1 /*
   2  * Copyright (c) 2001, 2010, 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 
  26 package java.io;
  27 
  28 /**
  29  * Utility methods for packing/unpacking primitive values in/out of byte arrays
  30  * using big-endian byte ordering.
  31  */
  32 class Bits {
  33 
  34     /*
  35      * Methods for unpacking primitive values from byte arrays starting at
  36      * given offsets.
  37      */
  38 
  39     static boolean getBoolean(byte[] b, int off) {
  40         return b[off] != 0;
  41     }
  42 
  43     static char getChar(byte[] b, int off) {
  44         return (char) ((b[off + 1] & 0xFF) +
  45                        (b[off] << 8));
  46     }
  47 
  48     static short getShort(byte[] b, int off) {
  49         return (short) ((b[off + 1] & 0xFF) +
  50                         (b[off] << 8));
  51     }
  52 
  53     static int getInt(byte[] b, int off) {
  54         return ((b[off + 3] & 0xFF)      ) +
  55                ((b[off + 2] & 0xFF) <<  8) +
  56                ((b[off + 1] & 0xFF) << 16) +
  57                ((b[off    ]       ) << 24);
  58     }
  59 
  60     static float getFloat(byte[] b, int off) {
  61         return Float.intBitsToFloat(getInt(b, off));
  62     }
  63 
  64     static long getLong(byte[] b, int off) {
  65         return ((b[off + 7] & 0xFFL)      ) +
  66                ((b[off + 6] & 0xFFL) <<  8) +
  67                ((b[off + 5] & 0xFFL) << 16) +
  68                ((b[off + 4] & 0xFFL) << 24) +
  69                ((b[off + 3] & 0xFFL) << 32) +
  70                ((b[off + 2] & 0xFFL) << 40) +
  71                ((b[off + 1] & 0xFFL) << 48) +
  72                (((long) b[off])      << 56);
  73     }
  74 
  75     static double getDouble(byte[] b, int off) {
  76         return Double.longBitsToDouble(getLong(b, off));
  77     }
  78 
  79     /*
  80      * Methods for packing primitive values into byte arrays starting at given
  81      * offsets.
  82      */
  83 
  84     static void putBoolean(byte[] b, int off, boolean val) {
  85         b[off] = (byte) (val ? 1 : 0);
  86     }
  87 
  88     static void putChar(byte[] b, int off, char val) {
  89         b[off + 1] = (byte) (val      );
  90         b[off    ] = (byte) (val >>> 8);
  91     }
  92 
  93     static void putShort(byte[] b, int off, short val) {
  94         b[off + 1] = (byte) (val      );
  95         b[off    ] = (byte) (val >>> 8);
  96     }
  97 
  98     static void putInt(byte[] b, int off, int val) {
  99         b[off + 3] = (byte) (val       );
 100         b[off + 2] = (byte) (val >>>  8);
 101         b[off + 1] = (byte) (val >>> 16);
 102         b[off    ] = (byte) (val >>> 24);
 103     }
 104 
 105     static void putFloat(byte[] b, int off, float val) {
 106         putInt(b, off,  Float.floatToIntBits(val));
 107     }
 108 
 109     static void putLong(byte[] b, int off, long val) {
 110         b[off + 7] = (byte) (val       );
 111         b[off + 6] = (byte) (val >>>  8);
 112         b[off + 5] = (byte) (val >>> 16);
 113         b[off + 4] = (byte) (val >>> 24);
 114         b[off + 3] = (byte) (val >>> 32);
 115         b[off + 2] = (byte) (val >>> 40);
 116         b[off + 1] = (byte) (val >>> 48);
 117         b[off    ] = (byte) (val >>> 56);
 118     }
 119 
 120     static void putDouble(byte[] b, int off, double val) {
 121         putLong(b, off, Double.doubleToLongBits(val));
 122     }
 123 }