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1 /* Copyright (C) 2007, 2009 Free Software Foundation, Inc.
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2
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3 This file is part of GCC.
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4
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5 GCC is free software; you can redistribute it and/or modify it under
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6 the terms of the GNU General Public License as published by the Free
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7 Software Foundation; either version 3, or (at your option) any later
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8 version.
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9
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10 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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11 WARRANTY; without even the implied warranty of MERCHANTABILITY or
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12 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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13 for more details.
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14
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15 Under Section 7 of GPL version 3, you are granted additional
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16 permissions described in the GCC Runtime Library Exception, version
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17 3.1, as published by the Free Software Foundation.
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18
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19 You should have received a copy of the GNU General Public License and
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20 a copy of the GCC Runtime Library Exception along with this program;
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21 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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22 <http://www.gnu.org/licenses/>. */
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23
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24 #include "bid_internal.h"
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25
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26 #define MAX_FORMAT_DIGITS 16
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27 #define DECIMAL_EXPONENT_BIAS 398
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28 #define MAX_DECIMAL_EXPONENT 767
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29
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30 #if DECIMAL_CALL_BY_REFERENCE
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31
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32 void
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33 bid64_scalb (UINT64 * pres, UINT64 * px,
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34 int *pn _RND_MODE_PARAM _EXC_FLAGS_PARAM _EXC_MASKS_PARAM
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35 _EXC_INFO_PARAM) {
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36 UINT64 x;
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37 int n;
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38 #else
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39
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40 UINT64
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41 bid64_scalb (UINT64 x,
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42 int n _RND_MODE_PARAM _EXC_FLAGS_PARAM _EXC_MASKS_PARAM
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43 _EXC_INFO_PARAM) {
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44 #endif
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45 UINT64 sign_x, coefficient_x, res;
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46 SINT64 exp64;
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47 int exponent_x, rmode;
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48
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49 #if DECIMAL_CALL_BY_REFERENCE
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50 #if !DECIMAL_GLOBAL_ROUNDING
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51 _IDEC_round rnd_mode = *prnd_mode;
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52 #endif
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53 x = *px;
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54 n = *pn;
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55 #endif
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56
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57 // unpack arguments, check for NaN or Infinity
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58 if (!unpack_BID64 (&sign_x, &exponent_x, &coefficient_x, x)) {
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59 // x is Inf. or NaN or 0
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60 #ifdef SET_STATUS_FLAGS
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61 if ((x & SNAN_MASK64) == SNAN_MASK64) // y is sNaN
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62 __set_status_flags (pfpsf, INVALID_EXCEPTION);
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63 #endif
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64 if (coefficient_x)
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65 res = coefficient_x & QUIET_MASK64;
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66 else {
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67 exp64 = (SINT64) exponent_x + (SINT64) n;
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68 if(exp64<0) exp64=0;
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69 if(exp64>MAX_DECIMAL_EXPONENT) exp64=MAX_DECIMAL_EXPONENT;
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70 exponent_x = exp64;
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71 res = very_fast_get_BID64 (sign_x, exponent_x, coefficient_x); // 0
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72 }
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73 BID_RETURN (res);
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74 }
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75
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76 exp64 = (SINT64) exponent_x + (SINT64) n;
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77 exponent_x = exp64;
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78
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79 if ((UINT32) exponent_x <= MAX_DECIMAL_EXPONENT) {
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80 res = very_fast_get_BID64 (sign_x, exponent_x, coefficient_x);
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81 BID_RETURN (res);
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82 }
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83 // check for overflow
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84 if (exp64 > MAX_DECIMAL_EXPONENT) {
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85 // try to normalize coefficient
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86 while ((coefficient_x < 1000000000000000ull)
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87 && (exp64 > MAX_DECIMAL_EXPONENT)) {
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88 // coefficient_x < 10^15, scale by 10
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89 coefficient_x = (coefficient_x << 1) + (coefficient_x << 3);
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90 exponent_x--;
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91 exp64--;
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92 }
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93 if (exp64 <= MAX_DECIMAL_EXPONENT) {
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94 res = very_fast_get_BID64 (sign_x, exponent_x, coefficient_x);
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95 BID_RETURN (res);
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96 } else
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97 exponent_x = 0x7fffffff; // overflow
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98 }
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99 // exponent < 0
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100 // the BID pack routine will round the coefficient
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101 rmode = rnd_mode;
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102 res = get_BID64 (sign_x, exponent_x, coefficient_x, rmode, pfpsf);
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103 BID_RETURN (res);
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104
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105 }
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