gcc/ada/s-direio.ads

   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) 1992-2008, 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 2,  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.  See the GNU General Public License --
  17 -- for  more details.  You should have  received  a copy of the GNU General --
  18 -- Public License  distributed with GNAT;  see file COPYING.  If not, write --
  19 -- to  the  Free Software Foundation,  51  Franklin  Street,  Fifth  Floor, --
  20 -- Boston, MA 02110-1301, USA.                                              --
  21 --                                                                          --
  22 -- As a special exception,  if other files  instantiate  generics from this --
  23 -- unit, or you link  this unit with other files  to produce an executable, --
  24 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  25 -- covered  by the  GNU  General  Public  License.  This exception does not --
  26 -- however invalidate  any other reasons why  the executable file  might be --
  27 -- covered by the  GNU Public License.                                      --
  28 --                                                                          --
  29 -- GNAT was originally developed  by the GNAT team at  New York University. --
  30 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  31 --                                                                          --
  32 ------------------------------------------------------------------------------
  33
  34 --  This package contains the declaration of the control block used for
  35 --  Direct_IO. This must be declared at the outer library level. It also
  36 --  contains code that is shared between instances of Direct_IO.
  37
  38 with Interfaces.C_Streams;
  39 with Ada.Streams;
  40 with System.File_Control_Block;
  41 with System.Storage_Elements;
  42
  43 package System.Direct_IO is
  44
  45    package FCB renames System.File_Control_Block;
  46
  47    type Operation is (Op_Read, Op_Write, Op_Other);
  48    --  Type used to record last operation (to optimize sequential operations)
  49
  50    subtype Count is Interfaces.C_Streams.long;
  51    --  The Count type in each instantiation is derived from this type
  52
  53    subtype Positive_Count is Count range 1 .. Count'Last;
  54
  55    type Direct_AFCB is new FCB.AFCB with record
  56       Index : Count := 1;
  57       --  Current Index value
  58
  59       Bytes : Interfaces.C_Streams.size_t;
  60       --  Length of item in bytes (set from inside generic template)
  61
  62       Last_Op : Operation := Op_Other;
  63       --  Last operation performed on file, used to avoid unnecessary
  64       --  repositioning between successive read or write operations.
  65    end record;
  66
  67    function AFCB_Allocate (Control_Block : Direct_AFCB) return FCB.AFCB_Ptr;
  68
  69    procedure AFCB_Close (File : not null access Direct_AFCB);
  70    procedure AFCB_Free  (File : not null access Direct_AFCB);
  71
  72    procedure Read
  73      (File : in out Direct_AFCB;
  74       Item : out Ada.Streams.Stream_Element_Array;
  75       Last : out Ada.Streams.Stream_Element_Offset);
  76    --  Required overriding of Read, not actually used for Direct_IO
  77
  78    procedure Write
  79      (File : in out Direct_AFCB;
  80       Item : Ada.Streams.Stream_Element_Array);
  81    --  Required overriding of Write, not actually used for Direct_IO
  82
  83    type File_Type is access all Direct_AFCB;
  84    --  File_Type in individual instantiations is derived from this type
  85
  86    procedure Create
  87      (File : in out File_Type;
  88       Mode : FCB.File_Mode := FCB.Inout_File;
  89       Name : String := "";
  90       Form : String := "");
  91
  92    function End_Of_File (File : File_Type) return Boolean;
  93
  94    function Index (File : File_Type) return Positive_Count;
  95
  96    procedure Open
  97      (File : in out File_Type;
  98       Mode : FCB.File_Mode;
  99       Name : String;
 100       Form : String := "");
 101
 102    procedure Read
 103      (File : File_Type;
 104       Item : System.Address;
 105       Size : Interfaces.C_Streams.size_t;
 106       From : Positive_Count);
 107
 108    procedure Read
 109      (File : File_Type;
 110       Item : System.Address;
 111       Size : Interfaces.C_Streams.size_t);
 112
 113    procedure Reset (File : in out File_Type; Mode : FCB.File_Mode);
 114    procedure Reset (File : in out File_Type);
 115
 116    procedure Set_Index (File : File_Type; To : Positive_Count);
 117
 118    function Size (File : File_Type) return Count;
 119
 120    procedure Write
 121      (File   : File_Type;
 122       Item   : System.Address;
 123       Size   : Interfaces.C_Streams.size_t;
 124       Zeroes : System.Storage_Elements.Storage_Array);
 125    --  Note: Zeroes is the buffer of zeroes used to fill out partial records
 126
 127    --  The following procedures have a File_Type formal of mode IN OUT because
 128    --  they may close the original file. The Close operation may raise an
 129    --  exception, but in that case we want any assignment to the formal to
 130    --  be effective anyway, so it must be passed by reference (or the caller
 131    --  will be left with a dangling pointer).
 132
 133    pragma Export_Procedure
 134      (Internal        => Reset,
 135       External        => "",
 136       Parameter_Types => (File_Type),
 137       Mechanism       => Reference);
 138    pragma Export_Procedure
 139      (Internal        => Reset,
 140       External        => "",
 141       Parameter_Types => (File_Type, FCB.File_Mode),
 142       Mechanism       => (File => Reference));
 143
 144 end System.Direct_IO;