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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 -- S Y S T E M . D I R E C T _ I O --
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6 -- --
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7 -- S p e c --
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8 -- --
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131
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9 -- Copyright (C) 1992-2018, Free Software Foundation, Inc. --
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111
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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 contains the declaration of the control block used for
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33 -- Direct_IO. This must be declared at the outer library level. It also
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34 -- contains code that is shared between instances of Direct_IO.
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35
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36 with Interfaces.C_Streams;
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37 with Ada.Streams;
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38 with System.File_Control_Block;
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39 with System.Storage_Elements;
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40
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41 package System.Direct_IO is
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42
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43 package FCB renames System.File_Control_Block;
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44
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45 type Operation is (Op_Read, Op_Write, Op_Other);
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46 -- Type used to record last operation (to optimize sequential operations)
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47
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48 subtype Count is Interfaces.C_Streams.int64;
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49 -- The Count type in each instantiation is derived from this type
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50
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51 subtype Positive_Count is Count range 1 .. Count'Last;
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52
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53 type Direct_AFCB is new FCB.AFCB with record
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54 Index : Count := 1;
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55 -- Current Index value
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56
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57 Bytes : Interfaces.C_Streams.size_t;
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58 -- Length of item in bytes (set from inside generic template)
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59
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60 Last_Op : Operation := Op_Other;
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61 -- Last operation performed on file, used to avoid unnecessary
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62 -- repositioning between successive read or write operations.
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63 end record;
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64
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65 function AFCB_Allocate (Control_Block : Direct_AFCB) return FCB.AFCB_Ptr;
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66
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67 procedure AFCB_Close (File : not null access Direct_AFCB);
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68 procedure AFCB_Free (File : not null access Direct_AFCB);
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69
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70 procedure Read
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71 (File : in out Direct_AFCB;
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72 Item : out Ada.Streams.Stream_Element_Array;
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73 Last : out Ada.Streams.Stream_Element_Offset);
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74 -- Required overriding of Read, not actually used for Direct_IO
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75
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76 procedure Write
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77 (File : in out Direct_AFCB;
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78 Item : Ada.Streams.Stream_Element_Array);
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79 -- Required overriding of Write, not actually used for Direct_IO
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80
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81 type File_Type is access all Direct_AFCB;
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82 -- File_Type in individual instantiations is derived from this type
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83
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84 procedure Create
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85 (File : in out File_Type;
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86 Mode : FCB.File_Mode := FCB.Inout_File;
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87 Name : String := "";
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88 Form : String := "");
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89
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90 function End_Of_File (File : File_Type) return Boolean;
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91
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92 function Index (File : File_Type) return Positive_Count;
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93
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94 procedure Open
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95 (File : in out File_Type;
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96 Mode : FCB.File_Mode;
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97 Name : String;
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98 Form : String := "");
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99
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100 procedure Read
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101 (File : File_Type;
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102 Item : System.Address;
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103 Size : Interfaces.C_Streams.size_t;
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104 From : Positive_Count);
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105
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106 procedure Read
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107 (File : File_Type;
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108 Item : System.Address;
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109 Size : Interfaces.C_Streams.size_t);
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110
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111 procedure Reset (File : in out File_Type; Mode : FCB.File_Mode);
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112 procedure Reset (File : in out File_Type);
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113
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114 procedure Set_Index (File : File_Type; To : Positive_Count);
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115
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116 function Size (File : File_Type) return Count;
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117
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118 procedure Write
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119 (File : File_Type;
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120 Item : System.Address;
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121 Size : Interfaces.C_Streams.size_t;
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122 Zeroes : System.Storage_Elements.Storage_Array);
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123 -- Note: Zeroes is the buffer of zeroes used to fill out partial records
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124
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125 -- The following procedures have a File_Type formal of mode IN OUT because
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126 -- they may close the original file. The Close operation may raise an
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127 -- exception, but in that case we want any assignment to the formal to
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128 -- be effective anyway, so it must be passed by reference (or the caller
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129 -- will be left with a dangling pointer).
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130
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131 pragma Export_Procedure
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132 (Internal => Reset,
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133 External => "",
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134 Parameter_Types => (File_Type),
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135 Mechanism => Reference);
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136 pragma Export_Procedure
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137 (Internal => Reset,
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138 External => "",
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139 Parameter_Types => (File_Type, FCB.File_Mode),
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140 Mechanism => (File => Reference));
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141
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142 end System.Direct_IO;
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