| 1 | /****************************************************************
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| 2 |
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| 3 | The author of this software is David M. Gay.
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| 4 |
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| 5 | Copyright (C) 1998, 1999 by Lucent Technologies
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| 6 | All Rights Reserved
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| 7 |
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| 8 | Permission to use, copy, modify, and distribute this software and
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| 9 | its documentation for any purpose and without fee is hereby
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| 10 | granted, provided that the above copyright notice appear in all
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| 11 | copies and that both that the copyright notice and this
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| 12 | permission notice and warranty disclaimer appear in supporting
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| 13 | documentation, and that the name of Lucent or any of its entities
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| 14 | not be used in advertising or publicity pertaining to
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| 15 | distribution of the software without specific, written prior
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| 16 | permission.
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| 17 |
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| 18 | LUCENT DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
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| 19 | INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS.
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| 20 | IN NO EVENT SHALL LUCENT OR ANY OF ITS ENTITIES BE LIABLE FOR ANY
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| 21 | SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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| 22 | WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER
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| 23 | IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
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| 24 | ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
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| 25 | THIS SOFTWARE.
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| 26 |
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| 27 | ****************************************************************/
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| 28 |
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| 29 | /* Please send bug reports to
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| 30 | David M. Gay
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| 31 | Bell Laboratories, Room 2C-463
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| 32 | 600 Mountain Avenue
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| 33 | Murray Hill, NJ 07974-0636
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| 34 | U.S.A.
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| 35 | dmg@bell-labs.com
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| 36 | */
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| 37 |
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| 38 | #include "gdtoaimp.h"
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| 39 |
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| 40 | double
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| 41 | ulp
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| 42 | #ifdef KR_headers
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| 43 | (x) double x;
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| 44 | #else
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| 45 | (double x)
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| 46 | #endif
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| 47 | {
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| 48 | Long L;
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| 49 | double a;
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| 50 |
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| 51 | L = (word0(x) & Exp_mask) - (P-1)*Exp_msk1;
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| 52 | #ifndef Sudden_Underflow
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| 53 | if (L > 0) {
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| 54 | #endif
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| 55 | #ifdef IBM
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| 56 | L |= Exp_msk1 >> 4;
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| 57 | #endif
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| 58 | word0(a) = L;
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| 59 | word1(a) = 0;
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| 60 | #ifndef Sudden_Underflow
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| 61 | }
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| 62 | else {
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| 63 | L = -L >> Exp_shift;
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| 64 | if (L < Exp_shift) {
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| 65 | word0(a) = 0x80000 >> L;
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| 66 | word1(a) = 0;
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| 67 | }
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| 68 | else {
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| 69 | word0(a) = 0;
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| 70 | L -= Exp_shift;
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| 71 | word1(a) = L >= 31 ? 1 : 1 << 31 - L;
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| 72 | }
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| 73 | }
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| 74 | #endif
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| 75 | return a;
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| 76 | }
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