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------------------------------------------------------------------------------
-- --
-- GNAT COMPILER COMPONENTS --
-- --
-- I N T E R F A C E S . C . P O I N T E R S --
-- --
-- B o d y --
-- --
-- $Revision: 1.15 $
-- --
-- Copyright (C) 1992-2001 Free Software Foundation, Inc. --
-- --
-- GNAT is free software; you can redistribute it and/or modify it under --
-- terms of the GNU General Public License as published by the Free Soft- --
-- ware Foundation; either version 2, or (at your option) any later ver- --
-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
-- for more details. You should have received a copy of the GNU General --
-- Public License distributed with GNAT; see file COPYING. If not, write --
-- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
-- MA 02111-1307, USA. --
-- --
-- As a special exception, if other files instantiate generics from this --
-- unit, or you link this unit with other files to produce an executable, --
-- this unit does not by itself cause the resulting executable to be --
-- covered by the GNU General Public License. This exception does not --
-- however invalidate any other reasons why the executable file might be --
-- covered by the GNU Public License. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- It is now maintained by Ada Core Technologies Inc (http://www.gnat.com). --
-- --
------------------------------------------------------------------------------
with Interfaces.C.Strings; use Interfaces.C.Strings;
with System; use System;
with Unchecked_Conversion;
package body Interfaces.C.Pointers is
type Addr is mod Memory_Size;
function To_Pointer is new Unchecked_Conversion (Addr, Pointer);
function To_Addr is new Unchecked_Conversion (Pointer, Addr);
function To_Addr is new Unchecked_Conversion (ptrdiff_t, Addr);
function To_Ptrdiff is new Unchecked_Conversion (Addr, ptrdiff_t);
Elmt_Size : constant ptrdiff_t :=
(Element_Array'Component_Size
+ Storage_Unit - 1) / Storage_Unit;
subtype Index_Base is Index'Base;
---------
-- "+" --
---------
function "+" (Left : in Pointer; Right : in ptrdiff_t) return Pointer is
begin
if Left = null then
raise Pointer_Error;
end if;
return To_Pointer (To_Addr (Left) + To_Addr (Elmt_Size * Right));
end "+";
function "+" (Left : in ptrdiff_t; Right : in Pointer) return Pointer is
begin
if Right = null then
raise Pointer_Error;
end if;
return To_Pointer (To_Addr (Elmt_Size * Left) + To_Addr (Right));
end "+";
---------
-- "-" --
---------
function "-" (Left : in Pointer; Right : in ptrdiff_t) return Pointer is
begin
if Left = null then
raise Pointer_Error;
end if;
return To_Pointer (To_Addr (Left) - To_Addr (Right * Elmt_Size));
end "-";
function "-" (Left : in Pointer; Right : in Pointer) return ptrdiff_t is
begin
if Left = null or else Right = null then
raise Pointer_Error;
end if;
return To_Ptrdiff (To_Addr (Left) - To_Addr (Right)) / Elmt_Size;
end "-";
----------------
-- Copy_Array --
----------------
procedure Copy_Array
(Source : in Pointer;
Target : in Pointer;
Length : in ptrdiff_t)
is
T : Pointer := Target;
S : Pointer := Source;
begin
if S = null or else T = null then
raise Dereference_Error;
else
for J in 1 .. Length loop
T.all := S.all;
Increment (T);
Increment (S);
end loop;
end if;
end Copy_Array;
---------------------------
-- Copy_Terminated_Array --
---------------------------
procedure Copy_Terminated_Array
(Source : in Pointer;
Target : in Pointer;
Limit : in ptrdiff_t := ptrdiff_t'Last;
Terminator : in Element := Default_Terminator)
is
S : Pointer := Source;
T : Pointer := Target;
L : ptrdiff_t := Limit;
begin
if S = null or else T = null then
raise Dereference_Error;
else
while L > 0 loop
T.all := S.all;
exit when T.all = Terminator;
Increment (T);
Increment (S);
L := L - 1;
end loop;
end if;
end Copy_Terminated_Array;
---------------
-- Decrement --
---------------
procedure Decrement (Ref : in out Pointer) is
begin
Ref := Ref - 1;
end Decrement;
---------------
-- Increment --
---------------
procedure Increment (Ref : in out Pointer) is
begin
Ref := Ref + 1;
end Increment;
-----------
-- Value --
-----------
function Value
(Ref : in Pointer;
Terminator : in Element := Default_Terminator)
return Element_Array
is
P : Pointer;
L : constant Index_Base := Index'First;
H : Index_Base;
begin
if Ref = null then
raise Dereference_Error;
else
H := L;
P := Ref;
loop
exit when P.all = Terminator;
H := Index_Base'Succ (H);
Increment (P);
end loop;
declare
subtype A is Element_Array (L .. H);
type PA is access A;
function To_PA is new Unchecked_Conversion (Pointer, PA);
begin
return To_PA (Ref).all;
end;
end if;
end Value;
function Value
(Ref : in Pointer;
Length : in ptrdiff_t)
return Element_Array
is
L : Index_Base;
H : Index_Base;
begin
if Ref = null then
raise Dereference_Error;
-- For length zero, we need to return a null slice, but we can't make
-- the bounds of this slice Index'First, since this could cause a
-- Constraint_Error if Index'First = Index'Base'First.
elsif Length <= 0 then
declare
pragma Warnings (Off); -- kill warnings since X not assigned
X : Element_Array (Index'Succ (Index'First) .. Index'First);
pragma Warnings (On);
begin
return X;
end;
-- Normal case (length non-zero)
else
L := Index'First;
H := Index'Val (Index'Pos (Index'First) + Length - 1);
declare
subtype A is Element_Array (L .. H);
type PA is access A;
function To_PA is new Unchecked_Conversion (Pointer, PA);
begin
return To_PA (Ref).all;
end;
end if;
end Value;
--------------------
-- Virtual_Length --
--------------------
function Virtual_Length
(Ref : in Pointer;
Terminator : in Element := Default_Terminator)
return ptrdiff_t
is
P : Pointer;
C : ptrdiff_t;
begin
if Ref = null then
raise Dereference_Error;
else
C := 0;
P := Ref;
while P.all /= Terminator loop
C := C + 1;
Increment (P);
end loop;
return C;
end if;
end Virtual_Length;
end Interfaces.C.Pointers;
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