95 lines
2.8 KiB
C
95 lines
2.8 KiB
C
/* Copyright (C) 2007 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 2, or (at your option) any later
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version.
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In addition to the permissions in the GNU General Public License, the
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Free Software Foundation gives you unlimited permission to link the
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compiled version of this file into combinations with other programs,
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and to distribute those combinations without any restriction coming
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from the use of this file. (The General Public License restrictions
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do apply in other respects; for example, they cover modification of
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the file, and distribution when not linked into a combine
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executable.)
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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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You should have received a copy of the GNU General Public License
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along with GCC; see the file COPYING. If not, write to the Free
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Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301, USA. */
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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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#define MAX_DECIMAL_EXPONENT 767
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#if DECIMAL_CALL_BY_REFERENCE
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void
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__bid64_scalb (UINT64 * pres, UINT64 * px,
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int *pn _RND_MODE_PARAM _EXC_FLAGS_PARAM _EXC_MASKS_PARAM
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_EXC_INFO_PARAM) {
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UINT64 x;
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int n;
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#else
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UINT64
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__bid64_scalb (UINT64 x,
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int n _RND_MODE_PARAM _EXC_FLAGS_PARAM _EXC_MASKS_PARAM
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_EXC_INFO_PARAM) {
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#endif
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UINT64 sign_x, coefficient_x, res;
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int exponent_x, rmode;
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#if DECIMAL_CALL_BY_REFERENCE
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#if !DECIMAL_GLOBAL_ROUNDING
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_IDEC_round rnd_mode = *prnd_mode;
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#endif
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x = *px;
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n = *pn;
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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 or 0
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res = x;
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BID_RETURN (res);
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}
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exponent_x += n;
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if ((UINT32) exponent_x <= MAX_DECIMAL_EXPONENT) {
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res = very_fast_get_BID64 (sign_x, exponent_x, coefficient_x);
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BID_RETURN (res);
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}
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// check for overflow
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if (exponent_x > MAX_DECIMAL_EXPONENT) {
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// try to normalize coefficient
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while ((coefficient_x < 1000000000000000ull)
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&& (exponent_x > MAX_DECIMAL_EXPONENT)) {
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// coefficient_x < 10^15, scale by 10
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coefficient_x = (coefficient_x << 1) + (coefficient_x << 3);
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exponent_x--;
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}
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if (exponent_x <= MAX_DECIMAL_EXPONENT) {
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res = very_fast_get_BID64 (sign_x, exponent_x, coefficient_x);
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BID_RETURN (res);
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}
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}
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// exponent < 0
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// the BID pack routine will round the coefficient
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rmode = rnd_mode;
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res = get_BID64 (sign_x, exponent_x, coefficient_x, rmode, pfpsf);
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BID_RETURN (res);
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}
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