1------------------------------------------------------------------------------
2--                                                                          --
3--                        GNAT RUN-TIME COMPONENTS                          --
4--                                                                          --
5--                               S Y S T E M                                --
6--                                                                          --
7--                                 S p e c                                  --
8--                (OpenVMS 64bit GCC_ZCX DEC Threads Version)               --
9--                                                                          --
10--          Copyright (C) 1992-2013, Free Software Foundation, Inc.         --
11--                                                                          --
12-- This specification is derived from the Ada Reference Manual for use with --
13-- GNAT. The copyright notice above, and the license provisions that follow --
14-- apply solely to the  contents of the part following the private keyword. --
15--                                                                          --
16-- GNAT is free software;  you can  redistribute it  and/or modify it under --
17-- terms of the  GNU General Public License as published  by the Free Soft- --
18-- ware  Foundation;  either version 3,  or (at your option) any later ver- --
19-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
20-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
21-- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
22--                                                                          --
23-- As a special exception under Section 7 of GPL version 3, you are granted --
24-- additional permissions described in the GCC Runtime Library Exception,   --
25-- version 3.1, as published by the Free Software Foundation.               --
26--                                                                          --
27-- You should have received a copy of the GNU General Public License and    --
28-- a copy of the GCC Runtime Library Exception along with this program;     --
29-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
30-- <http://www.gnu.org/licenses/>.                                          --
31--                                                                          --
32-- GNAT was originally developed  by the GNAT team at  New York University. --
33-- Extensive contributions were provided by Ada Core Technologies Inc.      --
34--                                                                          --
35------------------------------------------------------------------------------
36
37package System is
38   pragma Pure;
39   --  Note that we take advantage of the implementation permission to make
40   --  this unit Pure instead of Preelaborable; see RM 13.7.1(15). In Ada
41   --  2005, this is Pure in any case (AI-362).
42
43   type Name is (SYSTEM_NAME_GNAT);
44   System_Name : constant Name := SYSTEM_NAME_GNAT;
45
46   --  System-Dependent Named Numbers
47
48   Min_Int               : constant := Long_Long_Integer'First;
49   Max_Int               : constant := Long_Long_Integer'Last;
50
51   Max_Binary_Modulus    : constant := 2 ** Long_Long_Integer'Size;
52   Max_Nonbinary_Modulus : constant := 2 ** Integer'Size - 1;
53
54   Max_Base_Digits       : constant := Long_Long_Float'Digits;
55   Max_Digits            : constant := Long_Long_Float'Digits;
56
57   Max_Mantissa          : constant := 63;
58   Fine_Delta            : constant := 2.0 ** (-Max_Mantissa);
59
60   Tick                  : constant := 0.01;
61
62   --  Storage-related Declarations
63
64   type Address is new Long_Integer;
65   Null_Address : constant Address;
66   --  Although this is declared as an integer type, no arithmetic operations
67   --  are available (see abstract declarations below), and furthermore there
68   --  is special processing in the compiler that prevents the use of integer
69   --  literals with this type (use To_Address to convert integer literals).
70   --
71   --  Conversion to and from Short_Address is however freely permitted, and
72   --  is indeed the reason that Address is declared as an integer type.
73
74   Storage_Unit : constant := 8;
75   Word_Size    : constant := 64;
76   Memory_Size  : constant := 2 ** 64;
77
78   --  Address comparison
79
80   function "<"  (Left, Right : Address) return Boolean;
81   function "<=" (Left, Right : Address) return Boolean;
82   function ">"  (Left, Right : Address) return Boolean;
83   function ">=" (Left, Right : Address) return Boolean;
84   function "="  (Left, Right : Address) return Boolean;
85
86   pragma Import (Intrinsic, "<");
87   pragma Import (Intrinsic, "<=");
88   pragma Import (Intrinsic, ">");
89   pragma Import (Intrinsic, ">=");
90   pragma Import (Intrinsic, "=");
91
92   --  Abstract declarations for arithmetic operations on type address.
93   --  These declarations are needed when Address is non-private. They
94   --  avoid excessive visibility of arithmetic operations on address
95   --  which are typically available elsewhere (e.g. Storage_Elements)
96   --  and which would cause excessive ambiguities in application code.
97
98   function "+"   (Left, Right : Address) return Address is abstract;
99   function "-"   (Left, Right : Address) return Address is abstract;
100   function "/"   (Left, Right : Address) return Address is abstract;
101   function "*"   (Left, Right : Address) return Address is abstract;
102   function "mod" (Left, Right : Address) return Address is abstract;
103
104   --  Other System-Dependent Declarations
105
106   type Bit_Order is (High_Order_First, Low_Order_First);
107   Default_Bit_Order : constant Bit_Order := Low_Order_First;
108   pragma Warnings (Off, Default_Bit_Order); -- kill constant condition warning
109
110   --  Priority-related Declarations (RM D.1)
111
112   Max_Priority           : constant Positive := 30;
113   Max_Interrupt_Priority : constant Positive := 31;
114
115   subtype Any_Priority       is Integer      range  0 .. 31;
116   subtype Priority           is Any_Priority range  0 .. 30;
117   subtype Interrupt_Priority is Any_Priority range 31 .. 31;
118
119   Default_Priority : constant Priority := 15;
120
121private
122
123   Null_Address : constant Address := 0;
124
125   --------------------------------------
126   -- System Implementation Parameters --
127   --------------------------------------
128
129   --  These parameters provide information about the target that is used
130   --  by the compiler. They are in the private part of System, where they
131   --  can be accessed using the special circuitry in the Targparm unit
132   --  whose source should be consulted for more detailed descriptions
133   --  of the individual switch values.
134
135   Backend_Divide_Checks     : constant Boolean := False;
136   Backend_Overflow_Checks   : constant Boolean := True;
137   Command_Line_Args         : constant Boolean := True;
138   Configurable_Run_Time     : constant Boolean := False;
139   Denorm                    : constant Boolean := False;
140   Duration_32_Bits          : constant Boolean := False;
141   Exit_Status_Supported     : constant Boolean := True;
142   Fractional_Fixed_Ops      : constant Boolean := False;
143   Frontend_Layout           : constant Boolean := False;
144   Machine_Overflows         : constant Boolean := False;
145   Machine_Rounds            : constant Boolean := True;
146   OpenVMS                   : constant Boolean := True;
147   VAX_Float                 : constant Boolean := False;
148   Preallocated_Stacks       : constant Boolean := False;
149   Signed_Zeros              : constant Boolean := True;
150   Stack_Check_Default       : constant Boolean := True;
151   Stack_Check_Probes        : constant Boolean := True;
152   Stack_Check_Limits        : constant Boolean := False;
153   Support_Aggregates        : constant Boolean := True;
154   Support_Atomic_Primitives : constant Boolean := True;
155   Support_Composite_Assign  : constant Boolean := True;
156   Support_Composite_Compare : constant Boolean := True;
157   Support_Long_Shifts       : constant Boolean := True;
158   Always_Compatible_Rep     : constant Boolean := True;
159   Suppress_Standard_Library : constant Boolean := False;
160   Use_Ada_Main_Program_Name : constant Boolean := False;
161   ZCX_By_Default            : constant Boolean := True;
162
163   --------------------------
164   -- Underlying Priorities --
165   ---------------------------
166
167   --  Important note: this section of the file must come AFTER the
168   --  definition of the system implementation parameters to ensure
169   --  that the value of these parameters is available for analysis
170   --  of the declarations here (using Rtsfind at compile time).
171
172   --  The underlying priorities table provides a generalized mechanism
173   --  for mapping from Ada priorities to system priorities. In some
174   --  cases a 1-1 mapping is not the convenient or optimal choice.
175
176   --  For DEC Threads OpenVMS, we use the full range of 31 priorities
177   --  in the Ada model, but map them by compression onto the more limited
178   --  range of priorities available in OpenVMS.
179
180   --  To replace the default values of the Underlying_Priorities mapping,
181   --  copy this source file into your build directory, edit the file to
182   --  reflect your desired behavior, and recompile with the command:
183
184   --     $ gcc -c -O3 -gnatpgn system.ads
185
186   --  then recompile the run-time parts that depend on this package:
187
188   --     $ gnatmake -a -gnatn -O3 <your application>
189
190   --  then force rebuilding your application if you need different options:
191
192   --     $ gnatmake -f <your options> <your application>
193
194   type Priorities_Mapping is array (Any_Priority) of Integer;
195   pragma Suppress_Initialization (Priorities_Mapping);
196   --  Suppress initialization in case gnat.adc specifies Normalize_Scalars
197
198   Underlying_Priorities : constant Priorities_Mapping :=
199
200     (Priority'First => 16,
201
202      1  => 17,
203      2  => 18,
204      3  => 18,
205      4  => 18,
206      5  => 18,
207      6  => 19,
208      7  => 19,
209      8  => 19,
210      9  => 20,
211      10 => 20,
212      11 => 21,
213      12 => 21,
214      13 => 22,
215      14 => 23,
216
217      Default_Priority   => 24,
218
219      16 => 25,
220      17 => 25,
221      18 => 25,
222      19 => 26,
223      20 => 26,
224      21 => 26,
225      22 => 27,
226      23 => 27,
227      24 => 27,
228      25 => 28,
229      26 => 28,
230      27 => 29,
231      28 => 29,
232      29 => 30,
233
234      Priority'Last      => 30,
235
236      Interrupt_Priority => 31);
237
238   ----------------------------
239   -- Special VMS Interfaces --
240   ----------------------------
241
242   procedure Lib_Stop (Cond_Value : Integer);
243   pragma Import (C, Lib_Stop);
244   pragma Import_Procedure (Lib_Stop, "LIB$STOP", Mechanism => (Value));
245   --  Interface to VMS condition handling. Used by RTSfind and pragma
246   --  {Import,Export}_Exception. Put here because this is the only
247   --  VMS specific package that doesn't drag in tasking.
248
249   ADA_GNAT : constant Boolean := True;
250   pragma Export_Object (ADA_GNAT, "ADA$GNAT");
251   --  Ubiquitous global symbol identifying a GNAT compiled image to VMS Debug.
252   --  Do not remove.
253
254   pragma Ident ("GNAT"); --  Gnat_Static_Version_String
255   --  Default ident for all VMS images.
256
257end System;
258