/*
 *  This file is part of the Jikes RVM project (http://jikesrvm.org).
 *
 *  This file is licensed to You under the Common Public License (CPL);
 *  You may not use this file except in compliance with the License. You
 *  may obtain a copy of the License at
 *
 *      http://www.opensource.org/licenses/cpl1.0.php
 *
 *  See the COPYRIGHT.txt file distributed with this work for information
 *  regarding copyright ownership.
 */
package org.mmtk.utility.options;

import org.mmtk.utility.Log;
import org.mmtk.utility.Conversions;

import org.vmmagic.pragma.*;
import org.vmmagic.unboxed.*;

/**
 * A memory option that stores values as a whole number of pages.
 */
public class PagesOption extends Option {
  // values
  protected int defaultValue;
  protected int value;

  /**
   * Create a new pages option.
   *
   * @param name The space separated name for the option.
   * @param desc The purpose of the option
   * @param defaultPages The default value of the option.
   */
  protected PagesOption(String name, String desc, int defaultPages) {
    super(PAGES_OPTION, name, desc);
    this.value = this.defaultValue = defaultPages;
  }

  /**
   * Read the current value of the option in pages.
   *
   * @return The option value.
   */
  @Uninterruptible
  public int getPages() {
    return this.value;
  }

  /**
   * Read the current value of the option in bytes.
   *
   * @return The option value.
   */
  @Uninterruptible
  public Extent getBytes() {
    return Conversions.pagesToBytes(this.value);
  }

  /**
   * Read the default value of the option in bytes.
   *
   * @return The default value.
   */
  @Uninterruptible
  public Extent getDefaultBytes() {
    return Conversions.pagesToBytes(this.defaultValue);
  }

  /**
   * Read the default value of the option in pages.
   *
   * @return The default value.
   */
  @Uninterruptible
  public int getDefaultPages() {
    return this.defaultValue;
  }

  /**
   * Update the value of the option, echoing the change if the echoOptions
   * option is set. A warning is raised if the value is not a whole multiple
   * of pages, and then the validate method is called to allow subclasses to
   * perform any additional validation.
   *
   * @param value The new value for the option.
   */
  public void setBytes(Extent value) {
    Extent oldValue = getBytes();
    if (Options.echoOptions.getValue()) {
      Log.write("Option '");
      Log.write(this.getKey());
      Log.write("' set ");
      Log.write(oldValue);
      Log.write(" -> ");
      Log.writeln(value);
    }
    int pages = Conversions.bytesToPagesUp(value);
    warnIf(value.NE(Conversions.pagesToBytes(pages)),
        "Value rounded up to a whole number of pages");
    this.value = Conversions.bytesToPagesUp(value);
    validate();
  }

  /**
   * Log the option value in raw format - delegate upwards
   * for fancier formatting.
   *
   * @param format Output format (see Option.java for possible values)
   */
  @Override
  void log(int format) {
    switch (format) {
      case RAW:
        Log.write(value);
        break;
      default:
        super.log(format);
    }
  }
}