/*

 * Copyright (c) 2012, 2016, 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.

 *

 */

#include "precompiled.hpp"

#include "memory/allocation.hpp"

#include "memory/metachunk.hpp"

#include "utilities/copy.hpp"

#include "utilities/debug.hpp"

class VirtualSpaceNode;

size_t Metachunk::object_alignment() {

  // Must align pointers and sizes to 8,

  // so that 64 bit types get correctly aligned.

  const size_t alignment = 8;

  // Make sure that the Klass alignment also agree.

  STATIC_ASSERT(alignment == (size_t)KlassAlignmentInBytes);

  return alignment;

}

size_t Metachunk::overhead() {

  return align_size_up(sizeof(Metachunk), object_alignment()) / BytesPerWord;

}

// Metachunk methods

Metachunk::Metachunk(size_t word_size,

                     VirtualSpaceNode* container)

    : Metabase<Metachunk>(word_size),

    _top(NULL),

    _container(container)

{

  _top = initial_top();

#ifdef ASSERT

  set_is_tagged_free(false);

  mangle(uninitMetaWordVal);

#endif

}

MetaWord* Metachunk::allocate(size_t word_size) {

  MetaWord* result = NULL;

  // If available, bump the pointer to allocate.

  if (free_word_size() >= word_size) {

    result = _top;

    _top = _top + word_size;

  }

  return result;

}

// _bottom points to the start of the chunk including the overhead.

size_t Metachunk::used_word_size() const {

  return pointer_delta(_top, bottom(), sizeof(MetaWord));

}

size_t Metachunk::free_word_size() const {

  return pointer_delta(end(), _top, sizeof(MetaWord));

}

void Metachunk::print_on(outputStream* st) const {

  st->print_cr("Metachunk:"

               " bottom " PTR_FORMAT " top " PTR_FORMAT

               " end " PTR_FORMAT " size " SIZE_FORMAT,

               p2i(bottom()), p2i(_top), p2i(end()), word_size());

  if (Verbose) {

    st->print_cr("    used " SIZE_FORMAT " free " SIZE_FORMAT,

                 used_word_size(), free_word_size());

  }

}

#ifndef PRODUCT

void Metachunk::mangle(juint word_value) {

  // Overwrite the payload of the chunk and not the links that

  // maintain list of chunks.

  HeapWord* start = (HeapWord*)initial_top();

  size_t size = word_size() - overhead();

  Copy::fill_to_words(start, size, word_value);

}

#endif // PRODUCT

void Metachunk::verify() {

#ifdef ASSERT

  // Cannot walk through the blocks unless the blocks have

  // headers with sizes.

  assert(bottom() <= _top &&

         _top <= (MetaWord*)end(),

         "Chunk has been smashed");

#endif

  return;

}