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/*
Copyright (c) 2005 Health Market Science, Inc.
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
USA
You can contact Health Market Science at info@healthmarketscience.com
or at the following address:
Health Market Science
2700 Horizon Drive
Suite 200
King of Prussia, PA 19406
*/
package com.healthmarketscience.jackcess;
import java.nio.ByteBuffer;
/**
* Byte manipulation and display utilities
* @author Tim McCune
*/
public final class ByteUtil {
private static final String[] HEX_CHARS = new String[] {
"0", "1", "2", "3", "4", "5", "6", "7",
"8", "9", "A", "B", "C", "D", "E", "F"};
private ByteUtil() {}
/**
* Convert an int from 4 bytes to 3
* @param i Int to convert
* @return Array of 3 bytes in little-endian order
*/
public static byte[] to3ByteInt(int i) {
byte[] rtn = new byte[3];
rtn[0] = (byte) (i & 0xFF);
rtn[1] = (byte) ((i >>> 8) & 0xFF);
rtn[2] = (byte) ((i >>> 16) & 0xFF);
return rtn;
}
/**
* Read a 3 byte int from a buffer in little-endian order
* @param buffer Buffer containing the bytes
* @param offset Offset at which to start reading the int
* @return The int
*/
public static int get3ByteInt(ByteBuffer buffer, int offset) {
int rtn = buffer.get(offset) & 0xff;
rtn += ((((int) buffer.get(offset + 1)) & 0xFF) << 8);
rtn += ((((int) buffer.get(offset + 2)) & 0xFF) << 16);
rtn &= 16777215; //2 ^ (8 * 3) - 1
return rtn;
}
/**
* Convert a byte buffer to a hexadecimal string for display
* @param buffer Buffer to display, starting at offset 0
* @param size Number of bytes to read from the buffer
* @return The display String
*/
public static String toHexString(ByteBuffer buffer, int size) {
return toHexString(buffer, 0, size);
}
/**
* Convert a byte buffer to a hexadecimal string for display
* @param buffer Buffer to display, starting at offset 0
* @param offset Offset at which to start reading the buffer
* @param size Number of bytes to read from the buffer
* @return The display String
*/
public static String toHexString(ByteBuffer buffer, int offset, int size) {
StringBuffer rtn = new StringBuffer();
int position = buffer.position();
buffer.position(offset);
for (int i = 0; i < size; i++) {
byte b = buffer.get();
byte h = (byte) (b & 0xF0);
h = (byte) (h >>> 4);
h = (byte) (h & 0x0F);
rtn.append(HEX_CHARS[(int) h]);
h = (byte) (b & 0x0F);
rtn.append(HEX_CHARS[(int) h] + " ");
if ((i + 1) % 4 == 0) {
rtn.append(" ");
}
if ((i + 1) % 24 == 0) {
rtn.append("\n");
}
}
buffer.position(position);
return rtn.toString();
}
}
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