    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017
    018package org.apache.commons.codec.binary;
    019
    020import org.apache.commons.codec.BinaryDecoder;
    021import org.apache.commons.codec.BinaryEncoder;
    022import org.apache.commons.codec.DecoderException;
    023import org.apache.commons.codec.EncoderException;
    024
    025/**
    026 * Converts between byte arrays and strings of "0"s and "1"s.
    027 *
    028 * <p>This class is immutable and thread-safe.</p>
    029 *
    030 * TODO: may want to add more bit vector functions like and/or/xor/nand
    031 * TODO: also might be good to generate boolean[] from byte[] et cetera.
    032 *
    033 * @since 1.3
    034 */
    035public class BinaryCodec implements BinaryDecoder, BinaryEncoder {
    036    /*
    037     * tried to avoid using ArrayUtils to minimize dependencies while using these empty arrays - dep is just not worth
    038     * it.
    039     */
    040    /** Empty char array. */
    041    private static final char[] EMPTY_CHAR_ARRAY = {};
    042
    043    /** Empty byte array. */
    044    private static final byte[] EMPTY_BYTE_ARRAY = {};
    045
    046    /** Mask for bit 0 of a byte. */
    047    private static final int BIT_0 = 1;
    048
    049    /** Mask for bit 1 of a byte. */
    050    private static final int BIT_1 = 0x02;
    051
    052    /** Mask for bit 2 of a byte. */
    053    private static final int BIT_2 = 0x04;
    054
    055    /** Mask for bit 3 of a byte. */
    056    private static final int BIT_3 = 0x08;
    057
    058    /** Mask for bit 4 of a byte. */
    059    private static final int BIT_4 = 0x10;
    060
    061    /** Mask for bit 5 of a byte. */
    062    private static final int BIT_5 = 0x20;
    063
    064    /** Mask for bit 6 of a byte. */
    065    private static final int BIT_6 = 0x40;
    066
    067    /** Mask for bit 7 of a byte. */
    068    private static final int BIT_7 = 0x80;
    069
    070    private static final int[] BITS = {BIT_0, BIT_1, BIT_2, BIT_3, BIT_4, BIT_5, BIT_6, BIT_7};
    071
    072    /**
    073     * Decodes a byte array where each byte represents an ASCII '0' or '1'.
    074     *
    075     * @param ascii
    076     *                  each byte represents an ASCII '0' or '1'
    077     * @return the raw encoded binary where each bit corresponds to a byte in the byte array argument
    078     */
    079    public static byte[] fromAscii(final byte[] ascii) {
    080        if (isEmpty(ascii)) {
    081            return EMPTY_BYTE_ARRAY;
    082        }
    083        final int asciiLength = ascii.length;
    084        // get length/8 times bytes with 3 bit shifts to the right of the length
    085        final byte[] raw = new byte[asciiLength >> 3];
    086        /*
    087         * We decr index jj by 8 as we go along to not recompute indices using multiplication every time inside the
    088         * loop.
    089         */
    090        for (int ii = 0, jj = asciiLength - 1; ii < raw.length; ii++, jj -= 8) {
    091            for (int bits = 0; bits < BITS.length; ++bits) {
    092                if (ascii[jj - bits] == '1') {
    093                    raw[ii] |= BITS[bits];
    094                }
    095            }
    096        }
    097        return raw;
    098    }
    099
    100    // ------------------------------------------------------------------------
    101    //
    102    // static codec operations
    103    //
    104    // ------------------------------------------------------------------------
    105    /**
    106     * Decodes a char array where each char represents an ASCII '0' or '1'.
    107     *
    108     * @param ascii
    109     *                  each char represents an ASCII '0' or '1'
    110     * @return the raw encoded binary where each bit corresponds to a char in the char array argument
    111     */
    112    public static byte[] fromAscii(final char[] ascii) {
    113        if (ascii == null || ascii.length == 0) {
    114            return EMPTY_BYTE_ARRAY;
    115        }
    116        final int asciiLength = ascii.length;
    117        // get length/8 times bytes with 3 bit shifts to the right of the length
    118        final byte[] raw = new byte[asciiLength >> 3];
    119        /*
    120         * We decr index jj by 8 as we go along to not recompute indices using multiplication every time inside the
    121         * loop.
    122         */
    123        for (int ii = 0, jj = asciiLength - 1; ii < raw.length; ii++, jj -= 8) {
    124            for (int bits = 0; bits < BITS.length; ++bits) {
    125                if (ascii[jj - bits] == '1') {
    126                    raw[ii] |= BITS[bits];
    127                }
    128            }
    129        }
    130        return raw;
    131    }
    132
    133    /**
    134     * Returns {@code true} if the given array is {@code null} or empty (size 0.)
    135     *
    136     * @param array
    137     *            the source array
    138     * @return {@code true} if the given array is {@code null} or empty (size 0.)
    139     */
    140    static boolean isEmpty(final byte[] array) {
    141        return array == null || array.length == 0;
    142    }
    143
    144    /**
    145     * Converts an array of raw binary data into an array of ASCII 0 and 1 character bytes - each byte is a truncated
    146     * char.
    147     *
    148     * @param raw
    149     *                  the raw binary data to convert
    150     * @return an array of 0 and 1 character bytes for each bit of the argument
    151     * @see org.apache.commons.codec.BinaryEncoder#encode(byte[])
    152     */
    153    public static byte[] toAsciiBytes(final byte[] raw) {
    154        if (isEmpty(raw)) {
    155            return EMPTY_BYTE_ARRAY;
    156        }
    157        final int rawLength = raw.length;
    158        // get 8 times the bytes with 3 bit shifts to the left of the length
    159        final byte[] l_ascii = new byte[rawLength << 3];
    160        /*
    161         * We decr index jj by 8 as we go along to not recompute indices using multiplication every time inside the
    162         * loop.
    163         */
    164        for (int ii = 0, jj = l_ascii.length - 1; ii < rawLength; ii++, jj -= 8) {
    165            for (int bits = 0; bits < BITS.length; ++bits) {
    166                if ((raw[ii] & BITS[bits]) == 0) {
    167                    l_ascii[jj - bits] = '0';
    168                } else {
    169                    l_ascii[jj - bits] = '1';
    170                }
    171            }
    172        }
    173        return l_ascii;
    174    }
    175
    176    /**
    177     * Converts an array of raw binary data into an array of ASCII 0 and 1 characters.
    178     *
    179     * @param raw
    180     *                  the raw binary data to convert
    181     * @return an array of 0 and 1 characters for each bit of the argument
    182     * @see org.apache.commons.codec.BinaryEncoder#encode(byte[])
    183     */
    184    public static char[] toAsciiChars(final byte[] raw) {
    185        if (isEmpty(raw)) {
    186            return EMPTY_CHAR_ARRAY;
    187        }
    188        final int rawLength = raw.length;
    189        // get 8 times the bytes with 3 bit shifts to the left of the length
    190        final char[] l_ascii = new char[rawLength << 3];
    191        /*
    192         * We decr index jj by 8 as we go along to not recompute indices using multiplication every time inside the
    193         * loop.
    194         */
    195        for (int ii = 0, jj = l_ascii.length - 1; ii < rawLength; ii++, jj -= 8) {
    196            for (int bits = 0; bits < BITS.length; ++bits) {
    197                if ((raw[ii] & BITS[bits]) == 0) {
    198                    l_ascii[jj - bits] = '0';
    199                } else {
    200                    l_ascii[jj - bits] = '1';
    201                }
    202            }
    203        }
    204        return l_ascii;
    205    }
    206
    207    /**
    208     * Converts an array of raw binary data into a String of ASCII 0 and 1 characters.
    209     *
    210     * @param raw
    211     *                  the raw binary data to convert
    212     * @return a String of 0 and 1 characters representing the binary data
    213     * @see org.apache.commons.codec.BinaryEncoder#encode(byte[])
    214     */
    215    public static String toAsciiString(final byte[] raw) {
    216        return new String(toAsciiChars(raw));
    217    }
    218
    219    /**
    220     * Decodes a byte array where each byte represents an ASCII '0' or '1'.
    221     *
    222     * @param ascii
    223     *                  each byte represents an ASCII '0' or '1'
    224     * @return the raw encoded binary where each bit corresponds to a byte in the byte array argument
    225     * @see org.apache.commons.codec.Decoder#decode(Object)
    226     */
    227    @Override
    228    public byte[] decode(final byte[] ascii) {
    229        return fromAscii(ascii);
    230    }
    231
    232    /**
    233     * Decodes a byte array where each byte represents an ASCII '0' or '1'.
    234     *
    235     * @param ascii
    236     *                  each byte represents an ASCII '0' or '1'
    237     * @return the raw encoded binary where each bit corresponds to a byte in the byte array argument
    238     * @throws DecoderException
    239     *                  if argument is not a byte[], char[] or String
    240     * @see org.apache.commons.codec.Decoder#decode(Object)
    241     */
    242    @Override
    243    public Object decode(final Object ascii) throws DecoderException {
    244        if (ascii == null) {
    245            return EMPTY_BYTE_ARRAY;
    246        }
    247        if (ascii instanceof byte[]) {
    248            return fromAscii((byte[]) ascii);
    249        }
    250        if (ascii instanceof char[]) {
    251            return fromAscii((char[]) ascii);
    252        }
    253        if (ascii instanceof String) {
    254            return fromAscii(((String) ascii).toCharArray());
    255        }
    256        throw new DecoderException("argument not a byte array");
    257    }
    258
    259    /**
    260     * Converts an array of raw binary data into an array of ASCII 0 and 1 characters.
    261     *
    262     * @param raw
    263     *                  the raw binary data to convert
    264     * @return 0 and 1 ASCII character bytes one for each bit of the argument
    265     * @see org.apache.commons.codec.BinaryEncoder#encode(byte[])
    266     */
    267    @Override
    268    public byte[] encode(final byte[] raw) {
    269        return toAsciiBytes(raw);
    270    }
    271
    272    /**
    273     * Converts an array of raw binary data into an array of ASCII 0 and 1 chars.
    274     *
    275     * @param raw
    276     *                  the raw binary data to convert
    277     * @return 0 and 1 ASCII character chars one for each bit of the argument
    278     * @throws EncoderException
    279     *                  if the argument is not a byte[]
    280     * @see org.apache.commons.codec.Encoder#encode(Object)
    281     */
    282    @Override
    283    public Object encode(final Object raw) throws EncoderException {
    284        if (!(raw instanceof byte[])) {
    285            throw new EncoderException("argument not a byte array");
    286        }
    287        return toAsciiChars((byte[]) raw);
    288    }
    289
    290    /**
    291     * Decodes a String where each char of the String represents an ASCII '0' or '1'.
    292     *
    293     * @param ascii
    294     *                  String of '0' and '1' characters
    295     * @return the raw encoded binary where each bit corresponds to a byte in the byte array argument
    296     * @see org.apache.commons.codec.Decoder#decode(Object)
    297     */
    298    public byte[] toByteArray(final String ascii) {
    299        if (ascii == null) {
    300            return EMPTY_BYTE_ARRAY;
    301        }
    302        return fromAscii(ascii.toCharArray());
    303    }
    304}