ANSEL Charset

Question

As part of a GEDCOM package I need to decode ANSEL encoded files so I have written an ANSEL Charset. This seems to work though, being the first Decoder I have written, I am not sure of the logic required for the decodeLoop() method of the CharsetDecoder.
I would appreciate any comments on the logic of the decodeLoop() method.
import java.nio.charset.*;
import java.nio.*;
* A Charset to decode the GEDCOM character encoding ANSEL.
* <br>
* Mainly taken from http://lcweb2.loc.gov/cocoon/codetables/45.html
* @author sabre
public class AnselCharset extends Charset
    private static final char[] ANSEL_CHARS = new char[256];
    static
        // The ASCII root
        for (int index = 0; index < 128; index++)
            ANSEL_CHARS[index] = (char)index;
        // Invalid characters traslation
        java.util.Arrays.fill(ANSEL_CHARS, 128, ANSEL_CHARS.length, '?');
        // The ANSEL characters
        ANSEL_CHARS[0x88]='\u0098';//NON-SORT BEGIN / START OF STRING
        ANSEL_CHARS[0x89]='\u009C';//NON-SORT END / STRING TERMINATOR
        ANSEL_CHARS[0x8D]='\u009C';//JOINER / ZERO WIDTH JOINER
        ANSEL_CHARS[0x8E]='\u009C';//NON-JOINER / ZERO WIDTH NON-JOINER
        ANSEL_CHARS[0xA1]='\u0141';//UPPERCASE POLISH L / LATIN CAPITAL LETTER L WITH STROKE
        ANSEL_CHARS[0xA2]='\u00D8';//UPPERCASE SCANDINAVIAN O / LATIN CAPITAL LETTER O WITH STROKE
        ANSEL_CHARS[0xA3]='\u0110';//UPPERCASE D WITH CROSSBAR / LATIN CAPITAL LETTER D WITH STROKE
        ANSEL_CHARS[0xA4]='\u00DE';//UPPERCASE ICELANDIC THORN / LATIN CAPITAL LETTER THORN (Icelandic)
        ANSEL_CHARS[0xA5]='\u00C6';//UPPERCASE DIGRAPH AE / LATIN CAPITAL LIGATURE AE
        ANSEL_CHARS[0xA6]='\u0152';//UPPERCASE DIGRAPH OE / LATIN CAPITAL LIGATURE OE
        ANSEL_CHARS[0xA7]='\u02B9';//SOFT SIGN, PRIME / MODIFIER LETTER PRIME
        ANSEL_CHARS[0xA8]='\u00B7';//MIDDLE DOT
        ANSEL_CHARS[0xA9]='\u266D';//MUSIC FLAT SIGN
        ANSEL_CHARS[0xAA]='\u00AE';//PATENT MARK / REGISTERED SIGN
        ANSEL_CHARS[0xAB]='\u00B1';//PLUS OR MINUS / PLUS-MINUS SIGN
        ANSEL_CHARS[0xAC]='\u01A0';//UPPERCASE O-HOOK / LATIN CAPITAL LETTER O WITH HORN
        ANSEL_CHARS[0xAD]='\u01AF';//UPPERCASE U-HOOK / LATIN CAPITAL LETTER U WITH HORN
        ANSEL_CHARS[0xAE]='\u02BC';//ALIF / MODIFIER LETTER APOSTROPHE
        ANSEL_CHARS[0xB0]='\u02BB';//AYN / MODIFIER LETTER TURNED COMMA
        ANSEL_CHARS[0xB1]='\u0142';//LOWERCASE POLISH L / LATIN SMALL LETTER L WITH STROKE
        ANSEL_CHARS[0xB2]='\u00F8';//LOWERCASE SCANDINAVIAN O / LATIN SMALL LETTER O WITH STROKE
        ANSEL_CHARS[0xB3]='\u0111';//LOWERCASE D WITH CROSSBAR / LATIN SMALL LETTER D WITH STROKE
        ANSEL_CHARS[0xB4]='\u00FE';//LOWERCASE ICELANDIC THORN / LATIN SMALL LETTER THORN (Icelandic)
        ANSEL_CHARS[0xB5]='\u00E6';//LOWERCASE DIGRAPH AE / LATIN SMALL LIGATURE AE
        ANSEL_CHARS[0xB6]='\u0153';//LOWERCASE DIGRAPH OE / LATIN SMALL LIGATURE OE
        ANSEL_CHARS[0xB7]='\u02BA';//HARD SIGN, DOUBLE PRIME / MODIFIER LETTER DOUBLE PRIME
        ANSEL_CHARS[0xB8]='\u0131';//LOWERCASE TURKISH I / LATIN SMALL LETTER DOTLESS I
        ANSEL_CHARS[0xB9]='\u00A3';//BRITISH POUND / POUND SIGN
        ANSEL_CHARS[0xBA]='\u00F0';//LOWERCASE ETH / LATIN SMALL LETTER ETH (Icelandic)
        ANSEL_CHARS[0xBC]='\u01A1';//LOWERCASE O-HOOK / LATIN SMALL LETTER O WITH HORN
        ANSEL_CHARS[0xBD]='\u01B0';//LOWERCASE U-HOOK / LATIN SMALL LETTER U WITH HORN
        ANSEL_CHARS[0xC0]='\u00B0';//DEGREE SIGN
        ANSEL_CHARS[0xC1]='\u2113';//SCRIPT SMALL L
        ANSEL_CHARS[0xC2]='\u2117';//SOUND RECORDING COPYRIGHT
        ANSEL_CHARS[0xC3]='\u00A9';//COPYRIGHT SIGN
        ANSEL_CHARS[0xC4]='\u266F';//MUSIC SHARP SIGN
        ANSEL_CHARS[0xC5]='\u00BF';//INVERTED QUESTION MARK
        ANSEL_CHARS[0xC6]='\u00A1';//INVERTED EXCLAMATION MARK
        ANSEL_CHARS[0xC7]='\u00DF';//ESZETT SYMBOL
        ANSEL_CHARS[0xC8]='\u20AC';//EURO SIGN
        ANSEL_CHARS[0xE0]='\u0309';//PSEUDO QUESTION MARK / COMBINING HOOK ABOVE
        ANSEL_CHARS[0xE1]='\u0300';//GRAVE / COMBINING GRAVE ACCENT (Varia)
        ANSEL_CHARS[0xE2]='\u0301';//ACUTE / COMBINING ACUTE ACCENT (Oxia)
        ANSEL_CHARS[0xE3]='\u0302';//CIRCUMFLEX / COMBINING CIRCUMFLEX ACCENT
        ANSEL_CHARS[0xE4]='\u0303';//TILDE / COMBINING TILDE
        ANSEL_CHARS[0xE5]='\u0304';//MACRON / COMBINING MACRON
        ANSEL_CHARS[0xE6]='\u0306';//BREVE / COMBINING BREVE (Vrachy)
        ANSEL_CHARS[0xE7]='\u0307';//SUPERIOR DOT / COMBINING DOT ABOVE
        ANSEL_CHARS[0xE8]='\u0308';//UMLAUT, DIAERESIS / COMBINING DIAERESIS (Dialytika)
        ANSEL_CHARS[0xE9]='\u030C';//HACEK / COMBINING CARON
        ANSEL_CHARS[0xEA]='\u030A';//CIRCLE ABOVE, ANGSTROM / COMBINING RING ABOVE
        ANSEL_CHARS[0xEB]='\u0361';//LIGATURE, FIRST HALF / COMBINING DOUBLE INVERTED BREVE     FE20     EFB8A0
        ANSEL_CHARS[0xEC]='\uFE21';//LIGATURE, SECOND HALF / COMBINING LIGATURE RIGHT HALF     FE21     EFB8A1
        ANSEL_CHARS[0xED]='\u0315';//HIGH COMMA, OFF CENTER / COMBINING COMMA ABOVE RIGHT
        ANSEL_CHARS[0xEE]='\u030B';//DOUBLE ACUTE / COMBINING DOUBLE ACUTE ACCENT
        ANSEL_CHARS[0xEF]='\u0310';//CANDRABINDU / COMBINING CANDRABINDU
        ANSEL_CHARS[0xF0]='\u0327';//CEDILLA / COMBINING CEDILLA
        ANSEL_CHARS[0xF1]='\u0328';//RIGHT HOOK, OGONEK / COMBINING OGONEK
        ANSEL_CHARS[0xF2]='\u0323';//DOT BELOW / COMBINING DOT BELOW
        ANSEL_CHARS[0xF3]='\u0324';//DOUBLE DOT BELOW / COMBINING DIAERESIS BELOW
        ANSEL_CHARS[0xF4]='\u0325';//CIRCLE BELOW / COMBINING RING BELOW
        ANSEL_CHARS[0xF5]='\u0333';//DOUBLE UNDERSCORE / COMBINING DOUBLE LOW LINE
        ANSEL_CHARS[0xF6]='\u0332';//UNDERSCORE / COMBINING LOW LINE
        ANSEL_CHARS[0xF7]='\u0326';//LEFT HOOK (COMMA BELOW) / COMBINING COMMA BELOW
        ANSEL_CHARS[0xF8]='\u031C';//RIGHT CEDILLA / COMBINING LEFT HALF RING BELOW
        ANSEL_CHARS[0xF9]='\u032E';//UPADHMANIYA / COMBINING BREVE BELOW
        ANSEL_CHARS[0xFA]='\uFE22';//DOUBLE TILDE, FIRST HALF / COMBINING DOUBLE TILDE     FE22     EFB8A2
        ANSEL_CHARS[0xFB]='\uFE23';//DOUBLE TILDE, SECOND HALF / COMBINING DOUBLE TILDE RIGHT HALF     FE23     EFB8A3
        ANSEL_CHARS[0xFE]='\u0313';//HIGH COMMA, CENTERED / COMBINING COMMA ABOVE (Psili)
    public AnselCharset()
        super("ANSEL", null);
    public CharsetDecoder newDecoder()
        return new Decoder(this);
    public CharsetEncoder newEncoder()
        throw new UnsupportedOperationException("ANSEL Encoding not supported");
    public boolean contains(Charset cs)
        return displayName().equals(cs.displayName());
    public boolean canEncode()
        return false;
    private static class Decoder extends CharsetDecoder
        private Decoder(Charset cs)
            super(cs, 1.0f, 1.0f);
        protected CoderResult decodeLoop(ByteBuffer in, CharBuffer out)
            while (in.hasRemaining())
                if (out.hasRemaining())
                    int b = in.get() & 0xff;
                    out.put(ANSEL_CHARS);
else
return CoderResult.OVERFLOW;
return CoderResult.UNDERFLOW;

Answer 1

> Thanks for this, I have been thinking of buying a
book on NIO so I might order the "Java NIO" book.
sabre, if you want to look before buying, you can view some pages (or the table of contents) through Google-books:
http://books.google.com/books?vid=ISBN0596002882&id=BSz14O3uQwsC&pg=PP1&lpg=PP1&dq=O'Reilly+Java+NIO&sig=8uC-pkytAU6y7RXDBKS_O6EwRAk