/* Woodstox Lite ("wool") XML processor
 *
 * Copyright (c) 2006- Tatu Saloranta, tatu.saloranta@iki.fi
 *
 * Licensed under the License specified in the file LICENSE which is
 * included with the source code.
 * You may not use this file except in compliance with the License.
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.fasterxml.aalto.out;

import java.io.*;

import javax.xml.stream.*;

import org.codehaus.stax2.ri.typed.AsciiValueEncoder;


import com.fasterxml.aalto.impl.ErrorConsts;
import com.fasterxml.aalto.util.XmlCharTypes;
import com.fasterxml.aalto.util.XmlChars;
import com.fasterxml.aalto.util.XmlConsts;

import static com.fasterxml.aalto.out.OutputCharTypes.*;

This abstract base class (partial implementation of XmlWriter) is used if the destination is byte-based OutputStream. 

Further, all existing implementations are for encodings that
are 7-bit ascii compatible. This is important since this means
that marker and separator characters are identical independent
of actual encoding. This would not hold if support for encodings
like EBCDIC were supported using this class.
/**
 * This abstract base class (partial implementation of {@link XmlWriter})
 * is used if the destination is byte-based {@link java.io.OutputStream}.
 *<p>
 * Further, all existing implementations are for encodings that
 * are 7-bit ascii compatible. This is important since this means
 * that marker and separator characters are identical independent
 * of actual encoding. This would not hold if support for encodings
 * like EBCDIC were supported using this class.
 */
public abstract class ByteXmlWriter
    extends XmlWriter
{
    
And this value determines size of the intermediate copy buffer
to use.
/**
     * And this value determines size of the intermediate copy buffer
     * to use.
     */
    final static int DEFAULT_FULL_BUFFER_SIZE = 4000;

    
Default intermediate copy buffer size, to be used for efficient
access to String content. Smaller, since it's in characters, plus
will not be used for actual write operations
/**
     * Default intermediate copy buffer size, to be used for efficient
     * access to String content. Smaller, since it's in characters, plus
     * will not be used for actual write operations
     */
    final static int DEFAULT_COPY_BUFFER_SIZE = 1000;

    
Let's try avoid short writes, since some output streams have
high per-call penalty (like network streams).
/**
     * Let's try avoid short writes, since some output streams have
     * high per-call penalty (like network streams).
     */
    final static int SMALL_WRITE = 250;

    final static byte BYTE_SPACE = (byte) ' ';
    final static byte BYTE_COLON = (byte) ':';
    final static byte BYTE_SEMICOLON = (byte) ';';
    final static byte BYTE_LBRACKET = (byte) '[';
    final static byte BYTE_RBRACKET = (byte) ']';
    final static byte BYTE_QMARK = (byte) '?';
    final static byte BYTE_EQ = (byte) '=';
    final static byte BYTE_SLASH = (byte) '/';
    final static byte BYTE_HASH = (byte) '#';
    final static byte BYTE_HYPHEN = (byte) '-';

    final static byte BYTE_LT = (byte) '<';
    final static byte BYTE_GT = (byte) '>';
    final static byte BYTE_AMP = (byte) '&';
    final static byte BYTE_QUOT = (byte) '"';
    final static byte BYTE_APOS = (byte) '\'';

    final static byte BYTE_A = (byte) 'a';
    final static byte BYTE_G = (byte) 'g';
    final static byte BYTE_L = (byte) 'l';
    final static byte BYTE_M = (byte) 'm';
    final static byte BYTE_O = (byte) 'o';
    final static byte BYTE_P = (byte) 'p';
    final static byte BYTE_Q = (byte) 'q';
    final static byte BYTE_S = (byte) 's';
    final static byte BYTE_T = (byte) 't';
    final static byte BYTE_U = (byte) 'u';
    final static byte BYTE_X = (byte) 'x';

    final static byte[] BYTES_CDATA_START = getAscii("<![CDATA[");
    final static byte[] BYTES_CDATA_END = getAscii("]]>");
    final static byte[] BYTES_COMMENT_START = getAscii("<!--");
    final static byte[] BYTES_COMMENT_END = getAscii("-->");

    final static byte[] BYTES_XMLDECL_START = getAscii("<?xml version='");
    final static byte[] BYTES_XMLDECL_ENCODING = getAscii(" encoding='");
    final static byte[] BYTES_XMLDECL_STANDALONE = getAscii(" standalone='");

    /*
    /**********************************************************************
    /* Output state, buffering
    /**********************************************************************
     */

    
Actual Writer to use for outputting buffered data as appropriate.
During active usage, remains as the writer initially set; set to
null when this writer is closed.
/**
     * Actual Writer to use for outputting buffered data as appropriate.
     * During active usage, remains as the writer initially set; set to
     * null when this writer is closed.
     */
    protected OutputStream _out;

    protected byte[] _outputBuffer;

    protected int _outputPtr;

    protected final int _outputBufferLen;

    
In case a split surrogate pair is output (which can occur for only
some of the methods, possibly depending on encoding),
the first part is temporarily stored within this member variable.
/**
     * In case a split surrogate pair is output (which can occur for only
     * some of the methods, possibly depending on encoding),
     * the first part is temporarily stored within this member variable.
     */
    protected int _surrogate = 0;

    /*
    /**********************************************************************
    /* Validation
    /**********************************************************************
     */

    
Validation tables used for verifying validity (and need for quoting)
/**
     * Validation tables used for verifying validity (and need for quoting)
     */
    final protected XmlCharTypes _charTypes;

    /*
    /**********************************************************************
    /* Life cycle
    /**********************************************************************
     */

    protected ByteXmlWriter(WriterConfig cfg, OutputStream out, XmlCharTypes charTypes)
    {
        super(cfg);
        _out = out;
        _outputBuffer = cfg.allocFullBBuffer(DEFAULT_FULL_BUFFER_SIZE);
        _outputBufferLen = _outputBuffer.length;
        _outputPtr = 0;
        _charTypes = charTypes;
    }

    @Override
    protected final int getOutputPtr() {
        return _outputPtr;
    }

    /*
    /**********************************************************************
    /* WNameFactory
    /**********************************************************************
     */

    @Override
    public final WName constructName(String localName)
        throws XMLStreamException
    {
        verifyNameComponent(localName);
        return doConstructName(localName);
    }

    @Override
    public WName constructName(String prefix, String localName)
        throws XMLStreamException
    {
        verifyNameComponent(prefix);
        verifyNameComponent(localName);
        return doConstructName(prefix, localName);
    }

    protected abstract WName doConstructName(String localName)
        throws XMLStreamException;

    protected abstract WName doConstructName(String prefix, String localName)
        throws XMLStreamException;

    
Method used to verify that a name component (prefix, local name)
is a legal as per xml 1.0 specification.
Throws:
IllegalArgumentException – If name component contains
 an invalid (non-name; or for the initial characters,
 non-name-first) character./**
     * Method used to verify that a name component (prefix, local name)
     * is a legal as per xml 1.0 specification.
     *
     * @throws IllegalArgumentException If name component contains
     *  an invalid (non-name; or for the initial characters,
     *  non-name-first) character.
     */
    protected void verifyNameComponent(String part)
        throws XMLStreamException
    {
        if (part == null || part.length() == 0) {
            reportNwfName(ErrorConsts.WERR_NAME_EMPTY);
        }
        int ch = (int) part.charAt(0);
        int len = part.length();
        int i;

        // First, special case: surrogates...
        if (ch >= SURR1_FIRST && ch <= SURR2_LAST) {
            // Can't start with surr2...
            if (ch >= SURR2_FIRST) {
                reportNwfName("Illegal surrogate pairing in name: first character ("+XmlChars.getCharDesc(ch)+") not valid surrogate first character");
            }
            // Unpaired? Not good either
            if (len < 2) {
                reportNwfName("Illegal surrogate pairing in name: incomplete surrogate (missing second half)");
            }
            // Otherwise let's decode code point for verification
            ch = calcSurrogate(ch, part.charAt(1), " in name");
            i = 2; // and skip second half of surrogate pair
        } else {
            i = 1;
        }
        if (!XmlChars.is10NameStartChar(ch)) {
            reportNwfName("Invalid name start character "+XmlChars.getCharDesc(ch)+" (name \""+part+"\")");
        }
        // Also, names can not use entities, must be natively expressable
        final int lastValid = getHighestEncodable();
        if (ch > lastValid) {
            reportNwfName("Illegal name start character "+XmlChars.getCharDesc(ch)+" (name \""+part+"\"): can not be expressed using effective encoding ("+_config.getActualEncoding()+")");
        }

        for (; i < len; ++i) {
            ch = part.charAt(i);
            if (ch >= SURR1_FIRST && ch <= SURR2_LAST) {
                // Can't start with surr2...
                if (ch >= SURR2_FIRST) {
                    reportNwfName("Illegal surrogate pairing in name: character at #"+i+" ("+XmlChars.getCharDesc(ch)+") not valid surrogate first character");
                }
                // Unpaired? Not good either
                ++i;
                if (i >= len) {
                    reportNwfName("Illegal surrogate pairing in name: name ends with incomplete surrogate pair");
                }
                // Otherwise let's decode code point for verification
                ch = calcSurrogate(ch, part.charAt(i), " in name");
            }
            if (ch > lastValid) {
                reportNwfName("Illegal name character "+XmlChars.getCharDesc(ch)+" (name \""+part+"\", index #"+i+"): can not be expressed using effective encoding ("+_config.getActualEncoding()+")");
            }
            if (!XmlChars.is10NameChar(ch)) {
                reportNwfName("Invalid name character "+XmlChars.getCharDesc(ch)+") in name (\""+part+"\"), index #"+i);
            }
        }
    }

    /*
    /**********************************************************************
    /* Abstract methods
    /**********************************************************************
     */

    
Method called to output a composite character, result of
combining 2 surrogate characters.
/**
     * Method called to output a composite character, result of
     * combining 2 surrogate characters.
     */
    abstract protected void outputSurrogates(int surr1, int surr2)
        throws IOException, XMLStreamException;

    abstract protected void output2ByteChar(int ch)
        throws IOException, XMLStreamException;

    
Method called to output a character beyond basic 1- or 2-byte
encoding (code 0x0800 and above), without being able to use
character entities
/**
     * Method called to output a character beyond basic 1- or 2-byte
     * encoding (code 0x0800 and above), without being able to use
     * character entities
     */
    abstract protected int outputStrictMultiByteChar(int ch, char[] cbuf, int inputOffset, int inputLen)
        throws IOException, XMLStreamException;

    
Method called to output a character beyond basic 1- or 2-byte
encoding (code 0x0800 and above); possibly using character
entities, if necessary
/**
     * Method called to output a character beyond basic 1- or 2-byte
     * encoding (code 0x0800 and above); possibly using character
     * entities, if necessary
     */
    abstract protected int outputMultiByteChar(int ch, char[] cbuf, int inputOffset, int inputLen)
        throws IOException, XMLStreamException;

    /*
    /**********************************************************************
    /* Low-level (pass-through) methods
    /**********************************************************************
     */

    @Override
    public void _releaseBuffers()
    {
        super._releaseBuffers();
        if (_outputBuffer != null) {
            _config.freeFullBBuffer(_outputBuffer);
            _outputBuffer = null;
        }
        if (_copyBuffer != null) {
            _config.freeFullCBuffer(_copyBuffer);
            _copyBuffer = null;
        }
    }

    @Override
    public void _closeTarget(boolean doClose) throws IOException
    {
        if (_out != null) { // just in case it's called multiple times
            if (doClose) {
                _out.close();
                _out = null;
            }
        }
    }

    @Override
    public final void flush() throws IOException
    {
        if (_out != null) {
            flushBuffer();
            _out.flush();
        }
    }

    /*
    /**********************************************************************
    /* Write methods, raw
    /**********************************************************************
     */

    @Override
    public final void writeRaw(String text, int offset, int len)
        throws IOException, XMLStreamException
    {
        while (len > 0) {
            char[] buf = _copyBuffer;
            final int blen = buf.length;
            final int len2 = (len < blen) ? len : blen;
            text.getChars(offset, offset+len2, buf, 0);
            writeRaw(buf, 0, len2);
            offset += len2;
            len -= len2;
        }
    }

    
This method is heavily encoding-dependant, so it needs
to be deferred to sub-classes
/**
     * This method is heavily encoding-dependant, so it needs
     * to be deferred to sub-classes
     */
    @Override
    public abstract void writeRaw(char[] cbuf, int offset, int len)
        throws IOException, XMLStreamException;

    /*
    /**********************************************************************
    /* Write methods, elements
    /**********************************************************************
     */

    @Override
    public final void writeStartTagStart(WName name)
        throws IOException, XMLStreamException
    {
        if (_surrogate != 0) {
            throwUnpairedSurrogate();
        }
        int ptr = _outputPtr;
        if ((ptr + name.serializedLength() + 1) > _outputBufferLen) {
            writeName(BYTE_LT, name); // let's offline slow case
            return;
        }
        byte[] bbuf = _outputBuffer;
        bbuf[ptr++] = BYTE_LT;
        ptr += name.appendBytes(bbuf, ptr);
        _outputPtr = ptr;
    }

    @Override
    public final void writeStartTagEnd()
        throws IOException, XMLStreamException
    {
        // inlined writeRaw(), gets called so often
        if (_surrogate != 0) {
            throwUnpairedSurrogate();
        }
        if (_outputPtr >= _outputBufferLen) {
            flushBuffer();
        }
        _outputBuffer[_outputPtr++] = BYTE_GT;
    }    

    @Override
    public void writeStartTagEmptyEnd()
        throws IOException
    {
        int ptr = _outputPtr;
        if ((ptr + 2) > _outputBufferLen) {
            flushBuffer();
            ptr = _outputPtr;
        }
        byte[] bbuf = _outputBuffer;
        bbuf[ptr++] = BYTE_SLASH;
        bbuf[ptr++] = BYTE_GT;
        _outputPtr = ptr;
    }

    @Override
    public final void writeEndTag(WName name)
        throws IOException, XMLStreamException
    {
        if (_surrogate != 0) {
            throwUnpairedSurrogate();
        }
        int ptr = _outputPtr;
        int len = name.serializedLength();
        if ((ptr + len + 3) > _outputBufferLen) {
            flushBuffer();
            // name longer than the buffer? can write it straight out
            if ((len + 3) > _outputBufferLen) {
                _out.write(BYTE_LT);
                _out.write(BYTE_SLASH);
                name.writeBytes(_out);
                // Last byte will fit in buffer ok though
                _outputBuffer[_outputPtr++] = BYTE_GT;
                return;
            }
            ptr = _outputPtr;
        }
        byte[] bbuf = _outputBuffer;
        bbuf[ptr++] = BYTE_LT;
        bbuf[ptr++] = BYTE_SLASH;
        ptr += name.appendBytes(bbuf, ptr);
        bbuf[ptr++] = BYTE_GT;
        _outputPtr = ptr;
    }    

    /*
    /**********************************************************************
    /* Write methods, attributes
    /**********************************************************************
     */

    @Override
    public final void writeAttribute(WName name, String value)
        throws IOException, XMLStreamException
    {
        int vlen = value.length();
        // Let's off-line rare case:
        if (vlen > _copyBufferLen) {
            writeLongAttribute(name, value, vlen);
            return;
        }
        char[] cbuf = _copyBuffer;
        if (vlen > 0) {
            value.getChars(0, vlen, cbuf, 0);
        }
        writeAttribute(name, cbuf, 0, vlen);
    }

    @Override
    public final void writeAttribute(WName name, char[] vbuf, int offset, int vlen)
        throws IOException, XMLStreamException
    {
        if (_surrogate != 0) {
            throwUnpairedSurrogate();
        }

        // Enough room?
        int ptr = _outputPtr;
        byte[] bbuf = _outputBuffer;

        if ((ptr + name.serializedLength()) >= _outputBufferLen) {
            writeName(BYTE_SPACE, name);
            ptr = _outputPtr;
        } else {
            bbuf[ptr++] = BYTE_SPACE;
            ptr += name.appendBytes(bbuf, ptr);
        }

        // And then the value
        if ((ptr + 3 + vlen) > _outputBufferLen) { // won't fit
            _outputPtr = ptr;
            flushBuffer();
            bbuf[_outputPtr++] = BYTE_EQ;
            bbuf[_outputPtr++] = BYTE_QUOT;
            if ((_outputPtr + vlen + 1) > _outputBufferLen) {
                writeAttrValue(vbuf, offset, vlen);
                writeRaw(BYTE_QUOT);
                return;
            }
            ptr = _outputPtr;
        } else {
            bbuf[ptr++] = BYTE_EQ;
            bbuf[ptr++] = BYTE_QUOT;
        }
        if (vlen > 0) {
            ptr = fastWriteAttrValue(vbuf, offset, vlen, bbuf, ptr);
        }
        bbuf[ptr++] = BYTE_QUOT;
        _outputPtr = ptr;
    }

    
Method called to copy given attribute value, when it's known that
it will completely fit in the output buffer without further checks
/**
     * Method called to copy given attribute value, when it's known that
     * it will completely fit in the output buffer without further checks
     */
    protected final int fastWriteAttrValue(char[] vbuf, int offset, int len,
                                           byte[] bbuf, int ptr)
        throws IOException, XMLStreamException
    {
        len += offset; // now marks the end

        main_loop:
        while (offset < len) {
            final int[] charTypes = _charTypes.ATTR_CHARS;

            inner_loop:
            while (true) {
                int ch = (int) vbuf[offset];
                if (ch >= OutputCharTypes.MAIN_TABLE_SIZE) {
                    break inner_loop;
                }
                if (charTypes[ch] != XmlCharTypes.CT_OK) {
                    // Here we do want to quote linefeed, too
                    break;
                }
                bbuf[ptr++] = (byte)ch;
                if (++offset >= len) {
                    break main_loop;
                }
            }

            _outputPtr = ptr;
            // Ok, so what did we hit? Invalid, or quotable?
            int ch = (int) vbuf[offset++];
            if (ch < OutputCharTypes.MAIN_TABLE_SIZE) {
                switch (charTypes[ch]) {
                case CT_INVALID:
                    reportInvalidChar(ch);
                    break;
                case CT_MULTIBYTE_2:
                    output2ByteChar(ch);
                    break;
                default:
                    writeAsEntity(ch);
                }
            } else {
                offset = outputMultiByteChar(ch, vbuf, offset, len);
            }

            /* Ok, need to mess with buffers a bit: plus, it's possible
             * that we may even need to flush the buffer as the guarantee
             * for fitting may not necessarily hold (but it will after
             * flushing)
             * Still enough room? (also for following quote -- caller
             * relies on that -- that's why >=, not >)
             */
            if ((len - offset) >= (_outputBufferLen - _outputPtr)) {
                flushBuffer();
            }
            ptr = _outputPtr;
        }

        return ptr;
    }

    protected final void writeAttrValue(char[] vbuf, int offset, int len)
        throws IOException, XMLStreamException
    {
        if (_surrogate != 0) {
            outputSurrogates(_surrogate, vbuf[offset]);
            ++offset;
            --len;
        }

        len += offset; // now marks the end

        main_loop:
        while (offset < len) {
            final int[] charTypes = _charTypes.ATTR_CHARS;

            inner_loop:
            while (true) {
                int ch = (int) vbuf[offset];
                if (ch >= OutputCharTypes.MAIN_TABLE_SIZE) {
                    break inner_loop;
                }
                if (charTypes[ch] != XmlCharTypes.CT_OK) {
                    break;
                }
                if (_outputPtr >= _outputBufferLen) {
                    flushBuffer();
                }
                _outputBuffer[_outputPtr++] = (byte)ch;
                if (++offset >= len) {
                    break main_loop;
                }
            }

            // Ok, so what did we hit?
            int ch = (int) vbuf[offset++];
            if (ch < OutputCharTypes.MAIN_TABLE_SIZE) {
                switch (charTypes[ch]) {
                case CT_INVALID:
                    reportInvalidChar(ch);
                case CT_MULTIBYTE_2:
                    output2ByteChar(ch);
                    break;
                default:
                    writeAsEntity(ch);
                    break;
                }
            } else {
                offset = outputMultiByteChar(ch, vbuf, offset, len);
                continue main_loop;
            }
        }
    }

    protected final void writeLongAttribute(WName name, String value, int vlen)
        throws IOException, XMLStreamException
    {
        writeRaw(BYTE_SPACE);
        int nlen = name.serializedLength();
        if ((_outputPtr + nlen) > _outputBufferLen) {
            flushBuffer();
            if (nlen > _outputBufferLen) {
                name.writeBytes(_out);
            } else {
                _outputPtr += name.appendBytes(_outputBuffer, _outputPtr);
            }
        } else {
            _outputPtr += name.appendBytes(_outputBuffer, _outputPtr);
        }
        writeRaw(BYTE_EQ, BYTE_QUOT);
        int offset = 0;
        while (vlen > 0) {
            char[] buf = _copyBuffer;
            final int blen = buf.length;
            int len2 = (vlen < blen) ? vlen : blen;
            value.getChars(offset, offset+len2, buf, 0);
            writeAttrValue(buf, 0, len2);
            offset += len2;
            vlen -= len2;
        }
        writeRaw(BYTE_QUOT);
    }

    /*
    /**********************************************************************
    /* Write methods, names
    /**********************************************************************
     */

    protected final void writeName(WName name)
        throws IOException
    {
        int ptr = _outputPtr;
        int len = name.serializedLength();
        if ((ptr + len) > _outputBufferLen) {
            flushBuffer();
            // name longer than the buffer? can write it straight out
            if (len >= _outputBufferLen) {
                name.writeBytes(_out);
                return;
            }
            ptr = _outputPtr;
        }
        ptr += name.appendBytes(_outputBuffer, ptr);
        _outputPtr = ptr;
    }

    protected final void writeName(byte preChar, WName name)
        throws IOException
    {
        flushBuffer();
        // name longer than the buffer? Need to write it straight out
        int len = name.serializedLength();
        if (len >= _outputBufferLen) {
            _out.write(preChar);
            name.writeBytes(_out);
            return;
        }
        int ptr = _outputPtr;
        byte[] buf = _outputBuffer;
        buf[ptr++] = preChar;
        ptr += name.appendBytes(buf, ptr);
        _outputPtr = ptr;
    }

    protected final void writeName(WName name, byte postChar)
        throws IOException
    {
        flushBuffer();
        // name longer than the buffer? Need to write it straight out
        if (name.serializedLength() >= _outputBufferLen) {
            name.writeBytes(_out);
            _out.write(postChar);
            return;
        }
        int ptr = _outputPtr;
        byte[] buf = _outputBuffer;
        ptr += name.appendBytes(buf, ptr);
        buf[ptr++] = postChar;
        _outputPtr = ptr;
    }

    private final void writeAttrNameEqQ(WName name)
        throws IOException, XMLStreamException
    {
        if (_surrogate != 0) {
            throwUnpairedSurrogate();
        }
        // Enough room for ' attr="' part?
        int nlen = name.serializedLength();
        int ptr = _outputPtr;
        if ((ptr + nlen + 3) >= _outputBufferLen) {
            flushBuffer();
            ptr = _outputPtr;
            // Still won't fit in buffer? Let's output pieces separately
            if ((ptr + nlen + 3) >= _outputBufferLen) {
                writeName(BYTE_SPACE, name);
                writeRaw(BYTE_EQ);
                writeRaw(BYTE_QUOT);
                return;
            }
        }
        byte[] bbuf = _outputBuffer;
        bbuf[ptr++] = BYTE_SPACE;
        ptr += name.appendBytes(bbuf, ptr);
        bbuf[ptr++] = BYTE_EQ;
        bbuf[ptr++] = BYTE_QUOT;
        _outputPtr = ptr;
    }

    /*
    /**********************************************************************
    /* Write methods, textual content
    /**********************************************************************
     */

    
Returns:
-1 to indicate succesful write, or index of the problematic
  character in input (first ']' from "]]>" sequence, in non-fixing
  mode)/**
     * @return -1 to indicate succesful write, or index of the problematic
     *   character in input (first ']' from "]]&gt;" sequence, in non-fixing
     *   mode)
     */
    @Override
    public int writeCData(String data)
        throws IOException, XMLStreamException
    {
        writeCDataStart(); // will check surrogates
        int len = data.length();
        int offset = 0;
        while (len > 0) {
            char[] buf = _copyBuffer;
            int blen = buf.length;

            // Can write all the rest?
            if (blen > len) {
                blen = len;
            }
            // Nope, can only do part
            data.getChars(offset, offset+blen, buf, 0);
            int cix = writeCDataContents(buf, 0, blen);
            if (cix >= 0) {
                return offset+cix;
            }
            offset += blen;
            len -= blen;
        }
        writeCDataEnd(); // will check surrogates
        return -1;
    }

    @Override
    public int writeCData(char[] cbuf, int offset, int len)
        throws IOException, XMLStreamException
    {
        writeCDataStart(); // will check surrogates
        int ix = writeCDataContents(cbuf, offset, len);
        if (ix < 0) {
            writeCDataEnd(); // will check surrogates
        }
        return ix;
    }    

    protected int writeCDataContents(char[] cbuf, int offset, int len)
        throws IOException, XMLStreamException
    {
        /* Unlike with writeCharacters() and fastWriteName(), let's not
         * worry about split buffers here: this is unlikely to become
         * performance bottleneck. This allows keeping it simple; and
         * should it matter, we could start doing fast version here
         * as well.
         */
        len += offset; // now marks the end

        main_loop:
        while (offset < len) {
            final int[] charTypes = _charTypes.OTHER_CHARS;

            inner_loop:
            while (true) {
                int ch = (int) cbuf[offset];
                if (ch >= OutputCharTypes.MAIN_TABLE_SIZE) {
                    break inner_loop;
                }
                if (charTypes[ch] != XmlCharTypes.CT_OK) {
                    break inner_loop;
                }
                if (_outputPtr >= _outputBufferLen) {
                    flushBuffer();
                }
                _outputBuffer[_outputPtr++] = (byte) ch;
                if (++offset >= len) {
                    break main_loop;
                }
            }

            // Ok, so what did we hit?
            int ch = (int) cbuf[offset++];
            if (ch < OutputCharTypes.MAIN_TABLE_SIZE) {
                switch (charTypes[ch]) {
                case CT_INVALID:
                    reportInvalidChar(ch);
                case CT_WS_CR: // No way to escape within CDATA
                case CT_WS_LF:
                    ++_locRowNr;
                    break;
                case CT_OUTPUT_MUST_QUOTE: // == MULTIBYTE_N value
                    reportFailedEscaping("CDATA", ch);
                case CT_MULTIBYTE_2:
                    // To off-line or not?
                    output2ByteChar(ch);
                    continue main_loop;
                case CT_RBRACKET:
                    /* !!! TBI: Need to split CData? Can do, but what about
                     *   content split around buffer boundary?
                     */
                    if (offset < len && cbuf[offset] == ']') {
                        if ((offset+1) < len && cbuf[offset+1] == '>') {
                            // Ok, need to output ']]' first, then end
                            offset += 2;
                            writeRaw(BYTE_RBRACKET, BYTE_RBRACKET);
                            writeCDataEnd();
                            // Then new start, and '>'
                            writeCDataStart();
                            writeRaw(BYTE_GT);
                        }
                        continue main_loop;
                    }
                    break;
                default: // Everything else should be outputtable as is
                    break;
                }
                if (_outputPtr >= _outputBufferLen) {
                    flushBuffer();
                }
                _outputBuffer[_outputPtr++] = (byte)ch;
            } else { // beyond 2-byte encodables; 3-byte, surrogates?
                offset = outputMultiByteChar(ch, cbuf, offset, len);
            }
        }
        return -1;
    }    

    @Override
    public final void writeCharacters(String text)
        throws IOException, XMLStreamException
    {
        final int len = text.length();

        // Not so common case, let's offline:
        if (len > _copyBufferLen) {
            longWriteCharacters(text);
            return;
        }
        if (len > 0) {
            char[] buf = _copyBuffer;
            text.getChars(0, len, buf, 0);
            writeCharacters(buf, 0, len);
        }
    }

    private final void longWriteCharacters(String text)
        throws IOException, XMLStreamException
    {
        int offset = 0;
        int len = text.length();
        char[] buf = _copyBuffer;

        do {
            final int blen = buf.length;
            int len2 = (len < blen) ? len : blen;
            text.getChars(offset, offset+len2, buf, 0);
            writeCharacters(buf, 0, len2);
            offset += len2;
            len -= len2;
        } while (len > 0);
    }

    @Override
    public final void writeCharacters(char[] cbuf, int offset, int len)
        throws IOException, XMLStreamException
    {
        if (_surrogate != 0) {
            outputSurrogates(_surrogate, cbuf[offset]);
            ++offset;
            --len;
        }

        // Ok, let's offline (what's sure to be) slow case first:
        // (with multi-byte chars, others may be, too).
        int ptr = _outputPtr;
        if ((ptr + len) > _outputBufferLen) {
            writeSplitCharacters(cbuf, offset, len);
            return;
        }
        len += offset; // now marks the end

        main_loop:
        while (offset < len) {
            final int[] charTypes = _charTypes.TEXT_CHARS;

            inner_loop:
            while (true) {
                int ch = (int) cbuf[offset];
                if (ch >= OutputCharTypes.MAIN_TABLE_SIZE) {
                    break inner_loop;
                }
                if (charTypes[ch] != XmlCharTypes.CT_OK) {
                    // This may look weird, but profiling showed that handling of LFs
                    // for indentation has measurable effect; plus, that checking it
                    // here will not slow down inner loop either
                    if (ch != '\n') {
                        break inner_loop;
                    }
                    ++_locRowNr;
                }
                _outputBuffer[ptr++] = (byte) ch;
                if (++offset >= len) {
                    break main_loop;
                }
            }
            // Ok, so what did we hit?
            int ch = (int) cbuf[offset++];
            if (ch < OutputCharTypes.MAIN_TABLE_SIZE) {
                switch (charTypes[ch]) {
                case CT_INVALID:
                    reportInvalidChar(ch);
                case CT_WS_CR:
                    // !!! TBI: line count
                    // Also, CR to be quoted?
                    if (_config.willEscapeCR()) {
                        _outputPtr = ptr;
                        writeAsEntity(ch);
                        break;
                    }
                    _outputBuffer[ptr++] = (byte)ch;
                    ++_locRowNr;
                    continue main_loop;
                case CT_WS_LF: // never occurs (handled in loop), but don't want to leave gaps
                    break;
                case CT_OUTPUT_MUST_QUOTE: // == MULTIBYTE_N value
                case CT_LT:
                case CT_AMP:
                    _outputPtr = ptr;
                    writeAsEntity(ch);
                    break;
                case CT_MULTIBYTE_2:
                    // To off-line or not?
                    _outputPtr = ptr;
                    output2ByteChar(ch);
                    break;
                case CT_RBRACKET: // may need to quote as well...
                    // Let's not quote if known not to be followed by '>'
                    if (offset >= len || cbuf[offset] == '>') {
                        _outputPtr = ptr;
                        writeAsEntity(ch);
                        break;
                    }
                    //  fall through
                default:
                    _outputBuffer[ptr++] = (byte)ch;
                    continue main_loop;
                }
            } else { // beyond 2-byte encodables; 3-byte, surrogates?
                _outputPtr = ptr;
                offset = outputMultiByteChar(ch, cbuf, offset, len);
            }

            /* At this point, it's not guaranteed any more that we'll
             * be able to fit all output into buffer without checks.
             * Let's verify: in the worst case, we'll just flush
             * whatever we had, to gain more room.
             */
            if ((len - offset) >= (_outputBufferLen - _outputPtr)) {
                flushBuffer();
            }
            ptr = _outputPtr;
        }
        _outputPtr = ptr;
    }

    
This method is called when it is possible that the output
may cross the output buffer boundary. Because of this, code
has to add more boundary checks.
/**
     * This method is called when it is possible that the output
     * may cross the output buffer boundary. Because of this, code
     * has to add more boundary checks.
     */
    private final void writeSplitCharacters(char[] cbuf, int offset, int len)
        throws IOException, XMLStreamException
    {
        // Note: caller handled surrogate already

        len += offset; // now marks the end

        main_loop:
        while (offset < len) {
            final int[] charTypes = _charTypes.TEXT_CHARS;

            inner_loop:
            while (true) {
                int ch = (int) cbuf[offset];
                if (ch >= OutputCharTypes.MAIN_TABLE_SIZE) {
                    break inner_loop;
                }
                if (charTypes[ch] != XmlCharTypes.CT_OK) {
                    if (ch != '\n') {
                        break inner_loop;
                    }
                    ++_locRowNr;
                }
                if (_outputPtr >= _outputBufferLen) {
                    flushBuffer();
                }
                _outputBuffer[_outputPtr++] = (byte)ch;
                if (++offset >= len) {
                    break main_loop;
                }
            }

            // Ok, so what did we hit?
            int ch = (int) cbuf[offset++];
            if (ch < OutputCharTypes.MAIN_TABLE_SIZE) {
                switch (charTypes[ch]) {
                case CT_INVALID:
                    reportInvalidChar(ch);
                case CT_WS_CR:
                    // !!! TBI: line count
                    // Also, CR to be quoted?
                    if (_config.willEscapeCR()) {
                        writeAsEntity(ch);
                        continue main_loop;
                    }
                    ++_locRowNr;
                    break;
                case CT_WS_LF: // can not occur, handled above, but let's keep sequence
                    break;
                case CT_OUTPUT_MUST_QUOTE:
                case CT_LT:
                case CT_AMP:
                    writeAsEntity(ch);
                    continue main_loop;
                case CT_MULTIBYTE_2: // 3, 4 and N can never occur
                    // To off-line or not?
                    output2ByteChar(ch);
                    continue main_loop;
                case CT_RBRACKET: // may need to quote as well...
                    // Let's not quote if known not to be followed by '>'
                    if (offset >= len || cbuf[offset] == '>') {
                        writeAsEntity(ch);
                        continue main_loop;
                    }
                    break;
                default:
                    break;
                }
            } else { // beyond 2-byte encodables; 3-byte, surrogates?
                offset = outputMultiByteChar(ch, cbuf, offset, len);
                continue;
            }

            if (_outputPtr >= _outputBufferLen) {
                flushBuffer();
            }
            _outputBuffer[_outputPtr++] = (byte)ch;
        }
    }    

    /*
    /**********************************************************************
    /* Write methods, typed (element) content
    /**********************************************************************
     */

    @Override
    public void writeTypedValue(AsciiValueEncoder enc)
        throws IOException, XMLStreamException
    {
        if (_surrogate != 0) {
            throwUnpairedSurrogate();
        }
        int free = _outputBufferLen - _outputPtr;
        if (enc.bufferNeedsFlush(free)) {
            flush();
        }
        while (true) {
            _outputPtr = enc.encodeMore(_outputBuffer, _outputPtr, _outputBufferLen);
            if (enc.isCompleted()) {
                break;
            }
            flushBuffer();
        }
    }

    @Override
    public final void writeAttribute(WName name, AsciiValueEncoder enc)
        throws IOException, XMLStreamException
    {
        writeAttrNameEqQ(name);

        // (inlined writeTypedVAlue()...)

        int free = _outputBufferLen - _outputPtr;
        if (enc.bufferNeedsFlush(free)) {
            flush();
        }
        while (true) {
            _outputPtr = enc.encodeMore(_outputBuffer, _outputPtr, _outputBufferLen);
            if (enc.isCompleted()) {
                break;
            }
            flushBuffer();
        }

        // (end of inlined writeTypedVAlue()...)

        if (_outputPtr >= _outputBufferLen) {
            flushBuffer();
        }
        _outputBuffer[_outputPtr++] = BYTE_QUOT;
    }

    /*
    /**********************************************************************
    /* Write methods, other
    /**********************************************************************
     */

    
Method that will try to output the content as specified. If
the content passed in has embedded "--" in it, it will either
add an intervening space between consequtive hyphens (if content
fixing is enabled), or return the offset of the first hyphen in
multi-hyphen sequence.
/**
     * Method that will try to output the content as specified. If
     * the content passed in has embedded "--" in it, it will either
     * add an intervening space between consequtive hyphens (if content
     * fixing is enabled), or return the offset of the first hyphen in
     * multi-hyphen sequence.
     */
    @Override
    public int writeComment(String data) throws IOException, XMLStreamException
    {
        writeCommentStart();

        int len = data.length();
        int offset = 0;
        while (len > 0) {
            char[] buf = _copyBuffer;
            final int blen = buf.length;
            int len2 = (len < blen) ? len : blen;
            // Nope, can only do part
            data.getChars(offset, offset+len2, buf, 0);
            int cix = writeCommentContents(buf, 0, len2);
            if (cix >= 0) {
                return offset+cix;
            }
            offset += blen;
            len -= blen;
        }
        writeCommentEnd();
        return -1;
    }

    
Note: the only way to fix comment contents is to inject a space
to split up consequtive '--' (or '-' that ends a comment).
/**
     * Note: the only way to fix comment contents is to inject a space
     * to split up consequtive '--' (or '-' that ends a comment).
     */
    protected int writeCommentContents(char[] cbuf, int offset, int len)
        throws IOException, XMLStreamException
    {
        /* Unlike with writeCharacters() and fastWriteName(), let's not
         * worry about split buffers here: this is unlikely to become
         * performance bottleneck. This allows keeping it simple; and
         * should it matter, we could start doing fast version here
         * as well.
         */
        len += offset; // now marks the end

        main_loop:
        while (offset < len) {
            final int[] charTypes = _charTypes.OTHER_CHARS;

            inner_loop:
            while (true) {
                int ch = (int) cbuf[offset];
                if (ch >= OutputCharTypes.MAIN_TABLE_SIZE) {
                    break inner_loop;
                }
                if (charTypes[ch] != XmlCharTypes.CT_OK) {
                    break inner_loop;
                }
                if (_outputPtr >= _outputBufferLen) {
                    flushBuffer();
                }
                _outputBuffer[_outputPtr++] = (byte) ch;
                if (++offset >= len) {
                    break main_loop;
                }
            }

            // Ok, so what did we hit?
            int ch = (int) cbuf[offset++];
            if (ch < OutputCharTypes.MAIN_TABLE_SIZE) {
                switch (charTypes[ch]) {
                case CT_INVALID:
                    reportInvalidChar(ch);
                case CT_WS_CR: // No way to escape within CDATA
                case CT_WS_LF:
                    ++_locRowNr;
                    break;
                case CT_OUTPUT_MUST_QUOTE: // == MULTIBYTE_N value
                    reportFailedEscaping("comment", ch);
                case CT_MULTIBYTE_2:
                    // To off-line or not?
                    output2ByteChar(ch);
                    continue main_loop;
                case CT_HYPHEN:
                    // No need if followed by non hyphen
                    if (offset < len && cbuf[offset] != '-') {
                        break;
                    }
                    // Two hyphens, or hyphen at end; must append a space
                    writeRaw(BYTE_HYPHEN, BYTE_SPACE);
                    continue main_loop;

                default: // Everything else should be outputtable as is
                    break;
                }
                if (_outputPtr >= _outputBufferLen) {
                    flushBuffer();
                }
                _outputBuffer[_outputPtr++] = (byte)ch;
            } else { // beyond 2-byte encodables; 3-byte, surrogates?
                offset = outputMultiByteChar(ch, cbuf, offset, len);
            }
        }
        return -1;
    }

    @Override
    public void writeDTD(String data)
        throws IOException, XMLStreamException
    {
        // !!! TBI: Check for char validity, similar to other methods?
        writeRaw(data, 0, data.length());
    }

    @Override
    public void writeDTD(WName rootName, String systemId, String publicId,
                         String internalSubset)
        throws IOException, XMLStreamException
    {
        // !!! TBI
        //if (true) throw new RuntimeException("DTD not implemented yet");
    }

    protected int writePIData(char[] cbuf, int offset, int len)
        throws IOException, XMLStreamException
    {
        /* Unlike with writeCharacters() and fastWriteName(), let's not
         * worry about split buffers here: this is unlikely to become
         * performance bottleneck. This allows keeping it simple; and
         * should it matter, we could start doing fast version here
         * as well.
         */
        len += offset; // now marks the end

        main_loop:
        while (offset < len) {
            final int[] charTypes = _charTypes.OTHER_CHARS;

            inner_loop:
            while (true) {
                int ch = (int) cbuf[offset];
                if (ch >= OutputCharTypes.MAIN_TABLE_SIZE) {
                    break inner_loop;
                }
                if (charTypes[ch] != XmlCharTypes.CT_OK) {
                    break inner_loop;
                }
                if (_outputPtr >= _outputBufferLen) {
                    flushBuffer();
                }
                _outputBuffer[_outputPtr++] = (byte) ch;
                if (++offset >= len) {
                    break main_loop;
                }
            }

            // Ok, so what did we hit?
            int ch = (int) cbuf[offset++];
            if (ch < OutputCharTypes.MAIN_TABLE_SIZE) {
                switch (charTypes[ch]) {
                case CT_INVALID:
                    reportInvalidChar(ch);
                case CT_WS_CR: // No way to escape within CDATA
                case CT_WS_LF:
                    ++_locRowNr;
                    break;
                case CT_OUTPUT_MUST_QUOTE: // == MULTIBYTE_N value
                    reportFailedEscaping("processing instruction", ch);
                case CT_MULTIBYTE_2:
                    // To off-line or not?
                    output2ByteChar(ch);
                    continue main_loop;
                case CT_QMARK:
                    // Problem, if we have '?>'
                    if (offset < len && cbuf[offset] == '>') {
                        return offset;
                    }
                    break;
                default: // Everything else should be outputtable as is
                    break;
                }
                if (_outputPtr >= _outputBufferLen) {
                    flushBuffer();
                }
                _outputBuffer[_outputPtr++] = (byte)ch;
            } else { // beyond 2-byte encodables; 3-byte, surrogates?
                offset = outputMultiByteChar(ch, cbuf, offset, len);
            }
        }
        return -1;
    }

    @Override
    public void writeEntityReference(WName name)
        throws IOException, XMLStreamException
    {
        writeRaw(BYTE_AMP); // will check surrogates
        writeName(name);
        writeRaw(BYTE_SEMICOLON);
    }

    @Override
    public int writePI(WName target, String data)
        throws IOException, XMLStreamException
    {
        writeRaw(BYTE_LT, BYTE_QMARK);
        writeName(target);
        if (data != null) {
            // Need to split etc
            writeRaw(BYTE_SPACE);

            int len = data.length();
            int offset = 0;
            while (len > 0) {
                char[] buf = _copyBuffer;
                int blen = buf.length;

                // Can write all the rest?
                if (blen > len) {
                    blen = len;
                }
                // Nope, can only do part
                data.getChars(offset, offset+blen, buf, 0);
                int cix = writePIData(buf, 0, blen);
                if (cix >= 0) {
                    return offset+cix;
                }
                offset += blen;
                len -= blen;
            }
        }
        writeRaw(BYTE_QMARK, BYTE_GT);
        return -1;
    }

    @Override
    public final void writeSpace(String data)
        throws IOException, XMLStreamException
    {
        int len = data.length();
        int offset = 0;

        while (len > 0) {
            char[] buf = _copyBuffer;
            final int blen = buf.length;
            int len2 = (len < blen) ? len : blen;
            data.getChars(offset, offset+len2, buf, 0);
            writeSpace(buf, 0, len2);
            offset += len2;
            len -= len2;
        }
    }

    @Override
    public void writeSpace(char[] cbuf, int offset, int len)
        throws IOException, XMLStreamException
    {
        if (_out == null) {
            return;
        }
        if (_surrogate != 0) { // can this actually happen?
            reportNwfContent(ErrorConsts.WERR_SPACE_CONTENT, (int)_surrogate, offset-1);
        }

        len += offset; // now marks the end
        while (offset < len) {
            char ch = cbuf[offset++];
            if (ch > 0x0020) {
                if (!_config.isXml11() || (ch != 0x0085 && ch != 0x2028)) {
                    reportNwfContent(ErrorConsts.WERR_SPACE_CONTENT, (int)ch, offset-1);
                }
            }
            if (_outputPtr >= _outputBufferLen) {
                flushBuffer();
            }
            // !!! Line counts?
            _outputBuffer[_outputPtr++] = (byte)ch;
        }
    }

    @Override
    public void writeXmlDeclaration(String version, String encoding, String standalone)
        throws IOException, XMLStreamException
    {
        writeRaw(BYTES_XMLDECL_START); // will check surrogates
        // !!! TBI: check validity
        writeRaw(version, 0, version.length());
        writeRaw(BYTE_APOS);
        
        if (encoding != null && encoding.length() > 0) {
            writeRaw(BYTES_XMLDECL_ENCODING);
            // !!! TBI: check validity
            writeRaw(encoding, 0, encoding.length());
            writeRaw(BYTE_APOS);
        }
        if (standalone != null) {
            writeRaw(BYTES_XMLDECL_STANDALONE);
            // !!! TBI: check validity
            writeRaw(standalone, 0, standalone.length());
            writeRaw(BYTE_APOS);
        }
        writeRaw(BYTE_QMARK, BYTE_GT);
    }    

    /*
    /**********************************************************************
    /* Shared helper output methods
    /**********************************************************************
     */

    protected final void writeCDataStart()
        throws IOException
    {
        writeRaw(BYTES_CDATA_START);
    }

    protected final void writeCDataEnd()
        throws IOException
    {
        writeRaw(BYTES_CDATA_END);
    }

    protected final void writeCommentStart()
        throws IOException
    {
        writeRaw(BYTES_COMMENT_START);
    }

    protected final void writeCommentEnd()
        throws IOException
    {
        writeRaw(BYTES_COMMENT_END);
    }

    /*
    /**********************************************************************
    /* Write methods, raw (unprocessed) output
    /**********************************************************************
     */

    protected final void writeRaw(byte b)
        throws IOException
    {
        if (_surrogate != 0) {
            throwUnpairedSurrogate();
        }
        if (_outputPtr >= _outputBufferLen) {
            flushBuffer();
        }
        _outputBuffer[_outputPtr++] = b;
    }

    protected final void writeRaw(byte b1, byte b2)
        throws IOException
    {
        if (_surrogate != 0) {
            throwUnpairedSurrogate();
        }
        if ((_outputPtr + 1) >= _outputBufferLen) {
            flushBuffer();
        }
        _outputBuffer[_outputPtr++] = b1;
        _outputBuffer[_outputPtr++] = b2;
    }

    protected final void writeRaw(byte[] buf)
        throws IOException
    {
        writeRaw(buf, 0, buf.length);
    }

    protected final void writeRaw(byte[] buf, int offset, int len)
        throws IOException
    {
        if (_surrogate != 0) {
            throwUnpairedSurrogate();
        }

        int ptr = _outputPtr;
        // Common case: fits right in the buffer
        if ((ptr + len) <= _outputBufferLen) {
            System.arraycopy(buf, offset, _outputBuffer, ptr, len);
            _outputPtr += len;
            return;
        }

        // If not, should we just flush + write?
        if (ptr > 0) {
            flush();
            ptr = _outputPtr;
        }
        if (len < SMALL_WRITE) {
            System.arraycopy(buf, offset, _outputBuffer, ptr, len);
            _outputPtr += len;
        } else {
            _out.write(buf, offset, len);
        }
    }

    /*
    /**********************************************************************
    /* Internal methods, problem reporting
    /**********************************************************************
     */

    protected final void throwUnpairedSurrogate()
        throws IOException
    {
        int surr = _surrogate;
        _surrogate = 0;
        throwUnpairedSurrogate(surr);
    }

    protected final void throwUnpairedSurrogate(int code)
        throws IOException
    {
        // Let's flush to make debugging easier
        flush();
        throw new IOException("Unpaired surrogate character (0x"+Integer.toHexString(code)+")");
    }

    /*
    /**********************************************************************
    /* Helper methods for sub-classes
    /**********************************************************************
     */

    protected final void flushBuffer()
        throws IOException
    {
        if ((_outputPtr > 0) && (_out != null)) {
            int ptr = _outputPtr;
            // Need to update location info, to keep it in sync
            _locPastChars += ptr;
            _locRowStartOffset -= ptr;
            _outputPtr = 0;
            _out.write(_outputBuffer, 0, ptr);
        }
    }

    protected final void writeAsEntity(int c)
        throws IOException
    {
        // Quickie check to avoid 

        byte[] buf = _outputBuffer;
        int ptr = _outputPtr;
        if ((ptr + 10) >= buf.length) { // &#x [up to 6 hex digits] ;
            flushBuffer();
            ptr = _outputPtr;
        }
        buf[ptr++] = BYTE_AMP;

        // Can use more optimal notation for 8-bit ascii stuff:
        if (c < 256) {
            /* Also; although not really mandatory, let's also
             * use pre-defined entities where possible.
             */
            if (c == '&') {
                buf[ptr++] = BYTE_A;
                buf[ptr++] = BYTE_M;
                buf[ptr++] = BYTE_P;
            } else if (c == '<') {
                buf[ptr++] = BYTE_L;
                buf[ptr++] = BYTE_T;
            } else if (c == '>') {
                buf[ptr++] = BYTE_G;
                buf[ptr++] = BYTE_T;
            } else if (c == '\'') {
                buf[ptr++] = BYTE_A;
                buf[ptr++] = BYTE_P;
                buf[ptr++] = BYTE_O;
                buf[ptr++] = BYTE_S;
            } else if (c == '"') {
                buf[ptr++] = BYTE_Q;
                buf[ptr++] = BYTE_U;
                buf[ptr++] = BYTE_O;
                buf[ptr++] = BYTE_T;
            } else {
                buf[ptr++] = BYTE_HASH;
                buf[ptr++] = BYTE_X;
                // Can use shortest quoting for tab, cr, lf:
                if (c >= 16) {
                    int digit = (c >> 4);
                    buf[ptr++] = (byte) ((digit < 10) ? ('0' + digit) : (('a' - 10) + digit));
                    c &= 0xF;
                }
                buf[ptr++] = (byte) ((c < 10) ? ('0' + c) : (('a' - 10) + c));
            }
        } else {
            buf[ptr++] = BYTE_HASH;
            buf[ptr++] = BYTE_X;

            // Ok, let's write the shortest possible sequence then:
            int shift = 20;
            int origPtr = ptr;

            do {
                int digit = (c >> shift) & 0xF;
                if (digit > 0 || (ptr != origPtr)) {
                    buf[ptr++] = (byte) ((digit < 10) ? ('0' + digit) : (('a' - 10) + digit));
                }
                shift -= 4;
            } while (shift > 0);
            c &= 0xF;
            buf[ptr++] = (byte) ((c < 10) ? ('0' + c) : (('a' - 10) + c));
        }
        buf[ptr++] = ';';
        _outputPtr = ptr;
    }

    protected final int calcSurrogate(int surr1, int surr2, String context)
        throws XMLStreamException
    {
        // First is known to be valid, but how about the other?
        if (surr2 < SURR2_FIRST || surr2 > SURR2_LAST) {
            String msg = "Incomplete surrogate pair"+context+": first char 0x"+Integer.toHexString(surr1)+", second 0x"+Integer.toHexString(surr2);
            reportNwfContent(msg);
        }
        int c = 0x10000 + ((surr1 - SURR1_FIRST) << 10) + (surr2 - SURR2_FIRST);
        if (c > XmlConsts.MAX_UNICODE_CHAR) { // illegal, as per RFC 3629
            reportInvalidChar(c);
        }
        return c;
    }

    /*
    /**********************************************************************
    /* Internal helper methods
    /**********************************************************************
     */

    protected final static byte[] getAscii(String str)
    {
        int len = str.length();
        byte[] result = new byte[len];
        getAscii(str, result, 0);
        return result;
    }

    protected final static void getAscii(String str, byte[] result)
    {
        int len = str.length();
        for (int i = 0; i < len; ++i) {
            result[i] = (byte) str.charAt(i);
        }
    }

    protected final static void getAscii(String str, byte[] result, int offset)
    {
        int len = str.length();
        for (int i = 0; i < len; ++i) {
            result[offset+i] = (byte) str.charAt(i);
        }
    }
}