280 lines
9.7 KiB
Java
280 lines
9.7 KiB
Java
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/* UTF_8.java --
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Copyright (C) 2002 Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package gnu.java.nio.charset;
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import java.nio.ByteBuffer;
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import java.nio.CharBuffer;
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import java.nio.charset.Charset;
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import java.nio.charset.CharsetDecoder;
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import java.nio.charset.CharsetEncoder;
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import java.nio.charset.CoderResult;
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/**
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* UTF-8 charset.
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*
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* <p> UTF-8 references:
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* <ul>
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* <li> <a href="http://ietf.org/rfc/rfc2279.txt">RFC 2279</a>
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* <li> The <a href="http://www.unicode.org/unicode/standard/standard.html">
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* Unicode standard</a> and
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* <a href="http://www.unicode.org/versions/corrigendum1.html">
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* Corrigendum</a>
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* </ul>
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*
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* @author Jesse Rosenstock
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*/
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final class UTF_8 extends Charset
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{
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UTF_8 ()
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{
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super ("UTF-8", null);
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}
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public boolean contains (Charset cs)
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{
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return cs instanceof US_ASCII || cs instanceof ISO_8859_1
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|| cs instanceof UTF_8 || cs instanceof UTF_16BE
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|| cs instanceof UTF_16LE || cs instanceof UTF_16;
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}
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public CharsetDecoder newDecoder ()
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{
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return new Decoder (this);
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}
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public CharsetEncoder newEncoder ()
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{
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return new Encoder (this);
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}
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private static final class Decoder extends CharsetDecoder
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{
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private Decoder (Charset cs)
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{
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super (cs, 1.0f, 1.0f);
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}
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protected CoderResult decodeLoop (ByteBuffer in, CharBuffer out)
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{
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// TODO: Optimize this in the case in.hasArray() / out.hasArray()
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int inPos = 0;
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try
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{
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while (in.hasRemaining ())
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{
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char c;
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byte b1 = in.get ();
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int highNibble = (b1 >> 4) & 0xF;
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switch (highNibble)
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{
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case 0: case 1: case 2: case 3:
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case 4: case 5: case 6: case 7:
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if (out.remaining () < 1)
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return CoderResult.OVERFLOW;
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out.put ((char) b1);
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inPos++;
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break;
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case 0xC: case 0xD:
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byte b2;
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if (in.remaining () < 1)
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return CoderResult.UNDERFLOW;
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if (out.remaining () < 1)
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return CoderResult.OVERFLOW;
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if (!isContinuation (b2 = in.get ()))
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return CoderResult.malformedForLength (1);
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c = (char) (((b1 & 0x1F) << 6) | (b2 & 0x3F));
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// check that we had the shortest encoding
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if (c <= 0x7F)
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return CoderResult.malformedForLength (2);
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out.put (c);
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inPos += 2;
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break;
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case 0xE:
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byte b3;
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if (in.remaining () < 2)
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return CoderResult.UNDERFLOW;
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if (out.remaining () < 1)
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return CoderResult.OVERFLOW;
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if (!isContinuation (b2 = in.get ()))
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return CoderResult.malformedForLength (1);
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if (!isContinuation (b3 = in.get ()))
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return CoderResult.malformedForLength (1);
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c = (char) (((b1 & 0x0F) << 12)
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| ((b2 & 0x3F) << 6)
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| (b3 & 0x3F));
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// check that we had the shortest encoding
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if (c <= 0x7FF)
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return CoderResult.malformedForLength (3);
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out.put (c);
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inPos += 3;
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break;
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default:
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return CoderResult.malformedForLength (1);
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}
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}
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return CoderResult.UNDERFLOW;
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}
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finally
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{
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// In case we did a get(), then encountered an error, reset the
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// position to before the error. If there was no error, this
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// will benignly reset the position to the value it already has.
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in.position (inPos);
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}
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}
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private static boolean isContinuation (byte b)
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{
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return (b & 0xC0) == 0x80;
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}
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}
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private static final class Encoder extends CharsetEncoder
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{
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private Encoder (Charset cs)
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{
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// According to
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// http://www-106.ibm.com/developerworks/unicode/library/utfencodingforms/index.html
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// On average, English takes slightly over one unit per code point.
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// Most Latin-script languages take about 1.1 bytes. Greek, Russian,
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// Arabic and Hebrew take about 1.7 bytes, and most others (including
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// Japanese, Chinese, Korean and Hindi) take about 3 bytes.
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// We assume we will be dealing with latin scripts, and use 1.1
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// for averageBytesPerChar.
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super (cs, 1.1f, 4.0f);
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}
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protected CoderResult encodeLoop (CharBuffer in, ByteBuffer out)
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{
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int inPos = 0;
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try
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{
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// TODO: Optimize this in the case in.hasArray() / out.hasArray()
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while (in.hasRemaining ())
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{
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int remaining = out.remaining ();
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char c = in.get ();
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// UCS-4 range (hex.) UTF-8 octet sequence (binary)
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// 0000 0000-0000 007F 0xxxxxxx
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// 0000 0080-0000 07FF 110xxxxx 10xxxxxx
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// 0000 0800-0000 FFFF 1110xxxx 10xxxxxx 10xxxxxx
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// Scalar Value UTF-16 byte 1 byte 2 byte 3 byte 4
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// 0000 0000 0xxx xxxx 0000 0000 0xxx xxxx 0xxx xxxx
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// 0000 0yyy yyxx xxxx 0000 0yyy yyxx xxxx 110y yyyy 10xx xxxx
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// zzzz yyyy yyxx xxxx zzzz yyyy yyxx xxxx 1110 zzzz 10yy yyyy 10xx xxxx
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// u uuuu zzzz yyyy yyxx xxxx 1101 10ww wwzz zzyy 1111 0uuu 10uu zzzz 10yy yyyy 10xx xxxx
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// + 1101 11yy yyxx xxxx
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// Note: uuuuu = wwww + 1
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if (c <= 0x7F)
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{
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if (remaining < 1)
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return CoderResult.OVERFLOW;
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out.put ((byte) c);
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inPos++;
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}
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else if (c <= 0x7FF)
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{
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if (remaining < 2)
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return CoderResult.OVERFLOW;
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out.put ((byte) (0xC0 | (c >> 6)));
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out.put ((byte) (0x80 | (c & 0x3F)));
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inPos++;
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}
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else if (0xD800 <= c && c <= 0xDFFF)
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{
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if (remaining < 4)
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return CoderResult.OVERFLOW;
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// we got a low surrogate without a preciding high one
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if (c > 0xDBFF)
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return CoderResult.malformedForLength (1);
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// high surrogates
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if (!in.hasRemaining ())
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return CoderResult.UNDERFLOW;
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char d = in.get ();
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// make sure d is a low surrogate
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if (d < 0xDC00 || d > 0xDFFF)
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return CoderResult.malformedForLength (1);
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// make the 32 bit value
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// int value2 = (c - 0xD800) * 0x400 + (d - 0xDC00) + 0x10000;
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int value = (((c & 0x3FF) << 10) | (d & 0x3FF)) + 0x10000;
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// assert value == value2;
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out.put ((byte) (0xF0 | (value >> 18)));
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out.put ((byte) (0x80 | ((value >> 12) & 0x3F)));
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out.put ((byte) (0x80 | ((value >> 6) & 0x3F)));
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out.put ((byte) (0x80 | ((value ) & 0x3F)));
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inPos += 2;
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}
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else
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{
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if (remaining < 3)
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return CoderResult.OVERFLOW;
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out.put ((byte) (0xE0 | (c >> 12)));
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out.put ((byte) (0x80 | ((c >> 6) & 0x3F)));
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out.put ((byte) (0x80 | (c & 0x3F)));
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inPos++;
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}
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}
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return CoderResult.UNDERFLOW;
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}
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finally
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{
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// In case we did a get(), then encountered an error, reset the
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// position to before the error. If there was no error, this
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// will benignly reset the position to the value it already has.
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in.position (inPos);
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}
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}
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}
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}
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