001    /*
002     *  This file is part of the Jikes RVM project (http://jikesrvm.org).
003     *
004     *  This file is licensed to You under the Eclipse Public License (EPL);
005     *  You may not use this file except in compliance with the License. You
006     *  may obtain a copy of the License at
007     *
008     *      http://www.opensource.org/licenses/eclipse-1.0.php
009     *
010     *  See the COPYRIGHT.txt file distributed with this work for information
011     *  regarding copyright ownership.
012     */
013    package org.vmutil.options;
014    
015    import org.vmmagic.pragma.Uninterruptible;
016    import org.vmmagic.unboxed.Extent;
017    
018    /**
019     * A memory option that stores values as a whole number of pages.
020     */
021    public class PagesOption extends Option {
022      // values
023      protected int defaultValue;
024      protected int value;
025    
026      /**
027       * Create a new pages option.
028       *
029       * @param set The option set this option belongs to.
030       * @param name The space separated name for the option.
031       * @param desc The purpose of the option
032       * @param defaultPages The default value of the option.
033       */
034      protected PagesOption(OptionSet set, String name, String desc, int defaultPages) {
035        super(set, PAGES_OPTION, name, desc);
036        this.value = this.defaultValue = defaultPages;
037      }
038    
039      /**
040       * Read the current value of the option in pages.
041       *
042       * @return The option value.
043       */
044      @Uninterruptible
045      public int getPages() {
046        return this.value;
047      }
048    
049      /**
050       * Read the current value of the option in bytes.
051       *
052       * @return The option value.
053       */
054      @Uninterruptible
055      public Extent getBytes() {
056        return set.pagesToBytes(this.value);
057      }
058    
059      /**
060       * Read the default value of the option in bytes.
061       *
062       * @return The default value.
063       */
064      @Uninterruptible
065      public Extent getDefaultBytes() {
066        return set.pagesToBytes(this.defaultValue);
067      }
068    
069      /**
070       * Read the default value of the option in pages.
071       *
072       * @return The default value.
073       */
074      @Uninterruptible
075      public int getDefaultPages() {
076        return this.defaultValue;
077      }
078    
079      /**
080       * Update the value of the option, echoing the change if logChanges is set.
081       * A warning is raised if the value is not a whole multiple of pages, and
082       * then the validate method is called to allow subclasses to perform any
083       * additional validation.
084       *
085       * @param value The new value for the option.
086       */
087      public void setBytes(Extent value) {
088        int pages = set.bytesToPages(value);
089        warnIf(value.NE(set.pagesToBytes(pages)), "Value rounded up to a whole number of pages");
090        setPages(pages);
091      }
092    
093      /**
094       * Update the value of the option, echoing the change if logChanges is set.
095       * The validate method is called to allow subclasses to perform any additional
096       * validation.
097       *
098       * @param pages The new value for the option.
099       */
100      public void setPages(int pages) {
101        this.value = pages;
102        validate();
103        set.logChange(this);
104      }
105    
106      /**
107       * Modify the default value of the option.
108       *
109       * @param value The new default value for the option.
110       */
111      public void setDefaultPages(int value) {
112        this.value = this.defaultValue = value;
113      }
114    }