1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
|
------------------------------------------------------------------------------
-- --
-- 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) 1992-2009, 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. --
-- --
------------------------------------------------------------------------------
-- This is the default VxWorks version of the package
-- 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 Task_Storage_Size is new Integer;
-- Type used in tasking units for task storage size
type Size_Type is new Task_Storage_Size;
-- Type used to provide task storage size to runtime
Unspecified_Size : constant Size_Type := Size_Type'First;
-- Value used to indicate that no size type is set
subtype Ratio is Size_Type range -1 .. 100;
Dynamic : constant Size_Type := -1;
-- The secondary stack ratio is a constant between 0 and 100 which
-- determines the percentage of the allocated task stack that is
-- used by the secondary stack (the rest being the primary stack).
-- The special value of minus one indicates that the secondary
-- stack is to be allocated from the heap instead.
Sec_Stack_Ratio : constant Ratio := Dynamic;
-- This constant defines the handling of the secondary stack
Sec_Stack_Dynamic : constant Boolean := Sec_Stack_Ratio = Dynamic;
-- Convenient Boolean for testing for dynamic secondary stack
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 := 14_336;
-- 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.
-- This value is chosen as the VxWorks default stack size is 20kB,
-- and a little more than 4kB is necessary for the run time.
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.
----------------------------------------------
-- 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 is not true
-- of all targets. For example, in OpenVMS long /= Long_Integer.
----------------------------------------------
-- 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.
----------------------
-- Locking Strategy --
----------------------
Single_Lock : constant Boolean := False;
-- Indicates whether a single lock should be used within the tasking
-- run-time to protect internal structures. If True, a single lock
-- will be used, meaning less locking/unlocking operations, but also
-- more global contention. In general, Single_Lock should be set to
-- True on single processor machines, and to False to multi-processor
-- systems, but this can vary from application to application and also
-- depends on the scheduling policy.
-------------------
-- 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 --
---------------------
Default_Attribute_Count : constant := 4;
-- Number of pre-allocated Address-sized task attributes stored in the
-- task control block.
--------------------
-- Runtime Traces --
--------------------
Runtime_Traces : constant Boolean := False;
-- This constant indicates whether the runtime outputs traces to a
-- predefined output or not (True means that traces are output).
-- See System.Traces for more details.
-----------------------
-- Task Image Length --
-----------------------
Max_Task_Image_Length : constant := 32;
-- 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;
|
