bytes_x86.hpp revision 11658:8a5735c11a84 
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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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
31class 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
78