-----------------------------------------------------------------------------
--                                                                          --
--                         GNAT COMPILER COMPONENTS                         --
--                                                                          --
--                         I N T E R F A C E S . C                          --
--                                                                          --
--                                 S p e c                                  --
--                                                                          --
--                            $Revision: 2 $                              --
--                                                                          --
-- This specification is adapted from the Ada Reference Manual for use with --
-- GNAT.  In accordance with the copyright of that document, you can freely --
-- copy and modify this specification,  provided that if you redistribute a --
-- modified version,  any changes that you have made are clearly indicated. --
--                                                                          --
------------------------------------------------------------------------------

with Unchecked_Conversion;

package Interfaces.C is
pragma Pure (C);

   --  Declaration's based on C's <limits.h>

   CHAR_BIT  : constant := 8;
   SCHAR_MIN : constant := -128;
   SCHAR_MAX : constant := 127;
   UCHAR_MAX : constant := 255;

   --  Signed and Unsigned Integers. Note that in GNAT, we have ensured that
   --  the standard predefined Ada types correspond to the standard C types

   type int   is new Integer;
   type short is new Short_Integer;
   type long  is new Long_Integer;

   type signed_char is range SCHAR_MIN .. SCHAR_MAX;
   for signed_char'Size use CHAR_BIT;

   type unsigned       is mod 2 ** Integer'Size;
   type unsigned_short is mod 2 ** Short_Integer'Size;
   type unsigned_long  is mod 2 ** Long_Integer'Size;

   type unsigned_char is mod (UCHAR_MAX + 1);
   for unsigned_char'Size use CHAR_BIT;

   subtype plain_char is unsigned_char; -- ??? should be parametrized

   type ptrdiff_t is new Integer;       -- ??? should be parametrized

   type size_t is mod 2 ** 32;          -- ??? should be parametrized

   --  Floating-Point

   type C_float     is new Float;

   type double      is new Standard.Long_Float;

   type long_double is new Standard.Long_Long_Float;

   ----------------------------
   -- Characters and Strings --
   ----------------------------

   type char is new Character;

   nul : constant char := char'First;

   function To_C   (Item : Character) return char;
   function To_Ada (Item : char)      return Character;

   type char_array is array (size_t range <>) of aliased char;
   pragma Pack (char_array);
   for char_array'Component_Size use CHAR_BIT;

   function Is_Nul_Terminated (Item : in char_array) return Boolean;

   function To_C
     (Item       : in String;
      Append_Nul : in Boolean := True)
      return       char_array;

   function To_Ada
     (Item     : in char_array;
      Trim_Nul : in Boolean := True)
      return     String;

   procedure To_C
     (Item       : in String;
      Target     : out char_array;
      Count      : out size_t;
      Append_Nul : in Boolean := True);

   procedure To_Ada
     (Item     : in char_array;
      Target   : out String;
      Count    : out Natural;
      Trim_Nul : in Boolean := True);

   ------------------------------------
   -- Wide Character and Wide String --
   ------------------------------------

   type wchar_t is new Wide_Character;
   wide_nul : constant wchar_t := wchar_t'First;

   function To_C   (Item : in Wide_Character) return wchar_t;
   function To_Ada (Item : in wchar_t)        return Wide_Character;

   type wchar_array is array (size_t range <>) of aliased wchar_t;
   pragma Pack (wchar_array);

   function Is_Nul_Terminated (Item : in wchar_array) return Boolean;

   function To_C
     (Item       : in Wide_String;
      Append_Nul : in Boolean := True)
      return       wchar_array;

   function To_Ada
     (Item     : in wchar_array;
      Trim_Nul : in Boolean := True)
      return     Wide_String;

   procedure To_C
     (Item       : in Wide_String;
      Target     : out wchar_array;
      Count      : out size_t;
      Append_Nul : in Boolean := True);

   procedure To_Ada
     (Item     : in wchar_array;
      Target   : out Wide_String;
      Count    : out Natural;
      Trim_Nul : in Boolean := True);

   Terminator_Error : exception;

private
   --  The following instantiations of unchecked conversion are used to
   --  provide functions for the renamings which appear below. We can't
   --  use direct instantiations of unchecked conversions for functions
   --  like To_Ada, since we would have the wrong formal parameter names.

   function Character_To_char is new
     Unchecked_Conversion (Character, char);

   function char_To_Character is new
     Unchecked_Conversion (char, Character);

   function wchar_t_To_Wide_Character is new
     Unchecked_Conversion (wchar_t, Wide_Character);

   function Wide_Character_To_wchar_t is new
     Unchecked_Conversion (Wide_Character, wchar_t);

   --  The following declarations don't work, because of a bug in renaming
   --  intrinsic functions. For now we have made separate bodies pending
   --  resolution of this bug ???.

--   function To_C (Item : Character) return char
--     renames Character_To_char;

--   function To_Ada (Item : char) return Character
--     renames char_To_Character;

--   function To_C (Item : in Wide_Character) return wchar_t
--     renames Wide_Character_To_wchar_t;

--   function To_Ada (Item : in wchar_t) return Wide_Character
--     renames wchar_t_To_Wide_Character;

end Interfaces.C;