------------------------------------------------------------------------------
--                                                                          --
--                         GNAT COMPILER COMPONENTS                         --
--                                                                          --
--                  S Y S T E M . A D D R E S S _ I M A G E                 --
--                                                                          --
--                                 B o d y                                  --
--                                                                          --
--          Copyright (C) 1992-2021, 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 Ada.Unchecked_Conversion;

function System.Address_Image (A : Address) return String is

   Result  : String (1 .. 2 * Address'Size / Storage_Unit);

   type Byte is mod 2 ** 8;
   for Byte'Size use 8;

   Hexdigs :
     constant array (Byte range 0 .. 15) of Character := "0123456789ABCDEF";

   type Bytes is array (1 .. Address'Size / Storage_Unit) of Byte;
   for Bytes'Size use Address'Size;

   function To_Bytes is new Ada.Unchecked_Conversion (Address, Bytes);

   Byte_Sequence : constant Bytes := To_Bytes (A);

   LE : constant := Standard'Default_Bit_Order;
   BE : constant := 1 - LE;
   --  Set to 1/0 for True/False for Little-Endian/Big-Endian

   Start : constant Natural := BE * (1) + LE * (Bytes'Length);
   Incr  : constant Integer := BE * (1) + LE * (-1);
   --  Start and increment for accessing characters of address string

   Ptr : Natural;
   --  Scan address string

begin
   Ptr := Start;
   for N in Bytes'Range loop
      Result (2 * N - 1) := Hexdigs (Byte_Sequence (Ptr) / 16);
      Result (2 * N)     := Hexdigs (Byte_Sequence (Ptr) mod 16);
      Ptr := Ptr + Incr;
   end loop;

   return Result;

end System.Address_Image;