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------------------------------------------------------------------------------
-- --
-- GNAT COMPILER COMPONENTS --
-- --
-- S Y S T E M . P A R A M E T E R S --
-- --
-- S p e c --
-- --
-- Copyright (C) 1992-2021, Free Software Foundation, Inc. --
-- --
-- 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. --
-- --
------------------------------------------------------------------------------
-- Default version used when no target-specific version is provided
-- This package defines some system dependent parameters for GNAT. These
-- are values that are referenced by the runtime library and are therefore
-- relevant to the target machine.
-- The parameters whose value is defined in the spec are not generally
-- expected to be changed. If they are changed, it will be necessary to
-- recompile the run-time library.
-- The parameters which are defined by functions can be changed by modifying
-- the body of System.Parameters in file s-parame.adb. A change to this body
-- requires only rebinding and relinking of the application.
-- Note: do not introduce any pragma Inline statements into this unit, since
-- otherwise the relinking and rebinding capability would be deactivated.
package System.Parameters is
pragma Pure;
---------------------------------------
-- Task And Stack Allocation Control --
---------------------------------------
type Size_Type is range
-(2 ** (Integer'(Standard'Address_Size) - 1)) ..
+(2 ** (Integer'(Standard'Address_Size) - 1)) - 1;
-- Type used to provide task stack sizes to the runtime. Sized to permit
-- stack sizes of up to half the total addressable memory space. This may
-- seem excessively large (even for 32-bit systems), however there are many
-- instances of users requiring large stack sizes (for example string
-- processing).
Unspecified_Size : constant Size_Type := Size_Type'First;
-- Value used to indicate that no size type is set
function Default_Stack_Size return Size_Type;
-- Default task stack size used if none is specified
function Minimum_Stack_Size return Size_Type;
-- Minimum task stack size permitted
function Adjust_Storage_Size (Size : Size_Type) return Size_Type;
-- Given the storage size stored in the TCB, return the Storage_Size
-- value required by the RM for the Storage_Size attribute. The
-- required adjustment is as follows:
--
-- when Size = Unspecified_Size, return Default_Stack_Size
-- when Size < Minimum_Stack_Size, return Minimum_Stack_Size
-- otherwise return given Size
Default_Env_Stack_Size : constant Size_Type := 8_192_000;
-- Assumed size of the environment task, if no other information is
-- available. This value is used when stack checking is enabled and
-- no GNAT_STACK_LIMIT environment variable is set.
Stack_Grows_Down : constant Boolean := True;
-- This constant indicates whether the stack grows up (False) or
-- down (True) in memory as functions are called. It is used for
-- proper implementation of the stack overflow check.
Runtime_Default_Sec_Stack_Size : constant Size_Type := 10 * 1024;
-- The run-time chosen default size for secondary stacks that may be
-- overridden by the user with the use of binder -D switch.
Sec_Stack_Dynamic : constant Boolean := True;
-- Indicates if secondary stacks can grow and shrink at run-time. If False,
-- the size of a secondary stack is fixed at the point of its creation.
------------------------------------
-- Characteristics of time_t type --
------------------------------------
time_t_bits : constant := Long_Integer'Size;
-- Number of bits in type time_t
----------------------------------------------
-- Characteristics of types in Interfaces.C --
----------------------------------------------
long_bits : constant := Long_Integer'Size;
-- Number of bits in type long and unsigned_long. The normal convention
-- is that this is the same as type Long_Integer, but this may not be true
-- of all targets.
ptr_bits : constant := Standard'Address_Size;
subtype C_Address is System.Address;
-- Number of bits in Interfaces.C pointers, normally a standard address
C_Malloc_Linkname : constant String := "__gnat_malloc";
-- Name of runtime function used to allocate such a pointer
----------------------------------------------
-- Behavior of Pragma Finalize_Storage_Only --
----------------------------------------------
-- Garbage_Collected is a Boolean constant whose value indicates the
-- effect of the pragma Finalize_Storage_Entry on a controlled type.
-- Garbage_Collected = False
-- The system releases all storage on program termination only,
-- but not other garbage collection occurs, so finalization calls
-- are omitted only for outer level objects can be omitted if
-- pragma Finalize_Storage_Only is used.
-- Garbage_Collected = True
-- The system provides full garbage collection, so it is never
-- necessary to release storage for controlled objects for which
-- a pragma Finalize_Storage_Only is used.
Garbage_Collected : constant Boolean := False;
-- The storage mode for this system (release on program exit)
---------------------
-- Tasking Profile --
---------------------
-- In the following sections, constant parameters are defined to
-- allow some optimizations and fine tuning within the tasking run time
-- based on restrictions on the tasking features.
-------------------
-- Task Abortion --
-------------------
No_Abort : constant Boolean := False;
-- This constant indicates whether abort statements and asynchronous
-- transfer of control (ATC) are disallowed. If set to True, it is
-- assumed that neither construct is used, and the run time does not
-- need to defer/undefer abort and check for pending actions at
-- completion points. A value of True for No_Abort corresponds to:
-- pragma Restrictions (No_Abort_Statements);
-- pragma Restrictions (Max_Asynchronous_Select_Nesting => 0);
---------------------
-- Task Attributes --
---------------------
Max_Attribute_Count : constant := 32;
-- Number of task attributes stored in the task control block
-----------------------
-- Task Image Length --
-----------------------
Max_Task_Image_Length : constant := 256;
-- This constant specifies the maximum length of a task's image
------------------------------
-- Exception Message Length --
------------------------------
Default_Exception_Msg_Max_Length : constant := 200;
-- This constant specifies the default number of characters to allow
-- in an exception message (200 is minimum required by RM 11.4.1(18)).
end System.Parameters;
|
