001/*
002 * $RCSfile: ArrayUtil.java,v $
003 * $Revision: 1.1 $
004 * $Date: 2005/02/11 05:02:24 $
005 * $State: Exp $
006 *
007 * Class:                   ArrayUtil
008 *
009 * Description:             Utillities for arrays.
010 *
011 *
012 *
013 * COPYRIGHT:
014 *
015 * This software module was originally developed by Raphaël Grosbois and
016 * Diego Santa Cruz (Swiss Federal Institute of Technology-EPFL); Joel
017 * Askelöf (Ericsson Radio Systems AB); and Bertrand Berthelot, David
018 * Bouchard, Félix Henry, Gerard Mozelle and Patrice Onno (Canon Research
019 * Centre France S.A) in the course of development of the JPEG2000
020 * standard as specified by ISO/IEC 15444 (JPEG 2000 Standard). This
021 * software module is an implementation of a part of the JPEG 2000
022 * Standard. Swiss Federal Institute of Technology-EPFL, Ericsson Radio
023 * Systems AB and Canon Research Centre France S.A (collectively JJ2000
024 * Partners) agree not to assert against ISO/IEC and users of the JPEG
025 * 2000 Standard (Users) any of their rights under the copyright, not
026 * including other intellectual property rights, for this software module
027 * with respect to the usage by ISO/IEC and Users of this software module
028 * or modifications thereof for use in hardware or software products
029 * claiming conformance to the JPEG 2000 Standard. Those intending to use
030 * this software module in hardware or software products are advised that
031 * their use may infringe existing patents. The original developers of
032 * this software module, JJ2000 Partners and ISO/IEC assume no liability
033 * for use of this software module or modifications thereof. No license
034 * or right to this software module is granted for non JPEG 2000 Standard
035 * conforming products. JJ2000 Partners have full right to use this
036 * software module for his/her own purpose, assign or donate this
037 * software module to any third party and to inhibit third parties from
038 * using this software module for non JPEG 2000 Standard conforming
039 * products. This copyright notice must be included in all copies or
040 * derivative works of this software module.
041 *
042 * Copyright (c) 1999/2000 JJ2000 Partners.
043 *
044 *
045 *
046 */
047
048
049package jj2000.j2k.util;
050
051/**
052 * This class contains a colleaction of utility static methods for arrays.
053 * */
054public class ArrayUtil {
055
056    /** The maximum array size to do element by element copying, larger
057     * arrays are copyied in a n optimized way. */
058    public static final int MAX_EL_COPYING = 8;
059
060    /** The number of elements to copy initially in an optimized array copy */
061    public static final int INIT_EL_COPYING = 4;
062
063    /**
064     * Reinitializes an int array to the given value in an optimized way. If
065     * the length of the array is less than MAX_EL_COPYING, then the array
066     * is set element by element in the normal way, otherwise the first
067     * INIT_EL_COPYING elements are set element by element and then
068     * System.arraycopy is used to set the other parts of the array.
069     *
070     * @param arr The array to set.
071     *
072     * @param val The value to set the array to.
073     *
074     *
075     * */
076    public static void intArraySet(int arr[], int val) {
077        int i,len,len2;
078
079        len = arr.length;
080        // Set array to 'val' in an optimized way
081        if (len < MAX_EL_COPYING) {
082            // Not worth doing optimized way
083            for (i=len-1; i>=0; i--) { // Set elements
084                arr[i] = val;
085            }
086        }
087        else { // Do in optimized way
088            len2 = len>>1;
089            for (i=0; i<INIT_EL_COPYING; i++) { // Set first elements
090                arr[i] = val;
091            }
092            for (; i <= len2 ; i<<=1) {
093                // Copy values doubling size each time
094                System.arraycopy(arr,0,arr,i,i);
095            }
096            if (i < len) { // Copy values to end
097                System.arraycopy(arr,0,arr,i,len-i);
098            }
099        }
100    }
101
102    /**
103     * Reinitializes a byte array to the given value in an optimized way. If
104     * the length of the array is less than MAX_EL_COPYING, then the array
105     * is set element by element in the normal way, otherwise the first
106     * INIT_EL_COPYING elements are set element by element and then
107     * System.arraycopy is used to set the other parts of the array.
108     *
109     * @param arr The array to set.
110     *
111     * @param val The value to set the array to.
112     *
113     *
114     * */
115    public static void byteArraySet(byte arr[], byte val) {
116        int i,len,len2;
117
118        len = arr.length;
119        // Set array to 'val' in an optimized way
120        if (len < MAX_EL_COPYING) {
121            // Not worth doing optimized way
122            for (i=len-1; i>=0; i--) { // Set elements
123                arr[i] = val;
124            }
125        }
126        else { // Do in optimized way
127            len2 = len>>1;
128            for (i=0; i<INIT_EL_COPYING; i++) { // Set first elements
129                arr[i] = val;
130            }
131            for (; i <= len2 ; i<<=1) {
132                // Copy values doubling size each time
133                System.arraycopy(arr,0,arr,i,i);
134            }
135            if (i < len) { // Copy values to end
136                System.arraycopy(arr,0,arr,i,len-i);
137            }
138        }
139    }
140
141}