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Diffstat (limited to 'src/org/apache/commons/codec/binary/BinaryCodec.java')
| -rw-r--r-- | src/org/apache/commons/codec/binary/BinaryCodec.java | 285 |
1 files changed, 285 insertions, 0 deletions
diff --git a/src/org/apache/commons/codec/binary/BinaryCodec.java b/src/org/apache/commons/codec/binary/BinaryCodec.java new file mode 100644 index 0000000..98c6409 --- /dev/null +++ b/src/org/apache/commons/codec/binary/BinaryCodec.java @@ -0,0 +1,285 @@ +/* + * 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)); + } +} |