------------------------------------------------------------------------------
------------------------------------------------------------------------------
-- This file is part of 'CryoDemo', a tutorial example for 'Cryostat'.      --
--                                                                          --
-- (C) 2020 Stanislav Datskovskiy ( www.loper-os.org )                      --
-- http://wot.deedbot.org/17215D118B7239507FAFED98B98228A001ABFFC7.html     --
--                                                                          --
-- You do not have, nor can you ever acquire the right to use, copy or      --
-- distribute this software ; Should you use this software for any purpose, --
-- or copy and distribute it to anyone or in any manner, you are breaking   --
-- the laws of whatever soi-disant jurisdiction, and you promise to         --
-- continue doing so for the indefinite future. In any case, please         --
-- always : read and understand any software ; verify any PGP signatures    --
-- that you use - for any purpose.                                          --
------------------------------------------------------------------------------
------------------------------------------------------------------------------

with Interfaces;  use Interfaces;
with ada.text_io; use  ada.text_io;

with Cryostat;


procedure CryoDemo is
   
   -- Path on disk for the example Cryostat backing file :
   File_Path : constant String := "cryotest.bin";
   
   -- Now, let's define an example data structure to place in a Cryostat :
   
   -- Example payload array's element type: byte.
   subtype ADatum is Unsigned_8;
   
   -- Let's make it 512MB - far bigger than a typical stack, to demonstrate
   -- that it will in fact reside in the Cryostat, rather than on the stack :
   A_MBytes : constant Unsigned_32 := 512;
   
   -- Example payload: an array.
   subtype ARange is Unsigned_32 range 0 .. (A_MBytes * 1024 * 1024) - 1;
   
   -- Complete the definition of the payload data structure :
   type TestArray is array(ARange) of ADatum;
   
   -- Declare a Cryostat which stores a TestArray :
   package Cryo is new Cryostat(Form     => TestArray,
                                Path     => File_Path,
                                Writable => True,  -- Permit writing
                                Create   => True); -- Create file if not exists
   
   -- Handy reference to the payload; no pointerisms needed !
   T : TestArray renames Cryo.Item;
   
   -- T can now be treated as if it lived on the stack :
   
begin
   
   Put_Line("T(0)    before :  " & ADatum'Image(T(0)));
   Put_Line("T(Last) before :  " & ADatum'Image(T(T'Last)));
   
   -- Increment each of the elements of T :
   for i in T'Range loop
      T(i) := T(i) + 1;
   end loop;
   
   Put_Line("T(0)    after  :  " & ADatum'Image(T(0)));
   Put_Line("T(Last) after  :  " & ADatum'Image(T(T'Last)));
   
   --- Optional, finalizer always syncs in this example
   --  Cryo.Sync;
   
   --- Test of Zap -- uncomment and get zeroized payload every time :
   --  Cryo.Zap;
   
   Put_Line("OK.");
   
end CryoDemo;