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| 1 | +/* | |
| 2 | + * Copyright (c) 1995, 1997, Oracle and/or its affiliates. All rights reserved. | |
| 3 | + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | |
| 4 | + * | |
| 5 | + * This code is free software; you can redistribute it and/or modify it | |
| 6 | + * under the terms of the GNU General Public License version 2 only, as | |
| 7 | + * published by the Free Software Foundation. Oracle designates this | |
| 8 | + * particular file as subject to the "Classpath" exception as provided | |
| 9 | + * by Oracle in the LICENSE file that accompanied this code. | |
| 10 | + * | |
| 11 | + * This code is distributed in the hope that it will be useful, but WITHOUT | |
| 12 | + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 13 | + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 14 | + * version 2 for more details (a copy is included in the LICENSE file that | |
| 15 | + * accompanied this code). | |
| 16 | + * | |
| 17 | + * You should have received a copy of the GNU General Public License version | |
| 18 | + * 2 along with this work; if not, write to the Free Software Foundation, | |
| 19 | + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
| 20 | + * | |
| 21 | + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | |
| 22 | + * or visit www.oracle.com if you need additional information or have any | |
| 23 | + * questions. | |
| 24 | + */ | |
| 25 | +package sun.misc; | |
| 26 | + | |
| 27 | +import java.io.OutputStream; | |
| 28 | +import java.io.InputStream; | |
| 29 | +import java.io.PrintStream; | |
| 30 | +import java.io.IOException; | |
| 31 | + | |
| 32 | +/** | |
| 33 | + * This class implements a robust character encoder. The encoder is designed | |
| 34 | + * to convert binary data into printable characters. The characters are | |
| 35 | + * assumed to exist but they are not assumed to be ASCII, the complete set | |
| 36 | + * is 0-9, A-Z, a-z, "(", and ")". | |
| 37 | + * | |
| 38 | + * The basic encoding unit is a 3 character atom. It encodes two bytes | |
| 39 | + * of data. Bytes are encoded into a 64 character set, the characters | |
| 40 | + * were chosen specifically because they appear in all codesets. | |
| 41 | + * We don't care what their numerical equivalent is because | |
| 42 | + * we use a character array to map them. This is like UUencoding | |
| 43 | + * with the dependency on ASCII removed. | |
| 44 | + * | |
| 45 | + * The three chars that make up an atom are encoded as follows: | |
| 46 | + * <pre> | |
| 47 | + * 00xxxyyy 00axxxxx 00byyyyy | |
| 48 | + * 00 = leading zeros, all values are 0 - 63 | |
| 49 | + * xxxyyy - Top 3 bits of X, Top 3 bits of Y | |
| 50 | + * axxxxx - a = X parity bit, xxxxx lower 5 bits of X | |
| 51 | + * byyyyy - b = Y parity bit, yyyyy lower 5 bits of Y | |
| 52 | + * </pre> | |
| 53 | + * | |
| 54 | + * The atoms are arranged into lines suitable for inclusion into an | |
| 55 | + * email message or text file. The number of bytes that are encoded | |
| 56 | + * per line is 48 which keeps the total line length under 80 chars) | |
| 57 | + * | |
| 58 | + * Each line has the form( | |
| 59 | + * <pre> | |
| 60 | + * *(LLSS)(DDDD)(DDDD)(DDDD)...(CRC) | |
| 61 | + * Where each (xxx) represents a three character atom. | |
| 62 | + * (LLSS) - 8 bit length (high byte), and sequence number | |
| 63 | + * modulo 256; | |
| 64 | + * (DDDD) - Data byte atoms, if length is odd, last data | |
| 65 | + * atom has (DD00) (high byte data, low byte 0) | |
| 66 | + * (CRC) - 16 bit CRC for the line, includes length, | |
| 67 | + * sequence, and all data bytes. If there is a | |
| 68 | + * zero pad byte (odd length) it is _NOT_ | |
| 69 | + * included in the CRC. | |
| 70 | + * </pre> | |
| 71 | + * | |
| 72 | + * @author Chuck McManis | |
| 73 | + * @see CharacterEncoder | |
| 74 | + * @see UCDecoder | |
| 75 | + */ | |
| 76 | +public class UCEncoder extends CharacterEncoder { | |
| 77 | + | |
| 78 | + /** this clase encodes two bytes per atom */ | |
| 79 | + protected int bytesPerAtom() { | |
| 80 | + return (2); | |
| 81 | + } | |
| 82 | + | |
| 83 | + /** this class encodes 48 bytes per line */ | |
| 84 | + protected int bytesPerLine() { | |
| 85 | + return (48); | |
| 86 | + } | |
| 87 | + | |
| 88 | + /* this is the UCE mapping of 0-63 to characters .. */ | |
| 89 | + private final static byte map_array[] = { | |
| 90 | + // 0 1 2 3 4 5 6 7 | |
| 91 | + (byte)'0',(byte)'1',(byte)'2',(byte)'3',(byte)'4',(byte)'5',(byte)'6',(byte)'7', // 0 | |
| 92 | + (byte)'8',(byte)'9',(byte)'A',(byte)'B',(byte)'C',(byte)'D',(byte)'E',(byte)'F', // 1 | |
| 93 | + (byte)'G',(byte)'H',(byte)'I',(byte)'J',(byte)'K',(byte)'L',(byte)'M',(byte)'N', // 2 | |
| 94 | + (byte)'O',(byte)'P',(byte)'Q',(byte)'R',(byte)'S',(byte)'T',(byte)'U',(byte)'V', // 3 | |
| 95 | + (byte)'W',(byte)'X',(byte)'Y',(byte)'Z',(byte)'a',(byte)'b',(byte)'c',(byte)'d', // 4 | |
| 96 | + (byte)'e',(byte)'f',(byte)'g',(byte)'h',(byte)'i',(byte)'j',(byte)'k',(byte)'l', // 5 | |
| 97 | + (byte)'m',(byte)'n',(byte)'o',(byte)'p',(byte)'q',(byte)'r',(byte)'s',(byte)'t', // 6 | |
| 98 | + (byte)'u',(byte)'v',(byte)'w',(byte)'x',(byte)'y',(byte)'z',(byte)'(',(byte)')' // 7 | |
| 99 | + }; | |
| 100 | + | |
| 101 | + private int sequence; | |
| 102 | + private byte tmp[] = new byte[2]; | |
| 103 | + private CRC16 crc = new CRC16(); | |
| 104 | + | |
| 105 | + /** | |
| 106 | + * encodeAtom - take two bytes and encode them into the correct | |
| 107 | + * three characters. If only one byte is to be encoded, the other | |
| 108 | + * must be zero. The padding byte is not included in the CRC computation. | |
| 109 | + */ | |
| 110 | + protected void encodeAtom(OutputStream outStream, byte data[], int offset, int len) throws IOException | |
| 111 | + { | |
| 112 | + int i; | |
| 113 | + int p1, p2; // parity bits | |
| 114 | + byte a, b; | |
| 115 | + | |
| 116 | + a = data[offset]; | |
| 117 | + if (len == 2) { | |
| 118 | + b = data[offset+1]; | |
| 119 | + } else { | |
| 120 | + b = 0; | |
| 121 | + } | |
| 122 | + crc.update(a); | |
| 123 | + if (len == 2) { | |
| 124 | + crc.update(b); | |
| 125 | + } | |
| 126 | + outStream.write(map_array[((a >>> 2) & 0x38) + ((b >>> 5) & 0x7)]); | |
| 127 | + p1 = 0; p2 = 0; | |
| 128 | + for (i = 1; i < 256; i = i * 2) { | |
| 129 | + if ((a & i) != 0) { | |
| 130 | + p1++; | |
| 131 | + } | |
| 132 | + if ((b & i) != 0) { | |
| 133 | + p2++; | |
| 134 | + } | |
| 135 | + } | |
| 136 | + p1 = (p1 & 1) * 32; | |
| 137 | + p2 = (p2 & 1) * 32; | |
| 138 | + outStream.write(map_array[(a & 31) + p1]); | |
| 139 | + outStream.write(map_array[(b & 31) + p2]); | |
| 140 | + return; | |
| 141 | + } | |
| 142 | + | |
| 143 | + /** | |
| 144 | + * Each UCE encoded line starts with a prefix of '*[XXX]', where | |
| 145 | + * the sequence number and the length are encoded in the first | |
| 146 | + * atom. | |
| 147 | + */ | |
| 148 | + protected void encodeLinePrefix(OutputStream outStream, int length) throws IOException { | |
| 149 | + outStream.write('*'); | |
| 150 | + crc.value = 0; | |
| 151 | + tmp[0] = (byte) length; | |
| 152 | + tmp[1] = (byte) sequence; | |
| 153 | + sequence = (sequence + 1) & 0xff; | |
| 154 | + encodeAtom(outStream, tmp, 0, 2); | |
| 155 | + } | |
| 156 | + | |
| 157 | + | |
| 158 | + /** | |
| 159 | + * each UCE encoded line ends with YYY and encoded version of the | |
| 160 | + * 16 bit checksum. The most significant byte of the check sum | |
| 161 | + * is always encoded FIRST. | |
| 162 | + */ | |
| 163 | + protected void encodeLineSuffix(OutputStream outStream) throws IOException { | |
| 164 | + tmp[0] = (byte) ((crc.value >>> 8) & 0xff); | |
| 165 | + tmp[1] = (byte) (crc.value & 0xff); | |
| 166 | + encodeAtom(outStream, tmp, 0, 2); | |
| 167 | + super.pStream.println(); | |
| 168 | + } | |
| 169 | + | |
| 170 | + /** | |
| 171 | + * The buffer prefix code is used to initialize the sequence number | |
| 172 | + * to zero. | |
| 173 | + */ | |
| 174 | + protected void encodeBufferPrefix(OutputStream a) throws IOException { | |
| 175 | + sequence = 0; | |
| 176 | + super.encodeBufferPrefix(a); | |
| 177 | + } | |
| 178 | +} | |