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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();
+ }
+
+}