Mercurial > hg > CbC > CbC_gcc
comparison gcc/ada/ttypes.ads @ 111:04ced10e8804
gcc 7
author | kono |
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date | Fri, 27 Oct 2017 22:46:09 +0900 |
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children | 84e7813d76e9 |
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1 ------------------------------------------------------------------------------ | |
2 -- -- | |
3 -- GNAT COMPILER COMPONENTS -- | |
4 -- -- | |
5 -- T T Y P E S -- | |
6 -- -- | |
7 -- S p e c -- | |
8 -- -- | |
9 -- Copyright (C) 1992-2014, 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 3, 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 COPYING3. If not, go to -- | |
19 -- http://www.gnu.org/licenses for a complete copy of the license. -- | |
20 -- -- | |
21 -- GNAT was originally developed by the GNAT team at New York University. -- | |
22 -- Extensive contributions were provided by Ada Core Technologies Inc. -- | |
23 -- -- | |
24 ------------------------------------------------------------------------------ | |
25 | |
26 -- This package contains constants describing target properties | |
27 | |
28 with Types; use Types; | |
29 with Get_Targ; | |
30 with Set_Targ; | |
31 | |
32 package Ttypes is | |
33 | |
34 ------------------------------ | |
35 -- Host/Target Dependencies -- | |
36 ------------------------------ | |
37 | |
38 -- It is vital to maintain a clear distinction between properties of | |
39 -- types on the host and types on the target, since in the general | |
40 -- case of a cross-compiler these will be different. | |
41 | |
42 -- This package provides definitions of values that describe the properties | |
43 -- of the target types. All instances of target dependencies, including the | |
44 -- definitions of such packages as Standard and System depend directly or | |
45 -- indirectly on the definitions in the Ttypes packages. | |
46 | |
47 -- In the source of the compiler, references to attributes such as | |
48 -- Integer'Size will give information regarding the host types (i.e. | |
49 -- the types within the compiler itself). Such references are therefore | |
50 -- almost always suspicious (it is hard for example to see that the | |
51 -- code in the compiler should even be using type Integer very much, | |
52 -- and certainly this code should not depend on the size of Integer). | |
53 | |
54 -- On the other hand, it is perfectly reasonable for the compiler to | |
55 -- require access to the size of type Integer for the target machine, | |
56 -- e.g. in constructing the internal representation of package Standard. | |
57 -- For this purpose, instead of referencing the attribute Integer'Size, | |
58 -- a reference to Ttypes.Standard_Integer_Size will provide the needed | |
59 -- value for the target type. | |
60 | |
61 -- Two approaches are used for handling target dependent values in the | |
62 -- standard library packages. Package Standard is handled specially, | |
63 -- being constructed internally (by package Stand). Target dependent | |
64 -- values needed in Stand are obtained by direct reference to Ttypes | |
65 -- and Ttypef. | |
66 | |
67 -- For package System, there is a separate version for each target, with | |
68 -- explicit declarations of the required, constants. | |
69 | |
70 -- Historical note: Originally we had in mind dealing with target dependent | |
71 -- differences by referencing appropriate attributes. Ada 95 already | |
72 -- defines most of the required attributes, and GNAT specific attributes | |
73 -- were defined to cover the remaining cases (such as Storage_Unit). | |
74 -- The additional attributes that have been added to GNAT (Address_Size, | |
75 -- Storage_Unit, and Word_Size) are redundant with respect to the | |
76 -- corresponding references to System constants. For example in a program, | |
77 -- System.Address_Size and Standard'Address_Size yield the same value. | |
78 -- These attributes have been retained for compatibility purposes, but | |
79 -- serve no purpose at this stage. | |
80 | |
81 -- Note that during compilation there are two versions of package System | |
82 -- around. The version that is directly with'ed by compiler packages | |
83 -- contains host-dependent definitions, which is what is needed in that | |
84 -- case (for example, System.Storage_Unit referenced in the source of the | |
85 -- compiler refers to the storage unit of the host, not the target). This | |
86 -- means that, like attribute references, any references to constants in | |
87 -- package System in the compiler code are suspicious, since it is strange | |
88 -- for the compiler to have such host dependencies. If the compiler needs | |
89 -- to access the target dependent values of such quantities as Storage_Unit | |
90 -- then it should reference the constants in this package (Ttypes), rather | |
91 -- than referencing System.Storage_Unit, or Standard'Storage_Unit, both of | |
92 -- which would yield the host value. | |
93 | |
94 --------------------------------------------------- | |
95 -- Target-Dependent Values for Types in Standard -- | |
96 --------------------------------------------------- | |
97 | |
98 -- Note: GNAT always supplies all the following integer and float types, | |
99 -- but depending on the machine, some of the types may be identical. For | |
100 -- example, on some machines, Short_Float may be the same as Float, and | |
101 -- Long_Long_Float may be the same as Long_Float. | |
102 | |
103 Standard_Short_Short_Integer_Size : constant Pos := | |
104 Set_Targ.Char_Size; | |
105 Standard_Short_Short_Integer_Width : constant Pos := | |
106 Get_Targ.Width_From_Size | |
107 (Standard_Short_Short_Integer_Size); | |
108 | |
109 Standard_Short_Integer_Size : constant Pos := | |
110 Set_Targ.Short_Size; | |
111 Standard_Short_Integer_Width : constant Pos := | |
112 Get_Targ.Width_From_Size | |
113 (Standard_Short_Integer_Size); | |
114 | |
115 Standard_Integer_Size : constant Pos := | |
116 Set_Targ.Int_Size; | |
117 Standard_Integer_Width : constant Pos := | |
118 Get_Targ.Width_From_Size | |
119 (Standard_Integer_Size); | |
120 | |
121 Standard_Long_Integer_Size : constant Pos := | |
122 Set_Targ.Long_Size; | |
123 Standard_Long_Integer_Width : constant Pos := | |
124 Get_Targ.Width_From_Size | |
125 (Standard_Long_Integer_Size); | |
126 | |
127 Standard_Long_Long_Integer_Size : constant Pos := | |
128 Set_Targ.Long_Long_Size; | |
129 Standard_Long_Long_Integer_Width : constant Pos := | |
130 Get_Targ.Width_From_Size | |
131 (Standard_Long_Long_Integer_Size); | |
132 | |
133 Standard_Short_Float_Size : constant Pos := | |
134 Set_Targ.Float_Size; | |
135 Standard_Short_Float_Digits : constant Pos := | |
136 Get_Targ.Digits_From_Size | |
137 (Standard_Short_Float_Size); | |
138 | |
139 Standard_Float_Size : constant Pos := | |
140 Set_Targ.Float_Size; | |
141 Standard_Float_Digits : constant Pos := | |
142 Get_Targ.Digits_From_Size | |
143 (Standard_Float_Size); | |
144 | |
145 Standard_Long_Float_Size : constant Pos := | |
146 Set_Targ.Double_Size; | |
147 Standard_Long_Float_Digits : constant Pos := | |
148 Get_Targ.Digits_From_Size | |
149 (Standard_Long_Float_Size); | |
150 | |
151 Standard_Long_Long_Float_Size : constant Pos := | |
152 Set_Targ.Long_Double_Size; | |
153 Standard_Long_Long_Float_Digits : constant Pos := | |
154 Get_Targ.Digits_From_Size | |
155 (Standard_Long_Long_Float_Size); | |
156 | |
157 Standard_Character_Size : constant Pos := Set_Targ.Char_Size; | |
158 | |
159 Standard_Wide_Character_Size : constant Pos := 16; | |
160 Standard_Wide_Wide_Character_Size : constant Pos := 32; | |
161 -- Standard wide character sizes | |
162 | |
163 -- Note: there is no specific control over the representation of | |
164 -- enumeration types. The convention used is that if an enumeration | |
165 -- type has fewer than 2**(Character'Size) elements, then the size | |
166 -- used is Character'Size, otherwise Integer'Size is used. | |
167 | |
168 -- Similarly, the size of fixed-point types depends on the size of the | |
169 -- corresponding integer type, which is the smallest predefined integer | |
170 -- type capable of representing the required range of values. | |
171 | |
172 ------------------------------------------------- | |
173 -- Target-Dependent Values for Types in System -- | |
174 ------------------------------------------------- | |
175 | |
176 System_Address_Size : constant Pos := Set_Targ.Pointer_Size; | |
177 -- System.Address'Size (also size of all thin pointers) | |
178 | |
179 System_Max_Binary_Modulus_Power : constant Pos := | |
180 Standard_Long_Long_Integer_Size; | |
181 | |
182 System_Max_Nonbinary_Modulus_Power : constant Pos := Standard_Integer_Size; | |
183 | |
184 System_Storage_Unit : constant Pos := Set_Targ.Bits_Per_Unit; | |
185 System_Word_Size : constant Pos := Set_Targ.Bits_Per_Word; | |
186 | |
187 System_Tick_Nanoseconds : constant Pos := 1_000_000_000; | |
188 -- Value of System.Tick in nanoseconds. At the moment, this is a fixed | |
189 -- constant (with value of 1.0 seconds), but later we should add this | |
190 -- value to the GCC configuration file so that its value can be made | |
191 -- configuration dependent. | |
192 | |
193 ----------------------------------------------------- | |
194 -- Target-Dependent Values for Types in Interfaces -- | |
195 ----------------------------------------------------- | |
196 | |
197 Interfaces_Wchar_T_Size : constant Pos := Set_Targ.Wchar_T_Size; | |
198 | |
199 ---------------------------------------- | |
200 -- Other Target-Dependent Definitions -- | |
201 ---------------------------------------- | |
202 | |
203 Maximum_Alignment : constant Pos := Set_Targ.Maximum_Alignment; | |
204 -- The maximum alignment, in storage units, that an object or type may | |
205 -- require on the target machine. | |
206 | |
207 System_Allocator_Alignment : constant Pos := | |
208 Set_Targ.System_Allocator_Alignment; | |
209 -- The alignment in storage units of addresses returned by malloc | |
210 | |
211 Max_Unaligned_Field : constant Pos := Set_Targ.Max_Unaligned_Field; | |
212 -- The maximum supported size in bits for a field that is not aligned | |
213 -- on a storage unit boundary. | |
214 | |
215 Bytes_Big_Endian : Boolean := Set_Targ.Bytes_BE /= 0; | |
216 -- Important note: for Ada purposes, the important setting is the bytes | |
217 -- endianness (Bytes_Big_Endian), not the bits value (Bits_Big_Endian). | |
218 -- This is because Ada bit addressing must be compatible with the byte | |
219 -- ordering (otherwise we would end up with non-contiguous fields). It | |
220 -- is rare for the two to be different, but if they are, Bits_Big_Endian | |
221 -- is relevant only for the generation of instructions with bit numbers, | |
222 -- and thus relevant only to the back end. Note that this is a variable | |
223 -- rather than a constant, since it can be modified (flipped) by -gnatd8. | |
224 | |
225 Target_Short_Enums : constant Boolean := Set_Targ.Short_Enums /= 0; | |
226 -- True if we are in short enums mode, where foreign convention | |
227 -- (in particular C and C++) enumeration types will be sized as in Ada, | |
228 -- using the shortest possibility from 8,16,32 bits, signed or unsigned. | |
229 -- A zero value means Short_Enums are not in use, and in this case all | |
230 -- foreign convention enumeration types are given the same size as c int. | |
231 | |
232 Target_Strict_Alignment : Boolean := | |
233 Set_Targ.Strict_Alignment /= 0; | |
234 -- True if instructions will fail if data is misaligned. Note that this | |
235 -- is a variable rather than a constant since it can be modified (set to | |
236 -- True) if the debug flag -gnatd.A is used. | |
237 | |
238 Target_Double_Float_Alignment : constant Nat := | |
239 Set_Targ.Double_Float_Alignment; | |
240 -- The default alignment of "double" floating-point types, i.e. floating | |
241 -- point types whose size is equal to 64 bits, or 0 if this alignment is | |
242 -- not lower than the largest power of 2 multiple of System.Storage_Unit | |
243 -- that does not exceed either the object size of the type or the maximum | |
244 -- allowed alignment. | |
245 | |
246 Target_Double_Scalar_Alignment : constant Nat := | |
247 Set_Targ.Double_Scalar_Alignment; | |
248 -- The default alignment of "double" or larger scalar types, i.e. scalar | |
249 -- types whose size is greater or equal to 64 bits, or 0 if this alignment | |
250 -- is not lower than the largest power of 2 multiple of System.Storage_Unit | |
251 -- that does not exceed either the object size of the type or the maximum | |
252 -- allowed alignment. | |
253 | |
254 end Ttypes; |