69 lines
2.1 KiB
C
69 lines
2.1 KiB
C
/* Copyright (C) 2007, 2009 Free Software Foundation, Inc.
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License as published by the Free
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Software Foundation; either version 3, or (at your option) any later
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version.
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GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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for more details.
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Under Section 7 of GPL version 3, you are granted additional
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permissions described in the GCC Runtime Library Exception, version
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3.1, as published by the Free Software Foundation.
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You should have received a copy of the GNU General Public License and
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a copy of the GCC Runtime Library Exception along with this program;
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see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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<http://www.gnu.org/licenses/>. */
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#include "bid_internal.h"
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#define MAX_FORMAT_DIGITS 16
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#define DECIMAL_EXPONENT_BIAS 398
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#if DECIMAL_CALL_BY_REFERENCE
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void
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bid64_logb (int * pres, UINT64 * px
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_EXC_FLAGS_PARAM _EXC_MASKS_PARAM _EXC_INFO_PARAM) {
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UINT64 x;
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#else
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int
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bid64_logb (UINT64 x _EXC_FLAGS_PARAM _EXC_MASKS_PARAM _EXC_INFO_PARAM) {
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#endif
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UINT64 sign_x, coefficient_x;
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int_double dx;
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int exponent_x, bin_expon_cx, digits;
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#if DECIMAL_CALL_BY_REFERENCE
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x = *px;
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#endif
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// unpack arguments, check for NaN or Infinity
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if (!unpack_BID64 (&sign_x, &exponent_x, &coefficient_x, x)) {
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// x is Inf. or NaN
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#ifdef SET_STATUS_FLAGS
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__set_status_flags (pfpsf, INVALID_EXCEPTION);
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#endif
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BID_RETURN (0x80000000);
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}
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// find number of digits in coefficient
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if (coefficient_x >= 1000000000000000ull) {
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digits = 16;
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} else {
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dx.d = (double)coefficient_x; // exact conversion;
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bin_expon_cx = (int)(dx.i >> 52) - 1023;
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digits = estimate_decimal_digits[bin_expon_cx];
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if (coefficient_x >= power10_table_128[digits].w[0])
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digits++;
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}
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exponent_x = exponent_x - DECIMAL_EXPONENT_BIAS + digits - 1;
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BID_RETURN (exponent_x);
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}
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