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------------------------------------------------------------------------------

--                                                                          --

--                        GNAT RUN-TIME COMPONENTS                          --

--                                                                          --

--                               S Y S T E M                                --

--                                                                          --

--                                 S p e c                                  --

--                (OpenVMS 64bit GCC_ZCX DEC Threads Version)               --

--                                                                          --

--          Copyright (C) 1992-2011, Free Software Foundation, Inc.         --

--                                                                          --

-- This specification is derived from the Ada Reference Manual for use with --

-- GNAT. The copyright notice above, and the license provisions that follow --

-- apply solely to the  contents of the part following the private keyword. --

--                                                                          --

-- GNAT is free software;  you can  redistribute it  and/or modify it under --

-- terms of the  GNU General Public License as published  by the Free Soft- --

-- ware  Foundation;  either version 3,  or (at your option) any later ver- --

-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --

-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --

-- or FITNESS FOR A PARTICULAR PURPOSE.                                     --

--                                                                          --

-- As a special exception under Section 7 of GPL version 3, you are granted --

-- additional permissions described in the GCC Runtime Library Exception,   --

-- version 3.1, as published by the Free Software Foundation.               --

--                                                                          --

-- You should have received a copy of the GNU General Public License and    --

-- a copy of the GCC Runtime Library Exception along with this program;     --

-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --

-- <http://www.gnu.org/licenses/>.                                          --

--                                                                          --

-- GNAT was originally developed  by the GNAT team at  New York University. --

-- Extensive contributions were provided by Ada Core Technologies Inc.      --

--                                                                          --

------------------------------------------------------------------------------

package System is

   pragma Pure;

   --  Note that we take advantage of the implementation permission to make

   --  this unit Pure instead of Preelaborable; see RM 13.7.1(15). In Ada

   --  2005, this is Pure in any case (AI-362).

   type Name is (SYSTEM_NAME_GNAT);

   System_Name : constant Name := SYSTEM_NAME_GNAT;

   --  System-Dependent Named Numbers

   Min_Int               : constant := Long_Long_Integer'First;

   Max_Int               : constant := Long_Long_Integer'Last;

   Max_Binary_Modulus    : constant := 2 ** Long_Long_Integer'Size;

   Max_Nonbinary_Modulus : constant := 2 ** Integer'Size - 1;

   Max_Base_Digits       : constant := Long_Long_Float'Digits;

   Max_Digits            : constant := Long_Long_Float'Digits;

   Max_Mantissa          : constant := 63;

   Fine_Delta            : constant := 2.0 ** (-Max_Mantissa);

   Tick                  : constant := 0.01;

   --  Storage-related Declarations

   type Address is new Long_Integer;

   Null_Address : constant Address;

   --  Although this is declared as an integer type, no arithmetic operations

   --  are available (see abstract declarations below), and furthermore there

   --  is special processing in the compiler that prevents the use of integer

   --  literals with this type (use To_Address to convert integer literals).

   --

   --  Conversion to and from Short_Address is however freely permitted, and

   --  is indeed the reason that Address is declared as an integer type.

   Storage_Unit : constant := 8;

   Word_Size    : constant := 64;

   Memory_Size  : constant := 2 ** 64;

   --  Address comparison

   function "<"  (Left, Right : Address) return Boolean;

   function "<=" (Left, Right : Address) return Boolean;

   function ">"  (Left, Right : Address) return Boolean;

   function ">=" (Left, Right : Address) return Boolean;

   function "="  (Left, Right : Address) return Boolean;

   pragma Import (Intrinsic, "<");

   pragma Import (Intrinsic, "<=");

   pragma Import (Intrinsic, ">");

   pragma Import (Intrinsic, ">=");

   pragma Import (Intrinsic, "=");

   --  Abstract declarations for arithmetic operations on type address.

   --  These declarations are needed when Address is non-private. They

   --  avoid excessive visibility of arithmetic operations on address

   --  which are typically available elsewhere (e.g. Storage_Elements)

   --  and which would cause excessive ambiguities in application code.

   function "+"   (Left, Right : Address) return Address is abstract;

   function "-"   (Left, Right : Address) return Address is abstract;

   function "/"   (Left, Right : Address) return Address is abstract;

   function "*"   (Left, Right : Address) return Address is abstract;

   function "mod" (Left, Right : Address) return Address is abstract;

   --  Other System-Dependent Declarations

   type Bit_Order is (High_Order_First, Low_Order_First);

   Default_Bit_Order : constant Bit_Order := Low_Order_First;

   pragma Warnings (Off, Default_Bit_Order); -- kill constant condition warning

   --  Priority-related Declarations (RM D.1)

   Max_Priority           : constant Positive := 30;

   Max_Interrupt_Priority : constant Positive := 31;

   subtype Any_Priority       is Integer      range  0 .. 31;

   subtype Priority           is Any_Priority range  0 .. 30;

   subtype Interrupt_Priority is Any_Priority range 31 .. 31;

   Default_Priority : constant Priority := 15;

private

   Null_Address : constant Address := 0;

   --------------------------------------

   -- System Implementation Parameters --

   --------------------------------------

   --  These parameters provide information about the target that is used

   --  by the compiler. They are in the private part of System, where they

   --  can be accessed using the special circuitry in the Targparm unit

   --  whose source should be consulted for more detailed descriptions

   --  of the individual switch values.

   Backend_Divide_Checks     : constant Boolean := False;

   Backend_Overflow_Checks   : constant Boolean := True;

   Command_Line_Args         : constant Boolean := True;

   Configurable_Run_Time     : constant Boolean := False;

   Denorm                    : constant Boolean := False;

   Duration_32_Bits          : constant Boolean := False;

   Exit_Status_Supported     : constant Boolean := True;

   Fractional_Fixed_Ops      : constant Boolean := False;

   Frontend_Layout           : constant Boolean := False;

   Machine_Overflows         : constant Boolean := False;

   Machine_Rounds            : constant Boolean := True;

   OpenVMS                   : constant Boolean := True;

   Preallocated_Stacks       : constant Boolean := False;

   Signed_Zeros              : constant Boolean := True;

   Stack_Check_Default       : constant Boolean := True;

   Stack_Check_Probes        : constant Boolean := True;

   Stack_Check_Limits        : constant Boolean := False;

   Support_Aggregates        : constant Boolean := True;

   Support_Composite_Assign  : constant Boolean := True;

   Support_Composite_Compare : constant Boolean := True;

   Support_Long_Shifts       : constant Boolean := True;

   Always_Compatible_Rep     : constant Boolean := True;

   Suppress_Standard_Library : constant Boolean := False;

   Use_Ada_Main_Program_Name : constant Boolean := False;

   ZCX_By_Default            : constant Boolean := True;

   --------------------------

   -- Underlying Priorities --

   ---------------------------

   --  Important note: this section of the file must come AFTER the

   --  definition of the system implementation parameters to ensure

   --  that the value of these parameters is available for analysis

   --  of the declarations here (using Rtsfind at compile time).

   --  The underlying priorities table provides a generalized mechanism

   --  for mapping from Ada priorities to system priorities. In some

   --  cases a 1-1 mapping is not the convenient or optimal choice.

   --  For DEC Threads OpenVMS, we use the full range of 31 priorities

   --  in the Ada model, but map them by compression onto the more limited

   --  range of priorities available in OpenVMS.

   --  To replace the default values of the Underlying_Priorities mapping,

   --  copy this source file into your build directory, edit the file to

   --  reflect your desired behavior, and recompile with the command:

   --     $ gcc -c -O3 -gnatpgn system.ads

   --  then recompile the run-time parts that depend on this package:

   --     $ gnatmake -a -gnatn -O3 <your application>

   --  then force rebuilding your application if you need different options:

   --     $ gnatmake -f <your options> <your application>

   type Priorities_Mapping is array (Any_Priority) of Integer;

   pragma Suppress_Initialization (Priorities_Mapping);

   --  Suppress initialization in case gnat.adc specifies Normalize_Scalars

   Underlying_Priorities : constant Priorities_Mapping :=

     (Priority'First => 16,

      1  => 17,

      2  => 18,

      3  => 18,

      4  => 18,

      5  => 18,

      6  => 19,

      7  => 19,

      8  => 19,

      9  => 20,

      10 => 20,

      11 => 21,

      12 => 21,

      13 => 22,

      14 => 23,

      Default_Priority   => 24,

      16 => 25,

      17 => 25,

      18 => 25,

      19 => 26,

      20 => 26,

      21 => 26,

      22 => 27,

      23 => 27,

      24 => 27,

      25 => 28,

      26 => 28,

      27 => 29,

      28 => 29,

      29 => 30,

      Priority'Last      => 30,

      Interrupt_Priority => 31);

   ----------------------------

   -- Special VMS Interfaces --

   ----------------------------

   procedure Lib_Stop (Cond_Value : Integer);

   pragma Interface (C, Lib_Stop);

   pragma Import_Procedure (Lib_Stop, "LIB$STOP", Mechanism => (Value));

   --  Interface to VMS condition handling. Used by RTSfind and pragma

   --  {Import,Export}_Exception. Put here because this is the only

   --  VMS specific package that doesn't drag in tasking.

   ADA_GNAT : constant Boolean := True;

   pragma Export_Object (ADA_GNAT, "ADA$GNAT");

   --  Ubiquitous global symbol identifying a GNAT compiled image to VMS Debug.

   --  Do not remove!

   pragma Ident ("GNAT"); --  Gnat_Static_Version_String

   --  Default ident for all VMS images.

end System;