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/*
* Copyright 2019-2024 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.power4j.tile.codec;
import lombok.experimental.UtilityClass;
import java.nio.ByteBuffer;
/**
* Converts hexadecimal Strings.
* Codes copied from {@code org.apache.commons.codec.binary.Hex}
*
* @author CJ ([email protected])
* @since 1.0
*/
@UtilityClass
public class Hex {
/**
* Used to build output as hex.
*/
private static final char[] DIGITS_LOWER = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd',
'e', 'f' };
/**
* Used to build output as hex.
*/
private static final char[] DIGITS_UPPER = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D',
'E', 'F' };
/**
* Converts an array of characters representing hexadecimal values into an array of
* bytes of those same values. The returned array will be half the length of the
* passed array, as it takes two characters to represent any given byte. An exception
* is thrown if the passed char array has an odd number of elements.
* @param data An array of characters containing hexadecimal digits
* @return A byte array containing binary data decoded from the supplied char array.
* @throws DecodeException Thrown if an odd number of characters or illegal characters
* are supplied
*/
public static byte[] decodeHex(final char[] data) throws DecodeException {
final byte[] out = new byte[data.length >> 1];
decodeHex(data, out, 0);
return out;
}
/**
* Converts an array of characters representing hexadecimal values into an array of
* bytes of those same values. The returned array will be half the length of the
* passed array, as it takes two characters to represent any given byte. An exception
* is thrown if the passed char array has an odd number of elements.
* @param data An array of characters containing hexadecimal digits
* @param out A byte array to contain the binary data decoded from the supplied char
* array.
* @param outOffset The position within {@code out} to start writing the decoded
* bytes.
* @return the number of bytes written to {@code out}.
* @throws DecodeException Thrown if an odd number of characters or illegal characters
* are supplied
*/
public static int decodeHex(final char[] data, final byte[] out, final int outOffset) throws DecodeException {
final int len = data.length;
if ((len & 0x01) != 0) {
throw new DecodeException("Odd number of characters.");
}
final int outLen = len >> 1;
if (out.length - outOffset < outLen) {
throw new DecodeException("Output array is not large enough to accommodate decoded data.");
}
// two characters form the hex value.
for (int i = outOffset, j = 0; j < len; i++) {
int f = toDigit(data[j], j) << 4;
j++;
f = f | toDigit(data[j], j);
j++;
out[i] = (byte) (f & 0xFF);
}
return outLen;
}
/**
* Converts an array of bytes into an array of characters representing the hexadecimal
* values of each byte in order. The returned array will be double the length of the
* passed array, as it takes two characters to represent any given byte.
* @param data a byte[] to convert to hex characters
* @return A char[] containing lower-case hexadecimal characters
*/
public static char[] encodeHex(final byte[] data) {
return encodeHex(data, true);
}
/**
* Converts an array of bytes into an array of characters representing the hexadecimal
* values of each byte in order. The returned array will be double the length of the
* passed array, as it takes two characters to represent any given byte.
* @param data a byte[] to convert to Hex characters
* @param toLowerCase {@code true} converts to lowercase, {@code false} to uppercase
* @return A char[] containing hexadecimal characters in the selected case
*/
public static char[] encodeHex(final byte[] data, final boolean toLowerCase) {
return encodeHex(data, toLowerCase ? DIGITS_LOWER : DIGITS_UPPER);
}
/**
* Converts an array of bytes into an array of characters representing the hexadecimal
* values of each byte in order. The returned array will be double the length of the
* passed array, as it takes two characters to represent any given byte.
* @param data a byte[] to convert to hex characters
* @param toDigits the output alphabet (must contain at least 16 chars)
* @return A char[] containing the appropriate characters from the alphabet For best
* results, this should be either upper- or lower-case hex.
*/
protected static char[] encodeHex(final byte[] data, final char[] toDigits) {
final int dataLength = data.length;
final char[] out = new char[dataLength << 1];
encodeHex(data, 0, dataLength, toDigits, out, 0);
return out;
}
/**
* Converts an array of bytes into an array of characters representing the hexadecimal
* values of each byte in order.
* @param data a byte[] to convert to hex characters
* @param dataOffset the position in {@code data} to start encoding from
* @param dataLen the number of bytes from {@code dataOffset} to encode
* @param toLowerCase {@code true} converts to lowercase, {@code false} to uppercase
* @return A char[] containing the appropriate characters from the alphabet For best
* results, this should be either upper- or lower-case hex.
*/
public static char[] encodeHex(final byte[] data, final int dataOffset, final int dataLen,
final boolean toLowerCase) {
final char[] out = new char[dataLen << 1];
encodeHex(data, dataOffset, dataLen, toLowerCase ? DIGITS_LOWER : DIGITS_UPPER, out, 0);
return out;
}
/**
* Converts an array of bytes into an array of characters representing the hexadecimal
* values of each byte in order.
* @param data a byte[] to convert to hex characters
* @param dataOffset the position in {@code data} to start encoding from
* @param dataLen the number of bytes from {@code dataOffset} to encode
* @param toLowerCase {@code true} converts to lowercase, {@code false} to uppercase
* @param out a char[] which will hold the resultant appropriate characters from the
* alphabet.
* @param outOffset the position within {@code out} at which to start writing the
* encoded characters.
*/
public static void encodeHex(final byte[] data, final int dataOffset, final int dataLen, final boolean toLowerCase,
final char[] out, final int outOffset) {
encodeHex(data, dataOffset, dataLen, toLowerCase ? DIGITS_LOWER : DIGITS_UPPER, out, outOffset);
}
/**
* Converts an array of bytes into an array of characters representing the hexadecimal
* values of each byte in order.
* @param data a byte[] to convert to hex characters
* @param dataOffset the position in {@code data} to start encoding from
* @param dataLen the number of bytes from {@code dataOffset} to encode
* @param toDigits the output alphabet (must contain at least 16 chars)
* @param out a char[] which will hold the resultant appropriate characters from the
* alphabet.
* @param outOffset the position within {@code out} at which to start writing the
* encoded characters.
*/
private static void encodeHex(final byte[] data, final int dataOffset, final int dataLen, final char[] toDigits,
final char[] out, final int outOffset) {
// two characters form the hex value.
for (int i = dataOffset, j = outOffset; i < dataOffset + dataLen; i++) {
out[j++] = toDigits[(0xF0 & data[i]) >>> 4];
out[j++] = toDigits[0x0F & data[i]];
}
}
/**
* Converts a byte buffer into an array of characters representing the hexadecimal
* values of each byte in order. The returned array will be double the length of the
* passed array, as it takes two characters to represent any given byte.
*
*
* All bytes identified by {@link ByteBuffer#remaining()} will be used; after this
* method the value {@link ByteBuffer#remaining() remaining()} will be zero.
*
* @param data a byte buffer to convert to hex characters
* @return A char[] containing lower-case hexadecimal characters
*/
public static char[] encodeHex(final ByteBuffer data) {
return encodeHex(data, true);
}
/**
* Converts a byte buffer into an array of characters representing the hexadecimal
* values of each byte in order. The returned array will be double the length of the
* passed array, as it takes two characters to represent any given byte.
*
*
* All bytes identified by {@link ByteBuffer#remaining()} will be used; after this
* method the value {@link ByteBuffer#remaining() remaining()} will be zero.
*
* @param data a byte buffer to convert to hex characters
* @param toLowerCase {@code true} converts to lowercase, {@code false} to uppercase
* @return A char[] containing hexadecimal characters in the selected case
*/
public static char[] encodeHex(final ByteBuffer data, final boolean toLowerCase) {
return encodeHex(data, toLowerCase ? DIGITS_LOWER : DIGITS_UPPER);
}
/**
* Converts a byte buffer into an array of characters representing the hexadecimal
* values of each byte in order. The returned array will be double the length of the
* passed array, as it takes two characters to represent any given byte.
*
*
* All bytes identified by {@link ByteBuffer#remaining()} will be used; after this
* method the value {@link ByteBuffer#remaining() remaining()} will be zero.
*
* @param byteBuffer a byte buffer to convert to hex characters
* @param toDigits the output alphabet (must be at least 16 characters)
* @return A char[] containing the appropriate characters from the alphabet For best
* results, this should be either upper- or lower-case hex.
*/
protected static char[] encodeHex(final ByteBuffer byteBuffer, final char[] toDigits) {
return encodeHex(toByteArray(byteBuffer), toDigits);
}
/**
* Converts an array of bytes into a String representing the hexadecimal values of
* each byte in order. The returned String will be double the length of the passed
* array, as it takes two characters to represent any given byte.
* @param data a byte[] to convert to hex characters
* @return A String containing lower-case hexadecimal characters
*/
public static String encodeHexString(final byte[] data) {
return new String(encodeHex(data));
}
/**
* Converts an array of bytes into a String representing the hexadecimal values of
* each byte in order. The returned String will be double the length of the passed
* array, as it takes two characters to represent any given byte.
* @param data a byte[] to convert to hex characters
* @param toLowerCase {@code true} converts to lowercase, {@code false} to uppercase
* @return A String containing lower-case hexadecimal characters
*/
public static String encodeHexString(final byte[] data, final boolean toLowerCase) {
return new String(encodeHex(data, toLowerCase));
}
/**
* Converts a byte buffer into a String representing the hexadecimal values of each
* byte in order. The returned String will be double the length of the passed array,
* as it takes two characters to represent any given byte.
*
*
* All bytes identified by {@link ByteBuffer#remaining()} will be used; after this
* method the value {@link ByteBuffer#remaining() remaining()} will be zero.
*
* @param data a byte buffer to convert to hex characters
* @return A String containing lower-case hexadecimal characters
*/
public static String encodeHexString(final ByteBuffer data) {
return new String(encodeHex(data));
}
/**
* Converts a byte buffer into a String representing the hexadecimal values of each
* byte in order. The returned String will be double the length of the passed array,
* as it takes two characters to represent any given byte.
*
*
* All bytes identified by {@link ByteBuffer#remaining()} will be used; after this
* method the value {@link ByteBuffer#remaining() remaining()} will be zero.
*
* @param data a byte buffer to convert to hex characters
* @param toLowerCase {@code true} converts to lowercase, {@code false} to uppercase
* @return A String containing lower-case hexadecimal characters
*/
public static String encodeHexString(final ByteBuffer data, final boolean toLowerCase) {
return new String(encodeHex(data, toLowerCase));
}
/**
* Convert the byte buffer to a byte array. All bytes identified by
* {@link ByteBuffer#remaining()} will be used.
* @param byteBuffer the byte buffer
* @return the byte[]
*/
private static byte[] toByteArray(final ByteBuffer byteBuffer) {
final int remaining = byteBuffer.remaining();
// Use the underlying buffer if possible
if (byteBuffer.hasArray()) {
final byte[] byteArray = byteBuffer.array();
if (remaining == byteArray.length) {
byteBuffer.position(remaining);
return byteArray;
}
}
// Copy the bytes
final byte[] byteArray = new byte[remaining];
byteBuffer.get(byteArray);
return byteArray;
}
/**
* Converts a hexadecimal character to an integer.
* @param ch A character to convert to an integer digit
* @param index The index of the character in the source
* @return An integer
* @throws DecodeException Thrown if ch is an illegal hex character
*/
protected static int toDigit(final char ch, final int index) throws DecodeException {
final int digit = Character.digit(ch, 16);
if (digit == -1) {
throw new DecodeException("Illegal hexadecimal character " + ch + " at index " + index);
}
return digit;
}
}