src/share/classes/sun/io/ByteToCharDoubleByte.java

/*
 * Copyright (c) 1997, 2002, 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.io;

/**
 * @author Limin Shi
 *         Sean Jiang
 */

public abstract class ByteToCharDoubleByte extends ByteToCharConverter {
    protected byte savedByte;

    /*
     * 1st level index, provided by subclass
     */
    protected short index1[];

    /*
     * 2nd level index, provided by subclass
     * every string has 0x10*(end-start+1) characters.
     */
    protected String  index2[];

    protected int start;
    protected int end;

    /*
     * Size of bad input that caused conversion to stop
     */
    protected int     badInputLength;

    public ByteToCharDoubleByte() {
        super();
        savedByte = 0;
    }


    public short[] getIndex1() {
        return(index1);
    }

    public String[] getIndex2() {
        return(index2);
    }

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

    /**
     * Converts sequences of bytes to characters.
     * Conversions that result in Exceptions can be restarted by calling
     * convert again, with appropriately modified parameters.
     * @return the characters written to output.
     * @param input byte array containing text in Double/single Byte
     * @param inStart offset in input array
     * @param inEnd offset of last byte to be converted
     * @param output character array to receive conversion result
     * @param outStart starting offset
     * @param outEnd offset of last byte to be written to
     * @throw UnsupportedCharacterException for any bytes
     * that cannot be converted to the external character set.
     */
    public int convert(byte[] input, int inOff, int inEnd,
                       char[] output, int outOff, int outEnd)
        throws UnknownCharacterException, MalformedInputException,
               ConversionBufferFullException
    {
        char    outputChar = REPLACE_CHAR;
        int     inputSize = 0;          // Size of input

        // Record beginning offsets
        charOff = outOff;
        byteOff = inOff;

        // Loop until we hit the end of the input
        while (byteOff < inEnd) {
            int byte1, byte2;

            if (savedByte == 0) {
                byte1 = input[byteOff];
                inputSize = 1;
            } else {
                byte1 = savedByte;
                savedByte = 0;
                inputSize = 0;
            }

            outputChar = convSingleByte(byte1);

            if (outputChar == REPLACE_CHAR) {   // DoubleByte char
                if (byteOff + inputSize >= inEnd) {
                    // split in the middle of a character
                    // save the first byte for next time around
                    savedByte = (byte) byte1;
                    byteOff += inputSize;
                    break;
                }

                byte1 &= 0xff;
                byte2 = input[byteOff + inputSize] & 0xff;

                inputSize++;
                outputChar = getUnicode(byte1, byte2);
            }

            if (outputChar == REPLACE_CHAR) {
                if (subMode)
                    outputChar = subChars[0];
                else {
                    badInputLength = inputSize;
                    throw new UnknownCharacterException();
                }
            }

            if (charOff >= outEnd)
                throw new ConversionBufferFullException();

            output[charOff++] = outputChar;
            byteOff += inputSize;
        }

        return charOff - outOff;
    }

    /**
     * Resets the converter.
     * Call this method to reset the converter to its initial state
     */
    public void reset() {
        byteOff = charOff = 0;
        savedByte = 0;
    }


    /*
     * Can be changed by subclass
     */
    protected char convSingleByte(int b) {
        if (b >= 0)
            return (char) b;
        return REPLACE_CHAR;
    }

    /*
     * Can be changed by subclass
     */
    protected char getUnicode(int byte1, int byte2) {
        // Fix for bug 4117820 - similar fix for bug 4121358 put
        // into ByteToCharEUC_JP.getUnicode()
        if (((byte1 < 0) || (byte1 > index1.length))
            || ((byte2 < start) || (byte2 > end)))
            return REPLACE_CHAR;

        int n = (index1[byte1] & 0xf) * (end - start + 1) + (byte2 - start);
        return index2[index1[byte1] >> 4].charAt(n);
    }

    protected final static char REPLACE_CHAR = '\uFFFD';
}