1 ------------------------------------------------------------------------------
3 -- GNAT RUNTIME COMPONENTS --
5 -- S Y S T E M . D I R E C T _ I O --
10 -- Copyright (C) 1992,1993,1994,1995,1996 Free Software Foundation, Inc. --
12 -- GNAT is free software; you can redistribute it and/or modify it under --
13 -- terms of the GNU General Public License as published by the Free Soft- --
14 -- ware Foundation; either version 2, or (at your option) any later ver- --
15 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
16 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
17 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
18 -- for more details. You should have received a copy of the GNU General --
19 -- Public License distributed with GNAT; see file COPYING. If not, write --
20 -- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
21 -- MA 02111-1307, USA. --
23 -- As a special exception, if other files instantiate generics from this --
24 -- unit, or you link this unit with other files to produce an executable, --
25 -- this unit does not by itself cause the resulting executable to be --
26 -- covered by the GNU General Public License. This exception does not --
27 -- however invalidate any other reasons why the executable file might be --
28 -- covered by the GNU Public License. --
30 -- GNAT was originally developed by the GNAT team at New York University. --
31 -- Extensive contributions were provided by Ada Core Technologies Inc. --
33 ------------------------------------------------------------------------------
35 -- This package contains the declaration of the control block used for
36 -- Direct_IO. This must be declared at the outer library level. It also
37 -- contains code that is shared between instances of Direct_IO.
39 with Interfaces
.C_Streams
;
41 with System
.File_Control_Block
;
42 with System
.Storage_Elements
;
44 package System
.Direct_IO
is
46 package FCB
renames System
.File_Control_Block
;
48 type Operation
is (Op_Read
, Op_Write
, Op_Other
);
49 -- Type used to record last operation (to optimize sequential operations)
51 subtype Count
is Interfaces
.C_Streams
.long
;
52 -- The Count type in each instantiation is derived from this type
54 subtype Positive_Count
is Count
range 1 .. Count
'Last;
56 type Direct_AFCB
is new FCB
.AFCB
with record
58 -- Current Index value
60 Bytes
: Interfaces
.C_Streams
.size_t
;
61 -- Length of item in bytes (set from inside generic template)
63 Last_Op
: Operation
:= Op_Other
;
64 -- Last operation performed on file, used to avoid unnecessary
65 -- repositioning between successive read or write operations.
68 function AFCB_Allocate
(Control_Block
: Direct_AFCB
) return FCB
.AFCB_Ptr
;
70 procedure AFCB_Close
(File
: access Direct_AFCB
);
71 procedure AFCB_Free
(File
: access Direct_AFCB
);
74 (File
: in out Direct_AFCB
;
75 Item
: out Ada
.Streams
.Stream_Element_Array
;
76 Last
: out Ada
.Streams
.Stream_Element_Offset
);
77 -- Required overriding of Read, not actually used for Direct_IO
80 (File
: in out Direct_AFCB
;
81 Item
: in Ada
.Streams
.Stream_Element_Array
);
82 -- Required overriding of Write, not actually used for Direct_IO
84 type File_Type
is access all Direct_AFCB
;
85 -- File_Type in individual instantiations is derived from this type
88 (File
: in out File_Type
;
89 Mode
: in FCB
.File_Mode
:= FCB
.Inout_File
;
90 Name
: in String := "";
91 Form
: in String := "");
93 function End_Of_File
(File
: in File_Type
) return Boolean;
95 function Index
(File
: in File_Type
) return Positive_Count
;
98 (File
: in out File_Type
;
99 Mode
: in FCB
.File_Mode
;
101 Form
: in String := "");
104 (File
: in File_Type
;
105 Item
: System
.Address
;
106 Size
: in Interfaces
.C_Streams
.size_t
;
107 From
: in Positive_Count
);
110 (File
: in File_Type
;
111 Item
: System
.Address
;
112 Size
: in Interfaces
.C_Streams
.size_t
);
114 procedure Reset
(File
: in out File_Type
; Mode
: in FCB
.File_Mode
);
116 procedure Reset
(File
: in out File_Type
);
118 procedure Set_Index
(File
: in File_Type
; To
: in Positive_Count
);
120 function Size
(File
: in File_Type
) return Count
;
123 (File
: in File_Type
;
124 Item
: System
.Address
;
125 Size
: in Interfaces
.C_Streams
.size_t
;
126 Zeroes
: System
.Storage_Elements
.Storage_Array
);
127 -- Note: Zeroes is the buffer of zeroes used to fill out partial records
129 end System
.Direct_IO
;