File : 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 -- --
24 -- --
25 -- --
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;