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Diffstat (limited to 'libjava/classpath/gnu/java/nio/charset/UTF_16Decoder.java')
| -rw-r--r-- | libjava/classpath/gnu/java/nio/charset/UTF_16Decoder.java | 167 |
1 files changed, 167 insertions, 0 deletions
diff --git a/libjava/classpath/gnu/java/nio/charset/UTF_16Decoder.java b/libjava/classpath/gnu/java/nio/charset/UTF_16Decoder.java new file mode 100644 index 000000000..e078a6919 --- /dev/null +++ b/libjava/classpath/gnu/java/nio/charset/UTF_16Decoder.java @@ -0,0 +1,167 @@ +/* UTF_16Decoder.java -- + Copyright (C) 2002, 2005 Free Software Foundation, Inc. + +This file is part of GNU Classpath. + +GNU Classpath is free software; you can redistribute it and/or modify +it under the terms of the GNU General Public License as published by +the Free Software Foundation; either version 2, or (at your option) +any later version. + +GNU Classpath 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 for more details. + +You should have received a copy of the GNU General Public License +along with GNU Classpath; see the file COPYING. If not, write to the +Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA +02110-1301 USA. + +Linking this library statically or dynamically with other modules is +making a combined work based on this library. Thus, the terms and +conditions of the GNU General Public License cover the whole +combination. + +As a special exception, the copyright holders of this library give you +permission to link this library with independent modules to produce an +executable, regardless of the license terms of these independent +modules, and to copy and distribute the resulting executable under +terms of your choice, provided that you also meet, for each linked +independent module, the terms and conditions of the license of that +module. An independent module is a module which is not derived from +or based on this library. If you modify this library, you may extend +this exception to your version of the library, but you are not +obligated to do so. If you do not wish to do so, delete this +exception statement from your version. */ + +package gnu.java.nio.charset; + +import java.nio.ByteBuffer; +import java.nio.CharBuffer; +import java.nio.charset.Charset; +import java.nio.charset.CharsetDecoder; +import java.nio.charset.CoderResult; + +/** + * Decoder for UTF-16, UTF-15LE, and UTF-16BE. + * + * @author Jesse Rosenstock + */ +final class UTF_16Decoder extends CharsetDecoder +{ + // byte orders + static final int BIG_ENDIAN = 0; + static final int LITTLE_ENDIAN = 1; + static final int UNKNOWN_ENDIAN = 2; + static final int MAYBE_BIG_ENDIAN = 3; + static final int MAYBE_LITTLE_ENDIAN = 4; + + private static final char BYTE_ORDER_MARK = 0xFEFF; + private static final char REVERSED_BYTE_ORDER_MARK = 0xFFFE; + + private final int originalByteOrder; + private int byteOrder; + + UTF_16Decoder (Charset cs, int byteOrder) + { + super (cs, 0.5f, 1.0f); + this.originalByteOrder = byteOrder; + this.byteOrder = byteOrder; + } + + protected CoderResult decodeLoop (ByteBuffer in, CharBuffer out) + { + // TODO: Optimize this in the case in.hasArray() / out.hasArray() + + int inPos = in.position (); + try + { + while (in.remaining () >= 2) + { + byte b1 = in.get (); + byte b2 = in.get (); + + // handle byte order mark + if (byteOrder == UNKNOWN_ENDIAN || + byteOrder == MAYBE_BIG_ENDIAN || + byteOrder == MAYBE_LITTLE_ENDIAN) + { + char c = (char) (((b1 & 0xFF) << 8) | (b2 & 0xFF)); + if (c == BYTE_ORDER_MARK) + { + if (byteOrder == MAYBE_LITTLE_ENDIAN) + { + return CoderResult.malformedForLength (2); + } + byteOrder = BIG_ENDIAN; + inPos += 2; + continue; + } + else if (c == REVERSED_BYTE_ORDER_MARK) + { + if (byteOrder == MAYBE_BIG_ENDIAN) + { + return CoderResult.malformedForLength (2); + } + byteOrder = LITTLE_ENDIAN; + inPos += 2; + continue; + } + else + { + // assume big or little endian, do not consume bytes, + // continue with normal processing + byteOrder = (byteOrder == MAYBE_LITTLE_ENDIAN ? + LITTLE_ENDIAN : BIG_ENDIAN); + } + } + + // FIXME: Change so you only do a single comparison here. + char c = (byteOrder == BIG_ENDIAN + ? (char) (((b1 & 0xFF) << 8) | (b2 & 0xFF)) + : (char) (((b2 & 0xFF) << 8) | (b1 & 0xFF))); + + if (0xD800 <= c && c <= 0xDFFF) + { + // c is a surrogate + + // make sure c is a high surrogate + if (c > 0xDBFF) + return CoderResult.malformedForLength (2); + if (in.remaining () < 2) + return CoderResult.UNDERFLOW; + byte b3 = in.get (); + byte b4 = in.get (); + char d = (byteOrder == BIG_ENDIAN + ? (char) (((b3 & 0xFF) << 8) | (b4 & 0xFF)) + : (char) (((b4 & 0xFF) << 8) | (b3 & 0xFF))); + // make sure d is a low surrogate + if (d < 0xDC00 || d > 0xDFFF) + return CoderResult.malformedForLength (2); + out.put (c); + out.put (d); + inPos += 4; + } + else + { + if (!out.hasRemaining ()) + return CoderResult.UNDERFLOW; + out.put (c); + inPos += 2; + } + } + + return CoderResult.UNDERFLOW; + } + finally + { + in.position (inPos); + } + } + + protected void implReset () + { + byteOrder = originalByteOrder; + } +} |