1 /* Copyright (C) 2007, 2009 Free Software Foundation, Inc. 2 3 This file is part of GCC. 4 5 GCC is free software; you can redistribute it and/or modify it under 6 the terms of the GNU General Public License as published by the Free 7 Software Foundation; either version 3, or (at your option) any later 8 version. 9 10 GCC is distributed in the hope that it will be useful, but WITHOUT ANY 11 WARRANTY; without even the implied warranty of MERCHANTABILITY or 12 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 13 for more details. 14 15 Under Section 7 of GPL version 3, you are granted additional 16 permissions described in the GCC Runtime Library Exception, version 17 3.1, as published by the Free Software Foundation. 18 19 You should have received a copy of the GNU General Public License and 20 a copy of the GCC Runtime Library Exception along with this program; 21 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 22 <http://www.gnu.org/licenses/>. */ 23 24 #include "bid_internal.h" 25 26 #define MAX_FORMAT_DIGITS 16 27 #define DECIMAL_EXPONENT_BIAS 398 28 29 #if DECIMAL_CALL_BY_REFERENCE 30 31 void 32 bid64_logb (int * pres, UINT64 * px 33 _EXC_FLAGS_PARAM _EXC_MASKS_PARAM _EXC_INFO_PARAM) { 34 UINT64 x; 35 #else 36 37 int 38 bid64_logb (UINT64 x _EXC_FLAGS_PARAM _EXC_MASKS_PARAM _EXC_INFO_PARAM) { 39 #endif 40 UINT64 sign_x, coefficient_x; 41 int_double dx; 42 int exponent_x, bin_expon_cx, digits; 43 44 #if DECIMAL_CALL_BY_REFERENCE 45 x = *px; 46 #endif 47 // unpack arguments, check for NaN or Infinity 48 if (!unpack_BID64 (&sign_x, &exponent_x, &coefficient_x, x)) { 49 // x is Inf. or NaN 50 #ifdef SET_STATUS_FLAGS 51 __set_status_flags (pfpsf, INVALID_EXCEPTION); 52 #endif 53 BID_RETURN (0x80000000); 54 } 55 // find number of digits in coefficient 56 if (coefficient_x >= 1000000000000000ull) { 57 digits = 16; 58 } else { 59 dx.d = (double)coefficient_x; // exact conversion; 60 bin_expon_cx = (int)(dx.i >> 52) - 1023; 61 digits = estimate_decimal_digits[bin_expon_cx]; 62 if (coefficient_x >= power10_table_128[digits].w[0]) 63 digits++; 64 } 65 exponent_x = exponent_x - DECIMAL_EXPONENT_BIAS + digits - 1; 66 67 BID_RETURN (exponent_x); 68 } 69