1 /*
   2  * Copyright (c) 2015, 2015, 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.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 package org.graalvm.word;
  26 
  27 /**
  28  * Utility methods on Pointers.
  29  */
  30 public final class PointerUtils {
  31 
  32     private PointerUtils() {
  33         // This is a class of static methods, so no need for any instances.
  34     }
  35 
  36     /**
  37      * The value of a null Pointer.
  38      *
  39      * @return A null Pointer value.
  40      */
  41     public static <T extends PointerBase> T nullPointer() {
  42         /* This method will be deleted soon. */
  43         return WordFactory.nullPointer();
  44     }
  45 
  46     /**
  47      * Predicate to check for the null Pointer value.
  48      *
  49      * @return Whether that Pointer is the null Pointer.
  50      */
  51     public static boolean isNull(ComparableWord that) {
  52         /* This method will be deleted soon. */
  53         return ((PointerBase) that).isNull();
  54     }
  55 
  56     /**
  57      * Predicate to check for a non-null Pointer value.
  58      *
  59      * @return Whether that Pointer is not the null Pointer.
  60      */
  61     public static boolean isNonNull(ComparableWord that) {
  62         /* This method will be deleted soon. */
  63         return ((PointerBase) that).isNonNull();
  64     }
  65 
  66     /**
  67      * Round a Pointer down to the nearest smaller multiple.
  68      *
  69      * @param that The Pointer to be rounded up.
  70      * @param multiple The multiple to which that Pointer should be decreased.
  71      * @return That Pointer, but rounded down.
  72      */
  73     public static Pointer roundDown(PointerBase that, Unsigned multiple) {
  74         return (Pointer) UnsignedUtils.roundDown((Unsigned) that, multiple);
  75     }
  76 
  77     /**
  78      * Round a Pointer up to the nearest larger multiple.
  79      *
  80      * @param that The Pointer to be rounded up.
  81      * @param multiple The multiple to which that Pointer should be increased.
  82      * @return That Pointer, but rounded up.
  83      */
  84     public static Pointer roundUp(PointerBase that, Unsigned multiple) {
  85         return (Pointer) UnsignedUtils.roundUp((Unsigned) that, multiple);
  86     }
  87 
  88     /**
  89      * Check that a Pointer is an even multiple.
  90      *
  91      * @param that The Pointer to be verified as a multiple.
  92      * @param multiple The multiple against which the Pointer should be verified.
  93      * @return true if that Pointer is a multiple, false otherwise.
  94      */
  95     public static boolean isAMultiple(PointerBase that, Unsigned multiple) {
  96         return that.equal(PointerUtils.roundDown(that, multiple));
  97     }
  98 
  99     /**
 100      * Return the distance between two Pointers.
 101      *
 102      * @param pointer1 A first Pointer.
 103      * @param pointer2 A second Pointer.
 104      * @return The distance in bytes between the two Pointers.
 105      */
 106     public static Unsigned absoluteDifference(PointerBase pointer1, PointerBase pointer2) {
 107         Pointer p1 = (Pointer) pointer1;
 108         Pointer p2 = (Pointer) pointer2;
 109         final Unsigned result;
 110         if (p1.aboveOrEqual(p2)) {
 111             result = p1.subtract(p2);
 112         } else {
 113             result = p2.subtract(p1);
 114         }
 115         return result;
 116     }
 117 
 118     /**
 119      * The minimum of two Pointers.
 120      *
 121      * @param x A Pointer.
 122      * @param y Another Pointer.
 123      * @return The whichever Pointer is smaller.
 124      */
 125     public static <T extends PointerBase> T min(T x, T y) {
 126         return (((Pointer) x).belowOrEqual((Pointer) y)) ? x : y;
 127     }
 128 
 129     /**
 130      * The maximum of two Pointers.
 131      *
 132      * @param x A Pointer.
 133      * @param y Another Pointer.
 134      * @return The whichever Pointer is larger.
 135      */
 136     public static <T extends PointerBase> T max(T x, T y) {
 137         return (((Pointer) x).aboveOrEqual((Pointer) y)) ? x : y;
 138     }
 139 }