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-- This file is part of 'Finite Field Arithmetic', aka 'FFA'.               --
--                                                                          --
-- (C) 2017 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.                                          --
--                                                                          --
-- See also http://trilema.com/2015/a-new-software-licensing-paradigm .     --
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with Interfaces;   use Interfaces;
with Interfaces.C; use Interfaces.C;


package OS is
   
   -- Receive a character from the TTY, and True if success (False if EOF)
   function Read_Char(C : out Character) return Boolean;
   
   -- Send a character to the TTY.
   procedure Write_Char(C : in Character);
   
   -- Send a Newline to the TTY.
   procedure Write_Newline;
   
   -- Exit with an error condition report.
   procedure Eggog(M : String);
   
   procedure Quit(Return_Code : Integer);
   pragma Import
     (Convention    => C,
      Entity        => Quit,
      External_Name => "exit");
   
private
   
   -- POSIX stdio:   
   EOF : constant int := -1;

   function GetChar return int;
   pragma Import(C, getchar);
   
   function PutChar(item: int) return int;
   pragma Import(C, putchar);
   
   -- GNATistic
   procedure To_Stderr(C : Character);
   pragma Import(Ada, To_Stderr, "__gnat_to_stderr_char");
   
   Sadness_Code : constant Integer := -1;
   
end OS;