------------------------------------------------------------------------------ -- -- -- 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) 1992-2001 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. -- -- Extensive contributions were provided by Ada Core Technologies Inc. -- -- -- ------------------------------------------------------------------------------ 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;