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;
}
}