179 lines
6.6 KiB
Java
179 lines
6.6 KiB
Java
/*
|
|
* Copyright (c) 1995, 1997, Oracle and/or its affiliates. All rights reserved.
|
|
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
|
|
*
|
|
* This code is free software; you can redistribute it and/or modify it
|
|
* under the terms of the GNU General Public License version 2 only, as
|
|
* published by the Free Software Foundation. Oracle designates this
|
|
* particular file as subject to the "Classpath" exception as provided
|
|
* by Oracle in the LICENSE file that accompanied this code.
|
|
*
|
|
* This code is distributed in the hope that it will be useful, but WITHOUT
|
|
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
|
|
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
|
|
* version 2 for more details (a copy is included in the LICENSE file that
|
|
* accompanied this code).
|
|
*
|
|
* You should have received a copy of the GNU General Public License version
|
|
* 2 along with this work; if not, write to the Free Software Foundation,
|
|
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
|
|
*
|
|
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
|
|
* or visit www.oracle.com if you need additional information or have any
|
|
* questions.
|
|
*/
|
|
package sun.misc;
|
|
|
|
import java.io.OutputStream;
|
|
import java.io.InputStream;
|
|
import java.io.PrintStream;
|
|
import java.io.IOException;
|
|
|
|
/**
|
|
* This class implements a robust character encoder. The encoder is designed
|
|
* to convert binary data into printable characters. The characters are
|
|
* assumed to exist but they are not assumed to be ASCII, the complete set
|
|
* is 0-9, A-Z, a-z, "(", and ")".
|
|
*
|
|
* The basic encoding unit is a 3 character atom. It encodes two bytes
|
|
* of data. Bytes are encoded into a 64 character set, the characters
|
|
* were chosen specifically because they appear in all codesets.
|
|
* We don't care what their numerical equivalent is because
|
|
* we use a character array to map them. This is like UUencoding
|
|
* with the dependency on ASCII removed.
|
|
*
|
|
* The three chars that make up an atom are encoded as follows:
|
|
* <pre>
|
|
* 00xxxyyy 00axxxxx 00byyyyy
|
|
* 00 = leading zeros, all values are 0 - 63
|
|
* xxxyyy - Top 3 bits of X, Top 3 bits of Y
|
|
* axxxxx - a = X parity bit, xxxxx lower 5 bits of X
|
|
* byyyyy - b = Y parity bit, yyyyy lower 5 bits of Y
|
|
* </pre>
|
|
*
|
|
* The atoms are arranged into lines suitable for inclusion into an
|
|
* email message or text file. The number of bytes that are encoded
|
|
* per line is 48 which keeps the total line length under 80 chars)
|
|
*
|
|
* Each line has the form(
|
|
* <pre>
|
|
* *(LLSS)(DDDD)(DDDD)(DDDD)...(CRC)
|
|
* Where each (xxx) represents a three character atom.
|
|
* (LLSS) - 8 bit length (high byte), and sequence number
|
|
* modulo 256;
|
|
* (DDDD) - Data byte atoms, if length is odd, last data
|
|
* atom has (DD00) (high byte data, low byte 0)
|
|
* (CRC) - 16 bit CRC for the line, includes length,
|
|
* sequence, and all data bytes. If there is a
|
|
* zero pad byte (odd length) it is _NOT_
|
|
* included in the CRC.
|
|
* </pre>
|
|
*
|
|
* @author Chuck McManis
|
|
* @see CharacterEncoder
|
|
* @see UCDecoder
|
|
*/
|
|
public class UCEncoder extends CharacterEncoder {
|
|
|
|
/** this clase encodes two bytes per atom */
|
|
protected int bytesPerAtom() {
|
|
return (2);
|
|
}
|
|
|
|
/** this class encodes 48 bytes per line */
|
|
protected int bytesPerLine() {
|
|
return (48);
|
|
}
|
|
|
|
/* this is the UCE mapping of 0-63 to characters .. */
|
|
private final static byte map_array[] = {
|
|
// 0 1 2 3 4 5 6 7
|
|
(byte)'0',(byte)'1',(byte)'2',(byte)'3',(byte)'4',(byte)'5',(byte)'6',(byte)'7', // 0
|
|
(byte)'8',(byte)'9',(byte)'A',(byte)'B',(byte)'C',(byte)'D',(byte)'E',(byte)'F', // 1
|
|
(byte)'G',(byte)'H',(byte)'I',(byte)'J',(byte)'K',(byte)'L',(byte)'M',(byte)'N', // 2
|
|
(byte)'O',(byte)'P',(byte)'Q',(byte)'R',(byte)'S',(byte)'T',(byte)'U',(byte)'V', // 3
|
|
(byte)'W',(byte)'X',(byte)'Y',(byte)'Z',(byte)'a',(byte)'b',(byte)'c',(byte)'d', // 4
|
|
(byte)'e',(byte)'f',(byte)'g',(byte)'h',(byte)'i',(byte)'j',(byte)'k',(byte)'l', // 5
|
|
(byte)'m',(byte)'n',(byte)'o',(byte)'p',(byte)'q',(byte)'r',(byte)'s',(byte)'t', // 6
|
|
(byte)'u',(byte)'v',(byte)'w',(byte)'x',(byte)'y',(byte)'z',(byte)'(',(byte)')' // 7
|
|
};
|
|
|
|
private int sequence;
|
|
private byte tmp[] = new byte[2];
|
|
private CRC16 crc = new CRC16();
|
|
|
|
/**
|
|
* encodeAtom - take two bytes and encode them into the correct
|
|
* three characters. If only one byte is to be encoded, the other
|
|
* must be zero. The padding byte is not included in the CRC computation.
|
|
*/
|
|
protected void encodeAtom(OutputStream outStream, byte data[], int offset, int len) throws IOException
|
|
{
|
|
int i;
|
|
int p1, p2; // parity bits
|
|
byte a, b;
|
|
|
|
a = data[offset];
|
|
if (len == 2) {
|
|
b = data[offset+1];
|
|
} else {
|
|
b = 0;
|
|
}
|
|
crc.update(a);
|
|
if (len == 2) {
|
|
crc.update(b);
|
|
}
|
|
outStream.write(map_array[((a >>> 2) & 0x38) + ((b >>> 5) & 0x7)]);
|
|
p1 = 0; p2 = 0;
|
|
for (i = 1; i < 256; i = i * 2) {
|
|
if ((a & i) != 0) {
|
|
p1++;
|
|
}
|
|
if ((b & i) != 0) {
|
|
p2++;
|
|
}
|
|
}
|
|
p1 = (p1 & 1) * 32;
|
|
p2 = (p2 & 1) * 32;
|
|
outStream.write(map_array[(a & 31) + p1]);
|
|
outStream.write(map_array[(b & 31) + p2]);
|
|
return;
|
|
}
|
|
|
|
/**
|
|
* Each UCE encoded line starts with a prefix of '*[XXX]', where
|
|
* the sequence number and the length are encoded in the first
|
|
* atom.
|
|
*/
|
|
protected void encodeLinePrefix(OutputStream outStream, int length) throws IOException {
|
|
outStream.write('*');
|
|
crc.value = 0;
|
|
tmp[0] = (byte) length;
|
|
tmp[1] = (byte) sequence;
|
|
sequence = (sequence + 1) & 0xff;
|
|
encodeAtom(outStream, tmp, 0, 2);
|
|
}
|
|
|
|
|
|
/**
|
|
* each UCE encoded line ends with YYY and encoded version of the
|
|
* 16 bit checksum. The most significant byte of the check sum
|
|
* is always encoded FIRST.
|
|
*/
|
|
protected void encodeLineSuffix(OutputStream outStream) throws IOException {
|
|
tmp[0] = (byte) ((crc.value >>> 8) & 0xff);
|
|
tmp[1] = (byte) (crc.value & 0xff);
|
|
encodeAtom(outStream, tmp, 0, 2);
|
|
super.pStream.println();
|
|
}
|
|
|
|
/**
|
|
* The buffer prefix code is used to initialize the sequence number
|
|
* to zero.
|
|
*/
|
|
protected void encodeBufferPrefix(OutputStream a) throws IOException {
|
|
sequence = 0;
|
|
super.encodeBufferPrefix(a);
|
|
}
|
|
}
|