1 /*

     2  * Copyright (c) 2017, 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

    21  * questions.

    22  */

    23 

    24 #ifndef SHARE_GC_Z_ZPAGETABLEENTRY_HPP

    25 #define SHARE_GC_Z_ZPAGETABLEENTRY_HPP

    26 

    27 #include "gc/z/zBitField.hpp"

    28 #include "memory/allocation.hpp"

    29 

    30 //

    31 // Page table entry layout

    32 // -----------------------

    33 //

    34 //   6

    35 //   3                                                                    1 0

    36 //  +----------------------------------------------------------------------+-+

    37 //  |11111111 11111111 11111111 11111111 11111111 11111111 11111111 1111111|1|

    38 //  +----------------------------------------------------------------------+-+

    39 //  |                                                                      |

    40 //  |                                          0-0 Relocating Flag (1-bit) *

    41 //  |

    42 //  |

    43 //  |

    44 //  * 63-1 Page address (63-bits)

    45 //

    46 

    47 class ZPage;

    48 

    49 class ZPageTableEntry {

    50 private:

    51   typedef ZBitField<uint64_t, bool,   0, 1>     field_relocating;

    52   typedef ZBitField<uint64_t, ZPage*, 1, 63, 1> field_page;

    53 

    54   uint64_t _entry;

    55 

    56 public:

    57   ZPageTableEntry() :

    58       _entry(0) {}

    59 

    60   ZPageTableEntry(ZPage* page, bool relocating) :

    61       _entry(field_page::encode(page) |

    62              field_relocating::encode(relocating)) {}

    63 

    64   bool relocating() const {

    65     return field_relocating::decode(_entry);

    66   }

    67 

    68   ZPage* page() const {

    69     return field_page::decode(_entry);

    70   }

    71 };

    72 

    73 #endif // SHARE_GC_Z_ZPAGETABLEENTRY_HPP