---------------------------------------------------------------- {{{ ----------
--: Copyright © 2020 … 2022 Martin Krischik «krischik@users.sourceforge.net»
-------------------------------------------------------------------------------
--: This library is free software; you can redistribute it and/or modify it
--: under the terms of the GNU Library General Public License as published by
--: the Free Software Foundation; either version 2 of the License, or (at your
--: option) any later version.
--:
--: This library is distributed in the hope that it will be useful, but WITHOUT
--: ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
--: FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public
--: License for more details.
--:
--: You should have received a copy of the GNU Library General Public License
--: along with this library; if not, write to the Free Software Foundation,
--: Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
---------------------------------------------------------------- }}} ----------
pragma License (Modified_Gpl);
pragma Ada_2022;

with Ada.Command_Line;
with Ada.IO_Exceptions;
with Ada.Exceptions;
with Ada.Sequential_IO;
with Ada.Text_IO;
with Interfaces;

---
--
procedure Create_Reset is
   type Byte is new Interfaces.Unsigned_8;
   type Address is new Interfaces.Unsigned_16;

   --  One of the cool feature of Ada is it's ability to set the lower and upper bound of an array to any value
   --  you want. So we can set use the actual ROM addresses as array index an save ourself the work and remove
   --  one potential error source.
   --
   type ROM_Type is
      array (Address range 16#8000# .. 16#FFFF#)
      of Byte;

   package ROM_IO is new Ada.Sequential_IO (ROM_Type);

   ROM_Output : ROM_IO.File_Type;

   --  65C02 related constants as named in the original WDC design document
   --
   NOP      : constant Byte    := 16#EA#;
   NMIB     : constant Address := 16#FFFA#;
   RESB     : constant Address := 16#FFFC#;
   BRK_IRQB : constant Address := 16#FFFE#;

   --  Another interesting feature Ada arrays is specifying the index of elements when initialising the array. As well
   --  specifying an value for all not explicitly initialised values. Makes setting up the ROM array super easy.
   --
   ROM : constant ROM_Type :=
      [NMIB + 0    => 16#00#,
      NMIB + 1     => 16#80#,
      RESB + 0     => 16#00#,
      RESB + 1     => 16#80#,
      BRK_IRQB + 0 => 16#00#,
      BRK_IRQB + 1 => 16#80#,
      others       => NOP];

   File_Name : constant String :=
      (if Ada.Command_Line.Argument_Count < 1 then "create_reset.rom" else Ada.Command_Line.Argument (1));
begin
   --  Just like Python Ada can write the whole array in one go.
   --
   ROM_IO.Create (ROM_Output, ROM_IO.Out_File, File_Name);
   ROM_IO.Write (ROM_Output, ROM);
   ROM_IO.Close (ROM_Output);
exception
   when Error : Ada.IO_Exceptions.Name_Error =>
      Ada.Text_IO.Put_Line ("File """ & File_Name & """ couldn't be created.");
      Ada.Text_IO.Put_Line (Ada.Exceptions.Exception_Information (Error));
   when Error : others =>
      Ada.Text_IO.Put_Line ("File """ & File_Name & """ couldn't be written.");
      Ada.Text_IO.Put_Line (Ada.Exceptions.Exception_Information (Error));
end Create_Reset;

---------------------------------------------------------------- {{{ ----------
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