    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 = new char[0];
    042
    043    /** Empty byte array. */
    044    private static final byte[] EMPTY_BYTE_ARRAY = new byte[0];
    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        // get length/8 times bytes with 3 bit shifts to the right of the length
    084        final byte[] l_raw = new byte[ascii.length >> 3];
    085        /*
    086         * We decr index jj by 8 as we go along to not recompute indices using multiplication every time inside the
    087         * loop.
    088         */
    089        for (int ii = 0, jj = ascii.length - 1; ii < l_raw.length; ii++, jj -= 8) {
    090            for (int bits = 0; bits < BITS.length; ++bits) {
    091                if (ascii[jj - bits] == '1') {
    092                    l_raw[ii] |= BITS[bits];
    093                }
    094            }
    095        }
    096        return l_raw;
    097    }
    098
    099    // ------------------------------------------------------------------------
    100    //
    101    // static codec operations
    102    //
    103    // ------------------------------------------------------------------------
    104    /**
    105     * Decodes a char array where each char represents an ASCII '0' or '1'.
    106     *
    107     * @param ascii
    108     *                  each char represents an ASCII '0' or '1'
    109     * @return the raw encoded binary where each bit corresponds to a char in the char array argument
    110     */
    111    public static byte[] fromAscii(final char[] ascii) {
    112        if (ascii == null || ascii.length == 0) {
    113            return EMPTY_BYTE_ARRAY;
    114        }
    115        // get length/8 times bytes with 3 bit shifts to the right of the length
    116        final byte[] l_raw = new byte[ascii.length >> 3];
    117        /*
    118         * We decr index jj by 8 as we go along to not recompute indices using multiplication every time inside the
    119         * loop.
    120         */
    121        for (int ii = 0, jj = ascii.length - 1; ii < l_raw.length; ii++, jj -= 8) {
    122            for (int bits = 0; bits < BITS.length; ++bits) {
    123                if (ascii[jj - bits] == '1') {
    124                    l_raw[ii] |= BITS[bits];
    125                }
    126            }
    127        }
    128        return l_raw;
    129    }
    130
    131    /**
    132     * Returns {@code true} if the given array is {@code null} or empty (size 0.)
    133     *
    134     * @param array
    135     *            the source array
    136     * @return {@code true} if the given array is {@code null} or empty (size 0.)
    137     */
    138    private static boolean isEmpty(final byte[] array) {
    139        return array == null || array.length == 0;
    140    }
    141
    142    /**
    143     * Converts an array of raw binary data into an array of ASCII 0 and 1 character bytes - each byte is a truncated
    144     * char.
    145     *
    146     * @param raw
    147     *                  the raw binary data to convert
    148     * @return an array of 0 and 1 character bytes for each bit of the argument
    149     * @see org.apache.commons.codec.BinaryEncoder#encode(byte[])
    150     */
    151    public static byte[] toAsciiBytes(final byte[] raw) {
    152        if (isEmpty(raw)) {
    153            return EMPTY_BYTE_ARRAY;
    154        }
    155        // get 8 times the bytes with 3 bit shifts to the left of the length
    156        final byte[] l_ascii = new byte[raw.length << 3];
    157        /*
    158         * We decr index jj by 8 as we go along to not recompute indices using multiplication every time inside the
    159         * loop.
    160         */
    161        for (int ii = 0, jj = l_ascii.length - 1; ii < raw.length; ii++, jj -= 8) {
    162            for (int bits = 0; bits < BITS.length; ++bits) {
    163                if ((raw[ii] & BITS[bits]) == 0) {
    164                    l_ascii[jj - bits] = '0';
    165                } else {
    166                    l_ascii[jj - bits] = '1';
    167                }
    168            }
    169        }
    170        return l_ascii;
    171    }
    172
    173    /**
    174     * Converts an array of raw binary data into an array of ASCII 0 and 1 characters.
    175     *
    176     * @param raw
    177     *                  the raw binary data to convert
    178     * @return an array of 0 and 1 characters for each bit of the argument
    179     * @see org.apache.commons.codec.BinaryEncoder#encode(byte[])
    180     */
    181    public static char[] toAsciiChars(final byte[] raw) {
    182        if (isEmpty(raw)) {
    183            return EMPTY_CHAR_ARRAY;
    184        }
    185        // get 8 times the bytes with 3 bit shifts to the left of the length
    186        final char[] l_ascii = new char[raw.length << 3];
    187        /*
    188         * We decr index jj by 8 as we go along to not recompute indices using multiplication every time inside the
    189         * loop.
    190         */
    191        for (int ii = 0, jj = l_ascii.length - 1; ii < raw.length; ii++, jj -= 8) {
    192            for (int bits = 0; bits < BITS.length; ++bits) {
    193                if ((raw[ii] & BITS[bits]) == 0) {
    194                    l_ascii[jj - bits] = '0';
    195                } else {
    196                    l_ascii[jj - bits] = '1';
    197                }
    198            }
    199        }
    200        return l_ascii;
    201    }
    202
    203    /**
    204     * Converts an array of raw binary data into a String of ASCII 0 and 1 characters.
    205     *
    206     * @param raw
    207     *                  the raw binary data to convert
    208     * @return a String of 0 and 1 characters representing the binary data
    209     * @see org.apache.commons.codec.BinaryEncoder#encode(byte[])
    210     */
    211    public static String toAsciiString(final byte[] raw) {
    212        return new String(toAsciiChars(raw));
    213    }
    214
    215    /**
    216     * Decodes a byte array where each byte represents an ASCII '0' or '1'.
    217     *
    218     * @param ascii
    219     *                  each byte represents an ASCII '0' or '1'
    220     * @return the raw encoded binary where each bit corresponds to a byte in the byte array argument
    221     * @see org.apache.commons.codec.Decoder#decode(Object)
    222     */
    223    @Override
    224    public byte[] decode(final byte[] ascii) {
    225        return fromAscii(ascii);
    226    }
    227
    228    /**
    229     * Decodes a byte array where each byte represents an ASCII '0' or '1'.
    230     *
    231     * @param ascii
    232     *                  each byte represents an ASCII '0' or '1'
    233     * @return the raw encoded binary where each bit corresponds to a byte in the byte array argument
    234     * @throws DecoderException
    235     *                  if argument is not a byte[], char[] or String
    236     * @see org.apache.commons.codec.Decoder#decode(Object)
    237     */
    238    @Override
    239    public Object decode(final Object ascii) throws DecoderException {
    240        if (ascii == null) {
    241            return EMPTY_BYTE_ARRAY;
    242        }
    243        if (ascii instanceof byte[]) {
    244            return fromAscii((byte[]) ascii);
    245        }
    246        if (ascii instanceof char[]) {
    247            return fromAscii((char[]) ascii);
    248        }
    249        if (ascii instanceof String) {
    250            return fromAscii(((String) ascii).toCharArray());
    251        }
    252        throw new DecoderException("argument not a byte array");
    253    }
    254
    255    /**
    256     * Converts an array of raw binary data into an array of ASCII 0 and 1 characters.
    257     *
    258     * @param raw
    259     *                  the raw binary data to convert
    260     * @return 0 and 1 ASCII character bytes one for each bit of the argument
    261     * @see org.apache.commons.codec.BinaryEncoder#encode(byte[])
    262     */
    263    @Override
    264    public byte[] encode(final byte[] raw) {
    265        return toAsciiBytes(raw);
    266    }
    267
    268    /**
    269     * Converts an array of raw binary data into an array of ASCII 0 and 1 chars.
    270     *
    271     * @param raw
    272     *                  the raw binary data to convert
    273     * @return 0 and 1 ASCII character chars one for each bit of the argument
    274     * @throws EncoderException
    275     *                  if the argument is not a byte[]
    276     * @see org.apache.commons.codec.Encoder#encode(Object)
    277     */
    278    @Override
    279    public Object encode(final Object raw) throws EncoderException {
    280        if (!(raw instanceof byte[])) {
    281            throw new EncoderException("argument not a byte array");
    282        }
    283        return toAsciiChars((byte[]) raw);
    284    }
    285
    286    /**
    287     * Decodes a String where each char of the String represents an ASCII '0' or '1'.
    288     *
    289     * @param ascii
    290     *                  String of '0' and '1' characters
    291     * @return the raw encoded binary where each bit corresponds to a byte in the byte array argument
    292     * @see org.apache.commons.codec.Decoder#decode(Object)
    293     */
    294    public byte[] toByteArray(final String ascii) {
    295        if (ascii == null) {
    296            return EMPTY_BYTE_ARRAY;
    297        }
    298        return fromAscii(ascii.toCharArray());
    299    }
    300}