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/* Copyright (C) 2007-2023 Free Software Foundation, Inc.
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 3, or (at your option) any later
version.
GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
for more details.
Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.
You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
<http://www.gnu.org/licenses/>. */
#include "bid_internal.h"
#define MAX_FORMAT_DIGITS 16
#define DECIMAL_EXPONENT_BIAS 398
#if DECIMAL_CALL_BY_REFERENCE
void
bid64_logb (int * pres, UINT64 * px
_EXC_FLAGS_PARAM _EXC_MASKS_PARAM _EXC_INFO_PARAM) {
UINT64 x;
#else
int
bid64_logb (UINT64 x _EXC_FLAGS_PARAM _EXC_MASKS_PARAM _EXC_INFO_PARAM) {
#endif
UINT64 sign_x, coefficient_x;
int_double dx;
int exponent_x, bin_expon_cx, digits;
#if DECIMAL_CALL_BY_REFERENCE
x = *px;
#endif
// unpack arguments, check for NaN or Infinity
if (!unpack_BID64 (&sign_x, &exponent_x, &coefficient_x, x)) {
// x is Inf. or NaN
#ifdef SET_STATUS_FLAGS
__set_status_flags (pfpsf, INVALID_EXCEPTION);
#endif
BID_RETURN (0x80000000);
}
// find number of digits in coefficient
if (coefficient_x >= 1000000000000000ull) {
digits = 16;
} else {
dx.d = (double)coefficient_x; // exact conversion;
bin_expon_cx = (int)(dx.i >> 52) - 1023;
digits = estimate_decimal_digits[bin_expon_cx];
if (coefficient_x >= power10_table_128[digits].w[0])
digits++;
}
exponent_x = exponent_x - DECIMAL_EXPONENT_BIAS + digits - 1;
BID_RETURN (exponent_x);
}
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