1------------------------------------------------------------------------------
2--                                                                          --
3--                         GNAT RUN-TIME COMPONENTS                         --
4--                                                                          --
5--                     S Y S T E M . D I R E C T _ I O                      --
6--                                                                          --
7--                                 S p e c                                  --
8--                                                                          --
9--          Copyright (C) 1992-2009, Free Software Foundation, Inc.         --
10--                                                                          --
11-- GNAT is free software;  you can  redistribute it  and/or modify it under --
12-- terms of the  GNU General Public License as published  by the Free Soft- --
13-- ware  Foundation;  either version 3,  or (at your option) any later ver- --
14-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
15-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
16-- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
17--                                                                          --
18-- As a special exception under Section 7 of GPL version 3, you are granted --
19-- additional permissions described in the GCC Runtime Library Exception,   --
20-- version 3.1, as published by the Free Software Foundation.               --
21--                                                                          --
22-- You should have received a copy of the GNU General Public License and    --
23-- a copy of the GCC Runtime Library Exception along with this program;     --
24-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
25-- <http://www.gnu.org/licenses/>.                                          --
26--                                                                          --
27-- GNAT was originally developed  by the GNAT team at  New York University. --
28-- Extensive contributions were provided by Ada Core Technologies Inc.      --
29--                                                                          --
30------------------------------------------------------------------------------
31
32--  This package contains the declaration of the control block used for
33--  Direct_IO. This must be declared at the outer library level. It also
34--  contains code that is shared between instances of Direct_IO.
35
36with Interfaces.C_Streams;
37with Ada.Streams;
38with System.File_Control_Block;
39with System.Storage_Elements;
40
41package System.Direct_IO is
42
43   package FCB renames System.File_Control_Block;
44
45   type Operation is (Op_Read, Op_Write, Op_Other);
46   --  Type used to record last operation (to optimize sequential operations)
47
48   subtype Count is Interfaces.C_Streams.long;
49   --  The Count type in each instantiation is derived from this type
50
51   subtype Positive_Count is Count range 1 .. Count'Last;
52
53   type Direct_AFCB is new FCB.AFCB with record
54      Index : Count := 1;
55      --  Current Index value
56
57      Bytes : Interfaces.C_Streams.size_t;
58      --  Length of item in bytes (set from inside generic template)
59
60      Last_Op : Operation := Op_Other;
61      --  Last operation performed on file, used to avoid unnecessary
62      --  repositioning between successive read or write operations.
63   end record;
64
65   function AFCB_Allocate (Control_Block : Direct_AFCB) return FCB.AFCB_Ptr;
66
67   procedure AFCB_Close (File : not null access Direct_AFCB);
68   procedure AFCB_Free  (File : not null access Direct_AFCB);
69
70   procedure Read
71     (File : in out Direct_AFCB;
72      Item : out Ada.Streams.Stream_Element_Array;
73      Last : out Ada.Streams.Stream_Element_Offset);
74   --  Required overriding of Read, not actually used for Direct_IO
75
76   procedure Write
77     (File : in out Direct_AFCB;
78      Item : Ada.Streams.Stream_Element_Array);
79   --  Required overriding of Write, not actually used for Direct_IO
80
81   type File_Type is access all Direct_AFCB;
82   --  File_Type in individual instantiations is derived from this type
83
84   procedure Create
85     (File : in out File_Type;
86      Mode : FCB.File_Mode := FCB.Inout_File;
87      Name : String := "";
88      Form : String := "");
89
90   function End_Of_File (File : File_Type) return Boolean;
91
92   function Index (File : File_Type) return Positive_Count;
93
94   procedure Open
95     (File : in out File_Type;
96      Mode : FCB.File_Mode;
97      Name : String;
98      Form : String := "");
99
100   procedure Read
101     (File : File_Type;
102      Item : System.Address;
103      Size : Interfaces.C_Streams.size_t;
104      From : Positive_Count);
105
106   procedure Read
107     (File : File_Type;
108      Item : System.Address;
109      Size : Interfaces.C_Streams.size_t);
110
111   procedure Reset (File : in out File_Type; Mode : FCB.File_Mode);
112   procedure Reset (File : in out File_Type);
113
114   procedure Set_Index (File : File_Type; To : Positive_Count);
115
116   function Size (File : File_Type) return Count;
117
118   procedure Write
119     (File   : File_Type;
120      Item   : System.Address;
121      Size   : Interfaces.C_Streams.size_t;
122      Zeroes : System.Storage_Elements.Storage_Array);
123   --  Note: Zeroes is the buffer of zeroes used to fill out partial records
124
125   --  The following procedures have a File_Type formal of mode IN OUT because
126   --  they may close the original file. The Close operation may raise an
127   --  exception, but in that case we want any assignment to the formal to
128   --  be effective anyway, so it must be passed by reference (or the caller
129   --  will be left with a dangling pointer).
130
131   pragma Export_Procedure
132     (Internal        => Reset,
133      External        => "",
134      Parameter_Types => (File_Type),
135      Mechanism       => Reference);
136   pragma Export_Procedure
137     (Internal        => Reset,
138      External        => "",
139      Parameter_Types => (File_Type, FCB.File_Mode),
140      Mechanism       => (File => Reference));
141
142end System.Direct_IO;
143