1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
5 -- I N T E R F A C E S . C . P O I N T E R S --
10 -- Copyright (C) 1992-2001 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 with Interfaces.C.Strings; use Interfaces.C.Strings;
36 with System; use System;
38 with Unchecked_Conversion;
40 package body Interfaces.C.Pointers is
42 type Addr is mod Memory_Size;
44 function To_Pointer is new Unchecked_Conversion (Addr, Pointer);
45 function To_Addr is new Unchecked_Conversion (Pointer, Addr);
46 function To_Addr is new Unchecked_Conversion (ptrdiff_t, Addr);
47 function To_Ptrdiff is new Unchecked_Conversion (Addr, ptrdiff_t);
49 Elmt_Size : constant ptrdiff_t :=
50 (Element_Array'Component_Size
51 + Storage_Unit - 1) / Storage_Unit;
53 subtype Index_Base is Index'Base;
59 function "+" (Left : in Pointer; Right : in ptrdiff_t) return Pointer is
65 return To_Pointer (To_Addr (Left) + To_Addr (Elmt_Size * Right));
68 function "+" (Left : in ptrdiff_t; Right : in Pointer) return Pointer is
74 return To_Pointer (To_Addr (Elmt_Size * Left) + To_Addr (Right));
81 function "-" (Left : in Pointer; Right : in ptrdiff_t) return Pointer is
87 return To_Pointer (To_Addr (Left) - To_Addr (Right * Elmt_Size));
90 function "-" (Left : in Pointer; Right : in Pointer) return ptrdiff_t is
92 if Left = null or else Right = null then
96 return To_Ptrdiff (To_Addr (Left) - To_Addr (Right)) / Elmt_Size;
104 (Source : in Pointer;
106 Length : in ptrdiff_t)
108 T : Pointer := Target;
109 S : Pointer := Source;
112 if S = null or else T = null then
113 raise Dereference_Error;
116 for J in 1 .. Length loop
124 ---------------------------
125 -- Copy_Terminated_Array --
126 ---------------------------
128 procedure Copy_Terminated_Array
129 (Source : in Pointer;
131 Limit : in ptrdiff_t := ptrdiff_t'Last;
132 Terminator : in Element := Default_Terminator)
134 S : Pointer := Source;
135 T : Pointer := Target;
136 L : ptrdiff_t := Limit;
139 if S = null or else T = null then
140 raise Dereference_Error;
145 exit when T.all = Terminator;
151 end Copy_Terminated_Array;
157 procedure Decrement (Ref : in out Pointer) is
166 procedure Increment (Ref : in out Pointer) is
177 Terminator : in Element := Default_Terminator)
181 L : constant Index_Base := Index'First;
186 raise Dereference_Error;
193 exit when P.all = Terminator;
194 H := Index_Base'Succ (H);
199 subtype A is Element_Array (L .. H);
202 function To_PA is new Unchecked_Conversion (Pointer, PA);
205 return To_PA (Ref).all;
212 Length : in ptrdiff_t)
220 raise Dereference_Error;
222 -- For length zero, we need to return a null slice, but we can't make
223 -- the bounds of this slice Index'First, since this could cause a
224 -- Constraint_Error if Index'First = Index'Base'First.
226 elsif Length <= 0 then
228 pragma Warnings (Off); -- kill warnings since X not assigned
229 X : Element_Array (Index'Succ (Index'First) .. Index'First);
230 pragma Warnings (On);
236 -- Normal case (length non-zero)
240 H := Index'Val (Index'Pos (Index'First) + Length - 1);
243 subtype A is Element_Array (L .. H);
246 function To_PA is new Unchecked_Conversion (Pointer, PA);
249 return To_PA (Ref).all;
258 function Virtual_Length
260 Terminator : in Element := Default_Terminator)
268 raise Dereference_Error;
274 while P.all /= Terminator loop
283 end Interfaces.C.Pointers;