------------------------------------------------------------------------------
------------------------------------------------------------------------------
-- This file is part of 'Cryostat', an Ada library for persistent storage.  --
--                                                                          --
-- (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.                                          --
------------------------------------------------------------------------------
------------------------------------------------------------------------------

------------------------------------------------------------------------------
-- WARNING : MIPS32/64 currently unsupported!                               --
-- See also: http://logs.nosuchlabs.com/log/trilema/2018-10-24#1865524      --
------------------------------------------------------------------------------

with Interfaces;   use Interfaces;
with Interfaces.C;
with System;       use System;


package Unix is

   pragma Preelaborate;
   
   -- Machine Word
   type Word is mod 2**Standard'Address_Size;
   
   -- Byte
   type Byte is mod 2**8;
   
   -- Unit int
   type Unix_Int is mod 2**Interfaces.C.int'Size;
   
   -- File descriptors
   type FD is new Unix_Int;
   
   type MM_Prot is new Unix_Int;
   PROT_READ   : constant MM_Prot := 1;
   PROT_WRITE  : constant MM_Prot := 2;
   
   type MM_Flags is new Unix_Int;
   MAP_NONE    : constant MM_Flags := 16#00#;
   MAP_FIXED   : constant MM_Flags := 16#10#;
   MAP_SHARED  : constant MM_Flags := 16#01#;
   MAP_PRIVATE : constant MM_Flags := 16#02#;
   -- TODO: MAP_HUGETLB
   
   -- Null Pointer
   NullPtr : constant Address := System'To_Address(0);
   
   function MMap
     (Start  : Address := NullPtr;
      Length : Word;
      Prot   : MM_Prot;
      Flags  : MM_Flags;
      Handle : FD;
      Off_T  : Word := 0)
     return Address;
   pragma Import(C, MMap, "mmap");
   
   -- Eggog code '-1' (posix uses instead of null here)
   MAP_FAILED : constant Address := System'To_Address(Word'Last);
   
   function MUnmap
     (Start  : Address;
      Length : Word)
     return Unix_Int;
   pragma Import(C, MUnmap, "munmap");
   
   type O_Flags is new Unix_Int;
   O_RDONLY : constant O_Flags := 8#00#;
   O_WRONLY : constant O_Flags := 8#01#;
   O_RDWR   : constant O_Flags := 8#02#;
   O_CREAT  : constant O_Flags := 8#0100#;
   
   type M_Flags is new Unix_Int;
   MS_ASYNC      : constant M_Flags := 1;
   MS_INVALIDATE : constant M_Flags := 2;
   MS_SYNC       : constant M_Flags := 4;
   
   function MSync
     (Addr   : Address;
      Length : Word;
      Flags  : M_Flags)
     return Unix_Int;
   pragma Import(C, MSync, "msync");
   
   function Open
     (Name  : System.Address;
      Flags : O_Flags;
      Mode  : Unix_Int := 8#666#) -- TODO
     return FD;
   pragma Import(C, Open, "open");
   
   -- '-1'
   FD_EGGOG : constant FD := FD'Last;
   
   function Close(Handle : FD) return Unix_Int;
   pragma Import(C, Close, "close");
   
   function FTruncate(Handle : FD; Length : Word) return Unix_Int;
   pragma Import(C, FTruncate, "ftruncate");
   
end Unix;