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+------------------------------------------------------------------------------
+-- --
+-- GNAT COMPILER COMPONENTS --
+-- --
+-- T T Y P E S --
+-- --
+-- S p e c --
+-- --
+-- Copyright (C) 1992-2013, 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. See the GNU General Public License --
+-- for more details. You should have received a copy of the GNU General --
+-- Public License distributed with GNAT; see file COPYING3. If not, go to --
+-- http://www.gnu.org/licenses for a complete copy of the license. --
+-- --
+-- GNAT was originally developed by the GNAT team at New York University. --
+-- Extensive contributions were provided by Ada Core Technologies Inc. --
+-- --
+------------------------------------------------------------------------------
+
+-- This package contains constants describing target properties
+
+with Types; use Types;
+with Get_Targ;
+with Set_Targ;
+
+package Ttypes is
+
+ ------------------------------
+ -- Host/Target Dependencies --
+ ------------------------------
+
+ -- It is vital to maintain a clear distinction between properties of
+ -- types on the host and types on the target, since in the general
+ -- case of a cross-compiler these will be different.
+
+ -- This package provides definitions of values that describe the properties
+ -- of the target types. All instances of target dependencies, including the
+ -- definitions of such packages as Standard and System depend directly or
+ -- indirectly on the definitions in the Ttypes packages.
+
+ -- In the source of the compiler, references to attributes such as
+ -- Integer'Size will give information regarding the host types (i.e.
+ -- the types within the compiler itself). Such references are therefore
+ -- almost always suspicious (it is hard for example to see that the
+ -- code in the compiler should even be using type Integer very much,
+ -- and certainly this code should not depend on the size of Integer).
+
+ -- On the other hand, it is perfectly reasonable for the compiler to
+ -- require access to the size of type Integer for the target machine,
+ -- e.g. in constructing the internal representation of package Standard.
+ -- For this purpose, instead of referencing the attribute Integer'Size,
+ -- a reference to Ttypes.Standard_Integer_Size will provide the needed
+ -- value for the target type.
+
+ -- Two approaches are used for handling target dependent values in the
+ -- standard library packages. Package Standard is handled specially,
+ -- being constructed internally (by package Stand). Target dependent
+ -- values needed in Stand are obtained by direct reference to Ttypes
+ -- and Ttypef.
+
+ -- For package System, the required constant values are obtained by
+ -- referencing appropriate attributes. Ada 95 already defines most of
+ -- the required attributes, and GNAT specific attributes have been
+ -- defined to cover the remaining cases (such as Storage_Unit). The
+ -- evaluation of these attributes obtains the required target dependent
+ -- values from Ttypes and Ttypef. The additional attributes that have
+ -- been added to GNAT (Address_Size, Storage_Unit, Word_Size, Max_Priority,
+ -- and Max_Interrupt_Priority) are for almost all purposes redundant with
+ -- respect to the corresponding references to System constants. For example
+ -- in a program, System.Address_Size and Standard'Address_Size yield the
+ -- same value. The critical use of the attribute is in writing the System
+ -- declaration of Address_Size which of course cannot refer to itself. By
+ -- this means we achieve complete target independence in the source code
+ -- of package System, i.e. there is only one copy of the source of System
+ -- for all targets.
+
+ -- Note that during compilation there are two versions of package System
+ -- around. The version that is directly with'ed by compiler packages
+ -- contains host-dependent definitions, which is what is needed in that
+ -- case (for example, System.Storage_Unit referenced in the source of the
+ -- compiler refers to the storage unit of the host, not the target). This
+ -- means that, like attribute references, any references to constants in
+ -- package System in the compiler code are suspicious, since it is strange
+ -- for the compiler to have such host dependencies. If the compiler needs
+ -- to access the target dependent values of such quantities as Storage_Unit
+ -- then it should reference the constants in this package (Ttypes), rather
+ -- than referencing System.Storage_Unit, or Standard'Storage_Unit, both of
+ -- which would yield the host value.
+
+ ---------------------------------------------------
+ -- Target-Dependent Values for Types in Standard --
+ ---------------------------------------------------
+
+ -- Note: GNAT always supplies all the following integer and float types,
+ -- but depending on the machine, some of the types may be identical. For
+ -- example, on some machines, Short_Float may be the same as Float, and
+ -- Long_Long_Float may be the same as Long_Float.
+
+ Standard_Short_Short_Integer_Size : constant Pos :=
+ Set_Targ.Char_Size;
+ Standard_Short_Short_Integer_Width : constant Pos :=
+ Get_Targ.Width_From_Size
+ (Standard_Short_Short_Integer_Size);
+
+ Standard_Short_Integer_Size : constant Pos :=
+ Set_Targ.Short_Size;
+ Standard_Short_Integer_Width : constant Pos :=
+ Get_Targ.Width_From_Size
+ (Standard_Short_Integer_Size);
+
+ Standard_Integer_Size : constant Pos :=
+ Set_Targ.Int_Size;
+ Standard_Integer_Width : constant Pos :=
+ Get_Targ.Width_From_Size
+ (Standard_Integer_Size);
+
+ Standard_Long_Integer_Size : constant Pos :=
+ Set_Targ.Long_Size;
+ Standard_Long_Integer_Width : constant Pos :=
+ Get_Targ.Width_From_Size
+ (Standard_Long_Integer_Size);
+
+ Standard_Long_Long_Integer_Size : constant Pos :=
+ Set_Targ.Long_Long_Size;
+ Standard_Long_Long_Integer_Width : constant Pos :=
+ Get_Targ.Width_From_Size
+ (Standard_Long_Long_Integer_Size);
+
+ Standard_Short_Float_Size : constant Pos :=
+ Set_Targ.Float_Size;
+ Standard_Short_Float_Digits : constant Pos :=
+ Get_Targ.Digits_From_Size
+ (Standard_Short_Float_Size);
+
+ Standard_Float_Size : constant Pos :=
+ Set_Targ.Float_Size;
+ Standard_Float_Digits : constant Pos :=
+ Get_Targ.Digits_From_Size
+ (Standard_Float_Size);
+
+ Standard_Long_Float_Size : constant Pos :=
+ Set_Targ.Double_Size;
+ Standard_Long_Float_Digits : constant Pos :=
+ Get_Targ.Digits_From_Size
+ (Standard_Long_Float_Size);
+
+ Standard_Long_Long_Float_Size : constant Pos :=
+ Set_Targ.Long_Double_Size;
+ Standard_Long_Long_Float_Digits : constant Pos :=
+ Get_Targ.Digits_From_Size
+ (Standard_Long_Long_Float_Size);
+
+ Standard_Character_Size : constant Pos := Set_Targ.Char_Size;
+
+ Standard_Wide_Character_Size : constant Pos := 16;
+ Standard_Wide_Wide_Character_Size : constant Pos := 32;
+ -- Standard wide character sizes
+
+ -- Note: there is no specific control over the representation of
+ -- enumeration types. The convention used is that if an enumeration
+ -- type has fewer than 2**(Character'Size) elements, then the size
+ -- used is Character'Size, otherwise Integer'Size is used.
+
+ -- Similarly, the size of fixed-point types depends on the size of the
+ -- corresponding integer type, which is the smallest predefined integer
+ -- type capable of representing the required range of values.
+
+ -------------------------------------------------
+ -- Target-Dependent Values for Types in System --
+ -------------------------------------------------
+
+ System_Address_Size : constant Pos := Set_Targ.Pointer_Size;
+ -- System.Address'Size (also size of all thin pointers)
+
+ System_Max_Binary_Modulus_Power : constant Pos :=
+ Standard_Long_Long_Integer_Size;
+
+ System_Max_Nonbinary_Modulus_Power : constant Pos := Standard_Integer_Size;
+
+ System_Storage_Unit : constant Pos := Set_Targ.Bits_Per_Unit;
+ System_Word_Size : constant Pos := Set_Targ.Bits_Per_Word;
+
+ System_Tick_Nanoseconds : constant Pos := 1_000_000_000;
+ -- Value of System.Tick in nanoseconds. At the moment, this is a fixed
+ -- constant (with value of 1.0 seconds), but later we should add this
+ -- value to the GCC configuration file so that its value can be made
+ -- configuration dependent.
+
+ -----------------------------------------------------
+ -- Target-Dependent Values for Types in Interfaces --
+ -----------------------------------------------------
+
+ Interfaces_Wchar_T_Size : constant Pos := Set_Targ.Wchar_T_Size;
+
+ ----------------------------------------
+ -- Other Target-Dependent Definitions --
+ ----------------------------------------
+
+ Maximum_Alignment : constant Pos := Set_Targ.Maximum_Alignment;
+ -- The maximum alignment, in storage units, that an object or type may
+ -- require on the target machine.
+
+ System_Allocator_Alignment : constant Pos :=
+ Set_Targ.System_Allocator_Alignment;
+ -- The alignment in storage units of addresses returned by malloc
+
+ Max_Unaligned_Field : constant Pos := Set_Targ.Max_Unaligned_Field;
+ -- The maximum supported size in bits for a field that is not aligned
+ -- on a storage unit boundary.
+
+ Bytes_Big_Endian : Boolean := Set_Targ.Bytes_BE /= 0;
+ -- Important note: for Ada purposes, the important setting is the bytes
+ -- endianness (Bytes_Big_Endian), not the bits value (Bits_Big_Endian).
+ -- This is because Ada bit addressing must be compatible with the byte
+ -- ordering (otherwise we would end up with non-contiguous fields). It
+ -- is rare for the two to be different, but if they are, Bits_Big_Endian
+ -- is relevant only for the generation of instructions with bit numbers,
+ -- and thus relevant only to the back end. Note that this is a variable
+ -- rather than a constant, since it can be modified (flipped) by -gnatd8.
+
+ Target_Short_Enums : constant Boolean := Set_Targ.Short_Enums /= 0;
+ -- True if we are in short enums mode, where foreign convention
+ -- (in particular C and C++) enumeration types will be sized as in Ada,
+ -- using the shortest possibility from 8,16,32 bits, signed or unsigned.
+ -- A zero value means Short_Enums are not in use, and in this case all
+ -- foreign convention enumeration types are given the same size as c int.
+
+ Target_Strict_Alignment : Boolean :=
+ Set_Targ.Strict_Alignment /= 0;
+ -- True if instructions will fail if data is misaligned. Note that this
+ -- is a variable rather than a constant since it can be modified (set to
+ -- True) if the debug flag -gnatd.A is used.
+
+ Target_Double_Float_Alignment : constant Nat :=
+ Set_Targ.Double_Float_Alignment;
+ -- The default alignment of "double" floating-point types, i.e. floating
+ -- point types whose size is equal to 64 bits, or 0 if this alignment is
+ -- not lower than the largest power of 2 multiple of System.Storage_Unit
+ -- that does not exceed either the object size of the type or the maximum
+ -- allowed alignment.
+
+ Target_Double_Scalar_Alignment : constant Nat :=
+ Set_Targ.Double_Scalar_Alignment;
+ -- The default alignment of "double" or larger scalar types, i.e. scalar
+ -- types whose size is greater or equal to 64 bits, or 0 if this alignment
+ -- is not lower than the largest power of 2 multiple of System.Storage_Unit
+ -- that does not exceed either the object size of the type or the maximum
+ -- allowed alignment.
+
+end Ttypes;