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1 /*
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2 * Copyright 2001-2004 Sun Microsystems, Inc. All Rights Reserved.
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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4 *
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5 * This code is free software; you can redistribute it and/or modify it
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6 * under the terms of the GNU General Public License version 2 only, as
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7 * published by the Free Software Foundation.
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8 *
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9 * This code is distributed in the hope that it will be useful, but WITHOUT
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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12 * version 2 for more details (a copy is included in the LICENSE file that
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13 * accompanied this code).
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14 *
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15 * You should have received a copy of the GNU General Public License version
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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18 *
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19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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20 * CA 95054 USA or visit www.sun.com if you need additional information or
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21 * have any questions.
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22 *
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23 */
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24
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25 package sun.jvm.hotspot.utilities;
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26
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27 /** Bit manipulation routines */
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28
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29 public class Bits {
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30 public static final int AllBits = ~0;
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31 public static final int NoBits = 0;
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32 public static final int OneBit = 1;
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33
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34 public static final int BitsPerByte = 8;
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35 public static final int BitsPerInt = 32;
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36
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37 public static final int LogBytesPerInt = 2;
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38 public static final int LogBytesPerLong = 3;
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39
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40
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41 public static int setBits(int x, int m) {
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42 return x | m;
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43 }
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44
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45 public static int clearBits(int x, int m) {
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46 return x & ~m;
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47 }
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48
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49 public static int nthBit(int n) {
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50 return (n > 32) ? 0 : (OneBit << n);
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51 }
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52
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53 public static int setNthBit(int x, int n) {
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54 return setBits(x, nthBit(n));
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55 }
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56
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57 public static int clearNthBit(int x, int n) {
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58 return clearBits(x, nthBit(n));
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59 }
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60
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61 public static boolean isSetNthBit(int word, int n) {
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62 return maskBits(word, nthBit(n)) != NoBits;
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63 }
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64
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65 public static int rightNBits(int n) {
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66 return (nthBit(n) - 1);
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67 }
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68
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69 public static int maskBits(int x, int m) {
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70 return x & m;
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71 }
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72
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73 public static long maskBitsLong(long x, long m) {
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74 return x & m;
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75 }
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76
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77 /** Returns integer round-up to the nearest multiple of s (s must be
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78 a power of two) */
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79 public static int roundTo(int x, int s) {
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80 int m = s - 1;
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81 return maskBits(x + m, ~m);
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82 }
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83 }
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