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1 ------------------------------------------------------------------------------
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2 -- --
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3 -- GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS --
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4 -- --
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5 -- S Y S T E M . T A S K I N G --
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6 -- --
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7 -- B o d y --
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8 -- --
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9 -- Copyright (C) 1992-2017, Free Software Foundation, Inc. --
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10 -- --
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11 -- GNARL 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 -- GNARL was developed by the GNARL team at Florida State 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 pragma Polling (Off);
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33 -- Turn off polling, we do not want ATC polling to take place during tasking
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34 -- operations. It causes infinite loops and other problems.
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35
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36 with System.Task_Primitives.Operations;
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37 with System.Storage_Elements;
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38
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39 package body System.Tasking is
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40
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41 package STPO renames System.Task_Primitives.Operations;
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42
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43 ---------------------
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44 -- Detect_Blocking --
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45 ---------------------
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46
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47 function Detect_Blocking return Boolean is
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48 GL_Detect_Blocking : Integer;
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49 pragma Import (C, GL_Detect_Blocking, "__gl_detect_blocking");
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50 -- Global variable exported by the binder generated file. A value equal
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51 -- to 1 indicates that pragma Detect_Blocking is active, while 0 is used
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52 -- for the pragma not being present.
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53
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54 begin
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55 return GL_Detect_Blocking = 1;
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56 end Detect_Blocking;
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57
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58 -----------------------
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59 -- Number_Of_Entries --
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60 -----------------------
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61
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62 function Number_Of_Entries (Self_Id : Task_Id) return Entry_Index is
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63 begin
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64 return Entry_Index (Self_Id.Entry_Num);
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65 end Number_Of_Entries;
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66
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67 ----------
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68 -- Self --
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69 ----------
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70
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71 function Self return Task_Id renames STPO.Self;
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72
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73 ------------------
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74 -- Storage_Size --
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75 ------------------
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76
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77 function Storage_Size (T : Task_Id) return System.Parameters.Size_Type is
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78 begin
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79 return
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80 System.Parameters.Size_Type
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81 (T.Common.Compiler_Data.Pri_Stack_Info.Size);
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82 end Storage_Size;
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83
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84 ---------------------
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85 -- Initialize_ATCB --
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86 ---------------------
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87
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88 procedure Initialize_ATCB
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89 (Self_ID : Task_Id;
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90 Task_Entry_Point : Task_Procedure_Access;
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91 Task_Arg : System.Address;
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92 Parent : Task_Id;
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93 Elaborated : Access_Boolean;
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94 Base_Priority : System.Any_Priority;
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95 Base_CPU : System.Multiprocessors.CPU_Range;
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96 Domain : Dispatching_Domain_Access;
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97 Task_Info : System.Task_Info.Task_Info_Type;
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98 Stack_Size : System.Parameters.Size_Type;
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99 T : Task_Id;
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100 Success : out Boolean)
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101 is
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102 begin
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103 T.Common.State := Unactivated;
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104
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105 -- Initialize T.Common.LL
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106
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107 STPO.Initialize_TCB (T, Success);
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108
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109 if not Success then
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110 return;
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111 end if;
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112
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113 -- Note that use of an aggregate here for this assignment
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114 -- would be illegal, because Common_ATCB is limited because
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115 -- Task_Primitives.Private_Data is limited.
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116
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117 T.Common.Parent := Parent;
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118 T.Common.Base_Priority := Base_Priority;
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119 T.Common.Base_CPU := Base_CPU;
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120
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121 -- The Domain defaults to that of the activator. But that can be null in
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122 -- the case of foreign threads (see Register_Foreign_Thread), in which
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123 -- case we default to the System_Domain.
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124
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125 if Domain /= null then
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126 T.Common.Domain := Domain;
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127 elsif Self_ID.Common.Domain /= null then
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128 T.Common.Domain := Self_ID.Common.Domain;
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129 else
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130 T.Common.Domain := System_Domain;
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131 end if;
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132 pragma Assert (T.Common.Domain /= null);
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133
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134 T.Common.Current_Priority := 0;
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135 T.Common.Protected_Action_Nesting := 0;
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136 T.Common.Call := null;
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137 T.Common.Task_Arg := Task_Arg;
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138 T.Common.Task_Entry_Point := Task_Entry_Point;
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139 T.Common.Activator := Self_ID;
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140 T.Common.Wait_Count := 0;
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141 T.Common.Elaborated := Elaborated;
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142 T.Common.Activation_Failed := False;
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143 T.Common.Task_Info := Task_Info;
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144 T.Common.Global_Task_Lock_Nesting := 0;
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145 T.Common.Fall_Back_Handler := null;
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146 T.Common.Specific_Handler := null;
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147 T.Common.Debug_Events := (others => False);
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148 T.Common.Task_Image_Len := 0;
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149
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150 if T.Common.Parent = null then
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151
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152 -- For the environment task, the adjusted stack size is meaningless.
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153 -- For example, an unspecified Stack_Size means that the stack size
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154 -- is determined by the environment, or can grow dynamically. The
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155 -- Stack_Checking algorithm therefore needs to use the requested
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156 -- size, or 0 in case of an unknown size.
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157
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158 T.Common.Compiler_Data.Pri_Stack_Info.Size :=
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159 Storage_Elements.Storage_Offset (Stack_Size);
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160
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161 else
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162 T.Common.Compiler_Data.Pri_Stack_Info.Size :=
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163 Storage_Elements.Storage_Offset
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164 (Parameters.Adjust_Storage_Size (Stack_Size));
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165 end if;
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166
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167 -- Link the task into the list of all tasks
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168
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169 T.Common.All_Tasks_Link := All_Tasks_List;
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170 All_Tasks_List := T;
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171 end Initialize_ATCB;
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172
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173 ----------------
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174 -- Initialize --
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175 ----------------
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176
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177 Main_Task_Image : constant String := "main_task";
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178 -- Image of environment task
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179
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180 Main_Priority : Integer;
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181 pragma Import (C, Main_Priority, "__gl_main_priority");
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182 -- Priority for main task. Note that this is of type Integer, not Priority,
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183 -- because we use the value -1 to indicate the default main priority, and
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184 -- that is of course not in Priority'range.
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185
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186 Main_CPU : Integer;
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187 pragma Import (C, Main_CPU, "__gl_main_cpu");
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188 -- Affinity for main task. Note that this is of type Integer, not
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189 -- CPU_Range, because we use the value -1 to indicate the unassigned
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190 -- affinity, and that is of course not in CPU_Range'Range.
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191
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192 Initialized : Boolean := False;
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193 -- Used to prevent multiple calls to Initialize
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194
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195 procedure Initialize is
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196 T : Task_Id;
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197 Base_Priority : Any_Priority;
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198 Base_CPU : System.Multiprocessors.CPU_Range;
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199 Success : Boolean;
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200
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201 use type System.Multiprocessors.CPU_Range;
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202
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203 begin
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204 if Initialized then
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205 return;
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206 end if;
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207
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208 Initialized := True;
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209
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210 -- Initialize Environment Task
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211
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212 Base_Priority :=
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213 (if Main_Priority = Unspecified_Priority
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214 then Default_Priority
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215 else Priority (Main_Priority));
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216
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217 Base_CPU :=
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218 (if Main_CPU = Unspecified_CPU
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219 then System.Multiprocessors.Not_A_Specific_CPU
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220 else System.Multiprocessors.CPU_Range (Main_CPU));
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221
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222 -- At program start-up the environment task is allocated to the default
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223 -- system dispatching domain.
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224 -- Make sure that the processors which are not available are not taken
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225 -- into account. Use Number_Of_CPUs to know the exact number of
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226 -- processors in the system at execution time.
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227
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228 System_Domain :=
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229 new Dispatching_Domain'
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230 (Multiprocessors.CPU'First .. Multiprocessors.Number_Of_CPUs =>
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231 True);
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232
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233 T := STPO.New_ATCB (0);
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234 Initialize_ATCB
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235 (Self_ID => null,
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236 Task_Entry_Point => null,
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237 Task_Arg => Null_Address,
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238 Parent => Null_Task,
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239 Elaborated => null,
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240 Base_Priority => Base_Priority,
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241 Base_CPU => Base_CPU,
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242 Domain => System_Domain,
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243 Task_Info => Task_Info.Unspecified_Task_Info,
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244 Stack_Size => 0,
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245 T => T,
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246 Success => Success);
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247 pragma Assert (Success);
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248
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249 STPO.Initialize (T);
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250 STPO.Set_Priority (T, T.Common.Base_Priority);
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251 T.Common.State := Runnable;
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252 T.Common.Task_Image_Len := Main_Task_Image'Length;
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253 T.Common.Task_Image (Main_Task_Image'Range) := Main_Task_Image;
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254
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255 Dispatching_Domain_Tasks :=
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256 new Array_Allocated_Tasks'
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257 (Multiprocessors.CPU'First .. Multiprocessors.Number_Of_CPUs => 0);
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258
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259 -- Signal that this task is being allocated to a processor
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260
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261 if Base_CPU /= System.Multiprocessors.Not_A_Specific_CPU then
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262
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263 -- Increase the number of tasks attached to the CPU to which this
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264 -- task is allocated.
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265
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266 Dispatching_Domain_Tasks (Base_CPU) :=
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267 Dispatching_Domain_Tasks (Base_CPU) + 1;
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268 end if;
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269
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270 -- Only initialize the first element since others are not relevant
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271 -- in ravenscar mode. Rest of the initialization is done in Init_RTS.
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272
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273 T.Entry_Calls (1).Self := T;
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274 end Initialize;
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275 end System.Tasking;
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