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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 _ P R I M I T I V E 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) 1991-2017, Florida State University --
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131
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10 -- Copyright (C) 1995-2018, AdaCore --
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111
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11 -- --
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12 -- GNAT is free software; you can redistribute it and/or modify it under --
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13 -- terms of the GNU General Public License as published by the Free Soft- --
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14 -- ware Foundation; either version 3, or (at your option) any later ver- --
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15 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
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16 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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17 -- or FITNESS FOR A PARTICULAR PURPOSE. --
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18 -- --
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19 -- As a special exception under Section 7 of GPL version 3, you are granted --
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20 -- additional permissions described in the GCC Runtime Library Exception, --
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21 -- version 3.1, as published by the Free Software Foundation. --
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22 -- --
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23 -- You should have received a copy of the GNU General Public License and --
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24 -- a copy of the GCC Runtime Library Exception along with this program; --
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25 -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
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26 -- <http://www.gnu.org/licenses/>. --
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27 -- --
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28 -- GNARL was developed by the GNARL team at Florida State University. --
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29 -- Extensive contributions were provided by Ada Core Technologies, Inc. --
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30 -- --
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31 ------------------------------------------------------------------------------
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32
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33 -- This is a POSIX-like version of this package
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34
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35 -- Note: this file can only be used for POSIX compliant systems
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36
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37 pragma Polling (Off);
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38 -- Turn off polling, we do not want ATC polling to take place during tasking
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39 -- operations. It causes infinite loops and other problems.
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40
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41 with System.OS_Interface;
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42
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43 package System.Task_Primitives is
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44 pragma Preelaborate;
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45
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46 type Lock is limited private;
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47 -- Should be used for implementation of protected objects
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48
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49 type RTS_Lock is limited private;
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50 -- Should be used inside the runtime system. The difference between Lock
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51 -- and the RTS_Lock is that the latter serves only as a semaphore so that
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52 -- we do not check for ceiling violations.
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53
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54 type Suspension_Object is limited private;
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55 -- Should be used for the implementation of Ada.Synchronous_Task_Control
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56
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57 type Task_Body_Access is access procedure;
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58 -- Pointer to the task body's entry point (or possibly a wrapper declared
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59 -- local to the GNARL).
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60
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61 type Private_Data is limited private;
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62 -- Any information that the GNULLI needs maintained on a per-task basis.
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63 -- A component of this type is guaranteed to be included in the
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64 -- Ada_Task_Control_Block.
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65
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66 subtype Task_Address is System.Address;
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67 Task_Address_Size : constant := Standard'Address_Size;
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68 -- Type used for task addresses and its size
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69
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70 Alternate_Stack_Size : constant := System.OS_Interface.Alternate_Stack_Size;
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71 -- Import value from System.OS_Interface
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72
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73 private
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74
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75 type RTS_Lock is new System.OS_Interface.pthread_mutex_t;
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76
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77 type Lock is record
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78 RW : aliased System.OS_Interface.pthread_rwlock_t;
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79 WO : aliased RTS_Lock;
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80 end record;
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81
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82 type Suspension_Object is record
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83 State : Boolean;
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84 pragma Atomic (State);
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85 -- Boolean that indicates whether the object is open. This field is
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86 -- marked Atomic to ensure that we can read its value without locking
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87 -- the access to the Suspension_Object.
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88
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89 Waiting : Boolean;
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90 -- Flag showing if there is a task already suspended on this object
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91
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92 L : aliased RTS_Lock;
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93 -- Protection for ensuring mutual exclusion on the Suspension_Object
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94
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95 CV : aliased System.OS_Interface.pthread_cond_t;
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96 -- Condition variable used to queue threads until condition is signaled
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97 end record;
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98
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99 type Private_Data is limited record
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100 Thread : aliased System.OS_Interface.pthread_t;
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101 pragma Atomic (Thread);
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102 -- Thread field may be updated by two different threads of control.
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103 -- (See, Enter_Task and Create_Task in s-taprop.adb). They put the same
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104 -- value (thr_self value). We do not want to use lock on those
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105 -- operations and the only thing we have to make sure is that they are
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106 -- updated in atomic fashion.
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107
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108 LWP : aliased System.Address;
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109 -- The purpose of this field is to provide a better tasking support on
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110 -- gdb. The order of the two first fields (Thread and LWP) is important.
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111 -- On targets where lwp is not relevant, this is equivalent to Thread.
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112
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113 CV : aliased System.OS_Interface.pthread_cond_t;
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114 -- Should be commented ??? (in all versions of taspri)
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115
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116 L : aliased RTS_Lock;
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117 -- Protection for all components is lock L
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118 end record;
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119
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120 end System.Task_Primitives;
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