| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You 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 |
| * |
| * http://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 org.apache.commons.rng.examples.stress; |
| |
| /** |
| * Encodes and decodes bytes as hexadecimal characters. |
| * |
| * <p>Adapted from commons-codec.</p> |
| */ |
| final class Hex { |
| /** |
| * Used to build 4-bit numbers as Hex. |
| */ |
| private static final char[] HEX_DIGITS = { |
| '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' |
| }; |
| |
| /** No public construction. */ |
| private Hex() {} |
| |
| /** |
| * 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. |
| * |
| * <p>This can be used to encode byte array seeds into a text representation.</p> |
| * |
| * @param data A byte[] to convert to Hex characters |
| * @return A char[] containing the lower-case Hex representation |
| */ |
| static char[] encodeHex(final byte[] data) { |
| final int l = data.length; |
| final char[] out = new char[l << 1]; |
| // Two characters form the hex value |
| for (int i = 0; i < l; i++) { |
| // Upper 4-bits |
| out[2 * i] = HEX_DIGITS[(0xf0 & data[i]) >>> 4]; |
| // Lower 4-bits |
| out[2 * i + 1] = HEX_DIGITS[ 0x0f & data[i]]; |
| } |
| 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 |
| * @return A byte array containing binary data decoded from the supplied char array. |
| * @throws IllegalArgumentException Thrown if an odd number or illegal of |
| * characters is supplied |
| */ |
| static byte[] decodeHex(final CharSequence data) { |
| final int len = data.length(); |
| |
| if ((len & 0x01) != 0) { |
| throw new IllegalArgumentException("Odd number of characters."); |
| } |
| |
| final byte[] out = new byte[len >> 1]; |
| |
| // Two characters form the hex value |
| for (int j = 0; j < len; j += 2) { |
| final int f = (toDigit(data, j) << 4) | |
| toDigit(data, j + 1); |
| out[j / 2] = (byte) f; |
| } |
| |
| return out; |
| } |
| |
| /** |
| * Converts a hexadecimal character to an integer. |
| * |
| * @param data An array of characters containing hexadecimal digits |
| * @param index The index of the character in the source |
| * @return An integer |
| * @throws IllegalArgumentException Thrown if ch is an illegal hex character |
| */ |
| private static int toDigit(final CharSequence data, final int index) { |
| final char ch = data.charAt(index); |
| final int digit = Character.digit(ch, 16); |
| if (digit == -1) { |
| throw new IllegalArgumentException("Illegal hexadecimal character " + ch + |
| " at index " + index); |
| } |
| return digit; |
| } |
| } |