1 /*
   2  * Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.
   3  * Copyright (c) 2016 SAP SE. All rights reserved.
   4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   5  *
   6  * This code is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License version 2 only, as
   8  * published by the Free Software Foundation.
   9  *
  10  * This code is distributed in the hope that it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  13  * version 2 for more details (a copy is included in the LICENSE file that
  14  * accompanied this code).
  15  *
  16  * You should have received a copy of the GNU General Public License version
  17  * 2 along with this work; if not, write to the Free Software Foundation,
  18  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  19  *
  20  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  21  * or visit www.oracle.com if you need additional information or have any
  22  * questions.
  23  *
  24  */
  25 
  26 #ifndef CPU_S390_VM_BYTES_S390_HPP
  27 #define CPU_S390_VM_BYTES_S390_HPP
  28 
  29 #include "memory/allocation.hpp"
  30 
  31 class Bytes: AllStatic {
  32  public:
  33   // Efficient reading and writing of unaligned unsigned data in
  34   // platform-specific byte ordering.
  35 
  36   // Use regular load and store for unaligned access.
  37   //
  38   // On z/Architecture, unaligned loads and stores are supported when using the
  39   // "traditional" load (LH, L/LY, LG) and store (STH, ST/STY, STG) instructions.
  40   // The penalty for unaligned access is just very few (two or three) ticks,
  41   // plus another few (two or three) ticks if the access crosses a cache line boundary.
  42   //
  43   // In short, it makes no sense on z/Architecture to piecemeal get or put unaligned data.
  44 
  45   // Returns true if the byte ordering used by Java is different from
  46   // the native byte ordering of the underlying machine.
  47   // z/Arch is big endian, thus, a swap between native and Java ordering
  48   // is always a no-op.
  49   static inline bool is_Java_byte_ordering_different() { return false; }
  50 
  51   // Only swap on little endian machines => suffix `_le'.
  52   static inline u2   swap_u2_le(u2 x) { return x; }
  53   static inline u4   swap_u4_le(u4 x) { return x; }
  54   static inline u8   swap_u8_le(u8 x) { return x; }
  55 
  56   static inline u2   get_native_u2(address p) { return *(u2*)p; }
  57   static inline u4   get_native_u4(address p) { return *(u4*)p; }
  58   static inline u8   get_native_u8(address p) { return *(u8*)p; }
  59 
  60   static inline void put_native_u2(address p, u2 x) { *(u2*)p = x; }
  61   static inline void put_native_u4(address p, u4 x) { *(u4*)p = x; }
  62   static inline void put_native_u8(address p, u8 x) { *(u8*)p = x; }
  63 
  64 #include "bytes_linux_s390.inline.hpp"
  65 
  66   // Efficient reading and writing of unaligned unsigned data in Java byte ordering (i.e. big-endian ordering)
  67   static inline u2   get_Java_u2(address p) { return get_native_u2(p); }
  68   static inline u4   get_Java_u4(address p) { return get_native_u4(p); }
  69   static inline u8   get_Java_u8(address p) { return get_native_u8(p); }
  70 
  71   static inline void put_Java_u2(address p, u2 x) { put_native_u2(p, x); }
  72   static inline void put_Java_u4(address p, u4 x) { put_native_u4(p, x); }
  73   static inline void put_Java_u8(address p, u8 x) { put_native_u8(p, x); }
  74 };
  75 
  76 #endif // CPU_S390_VM_BYTES_S390_HPP