| /* |
| * Copyright 2001-2004 The Apache Software Foundation. |
| * |
| * 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 |
| * |
| * 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; |
| |
| /** |
| * Translates between byte arrays and strings of "0"s and "1"s. |
| * |
| * <b>TODO:</b> may want to add more bit vector functions like and/or/xor/nand. |
| * <B>TODO:</b> also might be good to generate boolean[] |
| * from byte[] et. cetera. |
| * |
| * @author Apache Software Foundation |
| * @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[]) |
| */ |
| public byte[] encode(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(java.lang.Object) |
| */ |
| public Object encode(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(java.lang.Object) |
| */ |
| public Object decode(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) |
| */ |
| public byte[] decode(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(String ascii) { |
| if (ascii == null) { |
| return EMPTY_BYTE_ARRAY; |
| } |
| return fromAscii(ascii.toCharArray()); |
| } |
| |
| // ------------------------------------------------------------------------ |
| // |
| // static codec operations |
| // |
| // ------------------------------------------------------------------------ |
| /** |
| * Decodes a byte 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(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 |
| 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(byte[] 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 |
| 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; |
| } |
| |
| /** |
| * 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(byte[] raw) { |
| if (raw == null || raw.length == 0) { |
| return EMPTY_BYTE_ARRAY; |
| } |
| // get 8 times the bytes with 3 bit shifts to the left of the length |
| 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(byte[] raw) { |
| if (raw == null || raw.length == 0) { |
| return EMPTY_CHAR_ARRAY; |
| } |
| // get 8 times the bytes with 3 bit shifts to the left of the length |
| 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(byte[] raw) { |
| return new String(toAsciiChars(raw)); |
| } |
| } |