gcc/ada/5vsystem.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                        GNAT RUN-TIME COMPONENTS                          --
   4 --                                                                          --
   5 --                               S Y S T E M                                --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                       (OpenVMS DEC Threads Version)                      --
   9 --                                                                          --
  10 --          Copyright (C) 1992-2003 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 2,  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.  See the GNU General Public License --
  22 -- for  more details.  You should have  received  a copy of the GNU General --
  23 -- Public License  distributed with GNAT;  see file COPYING.  If not, write --
  24 -- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
  25 -- MA 02111-1307, USA.                                                      --
  26 --                                                                          --
  27 -- As a special exception,  if other files  instantiate  generics from this --
  28 -- unit, or you link  this unit with other files  to produce an executable, --
  29 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  30 -- covered  by the  GNU  General  Public  License.  This exception does not --
  31 -- however invalidate  any other reasons why  the executable file  might be --
  32 -- covered by the  GNU Public License.                                      --
  33 --                                                                          --
  34 -- GNAT was originally developed  by the GNAT team at  New York University. --
  35 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  36 --                                                                          --
  37 ------------------------------------------------------------------------------
  38
  39 package System is
  40 pragma Pure (System);
  41 --  Note that we take advantage of the implementation permission to
  42 --  make this unit Pure instead of Preelaborable, see RM 13.7(36)
  43
  44    type Name is (SYSTEM_NAME_GNAT);
  45    System_Name : constant Name := SYSTEM_NAME_GNAT;
  46
  47    --  System-Dependent Named Numbers
  48
  49    Min_Int               : constant := Long_Long_Integer'First;
  50    Max_Int               : constant := Long_Long_Integer'Last;
  51
  52    Max_Binary_Modulus    : constant := 2 ** Long_Long_Integer'Size;
  53    Max_Nonbinary_Modulus : constant := Integer'Last;
  54
  55    Max_Base_Digits       : constant := Long_Long_Float'Digits;
  56    Max_Digits            : constant := Long_Long_Float'Digits;
  57
  58    Max_Mantissa          : constant := 63;
  59    Fine_Delta            : constant := 2.0 ** (-Max_Mantissa);
  60
  61    Tick                  : constant := 0.01;
  62
  63    --  Storage-related Declarations
  64
  65    type Address is private;
  66    Null_Address : constant Address;
  67
  68    Storage_Unit : constant := 8;
  69    Word_Size    : constant := 32;
  70    Memory_Size  : constant := 2 ** 32;
  71
  72    --  Address comparison
  73
  74    function "<"  (Left, Right : Address) return Boolean;
  75    function "<=" (Left, Right : Address) return Boolean;
  76    function ">"  (Left, Right : Address) return Boolean;
  77    function ">=" (Left, Right : Address) return Boolean;
  78    function "="  (Left, Right : Address) return Boolean;
  79
  80    pragma Import (Intrinsic, "<");
  81    pragma Import (Intrinsic, "<=");
  82    pragma Import (Intrinsic, ">");
  83    pragma Import (Intrinsic, ">=");
  84    pragma Import (Intrinsic, "=");
  85
  86    --  Other System-Dependent Declarations
  87
  88    type Bit_Order is (High_Order_First, Low_Order_First);
  89    Default_Bit_Order : constant Bit_Order := Low_Order_First;
  90
  91    --  Priority-related Declarations (RM D.1)
  92
  93    Max_Priority           : constant Positive := 30;
  94    Max_Interrupt_Priority : constant Positive := 31;
  95
  96    subtype Any_Priority       is Integer      range  0 .. 31;
  97    subtype Priority           is Any_Priority range  0 .. 30;
  98    subtype Interrupt_Priority is Any_Priority range 31 .. 31;
  99
 100    Default_Priority : constant Priority := 15;
 101
 102 private
 103
 104    type Address is mod Memory_Size;
 105    Null_Address : constant Address := 0;
 106
 107    --------------------------------------
 108    -- System Implementation Parameters --
 109    --------------------------------------
 110
 111    --  These parameters provide information about the target that is used
 112    --  by the compiler. They are in the private part of System, where they
 113    --  can be accessed using the special circuitry in the Targparm unit
 114    --  whose source should be consulted for more detailed descriptions
 115    --  of the individual switch values.
 116
 117    AAMP                      : constant Boolean := False;
 118    Backend_Divide_Checks     : constant Boolean := False;
 119    Backend_Overflow_Checks   : constant Boolean := False;
 120    Command_Line_Args         : constant Boolean := True;
 121    Denorm                    : constant Boolean := False;
 122    Exit_Status_Supported     : constant Boolean := True;
 123    Fractional_Fixed_Ops      : constant Boolean := False;
 124    Frontend_Layout           : constant Boolean := False;
 125    Functions_Return_By_DSP   : constant Boolean := False;
 126    High_Integrity_Mode       : constant Boolean := False;
 127    Long_Shifts_Inlined       : constant Boolean := False;
 128    Machine_Overflows         : constant Boolean := False;
 129    Machine_Rounds            : constant Boolean := True;
 130    OpenVMS                   : constant Boolean := True;
 131    Signed_Zeros              : constant Boolean := True;
 132    Stack_Check_Default       : constant Boolean := True;
 133    Stack_Check_Probes        : constant Boolean := True;
 134    Use_Ada_Main_Program_Name : constant Boolean := False;
 135    ZCX_By_Default            : constant Boolean := True;
 136    GCC_ZCX_Support           : constant Boolean := False;
 137    Front_End_ZCX_Support     : constant Boolean := True;
 138
 139    --------------------------
 140    -- Underlying Priorities --
 141    ---------------------------
 142
 143    --  Important note: this section of the file must come AFTER the
 144    --  definition of the system implementation parameters to ensure
 145    --  that the value of these parameters is available for analysis
 146    --  of the declarations here (using Rtsfind at compile time).
 147
 148    --  The underlying priorities table provides a generalized mechanism
 149    --  for mapping from Ada priorities to system priorities. In some
 150    --  cases a 1-1 mapping is not the convenient or optimal choice.
 151
 152    --  For DEC Threads OpenVMS, we use the full range of 31 priorities
 153    --  in the Ada model, but map them by compression onto the more limited
 154    --  range of priorities available in OpenVMS.
 155
 156    --  To replace the default values of the Underlying_Priorities mapping,
 157    --  copy this source file into your build directory, edit the file to
 158    --  reflect your desired behavior, and recompile with the command:
 159
 160    --     $ gcc -c -O3 -gnatpgn system.ads
 161
 162    --  then recompile the run-time parts that depend on this package:
 163
 164    --     $ gnatmake -a -gnatn -O3 <your application>
 165
 166    --  then force rebuilding your application if you need different options:
 167
 168    --     $ gnatmake -f <your options> <your application>
 169
 170    type Priorities_Mapping is array (Any_Priority) of Integer;
 171    pragma Suppress_Initialization (Priorities_Mapping);
 172    --  Suppress initialization in case gnat.adc specifies Normalize_Scalars
 173
 174    Underlying_Priorities : constant Priorities_Mapping :=
 175
 176      (Priority'First => 16,
 177
 178       1  => 17,
 179       2  => 18,
 180       3  => 18,
 181       4  => 18,
 182       5  => 18,
 183       6  => 19,
 184       7  => 19,
 185       8  => 19,
 186       9  => 20,
 187       10 => 20,
 188       11 => 21,
 189       12 => 21,
 190       13 => 22,
 191       14 => 23,
 192
 193       Default_Priority   => 24,
 194
 195       16 => 25,
 196       17 => 25,
 197       18 => 25,
 198       19 => 26,
 199       20 => 26,
 200       21 => 26,
 201       22 => 27,
 202       23 => 27,
 203       24 => 27,
 204       25 => 28,
 205       26 => 28,
 206       27 => 29,
 207       28 => 29,
 208       29 => 30,
 209
 210       Priority'Last      => 30,
 211
 212       Interrupt_Priority => 31);
 213
 214    ----------------------------
 215    -- Special VMS Interfaces --
 216    ----------------------------
 217
 218    procedure Lib_Stop (I : in Integer);
 219    pragma Interface (C, Lib_Stop);
 220    pragma Import_Procedure (Lib_Stop, "LIB$STOP", Mechanism => (Value));
 221    --  Interface to VMS condition handling. Used by RTSfind and pragma
 222    --  {Import,Export}_Exception. Put here because this is the only
 223    --  VMS specific package that doesn't drag in tasking.
 224
 225 end System;