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