org.apache.commons.codec.binary.BinaryCodec Maven / Gradle / Ivy
/*
* 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
*/
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};
/**
* 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;
}
// ------------------------------------------------------------------------
//
// 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;
}
/**
* Returns {@code true} if the given array is {@code null} or empty (size 0.)
*
* @param array
* the source array
* @return {@code true} if the given array is {@code 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));
}
/**
* 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 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");
}
/**
* 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 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());
}
}