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/*
* Copyright (c) 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.
*
* 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.
*/
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.charset.Charset;
import java.nio.charset.CharsetDecoder;
import java.nio.charset.CoderResult;
/**
* An abstract base class for subclasses which decode
* IBM double byte only ebcdic host encodings such as ibm
* code pages 834 835 837 300,... etc
*
* The structure of IBM DBCS-only charsets is defined by the
* IBM Character Data Representation Architecture (CDRA) document
*
* http://www-306.ibm.com/software/globalization/cdra/appendix_a.jsp#HDRHEBDBST
*
*/
public abstract class DBCS_ONLY_IBM_EBCDIC_Decoder extends CharsetDecoder
{
protected static final char REPLACE_CHAR='\uFFFD';
protected short index1[];
protected String index2;
protected int mask1;
protected int mask2;
protected int shift;
protected DBCS_ONLY_IBM_EBCDIC_Decoder(Charset cs) {
super(cs, 0.5f, 1.0f);
}
// Check validity of dbcs ebcdic byte pair values
private static boolean isValidDoubleByte(int b1, int b2) {
return (b1 == 0x40 && b2 == 0x40) // DBCS-HOST SPACE
|| (0x41 <= b1 && b1 <= 0xfe &&
0x41 <= b2 && b2 <= 0xfe);
}
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 + 1 < sl) {
int b1 = sa[sp] & 0xff;
int b2 = sa[sp + 1] & 0xff;
if (!isValidDoubleByte(b1, b2)) {
return CoderResult.malformedForLength(2);
}
// Lookup in the two level index
int v = b1 * 256 + b2;
char outputChar = index2.charAt(index1[((v & mask1) >> shift)]
+ (v & mask2));
if (outputChar == REPLACE_CHAR)
return CoderResult.unmappableForLength(2);
if (dl - dp < 1)
return CoderResult.OVERFLOW;
da[dp++] = outputChar;
sp += 2;
}
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.remaining() > 1) {
int b1 = src.get() & 0xff;
int b2 = src.get() & 0xff;
if (!isValidDoubleByte(b1, b2)) {
return CoderResult.malformedForLength(2);
}
// Lookup in the two level index
int v = b1 * 256 + b2;
char outputChar = index2.charAt(index1[((v & mask1) >> shift)]
+ (v & mask2));
if (outputChar == REPLACE_CHAR)
return CoderResult.unmappableForLength(2);
if (!dst.hasRemaining())
return CoderResult.OVERFLOW;
dst.put(outputChar);
mark += 2;
}
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);
}
}
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