1 /*
   2  * Copyright (c) 1997, 2010, Oracle and/or its affiliates. All rights reserved.
   3  * Copyright (c) 2014, Red Hat Inc. All rights reserved.
   4  * Copyright (c) 2015, Linaro Ltd. All rights reserved.
   5  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   6  *
   7  * This code is free software; you can redistribute it and/or modify it
   8  * under the terms of the GNU General Public License version 2 only, as
   9  * published by the Free Software Foundation.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  *
  25  */
  26 
  27 #ifndef CPU_AARCH32_VM_BYTES_AARCH32_HPP
  28 #define CPU_AARCH32_VM_BYTES_AARCH32_HPP
  29 
  30 #include "memory/allocation.hpp"
  31 
  32 class Bytes: AllStatic {
  33  public:
  34   // Returns true if the byte ordering used by Java is different from the native byte ordering
  35   // of the underlying machine. For example, this is true for Intel x86, but false for Solaris
  36   // on Sparc.
  37   //
  38   // AArch32 is little-endian, Java is big-endian; returns true
  39   static inline bool is_Java_byte_ordering_different(){ return true; }
  40 
  41 
  42   // Efficient reading and writing of unaligned unsigned data in platform-specific byte ordering.
  43   // Since ARMv6 unaligned short and word accesses are handled by hardware.
  44   // However, unaligned double-word access causes kernel trap and software processing,
  45   // so we turn it to fast unalinged word access.
  46   static inline u2   get_native_u2(address p)         { return *(u2*)p; }
  47   static inline u4   get_native_u4(address p)         { return *(u4*)p; }
  48   static inline u8   get_native_u8(address p)         {
  49     if (!(uintptr_t(p) & 3)) {
  50       return *(u8*)p;
  51     }
  52     u4 *const a = (u4*) p;
  53     return (u8(a[1]) << 32) | a[0];
  54   }
  55 
  56   static inline void put_native_u2(address p, u2 x)   { *(u2*)p = x; }
  57   static inline void put_native_u4(address p, u4 x)   { *(u4*)p = x; }
  58   static inline void put_native_u8(address p, u8 x)   { *(u8*)p = x; }
  59 
  60 
  61   // Efficient reading and writing of unaligned unsigned data in Java
  62   // byte ordering (i.e. big-endian ordering). Byte-order reversal is
  63   // needed since AArch32 use little-endian format.
  64   static inline u2   get_Java_u2(address p)           { return swap_u2(get_native_u2(p)); }
  65   static inline u4   get_Java_u4(address p)           { return swap_u4(get_native_u4(p)); }
  66   static inline u8   get_Java_u8(address p)           { return swap_u8(get_native_u8(p)); }
  67 
  68   static inline void put_Java_u2(address p, u2 x)     { put_native_u2(p, swap_u2(x)); }
  69   static inline void put_Java_u4(address p, u4 x)     { put_native_u4(p, swap_u4(x)); }
  70   static inline void put_Java_u8(address p, u8 x)     {
  71     const u8 nx = swap_u8(x);
  72     if (!(uintptr_t(p) & 3)) {
  73       *(u8*)p = nx;
  74     } else {
  75       u4 *const a = (u4*) p;
  76       a[0] = nx;
  77       a[1] = nx >> 32;
  78     }
  79   }
  80 
  81   // Efficient swapping of byte ordering
  82   static inline u2   swap_u2(u2 x);                   // compiler-dependent implementation
  83   static inline u4   swap_u4(u4 x);                   // compiler-dependent implementation
  84   static inline u8   swap_u8(u8 x);
  85 };
  86 
  87 
  88 // The following header contains the implementations of swap_u2, swap_u4, and swap_u8[_base]
  89 
  90 #ifdef TARGET_OS_ARCH_linux_aarch32
  91 # include "bytes_linux_aarch32.inline.hpp"
  92 #endif
  93 
  94 #endif // CPU_AARCH32_VM_BYTES_AARCH32_HPP