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1 ------------------------------------------------------------------------------
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2 -- --
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3 -- GNAT RUN-TIME COMPONENTS --
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4 -- --
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5 -- S Y S T E M . A T O M I C _ P R I M I T I V E S --
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6 -- --
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7 -- B o d y --
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8 -- --
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131
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9 -- Copyright (C) 2012-2018, Free Software Foundation, Inc. --
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111
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10 -- --
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11 -- GNAT is free software; you can redistribute it and/or modify it under --
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12 -- terms of the GNU General Public License as published by the Free Soft- --
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13 -- ware Foundation; either version 3, or (at your option) any later ver- --
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14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
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15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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16 -- or FITNESS FOR A PARTICULAR PURPOSE. --
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17 -- --
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18 -- As a special exception under Section 7 of GPL version 3, you are granted --
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19 -- additional permissions described in the GCC Runtime Library Exception, --
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20 -- version 3.1, as published by the Free Software Foundation. --
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21 -- --
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22 -- You should have received a copy of the GNU General Public License and --
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23 -- a copy of the GCC Runtime Library Exception along with this program; --
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24 -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
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25 -- <http://www.gnu.org/licenses/>. --
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26 -- --
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27 -- GNAT was originally developed by the GNAT team at New York University. --
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28 -- Extensive contributions were provided by Ada Core Technologies Inc. --
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29 -- --
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30 ------------------------------------------------------------------------------
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31
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32 package body System.Atomic_Primitives is
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33
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34 ----------------------
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35 -- Lock_Free_Read_8 --
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36 ----------------------
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37
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38 function Lock_Free_Read_8 (Ptr : Address) return uint8 is
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39 begin
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40 if uint8'Atomic_Always_Lock_Free then
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41 return Atomic_Load_8 (Ptr, Acquire);
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42 else
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43 raise Program_Error;
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44 end if;
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45 end Lock_Free_Read_8;
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46
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47 -----------------------
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48 -- Lock_Free_Read_16 --
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49 -----------------------
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50
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51 function Lock_Free_Read_16 (Ptr : Address) return uint16 is
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52 begin
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53 if uint16'Atomic_Always_Lock_Free then
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54 return Atomic_Load_16 (Ptr, Acquire);
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55 else
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56 raise Program_Error;
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57 end if;
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58 end Lock_Free_Read_16;
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59
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60 -----------------------
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61 -- Lock_Free_Read_32 --
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62 -----------------------
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63
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64 function Lock_Free_Read_32 (Ptr : Address) return uint32 is
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65 begin
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66 if uint32'Atomic_Always_Lock_Free then
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67 return Atomic_Load_32 (Ptr, Acquire);
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68 else
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69 raise Program_Error;
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70 end if;
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71 end Lock_Free_Read_32;
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72
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73 -----------------------
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74 -- Lock_Free_Read_64 --
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75 -----------------------
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76
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77 function Lock_Free_Read_64 (Ptr : Address) return uint64 is
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78 begin
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79 if uint64'Atomic_Always_Lock_Free then
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80 return Atomic_Load_64 (Ptr, Acquire);
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81 else
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82 raise Program_Error;
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83 end if;
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84 end Lock_Free_Read_64;
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85
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86 ---------------------------
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87 -- Lock_Free_Try_Write_8 --
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88 ---------------------------
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89
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90 function Lock_Free_Try_Write_8
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91 (Ptr : Address;
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92 Expected : in out uint8;
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93 Desired : uint8) return Boolean
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94 is
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95 Actual : uint8;
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96
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97 begin
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98 if Expected /= Desired then
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99
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100 if uint8'Atomic_Always_Lock_Free then
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101 Actual := Sync_Compare_And_Swap_8 (Ptr, Expected, Desired);
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102 else
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103 raise Program_Error;
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104 end if;
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105
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106 if Actual /= Expected then
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107 Expected := Actual;
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108 return False;
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109 end if;
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110 end if;
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111
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112 return True;
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113 end Lock_Free_Try_Write_8;
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114
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115 ----------------------------
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116 -- Lock_Free_Try_Write_16 --
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117 ----------------------------
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118
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119 function Lock_Free_Try_Write_16
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120 (Ptr : Address;
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121 Expected : in out uint16;
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122 Desired : uint16) return Boolean
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123 is
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124 Actual : uint16;
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125
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126 begin
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127 if Expected /= Desired then
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128
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129 if uint16'Atomic_Always_Lock_Free then
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130 Actual := Sync_Compare_And_Swap_16 (Ptr, Expected, Desired);
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131 else
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132 raise Program_Error;
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133 end if;
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134
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135 if Actual /= Expected then
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136 Expected := Actual;
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137 return False;
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138 end if;
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139 end if;
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140
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141 return True;
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142 end Lock_Free_Try_Write_16;
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143
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144 ----------------------------
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145 -- Lock_Free_Try_Write_32 --
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146 ----------------------------
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147
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148 function Lock_Free_Try_Write_32
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149 (Ptr : Address;
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150 Expected : in out uint32;
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151 Desired : uint32) return Boolean
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152 is
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153 Actual : uint32;
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154
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155 begin
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156 if Expected /= Desired then
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157
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158 if uint32'Atomic_Always_Lock_Free then
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159 Actual := Sync_Compare_And_Swap_32 (Ptr, Expected, Desired);
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160 else
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161 raise Program_Error;
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162 end if;
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163
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164 if Actual /= Expected then
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165 Expected := Actual;
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166 return False;
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167 end if;
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168 end if;
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169
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170 return True;
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171 end Lock_Free_Try_Write_32;
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172
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173 ----------------------------
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174 -- Lock_Free_Try_Write_64 --
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175 ----------------------------
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176
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177 function Lock_Free_Try_Write_64
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178 (Ptr : Address;
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179 Expected : in out uint64;
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180 Desired : uint64) return Boolean
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181 is
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182 Actual : uint64;
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183
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184 begin
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185 if Expected /= Desired then
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186
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187 if uint64'Atomic_Always_Lock_Free then
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188 Actual := Sync_Compare_And_Swap_64 (Ptr, Expected, Desired);
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189 else
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190 raise Program_Error;
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191 end if;
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192
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193 if Actual /= Expected then
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194 Expected := Actual;
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195 return False;
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196 end if;
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197 end if;
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198
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199 return True;
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200 end Lock_Free_Try_Write_64;
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201 end System.Atomic_Primitives;
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