jdk-24/hotspot/src/cpu/x86/vm/bytes_x86.hpp

/*
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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#ifndef CPU_X86_VM_BYTES_X86_HPP
#define CPU_X86_VM_BYTES_X86_HPP

#include "memory/allocation.hpp"
#include "utilities/macros.hpp"

class Bytes: AllStatic {
 private:
#ifndef AMD64
  // Helper function for swap_u8
  static inline u8   swap_u8_base(u4 x, u4 y);        // compiler-dependent implementation
#endif // AMD64

 public:
  // Returns true if the byte ordering used by Java is different from the native byte ordering
  // of the underlying machine. For example, this is true for Intel x86, but false for Solaris
  // on Sparc.
  static inline bool is_Java_byte_ordering_different(){ return true; }


  // Efficient reading and writing of unaligned unsigned data in platform-specific byte ordering
  // (no special code is needed since x86 CPUs can access unaligned data)
  static inline u2   get_native_u2(address p)         { return *(u2*)p; }
  static inline u4   get_native_u4(address p)         { return *(u4*)p; }
  static inline u8   get_native_u8(address p)         { return *(u8*)p; }

  static inline void put_native_u2(address p, u2 x)   { *(u2*)p = x; }
  static inline void put_native_u4(address p, u4 x)   { *(u4*)p = x; }
  static inline void put_native_u8(address p, u8 x)   { *(u8*)p = x; }


  // Efficient reading and writing of unaligned unsigned data in Java
  // byte ordering (i.e. big-endian ordering). Byte-order reversal is
  // needed since x86 CPUs use little-endian format.
  static inline u2   get_Java_u2(address p)           { return swap_u2(get_native_u2(p)); }
  static inline u4   get_Java_u4(address p)           { return swap_u4(get_native_u4(p)); }
  static inline u8   get_Java_u8(address p)           { return swap_u8(get_native_u8(p)); }

  static inline void put_Java_u2(address p, u2 x)     { put_native_u2(p, swap_u2(x)); }
  static inline void put_Java_u4(address p, u4 x)     { put_native_u4(p, swap_u4(x)); }
  static inline void put_Java_u8(address p, u8 x)     { put_native_u8(p, swap_u8(x)); }


  // Efficient swapping of byte ordering
  static inline u2   swap_u2(u2 x);                   // compiler-dependent implementation
  static inline u4   swap_u4(u4 x);                   // compiler-dependent implementation
  static inline u8   swap_u8(u8 x);
};

// The following header contains the implementations of swap_u2, swap_u4, and swap_u8[_base]
#include OS_CPU_HEADER_INLINE(bytes)

#endif // CPU_X86_VM_BYTES_X86_HPP