1 /*

     2  * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.

     8  *

     9  * This code is distributed in the hope that it will be useful, but WITHOUT

    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    12  * version 2 for more details (a copy is included in the LICENSE file that

    13  * accompanied this code).

    14  *

    15  * You should have received a copy of the GNU General Public License version

    16  * 2 along with this work; if not, write to the Free Software Foundation,

    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    18  *

    19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    20  * or visit www.oracle.com if you need additional information or have any

    21  * questions.

    22  *

    23  */

    24 

    25 #ifndef SHARE_VM_UTILITIES_ENDIAN_HPP

    26 #define SHARE_VM_UTILITIES_ENDIAN_HPP

    27 

    28 #include "utilities/globalDefinitions.hpp"

    29 

    30 // Selectable endian handling. Endian handlers are used when accessing values

    31 // that are of unknown (until runtime) endian.  The only requirement of the values

    32 // accessed are that they are aligned to proper size boundaries (no misalignment.)

    33 // To select an endian handler, one should call Endian::get_handler(big_endian);

    34 // Where big_endian is true if big endian is required and false otherwise.  The

    35 // native endian handler can be fetched with Endian::get_native_handler();

    36 // To retrieve a value using the approprate endian, use one of the overloaded

    37 // calls to get. To set a value, then use one of the overloaded set calls.

    38 // Ex.

    39 //      s4 value; // Imported value;

    40 //      ...

    41 //      Endian* endian = Endian::get_handler(true);  // Use big endian

    42 //      s4 corrected = endian->get(value);

    43 //      endian->set(value, 1);

    44 //

    45 class Endian {

    46 public:

    47   virtual u2 get(u2 x) = 0;

    48   virtual u4 get(u4 x) = 0;

    49   virtual u8 get(u8 x) = 0;

    50   virtual s2 get(s2 x) = 0;

    51   virtual s4 get(s4 x) = 0;

    52   virtual s8 get(s8 x) = 0;

    53 

    54   virtual void set(u2& x, u2 y) = 0;

    55   virtual void set(u4& x, u4 y) = 0;

    56   virtual void set(u8& x, u8 y) = 0;

    57   virtual void set(s2& x, s2 y) = 0;

    58   virtual void set(s4& x, s4 y) = 0;

    59   virtual void set(s8& x, s8 y) = 0;

    60 

    61   // Quick little endian test.

    62   static bool is_little_endian() {  u4 x = 1; return *(u1 *)&x != 0; }

    63 

    64   // Quick big endian test.

    65   static bool is_big_endian() { return !is_little_endian(); }

    66 

    67   // Select an appropriate endian handler.

    68   static Endian* get_handler(bool big_endian);

    69 

    70   // Return the native endian handler.

    71   static Endian* get_native_handler();

    72 };

    73 

    74 // Normal endian handling.

    75 class NativeEndian : public Endian {

    76 private:

    77   static NativeEndian _native;

    78 

    79 public:

    80   u2 get(u2 x);

    81   u4 get(u4 x);

    82   u8 get(u8 x);

    83   s2 get(s2 x);

    84   s4 get(s4 x);

    85   s8 get(s8 x);

    86 

    87   void set(u2& x, u2 y);

    88   void set(u4& x, u4 y);

    89   void set(u8& x, u8 y);

    90   void set(s2& x, s2 y);

    91   void set(s4& x, s4 y);

    92   void set(s8& x, s8 y);

    93 

    94   static Endian* get_native() { return &_native; }

    95 };

    96 

    97 // Swapping endian handling.

    98 class SwappingEndian : public Endian {

    99 private:

   100   static SwappingEndian _swapping;

   101 

   102 public:

   103   u2 get(u2 x);

   104   u4 get(u4 x);

   105   u8 get(u8 x);

   106   s2 get(s2 x);

   107   s4 get(s4 x);

   108   s8 get(s8 x);

   109 

   110   void set(u2& x, u2 y);

   111   void set(u4& x, u4 y);

   112   void set(u8& x, u8 y);

   113   void set(s2& x, s2 y);

   114   void set(s4& x, s4 y);

   115   void set(s8& x, s8 y);

   116 

   117   static Endian* get_swapping() { return &_swapping; }

   118 };

   119 #endif // SHARE_VM_UTILITIES_ENDIAN_HPP