/*

 * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * 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.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

#ifndef SHARE_GC_Z_ZBITFIELD_HPP

#define SHARE_GC_Z_ZBITFIELD_HPP

#include "memory/allocation.hpp"

#include "utilities/debug.hpp"

//

//  Example

//  -------

//

//  typedef ZBitField<uint64_t, uint8_t,  0,  2, 3> field_word_aligned_size;

//  typedef ZBitField<uint64_t, uint32_t, 2, 30>    field_length;

//

//

//   6                                 3 3

//   3                                 2 1                               2 10

//  +-----------------------------------+---------------------------------+--+

//  |11111111 11111111 11111111 11111111|11111111 11111111 11111111 111111|11|

//  +-----------------------------------+---------------------------------+--+

//  |                                   |                                 |

//  |       31-2 field_length (30-bits) *                                 |

//  |                                                                     |

//  |                                1-0 field_word_aligned_size (2-bits) *

//  |

//  * 63-32 Unused (32-bits)

//

//

//  field_word_aligned_size::encode(16) = 2

//  field_length::encode(2342) = 9368

//

//  field_word_aligned_size::decode(9368 | 2) = 16

//  field_length::decode(9368 | 2) = 2342

//

template <typename ContainerType, typename ValueType, int FieldShift, int FieldBits, int ValueShift = 0>

class ZBitField : public AllStatic {

private:

  static const int ContainerBits = sizeof(ContainerType) * BitsPerByte;

  STATIC_ASSERT(FieldBits < ContainerBits);

  STATIC_ASSERT(FieldShift + FieldBits <= ContainerBits);

  STATIC_ASSERT(ValueShift + FieldBits <= ContainerBits);

  static const ContainerType FieldMask = (((ContainerType)1 << FieldBits) - 1);

public:

  static ValueType decode(ContainerType container) {

    return (ValueType)(((container >> FieldShift) & FieldMask) << ValueShift);

  }

  static ContainerType encode(ValueType value) {

    assert(((ContainerType)value & (FieldMask << ValueShift)) == (ContainerType)value, "Invalid value");

    return ((ContainerType)value >> ValueShift) << FieldShift;

  }

};

#endif // SHARE_GC_Z_ZBITFIELD_HPP