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-- Copyright (C) 1992-2003 Free Software Foundation, Inc. -- 10-- -- 11-- GNAT is free software; you can redistribute it and/or modify it under -- 12-- terms of the GNU General Public License as published by the Free Soft- -- 13-- ware Foundation; either version 2, or (at your option) any later ver- -- 14-- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- 15-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- 16-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License -- 17-- for more details. You should have received a copy of the GNU General -- 18-- Public License distributed with GNAT; see file COPYING. If not, write -- 19-- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, -- 20-- MA 02111-1307, USA. -- 21-- -- 22-- As a special exception, if other files instantiate generics from this -- 23-- unit, or you link this unit with other files to produce an executable, -- 24-- this unit does not by itself cause the resulting executable to be -- 25-- covered by the GNU General Public License. This exception does not -- 26-- however invalidate any other reasons why the executable file might be -- 27-- covered by the GNU Public License. -- 28-- -- 29-- GNAT was originally developed by the GNAT team at New York University. -- 30-- Extensive contributions were provided by Ada Core Technologies Inc. -- 31-- -- 32------------------------------------------------------------------------------ 33 34-- This is the HP version of this package 35-- Blank line intentional so that it lines up exactly with default. 36 37-- This package defines some system dependent parameters for GNAT. These 38-- are values that are referenced by the runtime library and are therefore 39-- relevant to the target machine. 40 41-- The parameters whose value is defined in the spec are not generally 42-- expected to be changed. If they are changed, it will be necessary to 43-- recompile the run-time library. 44 45-- The parameters which are defined by functions can be changed by modifying 46-- the body of System.Parameters in file s-parame.adb. A change to this body 47-- requires only rebinding and relinking of the application. 48 49-- Note: do not introduce any pragma Inline statements into this unit, since 50-- otherwise the relinking and rebinding capability would be deactivated. 51 52package System.Parameters is 53pragma Pure (Parameters); 54 55 --------------------------------------- 56 -- Task And Stack Allocation Control -- 57 --------------------------------------- 58 59 type Task_Storage_Size is new Integer; 60 -- Type used in tasking units for task storage size 61 62 type Size_Type is new Task_Storage_Size; 63 -- Type used to provide task storage size to runtime 64 65 Unspecified_Size : constant Size_Type := Size_Type'First; 66 -- Value used to indicate that no size type is set 67 68 subtype Ratio is Size_Type range -1 .. 100; 69 Dynamic : constant Size_Type := -1; 70 -- The secondary stack ratio is a constant between 0 and 100 which 71 -- determines the percentage of the allocated task stack that is 72 -- used by the secondary stack (the rest being the primary stack). 73 -- The special value of minus one indicates that the secondary 74 -- stack is to be allocated from the heap instead. 75 76 Sec_Stack_Ratio : constant Ratio := Dynamic; 77 -- This constant defines the handling of the secondary stack 78 79 Sec_Stack_Dynamic : constant Boolean := Sec_Stack_Ratio = Dynamic; 80 -- Convenient Boolean for testing for dynamic secondary stack 81 82 function Default_Stack_Size return Size_Type; 83 -- Default task stack size used if none is specified 84 85 function Minimum_Stack_Size return Size_Type; 86 -- Minimum task stack size permitted 87 88 function Adjust_Storage_Size (Size : Size_Type) return Size_Type; 89 -- Given the storage size stored in the TCB, return the Storage_Size 90 -- value required by the RM for the Storage_Size attribute. The 91 -- required adjustment is as follows: 92 -- 93 -- when Size = Unspecified_Size, return Default_Stack_Size 94 -- when Size < Minimum_Stack_Size, return Minimum_Stack_Size 95 -- otherwise return given Size 96 97 Default_Env_Stack_Size : constant Size_Type := 8_192_000; 98 -- Assumed size of the environment task, if no other information 99 -- is available. This value is used when stack checking is 100 -- enabled and no GNAT_STACK_LIMIT environment variable is set. 101 102 Stack_Grows_Down : constant Boolean := False; 103 -- This constant indicates whether the stack grows up (False) or 104 -- down (True) in memory as functions are called. It is used for 105 -- proper implementation of the stack overflow check. 106 107 ---------------------------------------------- 108 -- Characteristics of Types in Interfaces.C -- 109 ---------------------------------------------- 110 111 long_bits : constant := Long_Integer'Size; 112 -- Number of bits in type long and unsigned_long. The normal convention 113 -- is that this is the same as type Long_Integer, but this is not true 114 -- of all targets. For example, in OpenVMS long /= Long_Integer. 115 116 ---------------------------------------------- 117 -- Behavior of Pragma Finalize_Storage_Only -- 118 ---------------------------------------------- 119 120 -- Garbage_Collected is a Boolean constant whose value indicates the 121 -- effect of the pragma Finalize_Storage_Entry on a controlled type. 122 123 -- Garbage_Collected = False 124 125 -- The system releases all storage on program termination only, 126 -- but not other garbage collection occurs, so finalization calls 127 -- are ommitted only for outer level onjects can be omitted if 128 -- pragma Finalize_Storage_Only is used. 129 130 -- Garbage_Collected = True 131 132 -- The system provides full garbage collection, so it is never 133 -- necessary to release storage for controlled objects for which 134 -- a pragma Finalize_Storage_Only is used. 135 136 Garbage_Collected : constant Boolean := False; 137 -- The storage mode for this system (release on program exit) 138 139 --------------------- 140 -- Tasking Profile -- 141 --------------------- 142 143 -- In the following sections, constant parameters are defined to 144 -- allow some optimizations and fine tuning within the tasking run time 145 -- based on restrictions on the tasking features. 146 147 ---------------------- 148 -- Locking Strategy -- 149 ---------------------- 150 151 Single_Lock : constant Boolean := False; 152 -- Indicates whether a single lock should be used within the tasking 153 -- run-time to protect internal structures. If True, a single lock 154 -- will be used, meaning less locking/unlocking operations, but also 155 -- more global contention. In general, Single_Lock should be set to 156 -- True on single processor machines, and to False to multi-processor 157 -- systems, but this can vary from application to application and also 158 -- depends on the scheduling policy. 159 160 ------------------- 161 -- Task Abortion -- 162 ------------------- 163 164 No_Abort : constant Boolean := False; 165 -- This constant indicates whether abort statements and asynchronous 166 -- transfer of control (ATC) are disallowed. If set to True, it is 167 -- assumed that neither construct is used, and the run time does not 168 -- need to defer/undefer abort and check for pending actions at 169 -- completion points. A value of True for No_Abort corresponds to: 170 -- pragma Restrictions (No_Abort_Statements); 171 -- pragma Restrictions (Max_Asynchronous_Select_Nesting => 0); 172 173 ---------------------- 174 -- Dynamic Priority -- 175 ---------------------- 176 177 Dynamic_Priority_Support : constant Boolean := True; 178 -- This constant indicates whether dynamic changes of task priorities 179 -- are allowed (True means normal RM mode in which such changes are 180 -- allowed). In particular, if this is False, then we do not need to 181 -- poll for pending base priority changes at every abort completion 182 -- point. A value of False for Dynamic_Priority_Support corresponds 183 -- to pragma Restrictions (No_Dynamic_Priorities); 184 185 --------------------- 186 -- Task Attributes -- 187 --------------------- 188 189 Default_Attribute_Count : constant := 4; 190 -- Number of pre-allocated Address-sized task attributes stored in the 191 -- task control block. 192 193 -------------------- 194 -- Runtime Traces -- 195 -------------------- 196 197 Runtime_Traces : constant Boolean := False; 198 -- This constant indicates whether the runtime outputs traces to a 199 -- predefined output or not (True means that traces are output). 200 -- See System.Traces for more details. 201 202end System.Parameters; 203