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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 | } | ||