src/main/cpp/charsetencoder.cpp

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * 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.
 */
#include <log4cxx/logstring.h>
#include <log4cxx/helpers/charsetencoder.h>
#include <log4cxx/private/bytebuffer_priv.h>
#include <log4cxx/helpers/exception.h>
#include <apr_xlate.h>
#include <log4cxx/helpers/stringhelper.h>
#include <log4cxx/helpers/transcoder.h>
#include <algorithm>

#if !defined(LOG4CXX)
	#define LOG4CXX 1
#endif

#include <log4cxx/private/log4cxx_private.h>
#include <apr_portable.h>
#include <mutex>

#ifdef LOG4CXX_HAS_WCSTOMBS
	#include <stdlib.h>
#endif

using namespace LOG4CXX_NS;
using namespace LOG4CXX_NS::helpers;

IMPLEMENT_LOG4CXX_OBJECT(CharsetEncoder)

namespace LOG4CXX_NS
{

namespace helpers
{

#if APR_HAS_XLATE
/**
* A character encoder implemented using apr_xlate.
*/
class APRCharsetEncoder : public CharsetEncoder
{
	public:
		APRCharsetEncoder(const LogString& topage) : pool()
		{
#if LOG4CXX_LOGCHAR_IS_WCHAR
			const char* frompage = "WCHAR_T";
#endif
#if LOG4CXX_LOGCHAR_IS_UTF8
			const char* frompage = "UTF-8";
#endif
			std::string tpage(Transcoder::encodeCharsetName(topage));
			apr_status_t stat = apr_xlate_open(&convset,
					tpage.c_str(),
					frompage,
					pool.getAPRPool());

			if (stat != APR_SUCCESS)
			{
				throw IllegalArgumentException(topage);
			}
		}

		virtual ~APRCharsetEncoder()
		{
		}

		virtual log4cxx_status_t encode(const LogString& in,
			LogString::const_iterator& iter,
			ByteBuffer& out_param) override
		{
			auto& out = out_param.impl();
			apr_status_t stat;
			size_t outbytes_left = out.remaining();
			size_t initial_outbytes_left = outbytes_left;
			size_t position = out.position();

			if (iter == in.end())
			{
				std::lock_guard<std::mutex> lock(mutex);
				stat = apr_xlate_conv_buffer(convset, NULL, NULL,
						out.data() + position, &outbytes_left);
			}
			else
			{
				LogString::size_type inOffset = (iter - in.begin());
				apr_size_t inbytes_left =
					(in.size() - inOffset) * sizeof(LogString::value_type);
				apr_size_t initial_inbytes_left = inbytes_left;
				{
					std::lock_guard<std::mutex> lock(mutex);
					stat = apr_xlate_conv_buffer(convset,
							(const char*) (in.data() + inOffset),
							&inbytes_left,
							out.data() + position,
							&outbytes_left);
				}
				iter += ((initial_inbytes_left - inbytes_left) / sizeof(LogString::value_type));
			}

			out.increment_position((initial_outbytes_left - outbytes_left));
			return stat;
		}

		/**
		 * Add onto \c out an encoded equivalent of \c codePoint.
		 */
		log4cxx_status_t encode(unsigned int codePoint, ByteBuffer& out) override
		{
			apr_status_t result = APR_SUCCESS;
			if (codePoint <= 0x10FFFF && 4 <= out.remaining())
				out.increment_position(putUTF8CodePoint(codePoint, out.current()));
			else
				result = APR_BADARG;
			return result;
		}

	private:
		APRCharsetEncoder(const APRCharsetEncoder&);
		APRCharsetEncoder& operator=(const APRCharsetEncoder&);
		Pool pool;
		std::mutex mutex;
		apr_xlate_t* convset;
};
#endif

#if LOG4CXX_LOGCHAR_IS_WCHAR && LOG4CXX_HAS_WCSTOMBS
/**
 *  A character encoder implemented using wcstombs.
*/
class WcstombsCharsetEncoder : public CharsetEncoder
{
	public:
		WcstombsCharsetEncoder()
		{
		}

		/**
		 *   Converts a wchar_t to the default external multibyte encoding.
		 */
		log4cxx_status_t encode(const LogString& in,
			LogString::const_iterator& iter,
			ByteBuffer& out_param) override
		{
			auto& out = out_param.impl();
			log4cxx_status_t stat = APR_SUCCESS;

			if (iter != in.end())
			{
				size_t outbytes_left = out.remaining();
				size_t position = out.position();
				std::wstring::size_type inOffset = (iter - in.begin());
				enum { BUFSIZE = 256 };
				wchar_t buf[BUFSIZE];
				size_t chunkSize = BUFSIZE - 1;

				if (chunkSize * MB_LEN_MAX > outbytes_left)
				{
					chunkSize = outbytes_left / MB_LEN_MAX;
				}

				if (chunkSize > in.length() - inOffset)
				{
					chunkSize = in.length() - inOffset;
				}

				memset(buf, 0, BUFSIZE * sizeof(wchar_t));
				memcpy(buf,
					in.data() + inOffset,
					chunkSize * sizeof(wchar_t));
				size_t converted = wcstombs(out.data() + position, buf, outbytes_left);

				if (converted == (size_t) -1)
				{
					stat = APR_BADARG;

					//
					//   if unconvertable character was encountered
					//       repeatedly halve source to get fragment that
					//       can be converted
					for (chunkSize /= 2;
						chunkSize > 0;
						chunkSize /= 2)
					{
						buf[chunkSize] = 0;
						converted = wcstombs(out.data() + position, buf, outbytes_left);

						if (converted != (size_t) -1)
						{
							iter += chunkSize;
							out.increment_position(converted);
							break;
						}
					}
				}
				else
				{
					iter += chunkSize;
					out.increment_position(converted);
				}
			}

			return stat;
		}

		/**
		 * Add onto \c out an encoded equivalent of \c codePoint.
		 */
		log4cxx_status_t encode(unsigned int codePoint, ByteBuffer& out) override
		{
			apr_status_t result = APR_SUCCESS;
			if (codePoint <= 0x10FFFF && MB_LEN_MAX <= out.remaining())
			{
				auto ch = static_cast<wchar_t>(codePoint);
				auto converted = wcstombs(out.current(), &ch, 1);
				if (static_cast<std::size_t>(-1) == converted)
					result = APR_BADARG;
				else
					out.increment_position(converted);
			}
			else
				result = APR_BADARG;
			return result;
		}

	private:
		WcstombsCharsetEncoder(const WcstombsCharsetEncoder&);
		WcstombsCharsetEncoder& operator=(const WcstombsCharsetEncoder&);
};
#endif


/**
*   Encodes a LogString to US-ASCII.
*/
class USASCIICharsetEncoder : public CharsetEncoder
{
	public:
		USASCIICharsetEncoder()
		{
		}

		virtual log4cxx_status_t encode(const LogString& in,
			LogString::const_iterator& iter,
			ByteBuffer& out_param) override
		{
			auto& out = out_param.impl();
			log4cxx_status_t stat = APR_SUCCESS;

			if (iter != in.end())
			{
				while (out.remaining() > 0 && iter != in.end())
				{
					LogString::const_iterator prev(iter);
					unsigned int sv = Transcoder::decode(in, iter);

					if (sv <= 0x7F)
					{
						out.put((char) sv);
					}
					else
					{
						iter = prev;
						stat = APR_BADARG;
						break;
					}
				}
			}

			return stat;
		}

		/**
		 * Add onto \c out an encoded equivalent of \c codePoint.
		 */
		log4cxx_status_t encode(unsigned int codePoint, ByteBuffer& out) override
		{
			apr_status_t result = APR_SUCCESS;
			if (out.remaining() < 1)
				result = APR_BADARG;
			else if (codePoint <= 0x7F)
				out.put(static_cast<char>(codePoint));
			else if (Transcoder::LOSSCHAR == codePoint)
				out.put('?');
			else
				result = APR_BADARG;
			return result;
		}

	private:
		USASCIICharsetEncoder(const USASCIICharsetEncoder&);
		USASCIICharsetEncoder& operator=(const USASCIICharsetEncoder&);
};

/**
*   Converts a LogString to ISO-8859-1.
*/
class ISOLatinCharsetEncoder : public CharsetEncoder
{
	public:
		ISOLatinCharsetEncoder()
		{
		}

		virtual log4cxx_status_t encode(const LogString& in,
			LogString::const_iterator& iter,
			ByteBuffer& out_param) override
		{
			auto& out = out_param.impl();
			log4cxx_status_t stat = APR_SUCCESS;

			while (out.remaining() > 0 && iter != in.end())
			{
				LogString::const_iterator prev(iter);
				unsigned int sv = Transcoder::decode(in, iter);
				if (sv <= 0xFF)
					out.put(static_cast<char>(sv));
				else
				{
					iter = prev;
					stat = APR_BADARG;
					break;
				}
			}
			return stat;
		}

		/**
		 * Add onto \c out an encoded equivalent of \c codePoint.
		 */
		log4cxx_status_t encode(unsigned int codePoint, ByteBuffer& out) override
		{
			apr_status_t result = APR_SUCCESS;
			if (out.remaining() < 1)
				result = APR_BADARG;
			else if (codePoint <= 0xFF)
				out.put(static_cast<char>(codePoint));
			else if (Transcoder::LOSSCHAR == codePoint)
				out.put('?');
			else
				result = APR_BADARG;
			return result;
		}

	private:
		ISOLatinCharsetEncoder(const ISOLatinCharsetEncoder&);
		ISOLatinCharsetEncoder& operator=(const ISOLatinCharsetEncoder&);
};

/**
*   Encodes a LogString to a byte array when the encodings are identical.
*/
class TrivialCharsetEncoder : public CharsetEncoder
{
	public:
		TrivialCharsetEncoder()
		{
		}


		virtual log4cxx_status_t encode(const LogString& in,
			LogString::const_iterator& iter,
			ByteBuffer& out_param) override
		{
			auto& out = out_param.impl();
			if (iter != in.end())
			{
				size_t requested = in.length() - (iter - in.begin());

				if (requested > out.remaining() / sizeof(logchar))
				{
					requested = out.remaining() / sizeof(logchar);
				}

				memcpy(out.current(),
					(const char*) in.data() + (iter - in.begin()),
					requested * sizeof(logchar));
				iter += requested;
				out.increment_position(requested * sizeof(logchar));
			}

			return APR_SUCCESS;
		}

		/**
		 * Add onto \c out an encoded equivalent of \c codePoint.
		 */
		log4cxx_status_t encode(unsigned int codePoint, ByteBuffer& out) override
		{
			apr_status_t result = APR_SUCCESS;
			if (out.remaining() < 1)
				result = APR_BADARG;
			else if (codePoint <= 0xFF)
				out.put(static_cast<char>(codePoint));
			else if (Transcoder::LOSSCHAR == codePoint)
				out.put('?');
			else
				result = APR_BADARG;
			return result;
		}

	private:
		TrivialCharsetEncoder(const TrivialCharsetEncoder&);
		TrivialCharsetEncoder& operator=(const TrivialCharsetEncoder&);
};

/**
 *  Converts a LogString to UTF-8.
 */
class UTF8CharsetEncoder : public CharsetEncoder
{
	public:
		UTF8CharsetEncoder()
		{
		}

		virtual log4cxx_status_t encode(const LogString& in,
			LogString::const_iterator& iter,
			ByteBuffer& out_param) override
		{
			auto& out = out_param.impl();
			while (iter != in.end() && 4 <= out.remaining())
			{
				auto sv = Transcoder::getCodePoint(in, iter);
				out.increment_position(putUTF8CodePoint(sv, out.current()));
			}

			return APR_SUCCESS;
		}

		/**
		 * Add onto \c out an encoded equivalent of \c codePoint.
		 */
		log4cxx_status_t encode(unsigned int codePoint, ByteBuffer& out) override
		{
			apr_status_t result = APR_SUCCESS;
			if (codePoint <= 0x10FFFF && 4 <= out.remaining())
				out.increment_position(putUTF8CodePoint(codePoint, out.current()));
			else
				result = APR_BADARG;
			return result;
		}

	private:
		UTF8CharsetEncoder(const UTF8CharsetEncoder&);
		UTF8CharsetEncoder& operator=(const UTF8CharsetEncoder&);
};

/**
 *   Encodes a LogString to UTF16-BE.
 */
class UTF16BECharsetEncoder : public CharsetEncoder
{
	public:
		UTF16BECharsetEncoder()
		{
		}

		virtual log4cxx_status_t encode(const LogString& in,
			LogString::const_iterator& iter,
			ByteBuffer& out_param) override
		{
			auto& out = out_param.impl();
			while (iter != in.end() && 4 <= out.remaining())
			{
				auto sv = Transcoder::getCodePoint(in, iter);
				out.increment_position(putUTF16BECodePoint(sv, out.current()));
			}

			return APR_SUCCESS;
		}

		/**
		 * Add onto \c out an encoded equivalent of \c codePoint.
		 */
		log4cxx_status_t encode(unsigned int codePoint, ByteBuffer& out) override
		{
			apr_status_t result = APR_SUCCESS;
			if (codePoint <= 0x10FFFF && 4 <= out.remaining())
				Transcoder::encodeUTF16BE(codePoint, out);
			else
				result = APR_BADARG;
			return result;
		}

	private:
		UTF16BECharsetEncoder(const UTF16BECharsetEncoder&);
		UTF16BECharsetEncoder& operator=(const UTF16BECharsetEncoder&);
};

/**
 *   Encodes a LogString to UTF16-LE.
 */
class UTF16LECharsetEncoder : public CharsetEncoder
{
	public:
		UTF16LECharsetEncoder()
		{
		}


		virtual log4cxx_status_t encode(const LogString& in,
			LogString::const_iterator& iter,
			ByteBuffer& out_param) override
		{
			auto& out = out_param.impl();
			while (iter != in.end() && 4 <= out.remaining())
			{
				auto sv = Transcoder::getCodePoint(in, iter);
				out.increment_position(putUTF16LECodePoint(sv, out.current()));
			}

			return APR_SUCCESS;
		}

		/**
		 * Add onto \c out an encoded equivalent of \c codePoint.
		 */
		log4cxx_status_t encode(unsigned int codePoint, ByteBuffer& out) override
		{
			apr_status_t result = APR_SUCCESS;
			if (codePoint <= 0x10FFFF && 4 <= out.remaining())
				out.increment_position(putUTF16LECodePoint(codePoint, out.current()));
			else
				result = APR_BADARG;
			return result;
		}
	private:
		UTF16LECharsetEncoder(const UTF16LECharsetEncoder&);
		UTF16LECharsetEncoder& operator=(const UTF16LECharsetEncoder&);
};

/**
 *    Charset encoder that uses current locale settings.
 */
class LocaleCharsetEncoder : public CharsetEncoder
{
	public:
		LocaleCharsetEncoder() : state()
		{
		}
		log4cxx_status_t encode
			( const LogString&           in
			, LogString::const_iterator& nextCodePoint
			, ByteBuffer&                out_param
			) override
		{
			auto& out = out_param.impl();
			log4cxx_status_t result = APR_SUCCESS;
#if !LOG4CXX_CHARSET_EBCDIC
			char* current = out.current();
			size_t availableByteCount = out.remaining();
			size_t byteCount = 0;
			if (std::mbsinit(&this->state)) // ByteBuffer not partially encoded?
			{
				// Copy single byte characters
				for (;
					nextCodePoint != in.end() && byteCount < availableByteCount && static_cast<unsigned int>(*nextCodePoint) < 0x80;
					++nextCodePoint, ++byteCount, ++current)
				{
					*current = static_cast<char>(*nextCodePoint);
				}
			}
#endif
			// Encode characters that may require multiple bytes
			while (nextCodePoint != in.end() && byteCount < availableByteCount && MB_CUR_MAX <= (availableByteCount - byteCount))
			{
				auto ch = Transcoder::getCodePoint(in, nextCodePoint);
				auto n = std::wcrtomb(current, ch, &this->state);
				if (static_cast<std::size_t>(-1) == n) // not a valid wide character?
				{
					result = APR_BADARG;
					break;
				}
				byteCount += n;
				current += n;
			}
			out.increment_position(byteCount);
			return result;
		}

		/**
		 * Add onto \c out an encoded equivalent of \c codePoint.
		 */
		log4cxx_status_t encode(unsigned int codePoint, ByteBuffer& out) override
		{
			apr_status_t result = APR_SUCCESS;
			if (MB_CUR_MAX <= out.remaining())
			{
				auto n = std::wcrtomb(out.current(), codePoint, &this->state);
				if (static_cast<std::size_t>(-1) == n) // not a valid wide character?
					result = APR_BADARG;
				else
					out.increment_position(n);
			}
			else
				result = APR_BADARG;
			return result;
		}

	private:
		std::mbstate_t state;
};


} // namespace helpers

}  //namespace log4cxx



CharsetEncoder::CharsetEncoder()
{
}

CharsetEncoder::~CharsetEncoder()
{
}

CharsetEncoderPtr CharsetEncoder::getDefaultEncoder()
{
	static WideLife<CharsetEncoderPtr> encoder(createDefaultEncoder());

	//
	//  if invoked after static variable destruction
	//     (if logging is called in the destructor of a static object)
	//     then create a new decoder.
	//
	if (encoder.value() == 0)
	{
		return CharsetEncoderPtr( createDefaultEncoder() );
	}

	return encoder;
}

CharsetEncoder* CharsetEncoder::createDefaultEncoder()
{
#if LOG4CXX_CHARSET_UTF8
#if LOG4CXX_LOGCHAR_IS_UTF8
	return new TrivialCharsetEncoder();
#else
	return new UTF8CharsetEncoder();
#endif
#elif LOG4CXX_CHARSET_ISO88591
	return new ISOLatinCharsetEncoder();
#elif LOG4CXX_CHARSET_USASCII
	return new USASCIICharsetEncoder();
#elif LOG4CXX_LOGCHAR_IS_WCHAR && LOG4CXX_HAS_WCSTOMBS
	return new WcstombsCharsetEncoder();
#else
	return new LocaleCharsetEncoder();
#endif
}


CharsetEncoderPtr CharsetEncoder::getUTF8Encoder()
{
	return std::make_shared<UTF8CharsetEncoder>();
}



CharsetEncoderPtr CharsetEncoder::getEncoder(const LogString& charset)
{
	if (StringHelper::equalsIgnoreCase(charset, LOG4CXX_STR("UTF-8"), LOG4CXX_STR("utf-8"))
		|| StringHelper::equalsIgnoreCase(charset, LOG4CXX_STR("CP65001"), LOG4CXX_STR("cp65001")))
	{
		return std::make_shared<UTF8CharsetEncoder>();
	}
	else if (StringHelper::equalsIgnoreCase(charset, LOG4CXX_STR("C"), LOG4CXX_STR("c")) ||
		charset == LOG4CXX_STR("646") ||
		StringHelper::equalsIgnoreCase(charset, LOG4CXX_STR("US-ASCII"), LOG4CXX_STR("us-ascii")) ||
		StringHelper::equalsIgnoreCase(charset, LOG4CXX_STR("ISO646-US"), LOG4CXX_STR("iso646-US")) ||
		StringHelper::equalsIgnoreCase(charset, LOG4CXX_STR("ANSI_X3.4-1968"), LOG4CXX_STR("ansi_x3.4-1968")) ||
		StringHelper::equalsIgnoreCase(charset, LOG4CXX_STR("CP20127"), LOG4CXX_STR("cp20127")))
	{
		return std::make_shared<USASCIICharsetEncoder>();
	}
	else if (StringHelper::equalsIgnoreCase(charset, LOG4CXX_STR("ISO-8859-1"), LOG4CXX_STR("iso-8859-1")) ||
		StringHelper::equalsIgnoreCase(charset, LOG4CXX_STR("ISO-LATIN-1"), LOG4CXX_STR("iso-latin-1")) ||
		StringHelper::equalsIgnoreCase(charset, LOG4CXX_STR("CP1252"), LOG4CXX_STR("cp1252")))
	{
		return std::make_shared<ISOLatinCharsetEncoder>();
	}
	else if (StringHelper::equalsIgnoreCase(charset, LOG4CXX_STR("UTF-16BE"), LOG4CXX_STR("utf-16be"))
		|| StringHelper::equalsIgnoreCase(charset, LOG4CXX_STR("UTF-16"), LOG4CXX_STR("utf-16"))
		|| StringHelper::equalsIgnoreCase(charset, LOG4CXX_STR("CP1200"), LOG4CXX_STR("cp1200")))
	{
		return std::make_shared<UTF16BECharsetEncoder>();
	}
	else if (StringHelper::equalsIgnoreCase(charset, LOG4CXX_STR("UTF-16LE"), LOG4CXX_STR("utf-16le")))
	{
		return std::make_shared<UTF16LECharsetEncoder>();
	}
	else if (StringHelper::equalsIgnoreCase(charset, LOG4CXX_STR("LOCALE"), LOG4CXX_STR("locale")))
	{
		return std::make_shared<LocaleCharsetEncoder>();
	}

#if APR_HAS_XLATE
	return std::make_shared<APRCharsetEncoder>(charset);
#else
	throw IllegalArgumentException(charset);
#endif
}


void CharsetEncoder::reset()
{
}


void CharsetEncoder::encode(CharsetEncoderPtr& enc,
	const LogString& src,
	LogString::const_iterator& iter,
	ByteBuffer& dst)
{
	log4cxx_status_t stat = enc->encode(src, iter, dst);

	if (stat != APR_SUCCESS && iter != src.end())
	{
#if LOG4CXX_LOGCHAR_IS_WCHAR
		iter++;
#elif LOG4CXX_LOGCHAR_IS_UTF8

		//  advance past this character and all continuation characters
		do
		{
			++iter;
		}
		while (iter != src.end() &&
			   (*iter & 0xC0) == 0x80);

#else
#error logchar is unrecognized
#endif
		enc->encode(Transcoder::LOSSCHAR, dst);
	}
}

bool CharsetEncoder::isTriviallyCopyable(const LogString& src, const CharsetEncoderPtr& enc)
{
	bool result;
#if !LOG4CXX_CHARSET_EBCDIC
	if (dynamic_cast<LocaleCharsetEncoder*>(enc.get()))
	{
		result = src.end() == std::find_if(src.begin(), src.end()
			, [](const logchar& ch) -> bool { return 0x80 <= (unsigned int)ch; });
	}
	else
#endif
		result = !!dynamic_cast<TrivialCharsetEncoder*>(enc.get());
	return result;
}

size_t CharsetEncoder::putUTF8CodePoint(unsigned int ch, char* dst)
{
	if (ch < 0x80)
	{
		dst[0] = (char) ch;
		return 1;
	}
	else if (ch < 0x800)
	{
		dst[0] = (char) (0xC0 + (ch >> 6));
		dst[1] = (char) (0x80 + (ch & 0x3F));
		return 2;
	}
	else if (ch < 0x10000)
	{
		dst[0] = (char) (0xE0 + (ch >> 12));
		dst[1] = (char) (0x80 + ((ch >> 6) & 0x3F));
		dst[2] = (char) (0x80 + (ch & 0x3F));
		return 3;
	}
	else if (ch <= 0x10FFFF)
	{
		dst[0] = (char) (0xF0 + (ch >> 18));
		dst[1] = (char) (0x80 + ((ch >> 12) & 0x3F));
		dst[2] = (char) (0x80 + ((ch >> 6) & 0x3F));
		dst[3] = (char) (0x80 + (ch & 0x3F));
		return 4;
	}
	else
	{
		//
		//  output UTF-8 encoding of 0xFFFF
		//
		dst[0] = (char) 0xEF;
		dst[1] = (char) 0xBF;
		dst[2] = (char) 0xBF;
		return 3;
	}
}

size_t CharsetEncoder::putUTF16BECodePoint(unsigned int ch, char* dst)
{
	if (ch <= 0xFFFF)
	{
		dst[0] = (char) (ch >> 8);
		dst[1] = (char) (ch & 0xFF);
		return 2;
	}

	if (ch <= 0x10FFFF)
	{
		unsigned char w = (unsigned char) ((ch >> 16) - 1);
		dst[0] = (char) (0xD8 + (w >> 2));
		dst[1] = (char) (((w & 0x03) << 6) + ((ch >> 10) & 0x3F));
		dst[2] = (char) (0xDC + ((ch >> 8) & 0x03));
		dst[3] = (char) (ch & 0xFF);
		return 4;
	}

	dst[0] = dst[1] = (char) 0xFF;
	return 2;
}

size_t CharsetEncoder::putUTF16LECodePoint(unsigned int ch, char* dst)
{
	if (ch <= 0xFFFF)
	{
		dst[1] = (char) (ch >> 8);
		dst[0] = (char) (ch & 0xFF);
		return 2;
	}

	if (ch <= 0x10FFFF)
	{
		unsigned char w = (unsigned char) ((ch >> 16) - 1);
		dst[1] = (char) (0xD8 + (w >> 2));
		dst[0] = (char) (((w & 0x03) << 6) + ((ch >> 10) & 0x3F));
		dst[3] = (char) (0xDC + ((ch >> 8) & 0x03));
		dst[2] = (char) (ch & 0xFF);
		return 4;
	}

	dst[0] = dst[1] = (char) 0xFF;
	return 2;
}