL_MANH_SIZE; !(u.bits.manl & m); m >>= 1) 37136385Sstefanf b++; 38136385Sstefanf } else { 39136385Sstefanf m = 1lu << (LDBL_MANH_SIZE - 1); 40136385Sstefanf for (b = 0; !(u.bits.manh & m); m >>= 1) 41136385Sstefanf b++; 42136385Sstefanf } 43136385Sstefanf#ifdef LDBL_IMPLICIT_NBIT 44136385Sstefanf b++; 45136385Sstefanf#endif 46136385Sstefanf return (LDBL_MIN_EXP - b - 1); 47136385Sstefanf } else if (u.bits.exp < (LDBL_MAX_EXP << 1) - 1) 48136385Sstefanf return (u.bits.exp - LDBL_MAX_EXP + 1); 49136385Sstefanf else if (u.bits.manl != 0 || u.bits.manh != 0) 50136385Sstefanf return (FP_ILOGBNAN); 51136385Sstefanf else 52136385Sstefanf return (INT_MAX); 53136385Sstefanf} 54