ByteToCharEUC_TW.java

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 * 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
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 * questions.
 */

package sun.io;

import sun.nio.cs.ext.EUC_TW;

/*
 * @author Limin Shi
 */
public class ByteToCharEUC_TW extends ByteToCharConverter
{
    private final byte G0 = 0;
    private final byte G1 = 1;
    private final byte G2 = 2;
    private final byte G3 = 3;
    private final byte G4 = 4;
    private final byte MSB = (byte) 0x80;
    private final byte SS2 = (byte) 0x8E;
    private final byte P2 = (byte) 0xA2;
    private final byte P3 = (byte) 0xA3;

    protected final char REPLACE_CHAR = '\uFFFD';

    private byte firstByte = 0, state = G0;
    public static String unicodeCNS2, unicodeCNS3;
    private static String unicodeCNS4, unicodeCNS5, unicodeCNS6;
    private static String unicodeCNS7, unicodeCNS15;

    private int cnsPlane = 0;
    private final static EUC_TW nioCoder = new EUC_TW();

    public static String unicodeCNS1 = nioCoder.getUnicodeCNS1();

	static String[] cnsChars = {
	    unicodeCNS2 = nioCoder.getUnicodeCNS2(),
	    unicodeCNS3 = nioCoder.getUnicodeCNS3(),
	    unicodeCNS4 = nioCoder.getUnicodeCNS4(),
	    unicodeCNS5 = nioCoder.getUnicodeCNS5(),
	    unicodeCNS6 = nioCoder.getUnicodeCNS6(),
	    unicodeCNS7 = nioCoder.getUnicodeCNS7(),
	    unicodeCNS15 = nioCoder.getUnicodeCNS15()
	    };

    public ByteToCharEUC_TW() {
    }

    public int flush(char[] output, int outStart, int outEnd)
	throws MalformedInputException
    {
	if (state != G0) {
	    state = G0;
	    firstByte = 0;
	    badInputLength = 0;
	    throw new MalformedInputException();
	}
	reset();
	return 0;
    }

    public void reset() {
	state = G0;
	firstByte = 0;
	byteOff = charOff = 0;
    }

    /**
     * Character conversion
     */
    public int convert(byte[] input, int inOff, int inEnd,
                       char[] output, int outOff, int outEnd)
        throws UnknownCharacterException, MalformedInputException,
               ConversionBufferFullException
    {
	int inputSize = 0;
	char outputChar = (char) 0;

	byteOff = inOff;
	charOff = outOff;

        cnsPlane = 3;
	while (byteOff < inEnd) {
	    if (charOff >= outEnd) 
	 	throw new ConversionBufferFullException();

	    switch (state) {
	    case G0:
		if ( (input[byteOff] & MSB) == 0) {	// ASCII
		    outputChar = (char) input[byteOff];
		} else if (input[byteOff] == SS2) {	// Codeset 2
		    state = G2;
		} else {				// Codeset 1
		    firstByte = input[byteOff];
		    state = G1;
		}
		break;
	    case G1:
		inputSize = 2;
		if ( (input[byteOff] & MSB) != 0) {	// 2nd byte
		    cnsPlane = 1;
		    outputChar = convToUnicode(firstByte, 
					input[byteOff], unicodeCNS1);
		} else {				// Error
		    badInputLength = 1;
		    throw new MalformedInputException();
		}
		firstByte = 0;
		state = G0;
		break;
	    case G2:
		cnsPlane = (input[byteOff] & (byte)0x0f);
		// Adjust String array index for plan 15 
		cnsPlane = (cnsPlane == 15)? 8 : cnsPlane;

		if (cnsPlane < 15) {
		     state = G3;
		} else {
		    badInputLength = 2;
		    throw new MalformedInputException();
		}

		break;
	    case G3:
		if ( (input[byteOff] & MSB) != 0) {	// 1st byte
		    firstByte = input[byteOff];
		    state = G4;
		} else {				// Error
		    state = G0;
		    badInputLength = 2;
		    throw new MalformedInputException();
		}
		break;
	    case G4:
		if ( (input[byteOff] & MSB) != 0) {	// 2nd byte
			outputChar = convToUnicode(firstByte, 
						   input[byteOff], 
					           cnsChars[cnsPlane - 2]);
		} else {				// Error
		    badInputLength = 3;
		    throw new MalformedInputException();
		}
		firstByte = 0;
		state = G0;
		break;
	    }
	    byteOff++;

	    if (outputChar != (char) 0) {
		if (outputChar == REPLACE_CHAR) {
                    if (subMode) 		// substitution enabled
                        outputChar = subChars[0];
                    else {
                        badInputLength = inputSize;
                        throw new UnknownCharacterException();
                    }
                }
	        output[charOff++] = outputChar;
		outputChar = 0;
	    }
	}

	return charOff - outOff;
    }


    /**
     * Return the character set ID
     */
    public String getCharacterEncoding() {
        return "EUC_TW";
    }

    protected char convToUnicode(byte byte1, byte byte2, String table)
    {
	int index;

        if ((byte1 & 0xff) < 0xa1 || (byte2 & 0xff) < 0xa1 || 
	    (byte1 & 0xff) > 0xfe || (byte2 & 0xff) > 0xfe)
            return REPLACE_CHAR;
	index = (((byte1 & 0xff) - 0xa1) * 94)  + (byte2 & 0xff) - 0xa1;
	if (index < 0 || index >= table.length())
	    return REPLACE_CHAR;

	// Planes 3 and above containing zero value lead byte
	// to accommodate surrogates for mappings which decode to a surrogate
	// pair

	if (this.cnsPlane >= 3)
	   index = (index * 2) + 1;

	return table.charAt(index);
    }
}