1 /*
   2  * Copyright (c) 2009, 2011, 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.bytecode;
  24 
  25 /**
  26  * A collection of utility methods for dealing with bytes, particularly in byte arrays.
  27  */
  28 public class Bytes {
  29 
  30     /**
  31      * Gets a signed 1-byte value.
  32      *
  33      * @param data the array containing the data
  34      * @param bci the start index of the value to retrieve
  35      * @return the signed 1-byte value at index {@code bci} in array {@code data}
  36      */
  37     public static int beS1(byte[] data, int bci) {
  38         return data[bci];
  39     }
  40 
  41     /**
  42      * Gets a signed 2-byte big-endian value.
  43      *
  44      * @param data the array containing the data
  45      * @param bci the start index of the value to retrieve
  46      * @return the signed 2-byte, big-endian, value at index {@code bci} in array {@code data}
  47      */
  48     public static int beS2(byte[] data, int bci) {
  49         return (data[bci] << 8) | (data[bci + 1] & 0xff);
  50     }
  51 
  52     /**
  53      * Gets an unsigned 1-byte value.
  54      *
  55      * @param data the array containing the data
  56      * @param bci the start index of the value to retrieve
  57      * @return the unsigned 1-byte value at index {@code bci} in array {@code data}
  58      */
  59     public static int beU1(byte[] data, int bci) {
  60         return data[bci] & 0xff;
  61     }
  62 
  63     /**
  64      * Gets an unsigned 2-byte big-endian value.
  65      *
  66      * @param data the array containing the data
  67      * @param bci the start index of the value to retrieve
  68      * @return the unsigned 2-byte, big-endian, value at index {@code bci} in array {@code data}
  69      */
  70     public static int beU2(byte[] data, int bci) {
  71         return ((data[bci] & 0xff) << 8) | (data[bci + 1] & 0xff);
  72     }
  73 
  74     /**
  75      * Gets a signed 4-byte big-endian value.
  76      *
  77      * @param data the array containing the data
  78      * @param bci the start index of the value to retrieve
  79      * @return the signed 4-byte, big-endian, value at index {@code bci} in array {@code data}
  80      */
  81     public static int beS4(byte[] data, int bci) {
  82         return (data[bci] << 24) | ((data[bci + 1] & 0xff) << 16) | ((data[bci + 2] & 0xff) << 8) | (data[bci + 3] & 0xff);
  83     }
  84 
  85     /**
  86      * Gets either a signed 2-byte or a signed 4-byte big-endian value.
  87      *
  88      * @param data the array containing the data
  89      * @param bci the start index of the value to retrieve
  90      * @param fourByte if true, this method will return a 4-byte value
  91      * @return the signed 2 or 4-byte, big-endian, value at index {@code bci} in array {@code data}
  92      */
  93     public static int beSVar(byte[] data, int bci, boolean fourByte) {
  94         if (fourByte) {
  95             return beS4(data, bci);
  96         } else {
  97             return beS2(data, bci);
  98         }
  99     }
 100 }