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 --
9 -- Copyright (C) 1992-2010, Free Software Foundation, Inc. --
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. --
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. --
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/>. --
27 -- GNAT was originally developed by the GNAT team at New York University. --
28 -- Extensive contributions were provided by Ada Core Technologies Inc. --
30 ------------------------------------------------------------------------------
32 with Interfaces.C.Strings; use Interfaces.C.Strings;
33 with System; use System;
35 with Ada.Unchecked_Conversion;
37 package body Interfaces.C.Pointers is
39 type Addr is mod 2 ** System.Parameters.ptr_bits;
41 function To_Pointer is new Ada.Unchecked_Conversion (Addr, Pointer);
42 function To_Addr is new Ada.Unchecked_Conversion (Pointer, Addr);
43 function To_Addr is new Ada.Unchecked_Conversion (ptrdiff_t, Addr);
44 function To_Ptrdiff is new Ada.Unchecked_Conversion (Addr, ptrdiff_t);
46 Elmt_Size : constant ptrdiff_t :=
47 (Element_Array'Component_Size
48 + Storage_Unit - 1) / Storage_Unit;
50 subtype Index_Base is Index'Base;
56 function "+" (Left : Pointer; Right : ptrdiff_t) return Pointer is
62 return To_Pointer (To_Addr (Left) + To_Addr (Elmt_Size * Right));
65 function "+" (Left : ptrdiff_t; Right : Pointer) return Pointer is
71 return To_Pointer (To_Addr (Elmt_Size * Left) + To_Addr (Right));
78 function "-" (Left : Pointer; Right : ptrdiff_t) return Pointer is
84 return To_Pointer (To_Addr (Left) - To_Addr (Right * Elmt_Size));
87 function "-" (Left : Pointer; Right : Pointer) return ptrdiff_t is
89 if Left = null or else Right = null then
93 return To_Ptrdiff (To_Addr (Left) - To_Addr (Right)) / Elmt_Size;
105 T : Pointer := Target;
106 S : Pointer := Source;
109 if S = null or else T = null then
110 raise Dereference_Error;
113 for J in 1 .. Length loop
121 ---------------------------
122 -- Copy_Terminated_Array --
123 ---------------------------
125 procedure Copy_Terminated_Array
128 Limit : ptrdiff_t := ptrdiff_t'Last;
129 Terminator : Element := Default_Terminator)
131 S : Pointer := Source;
132 T : Pointer := Target;
133 L : ptrdiff_t := Limit;
136 if S = null or else T = null then
137 raise Dereference_Error;
142 exit when T.all = Terminator;
148 end Copy_Terminated_Array;
154 procedure Decrement (Ref : in out Pointer) is
163 procedure Increment (Ref : in out Pointer) is
174 Terminator : Element := Default_Terminator) return Element_Array
177 L : constant Index_Base := Index'First;
182 raise Dereference_Error;
189 exit when P.all = Terminator;
190 H := Index_Base'Succ (H);
195 subtype A is Element_Array (L .. H);
198 for PA'Size use System.Parameters.ptr_bits;
199 function To_PA is new Ada.Unchecked_Conversion (Pointer, PA);
202 return To_PA (Ref).all;
209 Length : ptrdiff_t) return Element_Array
216 raise Dereference_Error;
218 -- For length zero, we need to return a null slice, but we can't make
219 -- the bounds of this slice Index'First, since this could cause a
220 -- Constraint_Error if Index'First = Index'Base'First.
222 elsif Length <= 0 then
224 pragma Warnings (Off); -- kill warnings since X not assigned
225 X : Element_Array (Index'Succ (Index'First) .. Index'First);
226 pragma Warnings (On);
232 -- Normal case (length non-zero)
236 H := Index'Val (Index'Pos (Index'First) + Length - 1);
239 subtype A is Element_Array (L .. H);
242 for PA'Size use System.Parameters.ptr_bits;
243 function To_PA is new Ada.Unchecked_Conversion (Pointer, PA);
246 return To_PA (Ref).all;
255 function Virtual_Length
257 Terminator : Element := Default_Terminator) return ptrdiff_t
264 raise Dereference_Error;
270 while P.all /= Terminator loop
279 end Interfaces.C.Pointers;