IntFromByteArray
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/* * IntFromByteArray.java * * Created on May 21, 2004, 12:35 PM */ package util; /** This is a class to take care of inserting or getting the value of an int in an array of * bytes. */ public class IntFromByteArray { private boolean littleEndian; public static final IntFromByteArray LITTLEENDIAN = new IntFromByteArray(true); public static final IntFromByteArray BIGENDIAN = new IntFromByteArray(false); /** * @param args the command line arguments */ /*public static void main(String args[]) { byte[] test = { 1, 2, 3, 4, 5, 6, 7, 8, 9 }; IntFromByteArray ifba = new IntFromByteArray(true); int[] newArray = ifba.getIntArray(test); for(int i = 0; i < newArray.length; i++) System.out.print(PadString.padHex(newArray[i], 8) + " "); }*/ public IntFromByteArray(boolean littleEndian) { this.littleEndian = littleEndian; } public int getInteger(byte[] array, int location) { if((location + 3) >= array.length) throw new ArrayIndexOutOfBoundsException("location = " + location + ", number of bytes = " + array.length + " (note: 4 available bytes are needed)"); int retVal = 0; // reverse the byte to simulate little endian if(littleEndian) { retVal = retVal | ((array[location++] << 0) & 0x000000FF); retVal = retVal | ((array[location++] << 8) & 0x0000FF00); retVal = retVal | ((array[location++] << 16) & 0x00FF0000); retVal = retVal | ((array[location++] << 24) & 0xFF000000); } else { retVal = retVal | ((array[location++] << 24) & 0xFF000000); retVal = retVal | ((array[location++] << 16) & 0x00FF0000); retVal = retVal | ((array[location++] << 8) & 0x0000FF00); retVal = retVal | ((array[location++] << 0) & 0x000000FF); } return retVal; } /** This function is used to insert the byte into a specified spot in * an int array. This is used to simulate pointers used in C++. * Note that this works in little endian only. * @param intBuffer The buffer to insert the int into. * @param b The byte we're inserting. * @param location The location (which byte) we're inserting it into. * @return The new array - this is returned for convenience only. */ public byte[] insertInteger(byte[] array, int location, int b) { if(location + 3 >= array.length) throw new ArrayIndexOutOfBoundsException("location = " + location + ", length = " + array.length + " - note that we need 4 bytes to insert an int"); if(littleEndian) { array[location++] = (byte)((b & 0x000000FF) >> 0); array[location++] = (byte)((b & 0x0000FF00) >> 8); array[location++] = (byte)((b & 0x00FF0000) >> 16); array[location++] = (byte)((b & 0xFF000000) >> 24); } else { array[location++] = (byte)((b & 0xFF000000) >> 24); array[location++] = (byte)((b & 0x00FF0000) >> 16); array[location++] = (byte)((b & 0x0000FF00) >> 8); array[location++] = (byte)((b & 0x000000FF) >> 0); } return array; } /** Note: This will cut off the end bytes to ensure it's a multiple of 4 */ public int[] getIntArray(byte[] array) { int[] newArray = new int[array.length / 4]; int pos = 0; for(int i = 0; i < newArray.length; i++) { if(littleEndian) { newArray[i] |= ((array[pos++] << 0) & 0x000000FF); newArray[i] |= ((array[pos++] << 8) & 0x0000FF00); newArray[i] |= ((array[pos++] << 16) & 0x00FF0000); newArray[i] |= ((array[pos++] << 24) & 0xFF000000); } else { newArray[i] |= array[pos++] << 24; newArray[i] |= array[pos++] << 16; newArray[i] |= array[pos++] << 8; newArray[i] |= array[pos++] << 0; } } return newArray; } }