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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 -- G N A T . T H R E A D S --
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6 -- --
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7 -- S p e c --
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8 -- --
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9 -- Copyright (C) 1998-2017, AdaCore --
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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 -- This package provides facilities for creation or registration of foreign
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33 -- threads for use as Ada tasks. In order to execute general Ada code, the
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34 -- run-time system must know about all tasks. This package allows foreign
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35 -- code, e.g. a C program, to create a thread that the Ada run-time knows
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36 -- about, or to register the current thread.
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37
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38 -- For some implementations of GNAT Pro, the registration of foreign threads
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39 -- is automatic. However, in such implementations, if the Ada program has no
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40 -- tasks at all and no tasking constructs other than delay, then by default
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41 -- the non-tasking version of the Ada run-time will be loaded. If foreign
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42 -- threads are present, it is important to ensure that the tasking version
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43 -- of the Ada run time is loaded. This may be achieved by adding "with
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44 -- GNAT.Threads" to any unit in the partition.
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45
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46 with System;
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47 with Ada.Task_Identification;
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48
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49 package GNAT.Threads is
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50
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51 type Void_Ptr is access all Integer;
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52
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53 function Create_Thread
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54 (Code : System.Address; -- pointer
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55 Parm : Void_Ptr; -- pointer
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56 Size : Natural; -- int
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57 Prio : Integer) -- int
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58 return System.Address;
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59 pragma Export (C, Create_Thread, "__gnat_create_thread");
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60 -- Creates a thread with the given (Size) stack size in bytes, and
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61 -- the given (Prio) priority. The task will execute a call to the
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62 -- procedure whose address is given by Code. This procedure has
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63 -- the prototype
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64 --
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65 -- void thread_code (void *id, void *parm);
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66 --
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67 -- where id is the id of the created task, and parm is the parameter
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68 -- passed to Create_Thread. The called procedure is the body of the
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69 -- code for the task, the task will be automatically terminated when
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70 -- the procedure returns.
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71 --
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72 -- This function returns the Ada Id of the created task that can then be
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73 -- used as a parameter to the procedures below.
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74 --
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75 -- C declaration:
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76 --
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77 -- extern void *__gnat_create_thread
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78 -- (void (*code)(void *, void *), void *parm, int size, int prio);
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79
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80 function Register_Thread return System.Address;
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81 pragma Export (C, Register_Thread, "__gnat_register_thread");
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82 -- Create an Ada task Id for the current thread if needed.
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83 -- If the thread could not be registered, System.Null_Address is returned.
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84 --
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85 -- This function returns the Ada Id of the current task that can then be
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86 -- used as a parameter to the procedures below.
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87 --
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88 -- C declaration:
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89 --
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90 -- extern void *__gnat_register_thread ();
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91 --
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92 -- Here is a typical usage of the Register/Unregister_Thread procedures:
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93 --
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94 -- void thread_body ()
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95 -- {
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96 -- void *task_id = __gnat_register_thread ();
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97 -- ... thread body ...
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98 -- __gnat_unregister_thread ();
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99 -- }
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100
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101 procedure Unregister_Thread;
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102 pragma Export (C, Unregister_Thread, "__gnat_unregister_thread");
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103 -- Unregister the current task from the GNAT run time and destroy the
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104 -- memory allocated for its task id.
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105 --
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106 -- C declaration:
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107 --
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108 -- extern void __gnat_unregister_thread ();
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109
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110 procedure Unregister_Thread_Id (Thread : System.Address);
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111 pragma Export (C, Unregister_Thread_Id, "__gnat_unregister_thread_id");
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112 -- Unregister the task associated with Thread from the GNAT run time and
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113 -- destroy the memory allocated for its task id.
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114 -- If no task id is associated with Thread, do nothing.
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115 --
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116 -- C declaration:
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117 --
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118 -- extern void __gnat_unregister_thread_id (pthread_t *thread);
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119
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120 procedure Destroy_Thread (Id : System.Address);
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121 pragma Export (C, Destroy_Thread, "__gnat_destroy_thread");
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122 -- This procedure may be used to prematurely abort the created thread.
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123 -- The value Id is the value that was passed to the thread code procedure
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124 -- at activation time.
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125 --
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126 -- C declaration:
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127 --
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128 -- extern void __gnat_destroy_thread (void *id);
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129
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130 procedure Get_Thread (Id : System.Address; Thread : System.Address);
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131 pragma Export (C, Get_Thread, "__gnat_get_thread");
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132 -- This procedure is used to retrieve the thread id of a given task.
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133 -- The value Id is the value that was passed to the thread code procedure
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134 -- at activation time.
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135 -- Thread is a pointer to a thread id that will be updated by this
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136 -- procedure.
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137 --
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138 -- C declaration:
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139 --
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140 -- extern void __gnat_get_thread (void *id, pthread_t *thread);
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141
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142 function To_Task_Id
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143 (Id : System.Address)
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144 return Ada.Task_Identification.Task_Id;
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145 -- Ada interface only.
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146 -- Given a low level Id, as returned by Create_Thread, return a Task_Id,
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147 -- so that operations in Ada.Task_Identification can be used.
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148
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149 end GNAT.Threads;
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