1 /* Copyright (C) 2007-2020 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
bid64_logb(int * pres,UINT64 * px _EXC_FLAGS_PARAM _EXC_MASKS_PARAM _EXC_INFO_PARAM)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