gcc/ada/system.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                        GNAT RUN-TIME COMPONENTS                          --
   4 --                                                                          --
   5 --                               S Y S T E M                                --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                            (Compiler Version)                            --
   9 --                                                                          --
  10 --          Copyright (C) 1992-2015, 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
  37 --  This version of System is a generic version that is used in building the
  38 --  compiler. Right now, we have a host/target problem if we try to use the
  39 --  "proper" System, and since the compiler itself does not care about most
  40 --  System parameters, this generic version works fine.
  41
  42 pragma Restrictions (No_Implicit_Dynamic_Code);
  43 --  We want to avoid trampolines in the compiler, so it can be used in systems
  44 --  which prevent execution of code on the stack, e.g. in windows environments
  45 --  with DEP (Data Execution Protection) enabled.
  46
  47 package System is
  48    pragma Pure;
  49    --  Note that we take advantage of the implementation permission to make
  50    --  this unit Pure instead of Preelaborable; see RM 13.7.1(15). In Ada
  51    --  2005, this is Pure in any case (AI-362).
  52
  53    pragma No_Elaboration_Code_All;
  54    --  Allow the use of that restriction in units that WITH this unit
  55
  56    type Name is (SYSTEM_NAME_GNAT);
  57    System_Name : constant Name := SYSTEM_NAME_GNAT;
  58
  59    --  System-Dependent Named Numbers
  60
  61    Min_Int               : constant := Long_Long_Integer'First;
  62    Max_Int               : constant := Long_Long_Integer'Last;
  63
  64    Max_Binary_Modulus    : constant := 2 ** Long_Long_Integer'Size;
  65    Max_Nonbinary_Modulus : constant := 2 ** Integer'Size - 1;
  66
  67    Max_Base_Digits       : constant := Long_Long_Float'Digits;
  68    Max_Digits            : constant := Long_Long_Float'Digits;
  69
  70    Max_Mantissa          : constant := 63;
  71    Fine_Delta            : constant := 2.0 ** (-Max_Mantissa);
  72
  73    Tick                  : constant := 0.01;
  74
  75    --  Storage-related Declarations
  76
  77    type Address is private;
  78    --  Note that we do NOT add pragma Preelaborable_Initialization in this
  79    --  version of System, since it is used for the compiler only, and typical
  80    --  earlier bootstrap compilers don't support this pragma. We don't need
  81    --  it in this context, so there is no problem in omitting it.
  82    Null_Address : constant Address;
  83
  84    Storage_Unit : constant := Standard'Storage_Unit;
  85    Word_Size    : constant := Standard'Word_Size;
  86    Memory_Size  : constant := 2 ** Standard'Address_Size;
  87
  88    --  Address comparison
  89
  90    function "<"  (Left, Right : Address) return Boolean;
  91    function "<=" (Left, Right : Address) return Boolean;
  92    function ">"  (Left, Right : Address) return Boolean;
  93    function ">=" (Left, Right : Address) return Boolean;
  94    function "="  (Left, Right : Address) return Boolean;
  95
  96    pragma Import (Intrinsic, "<");
  97    pragma Import (Intrinsic, "<=");
  98    pragma Import (Intrinsic, ">");
  99    pragma Import (Intrinsic, ">=");
 100    pragma Import (Intrinsic, "=");
 101
 102    --  Other System-Dependent Declarations
 103
 104    type Bit_Order is (High_Order_First, Low_Order_First);
 105    Default_Bit_Order : constant Bit_Order :=
 106                          Bit_Order'Val (Standard'Default_Bit_Order);
 107    pragma Warnings (Off, Default_Bit_Order); -- kill constant condition warning
 108
 109    --  Priority-related Declarations (RM D.1)
 110
 111    Max_Priority           : constant Positive := 30;
 112    Max_Interrupt_Priority : constant Positive := 31;
 113
 114    subtype Any_Priority       is Integer      range  0 .. 31;
 115    subtype Priority           is Any_Priority range  0 .. 30;
 116    subtype Interrupt_Priority is Any_Priority range 31 .. 31;
 117
 118    Default_Priority : constant Priority := 15;
 119
 120 private
 121
 122    type Address is mod Memory_Size;
 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 by
 130    --  the compiler. They are in the private part of System, where they can be
 131    --  accessed using the special circuitry in the Targparm unit whose source
 132    --  should be consulted for more detailed descriptions of the individual
 133    --  switch values.
 134
 135    --  This version of system.ads is used only for building the compiler.
 136    --  We really ought to use the proper target system (i.e. the one that
 137    --  corresponds to the host for the compiler), but that causes as yet
 138    --  unsolved makefile problems. For the most part the setting of these
 139    --  parameters is not too critical for the compiler version (e.g. we
 140    --  do not use floating-point anyway in the compiler).
 141
 142    AAMP                      : constant Boolean := False;
 143    Backend_Divide_Checks     : constant Boolean := False;
 144    Backend_Overflow_Checks   : constant Boolean := False;
 145    Command_Line_Args         : constant Boolean := True;
 146    Configurable_Run_Time     : constant Boolean := False;
 147    Denorm                    : constant Boolean := True;
 148    Duration_32_Bits          : constant Boolean := False;
 149    Exit_Status_Supported     : constant Boolean := True;
 150    Fractional_Fixed_Ops      : constant Boolean := False;
 151    Frontend_Layout           : constant Boolean := False;
 152    Machine_Overflows         : constant Boolean := False;
 153    Machine_Rounds            : constant Boolean := True;
 154    Preallocated_Stacks       : constant Boolean := False;
 155    Signed_Zeros              : constant Boolean := True;
 156    Stack_Check_Default       : constant Boolean := False;
 157    Stack_Check_Probes        : constant Boolean := False;
 158    Stack_Check_Limits        : constant Boolean := False;
 159    Support_Aggregates        : constant Boolean := True;
 160    Support_Composite_Assign  : constant Boolean := True;
 161    Support_Composite_Compare : constant Boolean := True;
 162    Support_Long_Shifts       : constant Boolean := True;
 163    Always_Compatible_Rep     : constant Boolean := True;
 164    Suppress_Standard_Library : constant Boolean := False;
 165    Use_Ada_Main_Program_Name : constant Boolean := False;
 166    Frontend_Exceptions       : constant Boolean := True;
 167    ZCX_By_Default            : constant Boolean := False;
 168
 169    --  Obsolete entries, to be removed eventually (bootstrap issues)
 170
 171    Front_End_ZCX_Support     : constant Boolean := False;
 172    High_Integrity_Mode       : constant Boolean := False;
 173    Long_Shifts_Inlined       : constant Boolean := True;
 174    Functions_Return_By_DSP   : constant Boolean := False;
 175    Support_64_Bit_Divides    : constant Boolean := True;
 176    GCC_ZCX_Support           : constant Boolean := False;
 177
 178 end System;