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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 -- SYSTEM.TASK_PRIMITIVES.OPERATIONS.MONOTONIC --
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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 -- This is the Monotonic version of this package for Posix and Linux targets.
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33
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34 separate (System.Task_Primitives.Operations)
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35 package body Monotonic is
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36
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37 -----------------------
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38 -- Local Subprograms --
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39 -----------------------
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40
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41 procedure Compute_Deadline
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42 (Time : Duration;
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43 Mode : ST.Delay_Modes;
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44 Check_Time : out Duration;
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45 Abs_Time : out Duration;
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46 Rel_Time : out Duration);
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47 -- Helper for Timed_Sleep and Timed_Delay: given a deadline specified by
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48 -- Time and Mode, compute the current clock reading (Check_Time), and the
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49 -- target absolute and relative clock readings (Abs_Time, Rel_Time). The
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50 -- epoch for Time depends on Mode; the epoch for Check_Time and Abs_Time
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51 -- is always that of CLOCK_RT_Ada.
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52
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53 ---------------------
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54 -- Monotonic_Clock --
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55 ---------------------
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56
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57 function Monotonic_Clock return Duration is
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58 TS : aliased timespec;
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59 Result : Interfaces.C.int;
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60 begin
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61 Result := clock_gettime
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62 (clock_id => OSC.CLOCK_RT_Ada, tp => TS'Unchecked_Access);
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63 pragma Assert (Result = 0);
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64
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65 return To_Duration (TS);
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66 end Monotonic_Clock;
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67
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68 -------------------
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69 -- RT_Resolution --
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70 -------------------
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71
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72 function RT_Resolution return Duration is
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73 TS : aliased timespec;
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74 Result : Interfaces.C.int;
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75
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76 begin
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77 Result := clock_getres (OSC.CLOCK_REALTIME, TS'Unchecked_Access);
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78 pragma Assert (Result = 0);
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79
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80 return To_Duration (TS);
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81 end RT_Resolution;
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82
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83 ----------------------
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84 -- Compute_Deadline --
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85 ----------------------
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86
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87 procedure Compute_Deadline
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88 (Time : Duration;
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89 Mode : ST.Delay_Modes;
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90 Check_Time : out Duration;
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91 Abs_Time : out Duration;
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92 Rel_Time : out Duration)
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93 is
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94 begin
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95 Check_Time := Monotonic_Clock;
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96
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97 -- Relative deadline
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98
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99 if Mode = Relative then
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100 Abs_Time := Duration'Min (Time, Max_Sensible_Delay) + Check_Time;
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101
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102 if Relative_Timed_Wait then
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103 Rel_Time := Duration'Min (Max_Sensible_Delay, Time);
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104 end if;
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105
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106 pragma Warnings (Off);
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107 -- Comparison "OSC.CLOCK_RT_Ada = OSC.CLOCK_REALTIME" is compile
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108 -- time known.
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109
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110 -- Absolute deadline specified using the tasking clock (CLOCK_RT_Ada)
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111
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112 elsif Mode = Absolute_RT
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113 or else OSC.CLOCK_RT_Ada = OSC.CLOCK_REALTIME
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114 then
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115 pragma Warnings (On);
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116 Abs_Time := Duration'Min (Check_Time + Max_Sensible_Delay, Time);
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117
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118 if Relative_Timed_Wait then
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119 Rel_Time := Duration'Min (Max_Sensible_Delay, Time - Check_Time);
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120 end if;
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121
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122 -- Absolute deadline specified using the calendar clock, in the
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123 -- case where it is not the same as the tasking clock: compensate for
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124 -- difference between clock epochs (Base_Time - Base_Cal_Time).
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125
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126 else
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127 declare
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128 Cal_Check_Time : constant Duration := OS_Primitives.Clock;
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129 RT_Time : constant Duration :=
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130 Time + Check_Time - Cal_Check_Time;
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131
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132 begin
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133 Abs_Time :=
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134 Duration'Min (Check_Time + Max_Sensible_Delay, RT_Time);
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135
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136 if Relative_Timed_Wait then
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137 Rel_Time :=
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138 Duration'Min (Max_Sensible_Delay, RT_Time - Check_Time);
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139 end if;
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140 end;
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141 end if;
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142 end Compute_Deadline;
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143
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144 -----------------
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145 -- Timed_Sleep --
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146 -----------------
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147
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148 -- This is for use within the run-time system, so abort is
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149 -- assumed to be already deferred, and the caller should be
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150 -- holding its own ATCB lock.
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151
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152 procedure Timed_Sleep
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153 (Self_ID : ST.Task_Id;
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154 Time : Duration;
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155 Mode : ST.Delay_Modes;
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156 Reason : System.Tasking.Task_States;
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157 Timedout : out Boolean;
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158 Yielded : out Boolean)
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159 is
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160 pragma Unreferenced (Reason);
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161
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162 Base_Time : Duration;
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163 Check_Time : Duration;
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164 Abs_Time : Duration;
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165 Rel_Time : Duration;
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166
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167 Request : aliased timespec;
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168 Result : Interfaces.C.int;
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169
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170 begin
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171 Timedout := True;
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172 Yielded := False;
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173
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174 Compute_Deadline
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175 (Time => Time,
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176 Mode => Mode,
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177 Check_Time => Check_Time,
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178 Abs_Time => Abs_Time,
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179 Rel_Time => Rel_Time);
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180 Base_Time := Check_Time;
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181
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182 if Abs_Time > Check_Time then
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183 Request :=
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184 To_Timespec (if Relative_Timed_Wait then Rel_Time else Abs_Time);
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185
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186 loop
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187 exit when Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level;
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188
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189 Result :=
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190 pthread_cond_timedwait
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191 (cond => Self_ID.Common.LL.CV'Access,
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192 mutex => (if Single_Lock
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193 then Single_RTS_Lock'Access
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194 else Self_ID.Common.LL.L'Access),
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195 abstime => Request'Access);
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196
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197 Check_Time := Monotonic_Clock;
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198 exit when Abs_Time <= Check_Time or else Check_Time < Base_Time;
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199
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200 if Result in 0 | EINTR then
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201
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202 -- Somebody may have called Wakeup for us
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203
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204 Timedout := False;
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205 exit;
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206 end if;
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207
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208 pragma Assert (Result = ETIMEDOUT);
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209 end loop;
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210 end if;
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211 end Timed_Sleep;
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212
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213 -----------------
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214 -- Timed_Delay --
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215 -----------------
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216
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217 -- This is for use in implementing delay statements, so we assume the
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218 -- caller is abort-deferred but is holding no locks.
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219
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220 procedure Timed_Delay
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221 (Self_ID : ST.Task_Id;
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222 Time : Duration;
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223 Mode : ST.Delay_Modes)
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224 is
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225 Base_Time : Duration;
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226 Check_Time : Duration;
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227 Abs_Time : Duration;
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228 Rel_Time : Duration;
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229 Request : aliased timespec;
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230
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231 Result : Interfaces.C.int;
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232 pragma Warnings (Off, Result);
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233
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234 begin
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235 if Single_Lock then
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236 Lock_RTS;
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237 end if;
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238
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239 Write_Lock (Self_ID);
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240
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241 Compute_Deadline
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242 (Time => Time,
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243 Mode => Mode,
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244 Check_Time => Check_Time,
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245 Abs_Time => Abs_Time,
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246 Rel_Time => Rel_Time);
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247 Base_Time := Check_Time;
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248
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249 if Abs_Time > Check_Time then
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250 Request :=
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251 To_Timespec (if Relative_Timed_Wait then Rel_Time else Abs_Time);
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252 Self_ID.Common.State := Delay_Sleep;
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253
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254 loop
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255 exit when Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level;
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256
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257 Result :=
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258 pthread_cond_timedwait
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259 (cond => Self_ID.Common.LL.CV'Access,
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260 mutex => (if Single_Lock
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261 then Single_RTS_Lock'Access
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262 else Self_ID.Common.LL.L'Access),
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263 abstime => Request'Access);
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264
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265 Check_Time := Monotonic_Clock;
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266 exit when Abs_Time <= Check_Time or else Check_Time < Base_Time;
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267
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268 pragma Assert (Result in 0 | ETIMEDOUT | EINTR);
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269 end loop;
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270
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271 Self_ID.Common.State := Runnable;
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272 end if;
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273
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274 Unlock (Self_ID);
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275
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276 if Single_Lock then
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277 Unlock_RTS;
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278 end if;
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279
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280 Result := sched_yield;
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281 end Timed_Delay;
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282
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283 end Monotonic;
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