SimpleEUCDecoder.java

/*
 * Copyright (c) 2003, 2006, 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
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 */



/**
 * Simple EUC-like decoder used by IBM01383 and IBM970
 * supports G1 - no support for G2 or G3
 */

package sun.nio.cs.ext;

import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.charset.Charset;
import java.nio.charset.CharsetDecoder;
import java.nio.charset.CoderResult;

abstract class SimpleEUCDecoder
    extends CharsetDecoder
{
    private final int SS2 =  0x8E;
    private final int SS3 =  0x8F;

    protected static String  mappingTableG1;
    protected static String  byteToCharTable;

    protected SimpleEUCDecoder(Charset cs) {
	super(cs, 0.5f, 1.0f);
    }

    private CoderResult decodeArrayLoop(ByteBuffer src, CharBuffer dst) {
	byte[] sa = src.array();
	int sp = src.arrayOffset() + src.position();
	int sl = src.arrayOffset() + src.limit();
	assert (sp <= sl);
	sp = (sp <= sl ? sp : sl);
	char[] da = dst.array();
	int dp = dst.arrayOffset() + dst.position();
	int dl = dst.arrayOffset() + dst.limit();
	assert (dp <= dl);
	dp = (dp <= dl ? dp : dl);

	try {
	    while (sp < sl) {
                int byte1, byte2;
		int inputSize = 1;
                char outputChar = '\uFFFD';

		byte1 = sa[sp] & 0xff;

		if ( byte1 <= 0x9f ) {  // < 0x9f has its own table (G0)
		    if (byte1 == SS2 || byte1 == SS3 ) {
		        // No support provided for G2/G3 at this time.
		        return CoderResult.malformedForLength(1);
		    }
		    outputChar = byteToCharTable.charAt(byte1);
		} else if (byte1 < 0xa1 || byte1 > 0xfe) {  // invalid range?
		    return CoderResult.malformedForLength(1);
		} else {                                        // (G1)
		    if (sl - sp < 2) {
		        return CoderResult.UNDERFLOW;
		    }
		    byte2 = sa[sp + 1] & 0xff;
                    inputSize++;
                    if ( byte2 < 0xa1 || byte2 > 0xfe) { 
		        return CoderResult.malformedForLength(2);
		    }
		    outputChar = mappingTableG1.charAt(((byte1 - 0xa1) * 94) + byte2 - 0xa1);
		}
		if  (outputChar == '\uFFFD') {
		    return CoderResult.unmappableForLength(inputSize);
		}
                if (dl - dp < 1)
		    return CoderResult.OVERFLOW;
		da[dp++] = outputChar;
		sp += inputSize;
	    }
	    return CoderResult.UNDERFLOW;
	} finally {
	    src.position(sp - src.arrayOffset());
	    dst.position(dp - dst.arrayOffset());
	}
    }

    private CoderResult decodeBufferLoop(ByteBuffer src, CharBuffer dst) {
	int mark = src.position();

	try {
	    while (src.hasRemaining()) {
                char outputChar = '\uFFFD';
          	int inputSize = 1;
		int byte1, byte2;

		byte1 = src.get() & 0xff;
		if ( byte1 <= 0x9f ) {
                    if (byte1 == SS2 || byte1 == SS3 ) {
		        return CoderResult.malformedForLength(1);
		    }
		    outputChar = byteToCharTable.charAt(byte1);
		} else if (byte1 < 0xa1 || byte1 > 0xfe) { 
		    return CoderResult.malformedForLength(1);
		} else {                                 
		    if (!src.hasRemaining()) {
		        return CoderResult.UNDERFLOW;
		    }
		    byte2 = src.get() & 0xff;
                    inputSize++;
                    if ( byte2 < 0xa1 || byte2 > 0xfe) { 
		        return CoderResult.malformedForLength(2);
		    }
		    outputChar = mappingTableG1.charAt(((byte1 - 0xa1) * 94) + byte2 - 0xa1);
		}
                if (outputChar == '\uFFFD') {
		    return CoderResult.unmappableForLength(inputSize);
		}
		if (!dst.hasRemaining())
		    return CoderResult.OVERFLOW;
		    dst.put(outputChar);
		mark += inputSize;
	    }
	    return CoderResult.UNDERFLOW;
	} finally {
	    src.position(mark);
	}
    }

    protected CoderResult decodeLoop(ByteBuffer src, CharBuffer dst) {
	if (src.hasArray() && dst.hasArray())
	    return decodeArrayLoop(src, dst);
	else
	    return decodeBufferLoop(src, dst);
    }
}