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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) 2001-2017, 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 -- This is a VxWorks version of this package
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33
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34 pragma Polling (Off);
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35 -- Turn off polling, we do not want ATC polling to take place during tasking
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36 -- operations. It causes infinite loops and other problems.
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37
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38 with System.OS_Interface;
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39
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40 package System.Task_Primitives is
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41 pragma Preelaborate;
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42
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43 type Lock is limited private;
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44 -- Should be used for implementation of protected objects
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45
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46 type RTS_Lock is limited private;
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47 -- Should be used inside the runtime system. The difference between Lock
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48 -- and the RTS_Lock is that the later one serves only as a semaphore so
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49 -- that do not check for ceiling violations.
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50
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51 type Suspension_Object is limited private;
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52 -- Should be used for the implementation of Ada.Synchronous_Task_Control
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53
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54 type Task_Body_Access is access procedure;
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55 -- Pointer to the task body's entry point (or possibly a wrapper
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56 -- declared local to the GNARL).
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57
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58 type Private_Data is limited private;
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59 -- Any information that the GNULLI needs maintained on a per-task basis.
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60 -- A component of this type is guaranteed to be included in the
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61 -- Ada_Task_Control_Block.
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62
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63 subtype Task_Address is System.Address;
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64 Task_Address_Size : constant := Standard'Address_Size;
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65 -- Type used for task addresses and its size
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66
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67 Alternate_Stack_Size : constant := 0;
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68 -- No alternate signal stack is used on this platform
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69
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70 private
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71
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72 type Priority_Type is (Prio_None, Prio_Protect, Prio_Inherit);
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73
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74 type Lock is record
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75 Mutex : System.OS_Interface.SEM_ID;
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76 Protocol : Priority_Type;
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77
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78 Prio_Ceiling : System.OS_Interface.int;
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79 -- Priority ceiling of lock
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80 end record;
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81
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82 type RTS_Lock is new Lock;
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83
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84 type Suspension_Object is record
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85 State : Boolean;
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86 pragma Atomic (State);
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87 -- Boolean that indicates whether the object is open. This field is
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88 -- marked Atomic to ensure that we can read its value without locking
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89 -- the access to the Suspension_Object.
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90
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91 Waiting : Boolean;
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92 -- Flag showing if there is a task already suspended on this object
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93
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94 L : aliased System.OS_Interface.SEM_ID;
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95 -- Protection for ensuring mutual exclusion on the Suspension_Object
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96
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97 CV : aliased System.OS_Interface.SEM_ID;
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98 -- Condition variable used to queue threads until condition is signaled
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99 end record;
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100
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101 type Private_Data is limited record
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102 Thread : aliased System.OS_Interface.t_id := 0;
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103 pragma Atomic (Thread);
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104 -- Thread field may be updated by two different threads of control.
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105 -- (See, Enter_Task and Create_Task in s-taprop.adb).
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106 -- They put the same value (thr_self value). We do not want to
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107 -- use lock on those operations and the only thing we have to
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108 -- make sure is that they are updated in atomic fashion.
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109
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110 LWP : aliased System.OS_Interface.t_id := 0;
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111 -- The purpose of this field is to provide a better tasking support on
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112 -- gdb. The order of the two first fields (Thread and LWP) is important.
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113 -- On targets where lwp is not relevant, this is equivalent to Thread.
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114
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115 CV : aliased System.OS_Interface.SEM_ID;
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116
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117 L : aliased RTS_Lock;
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118 -- Protection for all components is lock L
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119 end record;
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120
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121 end System.Task_Primitives;
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