------------------------------------------------------------------------------ -- -- -- 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) 1992-2018, 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 -- -- . -- -- -- -- 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;