1 /*
   2  * Copyright (c) 1997, 2016, 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
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  22  *
  23  */
  24 
  25 #ifndef CPU_X86_VM_BYTES_X86_HPP
  26 #define CPU_X86_VM_BYTES_X86_HPP
  27 
  28 #include "memory/allocation.hpp"
  29 #include "utilities/macros.hpp"
  30 
  31 class Bytes: AllStatic {
  32  private:
  33 #ifndef AMD64
  34   // Helper function for swap_u8
  35   static inline u8   swap_u8_base(u4 x, u4 y);        // compiler-dependent implementation
  36 #endif // AMD64
  37 
  38  public:
  39   // Returns true if the byte ordering used by Java is different from the native byte ordering
  40   // of the underlying machine. For example, this is true for Intel x86, but false for Solaris
  41   // on Sparc.
  42   static inline bool is_Java_byte_ordering_different(){ return true; }
  43 
  44 
  45   // Efficient reading and writing of unaligned unsigned data in platform-specific byte ordering
  46   // (no special code is needed since x86 CPUs can access unaligned data)
  47   static inline u2   get_native_u2(address p)         { return *(u2*)p; }
  48   static inline u4   get_native_u4(address p)         { return *(u4*)p; }
  49   static inline u8   get_native_u8(address p)         { return *(u8*)p; }
  50 
  51   static inline void put_native_u2(address p, u2 x)   { *(u2*)p = x; }
  52   static inline void put_native_u4(address p, u4 x)   { *(u4*)p = x; }
  53   static inline void put_native_u8(address p, u8 x)   { *(u8*)p = x; }
  54 
  55 
  56   // Efficient reading and writing of unaligned unsigned data in Java
  57   // byte ordering (i.e. big-endian ordering). Byte-order reversal is
  58   // needed since x86 CPUs use little-endian format.
  59   static inline u2   get_Java_u2(address p)           { return swap_u2(get_native_u2(p)); }
  60   static inline u4   get_Java_u4(address p)           { return swap_u4(get_native_u4(p)); }
  61   static inline u8   get_Java_u8(address p)           { return swap_u8(get_native_u8(p)); }
  62 
  63   static inline void put_Java_u2(address p, u2 x)     { put_native_u2(p, swap_u2(x)); }
  64   static inline void put_Java_u4(address p, u4 x)     { put_native_u4(p, swap_u4(x)); }
  65   static inline void put_Java_u8(address p, u8 x)     { put_native_u8(p, swap_u8(x)); }
  66 
  67 
  68   // Efficient swapping of byte ordering
  69   static inline u2   swap_u2(u2 x);                   // compiler-dependent implementation
  70   static inline u4   swap_u4(u4 x);                   // compiler-dependent implementation
  71   static inline u8   swap_u8(u8 x);
  72 };
  73 
  74 // The following header contains the implementations of swap_u2, swap_u4, and swap_u8[_base]
  75 #include OS_CPU_HEADER_INLINE(bytes)
  76 
  77 #endif // CPU_X86_VM_BYTES_X86_HPP