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: package jj2000.j2k.util;
049:
050: /**
051: * This class contains a colleaction of utility static methods for arrays.
052: * */
053: public class ArrayUtil {
054:
055: /** The maximum array size to do element by element copying, larger
056: * arrays are copyied in a n optimized way. */
057: public static final int MAX_EL_COPYING = 8;
058:
059: /** The number of elements to copy initially in an optimized array copy */
060: public static final int INIT_EL_COPYING = 4;
061:
062: /**
063: * Reinitializes an int array to the given value in an optimized way. If
064: * the length of the array is less than MAX_EL_COPYING, then the array
065: * is set element by element in the normal way, otherwise the first
066: * INIT_EL_COPYING elements are set element by element and then
067: * System.arraycopy is used to set the other parts of the array.
068: *
069: * @param arr The array to set.
070: *
071: * @param val The value to set the array to.
072: *
073: *
074: * */
075: public static void intArraySet(int arr[], int val) {
076: int i, len, len2;
077:
078: len = arr.length;
079: // Set array to 'val' in an optimized way
080: if (len < MAX_EL_COPYING) {
081: // Not worth doing optimized way
082: for (i = len - 1; i >= 0; i--) { // Set elements
083: arr[i] = val;
084: }
085: } else { // Do in optimized way
086: len2 = len >> 1;
087: for (i = 0; i < INIT_EL_COPYING; i++) { // Set first elements
088: arr[i] = val;
089: }
090: for (; i <= len2; i <<= 1) {
091: // Copy values doubling size each time
092: System.arraycopy(arr, 0, arr, i, i);
093: }
094: if (i < len) { // Copy values to end
095: System.arraycopy(arr, 0, arr, i, len - i);
096: }
097: }
098: }
099:
100: /**
101: * Reinitializes a byte array to the given value in an optimized way. If
102: * the length of the array is less than MAX_EL_COPYING, then the array
103: * is set element by element in the normal way, otherwise the first
104: * INIT_EL_COPYING elements are set element by element and then
105: * System.arraycopy is used to set the other parts of the array.
106: *
107: * @param arr The array to set.
108: *
109: * @param val The value to set the array to.
110: *
111: *
112: * */
113: public static void byteArraySet(byte arr[], byte val) {
114: int i, len, len2;
115:
116: len = arr.length;
117: // Set array to 'val' in an optimized way
118: if (len < MAX_EL_COPYING) {
119: // Not worth doing optimized way
120: for (i = len - 1; i >= 0; i--) { // Set elements
121: arr[i] = val;
122: }
123: } else { // Do in optimized way
124: len2 = len >> 1;
125: for (i = 0; i < INIT_EL_COPYING; i++) { // Set first elements
126: arr[i] = val;
127: }
128: for (; i <= len2; i <<= 1) {
129: // Copy values doubling size each time
130: System.arraycopy(arr, 0, arr, i, i);
131: }
132: if (i < len) { // Copy values to end
133: System.arraycopy(arr, 0, arr, i, len - i);
134: }
135: }
136: }
137:
138: }
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