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/*
 * 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.codec.binary;

import org.apache.commons.codec.BinaryDecoder;
import org.apache.commons.codec.BinaryEncoder;
import org.apache.commons.codec.DecoderException;
import org.apache.commons.codec.EncoderException;

/**
 * Converts between byte arrays and strings of "0"s and "1"s.
 *
 * 

This class is immutable and thread-safe.

* * TODO: may want to add more bit vector functions like and/or/xor/nand * TODO: also might be good to generate boolean[] from byte[] et cetera. * * @since 1.3 * @version $Id$ */ public class BinaryCodec implements BinaryDecoder, BinaryEncoder { /* * tried to avoid using ArrayUtils to minimize dependencies while using these empty arrays - dep is just not worth * it. */ /** Empty char array. */ private static final char[] EMPTY_CHAR_ARRAY = new char[0]; /** Empty byte array. */ private static final byte[] EMPTY_BYTE_ARRAY = new byte[0]; /** Mask for bit 0 of a byte. */ private static final int BIT_0 = 1; /** Mask for bit 1 of a byte. */ private static final int BIT_1 = 0x02; /** Mask for bit 2 of a byte. */ private static final int BIT_2 = 0x04; /** Mask for bit 3 of a byte. */ private static final int BIT_3 = 0x08; /** Mask for bit 4 of a byte. */ private static final int BIT_4 = 0x10; /** Mask for bit 5 of a byte. */ private static final int BIT_5 = 0x20; /** Mask for bit 6 of a byte. */ private static final int BIT_6 = 0x40; /** Mask for bit 7 of a byte. */ private static final int BIT_7 = 0x80; private static final int[] BITS = {BIT_0, BIT_1, BIT_2, BIT_3, BIT_4, BIT_5, BIT_6, BIT_7}; /** * Converts an array of raw binary data into an array of ASCII 0 and 1 characters. * * @param raw * the raw binary data to convert * @return 0 and 1 ASCII character bytes one for each bit of the argument * @see org.apache.commons.codec.BinaryEncoder#encode(byte[]) */ @Override public byte[] encode(final byte[] raw) { return toAsciiBytes(raw); } /** * Converts an array of raw binary data into an array of ASCII 0 and 1 chars. * * @param raw * the raw binary data to convert * @return 0 and 1 ASCII character chars one for each bit of the argument * @throws EncoderException * if the argument is not a byte[] * @see org.apache.commons.codec.Encoder#encode(Object) */ @Override public Object encode(final Object raw) throws EncoderException { if (!(raw instanceof byte[])) { throw new EncoderException("argument not a byte array"); } return toAsciiChars((byte[]) raw); } /** * Decodes a byte array where each byte represents an ASCII '0' or '1'. * * @param ascii * each byte represents an ASCII '0' or '1' * @return the raw encoded binary where each bit corresponds to a byte in the byte array argument * @throws DecoderException * if argument is not a byte[], char[] or String * @see org.apache.commons.codec.Decoder#decode(Object) */ @Override public Object decode(final Object ascii) throws DecoderException { if (ascii == null) { return EMPTY_BYTE_ARRAY; } if (ascii instanceof byte[]) { return fromAscii((byte[]) ascii); } if (ascii instanceof char[]) { return fromAscii((char[]) ascii); } if (ascii instanceof String) { return fromAscii(((String) ascii).toCharArray()); } throw new DecoderException("argument not a byte array"); } /** * Decodes a byte array where each byte represents an ASCII '0' or '1'. * * @param ascii * each byte represents an ASCII '0' or '1' * @return the raw encoded binary where each bit corresponds to a byte in the byte array argument * @see org.apache.commons.codec.Decoder#decode(Object) */ @Override public byte[] decode(final byte[] ascii) { return fromAscii(ascii); } /** * Decodes a String where each char of the String represents an ASCII '0' or '1'. * * @param ascii * String of '0' and '1' characters * @return the raw encoded binary where each bit corresponds to a byte in the byte array argument * @see org.apache.commons.codec.Decoder#decode(Object) */ public byte[] toByteArray(final String ascii) { if (ascii == null) { return EMPTY_BYTE_ARRAY; } return fromAscii(ascii.toCharArray()); } // ------------------------------------------------------------------------ // // static codec operations // // ------------------------------------------------------------------------ /** * Decodes a char array where each char represents an ASCII '0' or '1'. * * @param ascii * each char represents an ASCII '0' or '1' * @return the raw encoded binary where each bit corresponds to a char in the char array argument */ public static byte[] fromAscii(final char[] ascii) { if (ascii == null || ascii.length == 0) { return EMPTY_BYTE_ARRAY; } // get length/8 times bytes with 3 bit shifts to the right of the length final byte[] l_raw = new byte[ascii.length >> 3]; /* * We decr index jj by 8 as we go along to not recompute indices using multiplication every time inside the * loop. */ for (int ii = 0, jj = ascii.length - 1; ii < l_raw.length; ii++, jj -= 8) { for (int bits = 0; bits < BITS.length; ++bits) { if (ascii[jj - bits] == '1') { l_raw[ii] |= BITS[bits]; } } } return l_raw; } /** * Decodes a byte array where each byte represents an ASCII '0' or '1'. * * @param ascii * each byte represents an ASCII '0' or '1' * @return the raw encoded binary where each bit corresponds to a byte in the byte array argument */ public static byte[] fromAscii(final byte[] ascii) { if (isEmpty(ascii)) { return EMPTY_BYTE_ARRAY; } // get length/8 times bytes with 3 bit shifts to the right of the length final byte[] l_raw = new byte[ascii.length >> 3]; /* * We decr index jj by 8 as we go along to not recompute indices using multiplication every time inside the * loop. */ for (int ii = 0, jj = ascii.length - 1; ii < l_raw.length; ii++, jj -= 8) { for (int bits = 0; bits < BITS.length; ++bits) { if (ascii[jj - bits] == '1') { l_raw[ii] |= BITS[bits]; } } } return l_raw; } /** * Returns true if the given array is null or empty (size 0.) * * @param array * the source array * @return true if the given array is null or empty (size 0.) */ private static boolean isEmpty(final byte[] array) { return array == null || array.length == 0; } /** * Converts an array of raw binary data into an array of ASCII 0 and 1 character bytes - each byte is a truncated * char. * * @param raw * the raw binary data to convert * @return an array of 0 and 1 character bytes for each bit of the argument * @see org.apache.commons.codec.BinaryEncoder#encode(byte[]) */ public static byte[] toAsciiBytes(final byte[] raw) { if (isEmpty(raw)) { return EMPTY_BYTE_ARRAY; } // get 8 times the bytes with 3 bit shifts to the left of the length final byte[] l_ascii = new byte[raw.length << 3]; /* * We decr index jj by 8 as we go along to not recompute indices using multiplication every time inside the * loop. */ for (int ii = 0, jj = l_ascii.length - 1; ii < raw.length; ii++, jj -= 8) { for (int bits = 0; bits < BITS.length; ++bits) { if ((raw[ii] & BITS[bits]) == 0) { l_ascii[jj - bits] = '0'; } else { l_ascii[jj - bits] = '1'; } } } return l_ascii; } /** * Converts an array of raw binary data into an array of ASCII 0 and 1 characters. * * @param raw * the raw binary data to convert * @return an array of 0 and 1 characters for each bit of the argument * @see org.apache.commons.codec.BinaryEncoder#encode(byte[]) */ public static char[] toAsciiChars(final byte[] raw) { if (isEmpty(raw)) { return EMPTY_CHAR_ARRAY; } // get 8 times the bytes with 3 bit shifts to the left of the length final char[] l_ascii = new char[raw.length << 3]; /* * We decr index jj by 8 as we go along to not recompute indices using multiplication every time inside the * loop. */ for (int ii = 0, jj = l_ascii.length - 1; ii < raw.length; ii++, jj -= 8) { for (int bits = 0; bits < BITS.length; ++bits) { if ((raw[ii] & BITS[bits]) == 0) { l_ascii[jj - bits] = '0'; } else { l_ascii[jj - bits] = '1'; } } } return l_ascii; } /** * Converts an array of raw binary data into a String of ASCII 0 and 1 characters. * * @param raw * the raw binary data to convert * @return a String of 0 and 1 characters representing the binary data * @see org.apache.commons.codec.BinaryEncoder#encode(byte[]) */ public static String toAsciiString(final byte[] raw) { return new String(toAsciiChars(raw)); } }




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