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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 --
-- --
-- Copyright (C) 1992-2022, 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 3, 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. --
-- --
-- As a special exception under Section 7 of GPL version 3, you are granted --
-- additional permissions described in the GCC Runtime Library Exception, --
-- version 3.1, as published by the Free Software Foundation. --
-- --
-- You should have received a copy of the GNU General Public License and --
-- a copy of the GCC Runtime Library Exception along with this program; --
-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
-- <http://www.gnu.org/licenses/>. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
------------------------------------------------------------------------------
with Interfaces.C.Strings; use Interfaces.C.Strings;
with System; use System;
with Ada.Unchecked_Conversion;
package body Interfaces.C.Pointers is
type Addr is mod 2 ** System.Parameters.ptr_bits;
function To_Pointer is new Ada.Unchecked_Conversion (Addr, Pointer);
function To_Addr is new Ada.Unchecked_Conversion (Pointer, Addr);
function To_Addr is new Ada.Unchecked_Conversion (ptrdiff_t, Addr);
function To_Ptrdiff is new Ada.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 : Pointer; Right : 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 : ptrdiff_t; Right : 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 : Pointer; Right : 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 : Pointer; Right : 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 : Pointer;
Target : Pointer;
Length : ptrdiff_t)
is
T : Pointer;
S : Pointer;
begin
if Source = null or else Target = null then
raise Dereference_Error;
-- Forward copy
elsif To_Addr (Target) <= To_Addr (Source) then
T := Target;
S := Source;
for J in 1 .. Length loop
T.all := S.all;
Increment (T);
Increment (S);
end loop;
-- Backward copy
else
T := Target + Length;
S := Source + Length;
for J in 1 .. Length loop
Decrement (T);
Decrement (S);
T.all := S.all;
end loop;
end if;
end Copy_Array;
---------------------------
-- Copy_Terminated_Array --
---------------------------
procedure Copy_Terminated_Array
(Source : Pointer;
Target : Pointer;
Limit : ptrdiff_t := ptrdiff_t'Last;
Terminator : Element := Default_Terminator)
is
L : ptrdiff_t;
S : Pointer := Source;
begin
if Source = null or Target = null then
raise Dereference_Error;
end if;
-- Compute array limited length (including the terminator)
L := 0;
while L < Limit loop
L := L + 1;
exit when S.all = Terminator;
Increment (S);
end loop;
Copy_Array (Source, Target, L);
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 : Pointer;
Terminator : 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;
for PA'Size use System.Parameters.ptr_bits;
function To_PA is new Ada.Unchecked_Conversion (Pointer, PA);
begin
return To_PA (Ref).all;
end;
end if;
end Value;
function Value
(Ref : Pointer;
Length : 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;
for PA'Size use System.Parameters.ptr_bits;
function To_PA is new Ada.Unchecked_Conversion (Pointer, PA);
begin
return To_PA (Ref).all;
end;
end if;
end Value;
--------------------
-- Virtual_Length --
--------------------
function Virtual_Length
(Ref : Pointer;
Terminator : 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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