gcc/ada/s-parame.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                    S Y S T E M . P A R A M E T E R S                     --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                                                                          --
   9 --                            $Revision: 1.1 $
  10 --                                                                          --
  11 --          Copyright (C) 1992-2000 Free Software Foundation, Inc.          --
  12 --                                                                          --
  13 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  14 -- terms of the  GNU General Public License as published  by the Free Soft- --
  15 -- ware  Foundation;  either version 2,  or (at your option) any later ver- --
  16 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  17 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  18 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  19 -- for  more details.  You should have  received  a copy of the GNU General --
  20 -- Public License  distributed with GNAT;  see file COPYING.  If not, write --
  21 -- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
  22 -- MA 02111-1307, USA.                                                      --
  23 --                                                                          --
  24 -- As a special exception,  if other files  instantiate  generics from this --
  25 -- unit, or you link  this unit with other files  to produce an executable, --
  26 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  27 -- covered  by the  GNU  General  Public  License.  This exception does not --
  28 -- however invalidate  any other reasons why  the executable file  might be --
  29 -- covered by the  GNU Public License.                                      --
  30 --                                                                          --
  31 -- GNAT was originally developed  by the GNAT team at  New York University. --
  32 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  33 --                                                                          --
  34 ------------------------------------------------------------------------------
  35
  36 --  This is the default version used for all systems for which no special
  37 --  target-specific version of this package is provided.
  38
  39 --  This package defines some system dependent parameters for GNAT. These
  40 --  are values that are referenced by the runtime library and are therefore
  41 --  relevant to the target machine.
  42
  43 --  The parameters whose value is defined in the spec are not generally
  44 --  expected to be changed. If they are changed, it will be necessary to
  45 --  recompile the run-time library.
  46
  47 --  The parameters which are defined by functions can be changed by modifying
  48 --  the body of System.Parameters in file s-parame.adb. A change to this body
  49 --  requires only rebinding and relinking of the application.
  50
  51 --  Note: do not introduce any pragma Inline statements into this unit, since
  52 --  otherwise the relinking and rebinding capability would be deactivated.
  53
  54 package System.Parameters is
  55 pragma Pure (Parameters);
  56
  57    ---------------------------------------
  58    -- Task And Stack Allocation Control --
  59    ---------------------------------------
  60
  61    type Task_Storage_Size is new Integer;
  62    --  Type used in tasking units for task storage size
  63
  64    type Size_Type is new Task_Storage_Size;
  65    --  Type used to provide task storage size to runtime
  66
  67    Unspecified_Size : constant Size_Type := Size_Type'First;
  68    --  Value used to indicate that no size type is set
  69
  70    subtype Ratio is Size_Type range -1 .. 100;
  71    Dynamic : constant Size_Type := -1;
  72    --  The secondary stack ratio is a constant between 0 and 100 which
  73    --  determines the percentage of the allocated task stack that is
  74    --  used by the secondary stack (the rest being the primary stack).
  75    --  The special value of minus one indicates that the secondary
  76    --  stack is to be allocated from the heap instead.
  77
  78    Sec_Stack_Ratio : constant Ratio := Dynamic;
  79    --  This constant defines the handling of the secondary stack
  80
  81    Sec_Stack_Dynamic : constant Boolean := Sec_Stack_Ratio = Dynamic;
  82    --  Convenient Boolean for testing for dynamic secondary stack
  83
  84    function Default_Stack_Size return Size_Type;
  85    --  Default task stack size used if none is specified
  86
  87    function Minimum_Stack_Size return Size_Type;
  88    --  Minimum task stack size permitted
  89
  90    function Adjust_Storage_Size (Size : Size_Type) return Size_Type;
  91    --  Given the storage size stored in the TCB, return the Storage_Size
  92    --  value required by the RM for the Storage_Size attribute. The
  93    --  required adjustment is as follows:
  94    --
  95    --    when Size = Unspecified_Size, return Default_Stack_Size
  96    --    when Size < Minimum_Stack_Size, return Minimum_Stack_Size
  97    --    otherwise return given Size
  98
  99    Stack_Grows_Down  : constant Boolean := True;
 100    --  This constant indicates whether the stack grows up (False) or
 101    --  down (True) in memory as functions are called. It is used for
 102    --  proper implementation of the stack overflow check.
 103
 104    ----------------------------------------------
 105    -- Characteristics of types in Interfaces.C --
 106    ----------------------------------------------
 107
 108    long_bits : constant := Long_Integer'Size;
 109    --  Number of bits in type long and unsigned_long. The normal convention
 110    --  is that this is the same as type Long_Integer, but this is not true
 111    --  of all targets. For example, in OpenVMS long /= Long_Integer.
 112
 113    ----------------------------------------------
 114    -- Behavior of Pragma Finalize_Storage_Only --
 115    ----------------------------------------------
 116
 117    --  Garbage_Collected is a Boolean constant whose value indicates the
 118    --  effect of the pragma Finalize_Storage_Entry on a controlled type.
 119
 120    --    Garbage_Collected = False
 121
 122    --      The system releases all storage on program termination only,
 123    --      but not other garbage collection occurs, so finalization calls
 124    --      are ommitted only for outer level onjects can be omitted if
 125    --      pragma Finalize_Storage_Only is used.
 126
 127    --    Garbage_Collected = True
 128
 129    --      The system provides full garbage collection, so it is never
 130    --      necessary to release storage for controlled objects for which
 131    --      a pragma Finalize_Storage_Only is used.
 132
 133    Garbage_Collected : constant Boolean := False;
 134    --  The storage mode for this system (release on program exit)
 135
 136 end System.Parameters;