1 /* Software floating-point emulation. 2 ilogbl(x, exp) 3 Copyright (C) 1999-2017 Free Software Foundation, Inc. 4 This file is part of the GNU C Library. 5 Contributed by Jakub Jelinek (jj@ultra.linux.cz). 6 7 The GNU C Library is free software; you can redistribute it and/or 8 modify it under the terms of the GNU Lesser General Public 9 License as published by the Free Software Foundation; either 10 version 2.1 of the License, or (at your option) any later version. 11 12 The GNU C Library is distributed in the hope that it will be useful, 13 but WITHOUT ANY WARRANTY; without even the implied warranty of 14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 15 Lesser General Public License for more details. 16 17 You should have received a copy of the GNU Lesser General Public 18 License along with the GNU C Library; if not, see 19 <http://www.gnu.org/licenses/>. */ 20 21 /* ilogbl(long double x) 22 * return the binary exponent of non-zero x 23 * ilogbl(0) = 0x80000001 24 * ilogbl(inf/NaN) = 0x7fffffff (no signal is raised) 25 */ 26 27 #include "soft-fp.h" 28 #include "quad.h" 29 #include <math.h> 30 __ieee754_ilogbl(long double x)31int __ieee754_ilogbl (long double x) 32 { 33 FP_DECL_EX; 34 FP_DECL_Q(X); 35 36 /* 37 FP_UNPACK_Q(X, x); 38 switch (X_c) 39 { 40 case FP_CLS_ZERO: 41 return FP_ILOGB0; 42 case FP_CLS_NAN: 43 case FP_CLS_INF: 44 return FP_ILOGBNAN; 45 default: 46 return X_e; 47 } 48 */ 49 FP_UNPACK_RAW_Q(X, x); 50 switch (X_e) 51 { 52 default: 53 return X_e - _FP_EXPBIAS_Q; 54 case 0: 55 #if (2 * _FP_W_TYPE_SIZE) < _FP_FRACBITS_Q 56 if (_FP_FRAC_ZEROP_4(X)) 57 return FP_ILOGB0; 58 else 59 { 60 _FP_I_TYPE shift; 61 _FP_FRAC_CLZ_4(shift, X); 62 shift -= _FP_FRACXBITS_Q; 63 return X_e - _FP_EXPBIAS_Q - 1 + shift; 64 } 65 #else 66 if (_FP_FRAC_ZEROP_2(X)) 67 return FP_ILOGB0; 68 else 69 { 70 _FP_I_TYPE shift; 71 _FP_FRAC_CLZ_2(shift, X); 72 shift -= _FP_FRACXBITS_Q; 73 return X_e - _FP_EXPBIAS_Q - 1 + shift; 74 } 75 #endif 76 case _FP_EXPBIAS_Q: 77 return FP_ILOGBNAN; 78 } 79 } 80