| /* |
| * Copyright (c) 1995, 2000, 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.ByteArrayOutputStream; |
| import java.io.PushbackInputStream; |
| import java.io.PrintStream; |
| import java.io.IOException; |
| |
| /** |
| * This class implements a robust character decoder. The decoder will |
| * converted encoded text into binary data. |
| * |
| * 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> |
| * |
| * If an error is encountered during decoding this class throws a |
| * CEFormatException. The specific detail messages are: |
| * |
| * <pre> |
| * "UCDecoder: High byte parity error." |
| * "UCDecoder: Low byte parity error." |
| * "UCDecoder: Out of sequence line." |
| * "UCDecoder: CRC check failed." |
| * </pre> |
| * |
| * @author Chuck McManis |
| * @see CharacterEncoder |
| * @see UCEncoder |
| */ |
| public class UCDecoder extends CharacterDecoder { |
| |
| /** This class 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(); |
| |
| /** |
| * Decode one atom - reads the characters from the input stream, decodes |
| * them, and checks for valid parity. |
| */ |
| protected void decodeAtom(PushbackInputStream inStream, OutputStream outStream, int l) throws IOException { |
| int i, p1, p2, np1, np2; |
| byte a = -1, b = -1, c = -1; |
| byte high_byte, low_byte; |
| byte tmp[] = new byte[3]; |
| |
| i = inStream.read(tmp); |
| if (i != 3) { |
| throw new CEStreamExhausted(); |
| } |
| for (i = 0; (i < 64) && ((a == -1) || (b == -1) || (c == -1)); i++) { |
| if (tmp[0] == map_array[i]) { |
| a = (byte) i; |
| } |
| if (tmp[1] == map_array[i]) { |
| b = (byte) i; |
| } |
| if (tmp[2] == map_array[i]) { |
| c = (byte) i; |
| } |
| } |
| high_byte = (byte) (((a & 0x38) << 2) + (b & 0x1f)); |
| low_byte = (byte) (((a & 0x7) << 5) + (c & 0x1f)); |
| p1 = 0; |
| p2 = 0; |
| for (i = 1; i < 256; i = i * 2) { |
| if ((high_byte & i) != 0) |
| p1++; |
| if ((low_byte & i) != 0) |
| p2++; |
| } |
| np1 = (b & 32) / 32; |
| np2 = (c & 32) / 32; |
| if ((p1 & 1) != np1) { |
| throw new CEFormatException("UCDecoder: High byte parity error."); |
| } |
| if ((p2 & 1) != np2) { |
| throw new CEFormatException("UCDecoder: Low byte parity error."); |
| } |
| outStream.write(high_byte); |
| crc.update(high_byte); |
| if (l == 2) { |
| outStream.write(low_byte); |
| crc.update(low_byte); |
| } |
| } |
| |
| private ByteArrayOutputStream lineAndSeq = new ByteArrayOutputStream(2); |
| |
| /** |
| * decodeBufferPrefix initializes the sequence number to zero. |
| */ |
| protected void decodeBufferPrefix(PushbackInputStream inStream, OutputStream outStream) { |
| sequence = 0; |
| } |
| |
| /** |
| * decodeLinePrefix reads the sequence number and the number of |
| * encoded bytes from the line. If the sequence number is not the |
| * previous sequence number + 1 then an exception is thrown. |
| * UCE lines are line terminator immune, they all start with * |
| * so the other thing this method does is scan for the next line |
| * by looking for the * character. |
| * |
| * @exception CEFormatException out of sequence lines detected. |
| */ |
| protected int decodeLinePrefix(PushbackInputStream inStream, OutputStream outStream) throws IOException { |
| int i; |
| int nLen, nSeq; |
| byte xtmp[]; |
| int c; |
| |
| crc.value = 0; |
| while (true) { |
| c = inStream.read(tmp, 0, 1); |
| if (c == -1) { |
| throw new CEStreamExhausted(); |
| } |
| if (tmp[0] == '*') { |
| break; |
| } |
| } |
| lineAndSeq.reset(); |
| decodeAtom(inStream, lineAndSeq, 2); |
| xtmp = lineAndSeq.toByteArray(); |
| nLen = xtmp[0] & 0xff; |
| nSeq = xtmp[1] & 0xff; |
| if (nSeq != sequence) { |
| throw new CEFormatException("UCDecoder: Out of sequence line."); |
| } |
| sequence = (sequence + 1) & 0xff; |
| return (nLen); |
| } |
| |
| |
| /** |
| * this method reads the CRC that is at the end of every line and |
| * verifies that it matches the computed CRC. |
| * |
| * @exception CEFormatException if CRC check fails. |
| */ |
| protected void decodeLineSuffix(PushbackInputStream inStream, OutputStream outStream) throws IOException { |
| int i; |
| int lineCRC = crc.value; |
| int readCRC; |
| byte tmp[]; |
| |
| lineAndSeq.reset(); |
| decodeAtom(inStream, lineAndSeq, 2); |
| tmp = lineAndSeq.toByteArray(); |
| readCRC = ((tmp[0] << 8) & 0xFF00) + (tmp[1] & 0xff); |
| if (readCRC != lineCRC) { |
| throw new CEFormatException("UCDecoder: CRC check failed."); |
| } |
| } |
| } |
