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145
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1 /**
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2 * Contains a bitfield used by the GC.
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3 *
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4 * Copyright: Copyright Digital Mars 2005 - 2013.
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5 * License: $(WEB www.boost.org/LICENSE_1_0.txt, Boost License 1.0).
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6 * Authors: Walter Bright, David Friedman, Sean Kelly
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7 */
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8
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9 /* Copyright Digital Mars 2005 - 2013.
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10 * Distributed under the Boost Software License, Version 1.0.
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11 * (See accompanying file LICENSE or copy at
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12 * http://www.boost.org/LICENSE_1_0.txt)
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13 */
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14 module gc.bits;
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15
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16
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17 import core.bitop;
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18 import core.stdc.string;
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19 import core.stdc.stdlib;
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20 import core.exception : onOutOfMemoryError;
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21
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22 struct GCBits
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23 {
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24 alias size_t wordtype;
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25
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26 enum BITS_PER_WORD = (wordtype.sizeof * 8);
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27 enum BITS_SHIFT = (wordtype.sizeof == 8 ? 6 : 5);
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28 enum BITS_MASK = (BITS_PER_WORD - 1);
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29 enum BITS_1 = cast(wordtype)1;
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30
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31 wordtype* data;
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32 size_t nbits;
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33
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34 void Dtor() nothrow
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35 {
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36 if (data)
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37 {
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38 free(data);
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39 data = null;
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40 }
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41 }
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42
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43 void alloc(size_t nbits) nothrow
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44 {
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45 this.nbits = nbits;
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46 data = cast(typeof(data[0])*)calloc(nwords, data[0].sizeof);
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47 if (!data)
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48 onOutOfMemoryError();
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49 }
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50
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51 wordtype test(size_t i) const nothrow
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52 in
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53 {
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54 assert(i < nbits);
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55 }
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56 body
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57 {
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58 return core.bitop.bt(data, i);
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59 }
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60
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61 int set(size_t i) nothrow
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62 in
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63 {
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64 assert(i < nbits);
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65 }
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66 body
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67 {
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68 return core.bitop.bts(data, i);
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69 }
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70
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71 int clear(size_t i) nothrow
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72 in
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73 {
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74 assert(i <= nbits);
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75 }
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76 body
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77 {
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78 return core.bitop.btr(data, i);
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79 }
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80
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81 void zero() nothrow
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82 {
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83 memset(data, 0, nwords * wordtype.sizeof);
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84 }
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85
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86 void copy(GCBits *f) nothrow
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87 in
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88 {
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89 assert(nwords == f.nwords);
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90 }
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91 body
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92 {
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93 memcpy(data, f.data, nwords * wordtype.sizeof);
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94 }
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95
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96 @property size_t nwords() const pure nothrow
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97 {
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98 return (nbits + (BITS_PER_WORD - 1)) >> BITS_SHIFT;
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99 }
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100 }
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101
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102 unittest
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103 {
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104 GCBits b;
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105
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106 b.alloc(786);
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107 assert(!b.test(123));
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108 assert(!b.clear(123));
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109 assert(!b.set(123));
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110 assert(b.test(123));
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111 assert(b.clear(123));
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112 assert(!b.test(123));
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113
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114 b.set(785);
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115 b.set(0);
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116 assert(b.test(785));
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117 assert(b.test(0));
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118 b.zero();
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119 assert(!b.test(785));
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120 assert(!b.test(0));
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121
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122 GCBits b2;
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123 b2.alloc(786);
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124 b2.set(38);
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125 b.copy(&b2);
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126 assert(b.test(38));
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127 b2.Dtor();
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128 b.Dtor();
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129 }
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