/*+
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 * Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved.+
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.+
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 *+
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 * This code is free software; you can redistribute it and/or modify it+
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 * under the terms of the GNU General Public License version 2 only, as+
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 * published by the Free Software Foundation.+
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 *+
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 * This code is distributed in the hope that it will be useful, but WITHOUT+
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or+
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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License+
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 * version 2 for more details (a copy is included in the LICENSE file that+
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 * accompanied this code).+
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 *+
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 * You should have received a copy of the GNU General Public License version+
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 * 2 along with this work; if not, write to the Free Software Foundation,+
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 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.+
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 *+
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 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA+
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 * or visit www.oracle.com if you need additional information or have any+
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 * questions.+
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 *+
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 */+
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+
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#ifndef SHARE_VM_UTILITIES_SIZES_HPP+
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#define SHARE_VM_UTILITIES_SIZES_HPP+
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+
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#include "memory/allocation.hpp"+
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#include "utilities/globalDefinitions.hpp"+
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+
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// The following two classes are used to represent 'sizes' and 'offsets' in the VM;+
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// they serve as 'unit' types. ByteSize is used for sizes measured in bytes, while+
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// WordSize is used for sizes measured in machine words (i.e., 32bit or 64bit words+
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// depending on platform).+
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//+
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// The classes are defined with friend functions operating on them instead of member+
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// functions so that they (the classes) can be re-#define'd to int types in optimized+
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// mode. This allows full type checking and maximum safety in debug mode, and full+
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// optimizations (constant folding) and zero overhead (time and space wise) in the+
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// optimized build (some compilers do not optimize one-element value classes but+
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// instead create an object in memory - thus the overhead may be significant).+
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//+
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// Note: 1) DO NOT add new overloaded friend functions that do not have a unique function+
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//          function name but require signature types for resolution. This will not work+
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//          in optimized mode as both, ByteSize and WordSize are mapped to the same type+
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//          and thus the distinction would not be possible anymore (=> compiler errors).+
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//+
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//       2) DO NOT add non-static member functions as they cannot be mapped so something+
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//          compilable in the optimized build. Static member functions could be added+
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//          but require a corresponding class definition in the optimized build.+
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//+
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// These classes should help doing a transition from (currently) word-size based offsets+
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// to byte-size based offsets in the VM (this will be important if we desire to pack+
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// objects more densely in the VM for 64bit machines). Such a transition should proceed+
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// in two steps to minimize the risk of introducing hard-to-find bugs:+
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//+
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// a) first transition the whole VM into a form where all sizes are strongly typed+
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// b) change all WordSize's to ByteSize's where desired and fix the compilation errors+
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+
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+
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#ifdef ASSERT+
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+
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class ByteSize VALUE_OBJ_CLASS_SPEC {+
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 private:+
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  int _size;+
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+
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  // Note: This constructor must be private to avoid implicit conversions!+
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  ByteSize(int size)                                  { _size = size; }+
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+
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 public:+
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  // constructors+
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  inline friend ByteSize in_ByteSize(int size);+
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+
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  // accessors+
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  inline friend int in_bytes(ByteSize x);+
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+
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  // operators+
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  friend ByteSize operator + (ByteSize x, ByteSize y) { return ByteSize(in_bytes(x) + in_bytes(y)); }+
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  friend ByteSize operator - (ByteSize x, ByteSize y) { return ByteSize(in_bytes(x) - in_bytes(y)); }+
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  friend ByteSize operator * (ByteSize x, int      y) { return ByteSize(in_bytes(x) * y          ); }+
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+
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  // comparison+
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  friend bool operator == (ByteSize x, ByteSize y)    { return in_bytes(x) == in_bytes(y); }+
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  friend bool operator != (ByteSize x, ByteSize y)    { return in_bytes(x) != in_bytes(y); }+
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  friend bool operator <  (ByteSize x, ByteSize y)    { return in_bytes(x) <  in_bytes(y); }+
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  friend bool operator <= (ByteSize x, ByteSize y)    { return in_bytes(x) <= in_bytes(y); }+
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  friend bool operator >  (ByteSize x, ByteSize y)    { return in_bytes(x) >  in_bytes(y); }+
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  friend bool operator >= (ByteSize x, ByteSize y)    { return in_bytes(x) >= in_bytes(y); }+
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};+
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+
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inline ByteSize in_ByteSize(int size) { return ByteSize(size); }+
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inline int      in_bytes(ByteSize x)  { return x._size; }+
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+
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+
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class WordSize VALUE_OBJ_CLASS_SPEC {+
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 private:+
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  int _size;+
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+
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  // Note: This constructor must be private to avoid implicit conversions!+
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  WordSize(int size)                                  { _size = size; }+
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+
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 public:+
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  // constructors+
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  inline friend WordSize in_WordSize(int size);+
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+
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  // accessors+
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  inline friend int in_words(WordSize x);+
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+
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  // operators+
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  friend WordSize operator + (WordSize x, WordSize y) { return WordSize(in_words(x) + in_words(y)); }+
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  friend WordSize operator - (WordSize x, WordSize y) { return WordSize(in_words(x) - in_words(y)); }+
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  friend WordSize operator * (WordSize x, int      y) { return WordSize(in_words(x) * y          ); }+
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+
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  // comparison+
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  friend bool operator == (WordSize x, WordSize y)    { return in_words(x) == in_words(y); }+
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  friend bool operator != (WordSize x, WordSize y)    { return in_words(x) != in_words(y); }+
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  friend bool operator <  (WordSize x, WordSize y)    { return in_words(x) <  in_words(y); }+
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  friend bool operator <= (WordSize x, WordSize y)    { return in_words(x) <= in_words(y); }+
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  friend bool operator >  (WordSize x, WordSize y)    { return in_words(x) >  in_words(y); }+
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  friend bool operator >= (WordSize x, WordSize y)    { return in_words(x) >= in_words(y); }+
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};+
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+
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inline WordSize in_WordSize(int size) { return WordSize(size); }+
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inline int      in_words(WordSize x)  { return x._size; }+
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+
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+
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#else // ASSERT+
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+
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// The following definitions must match the corresponding friend declarations+
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// in the Byte/WordSize classes if they are typedef'ed to be int. This will+
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// be the case in optimized mode to ensure zero overhead for these types.+
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//+
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// Note: If a compiler does not inline these function calls away, one may+
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//       want to use #define's to make sure full optimization (constant+
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//       folding in particular) is possible.+
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+
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typedef int ByteSize;+
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inline ByteSize in_ByteSize(int size)                 { return size; }+
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inline int      in_bytes   (ByteSize x)               { return x; }+
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+
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typedef int WordSize;+
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inline WordSize in_WordSize(int size)                 { return size; }+
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inline int      in_words   (WordSize x)               { return x; }+
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+
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#endif // ASSERT+
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+
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+
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// Use the following #define to get C++ field member offsets+
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+
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#define byte_offset_of(klass,field)   in_ByteSize((int)offset_of(klass, field))+
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+
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#endif // SHARE_VM_UTILITIES_SIZES_HPP+
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