1 /* Copyright (C) 2007-2013 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 #define BID_128RES 25 #include "bid_internal.h" 26 27 BID128_FUNCTION_ARG1_NORND_CUSTOMRESTYPE(int, bid128_logb, x) 28 29 UINT128 CX; 30 UINT64 sign_x; 31 SINT64 D; 32 int_float f64, fx; 33 int exponent_x, bin_expon_cx, digits; 34 35 if (!unpack_BID128_value (&sign_x, &exponent_x, &CX, x)) { 36 #ifdef SET_STATUS_FLAGS 37 __set_status_flags (pfpsf, INVALID_EXCEPTION); 38 #endif 39 BID_RETURN_VAL (0x80000000); 40 } 41 // find number of digits in coefficient 42 // 2^64 43 f64.i = 0x5f800000; 44 // fx ~ CX 45 fx.d = (float) CX.w[1] * f64.d + (float) CX.w[0]; 46 bin_expon_cx = ((fx.i >> 23) & 0xff) - 0x7f; 47 digits = estimate_decimal_digits[bin_expon_cx]; 48 // scale = 38-estimate_decimal_digits[bin_expon_cx]; 49 D = CX.w[1] - power10_index_binexp_128[bin_expon_cx].w[1]; 50 if (D > 0 || (!D && CX.w[0] >= power10_index_binexp_128[bin_expon_cx].w[0])) { 51 digits++; 52 } 53 54 exponent_x = exponent_x - DECIMAL_EXPONENT_BIAS_128 - 1 + digits; 55 56 BID_RETURN_VAL (exponent_x); 57 58 } 59