text: /*
   * Copyright 2001-2004 Unicode, Inc.
   *
   * Disclaimer
   *
   * This source code is provided as is by Unicode, Inc. No claims are
   * made as to fitness for any particular purpose. No warranties of any
   * kind are expressed or implied. The recipient agrees to determine
   * applicability of information provided. If this file has been
   * purchased on magnetic or optical media from Unicode, Inc., the
   * sole remedy for any claim will be exchange of defective media
   * within 90 days of receipt.
   *
   * Limitations on Rights to Redistribute This Code
   *
   * Unicode, Inc. hereby grants the right to freely use the information
   * supplied in this file in the creation of products supporting the
   * Unicode Standard, and to make copies of this file in any form
   * for internal or external distribution as long as this notice
   * remains attached.
   */
  
  /* ---------------------------------------------------------------------
  
      Conversions between UTF32, UTF-16, and UTF-8. Source code file.
      Author: Mark E. Davis, 1994.
      Rev History: Rick McGowan, fixes & updates May 2001.
      Sept 2001: fixed const & error conditions per
      mods suggested by S. Parent & A. Lillich.
      June 2002: Tim Dodd added detection and handling of incomplete
      source sequences, enhanced error detection, added casts
      to eliminate compiler warnings.
      July 2003: slight mods to back out aggressive FFFE detection.
      Jan 2004: updated switches in from-UTF8 conversions.
      Oct 2004: updated to use UNI_MAX_LEGAL_UTF32 in UTF-32 conversions.
  
      See the header file "utf.h" for complete documentation.
  
  ------------------------------------------------------------------------ */
  
  #include "utf.h"
  #include <winpr/endian.h>
  
  #if __GNUC__
  #pragma GCC diagnostic push
  #pragma GCC diagnostic ignored "-Wimplicit-fallthrough"
  #endif
  static const int halfShift = 10; /* used for shifting by 10 bits */
  
  static const DWORD halfBase = 0x0010000UL;
  static const DWORD halfMask = 0x3FFUL;
  
  #define UNI_SUR_HIGH_START (DWORD)0xD800
  #define UNI_SUR_HIGH_END (DWORD)0xDBFF
  #define UNI_SUR_LOW_START (DWORD)0xDC00
  #define UNI_SUR_LOW_END (DWORD)0xDFFF
  
  /* --------------------------------------------------------------------- */
  
  ConversionResult ConvertUTF32toUTF16(const DWORD** sourceStart, const DWORD* sourceEnd,
                                       WCHAR** targetStart, WCHAR* targetEnd, ConversionFlags flags)
  {
  	ConversionResult result = conversionOK;
  	const DWORD* source = *sourceStart;
  	WCHAR* target = *targetStart;
  
  	while (source < sourceEnd)
  	{
  		DWORD ch;
  
  		if (target >= targetEnd)
  		{
  			result = targetExhausted;
  			break;
  		}
  
  		ch = *source++;
  
  		if (ch <= UNI_MAX_BMP) /* Target is a character <= 0xFFFF */
  		{
  			/* UTF-16 surrogate values are illegal in UTF-32; 0xffff or 0xfffe are both reserved
  			 * values */
  			if (ch >= UNI_SUR_HIGH_START && ch <= UNI_SUR_LOW_END)
  			{
  				if (flags == strictConversion)
  				{
  					--source; /* return to the illegal value itself */
  					result = sourceIllegal;
  					break;
  				}
  				else
  				{
  					*target++ = UNI_REPLACEMENT_CHAR;
  				}
  			}
  			else
  			{
  				*target++ = (WCHAR)ch; /* normal case */
  			}
  		}
  		else if (ch > UNI_MAX_LEGAL_UTF32)
  		{
  			if (flags == strictConversion)
  			{
  				result = sourceIllegal;
  			}
  			else
  			{
  				*target++ = UNI_REPLACEMENT_CHAR;
  			}
  		}
  		else
  		{
  			/* target is a character in range 0xFFFF - 0x10FFFF. */
  			if (target + 1 >= targetEnd)
  			{
  				--source; /* Back up source pointer! */
  				result = targetExhausted;
  				break;
  			}
  
  			ch -= halfBase;
  			*target++ = (WCHAR)((ch >> halfShift) + UNI_SUR_HIGH_START);
  			*target++ = (WCHAR)((ch & halfMask) + UNI_SUR_LOW_START);
  		}
  	}
  
  	*sourceStart = source;
  	*targetStart = target;
  	return result;
  }
  
  /* --------------------------------------------------------------------- */
  
  ConversionResult ConvertUTF16toUTF32(const WCHAR** sourceStart, const WCHAR* sourceEnd,
                                       DWORD** targetStart, DWORD* targetEnd, ConversionFlags flags)
  {
  	ConversionResult result = conversionOK;
  	const WCHAR* source = *sourceStart;
  	DWORD* target = *targetStart;
  	DWORD ch, ch2;
  
  	while (source < sourceEnd)
  	{
  		const WCHAR* oldSource =
  		    source; /*  In case we have to back up because of target overflow. */
  		ch = *source++;
  
  		/* If we have a surrogate pair, convert to UTF32 first. */
  		if (ch >= UNI_SUR_HIGH_START && ch <= UNI_SUR_HIGH_END)
  		{
  			/* If the 16 bits following the high surrogate are in the source buffer... */
  			if (source < sourceEnd)
  			{
  				ch2 = *source;
  
  				/* If it's a low surrogate, convert to UTF32. */
  				if (ch2 >= UNI_SUR_LOW_START && ch2 <= UNI_SUR_LOW_END)
  				{
  					ch = ((ch - UNI_SUR_HIGH_START) << halfShift) + (ch2 - UNI_SUR_LOW_START) +
  					     halfBase;
  					++source;
  				}
  				else if (flags == strictConversion) /* it's an unpaired high surrogate */
  				{
  					--source; /* return to the illegal value itself */
  					result = sourceIllegal;
  					break;
  				}
  			}
  			else /* We don't have the 16 bits following the high surrogate. */
  			{
  				--source; /* return to the high surrogate */
  				result = sourceExhausted;
  				break;
  			}
  		}
  		else if (flags == strictConversion)
  		{
  			/* UTF-16 surrogate values are illegal in UTF-32 */
  			if (ch >= UNI_SUR_LOW_START && ch <= UNI_SUR_LOW_END)
  			{
  				--source; /* return to the illegal value itself */
  				result = sourceIllegal;
  				break;
  			}
  		}
  
  		if (target >= targetEnd)
  		{
  			source = oldSource; /* Back up source pointer! */
  			result = targetExhausted;
  			break;
  		}
  
  		*target++ = ch;
  	}
  
  	*sourceStart = source;
  	*targetStart = target;
  #ifdef CVTUTF_DEBUG
  
  	if (result == sourceIllegal)
  	{
  		WLOG_WARN(TAG, "ConvertUTF16toUTF32 illegal seq 0x%04x,%04x", ch, ch2);
  	}
  
  #endif
  	return result;
  }
  
  /* --------------------------------------------------------------------- */
  
  /*
   * Index into the table below with the first byte of a UTF-8 sequence to
   * get the number of trailing bytes that are supposed to follow it.
   * Note that *legal* UTF-8 values can't have 4 or 5-bytes. The table is
   * left as-is for anyone who may want to do such conversion, which was
   * allowed in earlier algorithms.
   */
  static const char trailingBytesForUTF8[256] = {
  	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
  	2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5
  };
  
  /*
   * Magic values subtracted from a buffer value during UTF8 conversion.
   * This table contains as many values as there might be trailing bytes
   * in a UTF-8 sequence.
   */
  static const DWORD offsetsFromUTF8[6] = { 0x00000000UL, 0x00003080UL, 0x000E2080UL,
  	                                      0x03C82080UL, 0xFA082080UL, 0x82082080UL };
  
  /*
   * Once the bits are split out into bytes of UTF-8, this is a mask OR-ed
   * into the first byte, depending on how many bytes follow.  There are
   * as many entries in this table as there are UTF-8 sequence types.
   * (I.e., one byte sequence, two byte... etc.). Remember that sequencs
   * for *legal* UTF-8 will be 4 or fewer bytes total.
   */
  static const BYTE firstByteMark[7] = { 0x00, 0x00, 0xC0, 0xE0, 0xF0, 0xF8, 0xFC };
  
  /* --------------------------------------------------------------------- */
  
  /* The interface converts a whole buffer to avoid function-call overhead.
   * Constants have been gathered. Loops & conditionals have been removed as
   * much as possible for efficiency, in favor of drop-through switches.
   * (See "Note A" at the bottom of the file for equivalent code.)
   * If your compiler supports it, the "isLegalUTF8" call can be turned
   * into an inline function.
   */
  
  /* --------------------------------------------------------------------- */
  
  ConversionResult ConvertUTF16toUTF8(const WCHAR** sourceStart, const WCHAR* sourceEnd,
                                      BYTE** targetStart, BYTE* te, ConversionFlags flags)
  {
  	size_t pos = 0;
  	size_t end = 0;
  	const WCHAR* source;
  	const BOOL computeLength = (!te) ? TRUE : FALSE;
  	ConversionResult result = conversionOK;
  
  	if (targetStart && te)
  	{
  		const size_t s = (size_t)*targetStart;
  		const size_t e = (size_t)te;
  		if (s > e)
  			return sourceIllegal;
  		end = e - s;
  	}
  
  	source = *sourceStart;
  
  	while (source < sourceEnd)
  	{
  		DWORD ch;
  		unsigned short bytesToWrite = 0;
  		const DWORD byteMask = 0xBF;
  		const DWORD byteMark = 0x80;
  		const WCHAR* oldSource =
  		    source; /* In case we have to back up because of target overflow. */
  		Data_Read_UINT16(source, ch);
  		source++;
  
  		/* If we have a surrogate pair, convert to UTF32 first. */
  		if (ch >= UNI_SUR_HIGH_START && ch <= UNI_SUR_HIGH_END)
  		{
  			/* If the 16 bits following the high surrogate are in the source buffer... */
  			if (source < sourceEnd)
  			{
  				DWORD ch2;
  				Data_Read_UINT16(source, ch2);
  
  				/* If it's a low surrogate, convert to UTF32. */
  				if (ch2 >= UNI_SUR_LOW_START && ch2 <= UNI_SUR_LOW_END)
  				{
  					ch = ((ch - UNI_SUR_HIGH_START) << halfShift) + (ch2 - UNI_SUR_LOW_START) +
  					     halfBase;
  					++source;
  				}
  				else if (flags == strictConversion)
  				{
  					/* it's an unpaired high surrogate */
  					--source; /* return to the illegal value itself */
  					result = sourceIllegal;
  					break;
  				}
  			}
  			else
  			{
  				/* We don't have the 16 bits following the high surrogate. */
  				--source; /* return to the high surrogate */
  				result = sourceExhausted;
  				break;
  			}
  		}
  		else if (flags == strictConversion)
  		{
  			/* UTF-16 surrogate values are illegal in UTF-32 */
  			if (ch >= UNI_SUR_LOW_START && ch <= UNI_SUR_LOW_END)
  			{
  				--source; /* return to the illegal value itself */
  				result = sourceIllegal;
  				break;
  			}
  		}
  
  		/* Figure out how many bytes the result will require */
  		if (ch < (DWORD)0x80)
  		{
  			bytesToWrite = 1;
  		}
  		else if (ch < (DWORD)0x800)
  		{
  			bytesToWrite = 2;
  		}
  		else if (ch < (DWORD)0x10000)
  		{
  			bytesToWrite = 3;
  		}
  		else if (ch < (DWORD)0x110000)
  		{
  			bytesToWrite = 4;
  		}
  		else
  		{
  			bytesToWrite = 3;
  			ch = UNI_REPLACEMENT_CHAR;
  		}
  
  		pos += bytesToWrite;
  
  		if ((pos > end) && (!computeLength))
  		{
  			source = oldSource; /* Back up source pointer! */
  			pos -= bytesToWrite;
  			result = targetExhausted;
  			break;
  		}
  
  		if (!computeLength)
  		{
  			switch (bytesToWrite)
  			{
  				/* note: everything falls through. */
  				case 4:
  					(*targetStart)[--pos] = (BYTE)((ch | byteMark) & byteMask);
  					ch >>= 6;
  
  				case 3:
  					(*targetStart)[--pos] = (BYTE)((ch | byteMark) & byteMask);
  					ch >>= 6;
  
  				case 2:
  					(*targetStart)[--pos] = (BYTE)((ch | byteMark) & byteMask);
  					ch >>= 6;
  
  				case 1:
  					(*targetStart)[--pos] = (BYTE)(ch | firstByteMark[bytesToWrite]);
  			}
  		}
  		else
  		{
  			switch (bytesToWrite)
  			{
  				/* note: everything falls through. */
  				case 4:
  					--pos;
  
  				case 3:
  					--pos;
  
  				case 2:
  					--pos;
  
  				case 1:
  					--pos;
  			}
  		}
  
  		pos += bytesToWrite;
  	}
  
  	*sourceStart = source;
  	if (targetStart && *targetStart)
  		*targetStart = &(*targetStart)[pos];
  	else if (targetStart)
  		*targetStart = (BYTE*)pos;
  	return result;
  }
  
  /* --------------------------------------------------------------------- */
  
  /*
   * Utility routine to tell whether a sequence of bytes is legal UTF-8.
   * This must be called with the length pre-determined by the first byte.
   * If not calling this from ConvertUTF8to*, then the length can be set by:
   *  length = trailingBytesForUTF8[*source]+1;
   * and the sequence is illegal right away if there aren't that many bytes
   * available.
   * If presented with a length > 4, this returns FALSE.  The Unicode
   * definition of UTF-8 goes up to 4-byte sequences.
   */
  
  static BOOL isLegalUTF8(const BYTE* source, int length)
  {
  	BYTE a;
  	const BYTE* srcptr = source + length;
  
  	switch (length)
  	{
  		default:
  			return FALSE;
  
  		/* Everything else falls through when "TRUE"... */
  		case 4:
  			if ((a = (*--srcptr)) < 0x80 || a > 0xBF)
  				return FALSE;
  
  		case 3:
  			if ((a = (*--srcptr)) < 0x80 || a > 0xBF)
  				return FALSE;
  
  		case 2:
  			if ((a = (*--srcptr)) > 0xBF)
  				return FALSE;
  
  			switch (*source)
  			{
  				/* no fall-through in this inner switch */
  				case 0xE0:
  					if (a < 0xA0)
  						return FALSE;
  
  					break;
  
  				case 0xED:
  					if (a > 0x9F)
  						return FALSE;
  
  					break;
  
  				case 0xF0:
  					if (a < 0x90)
  						return FALSE;
  
  					break;
  
  				case 0xF4:
  					if (a > 0x8F)
  						return FALSE;
  
  					break;
  
  				default:
  					if (a < 0x80)
  						return FALSE;
  			}
  
  		case 1:
  			if (*source >= 0x80 && *source < 0xC2)
  				return FALSE;
  	}
  
  	if (*source > 0xF4)
  		return FALSE;
  
  	return TRUE;
  }
  
  /* --------------------------------------------------------------------- */
  
  /*
   * Exported function to return whether a UTF-8 sequence is legal or not.
   * This is not used here; it's just exported.
   */
  BOOL isLegalUTF8Sequence(const BYTE* source, const BYTE* sourceEnd)
  {
  	int length = trailingBytesForUTF8[*source] + 1;
  
  	if (source + length > sourceEnd)
  		return FALSE;
  
  	return isLegalUTF8(source, length);
  }
  
  /* --------------------------------------------------------------------- */
  
  ConversionResult ConvertUTF8toUTF16(const BYTE** sourceStart, const BYTE* sourceEnd,
                                      WCHAR** targetStart, WCHAR* targetEnd, ConversionFlags flags)
  {
  	size_t target = 0;
  	size_t end = 0;
  	const BYTE* source;
  	BOOL computeLength;
  	ConversionResult result;
  	computeLength = (!targetEnd) ? TRUE : FALSE;
  	result = conversionOK;
  	source = *sourceStart;
  
  	if (targetStart && targetEnd)
  	{
  		const size_t s = (size_t)*targetStart;
  		const size_t e = (size_t)targetEnd;
  		if (s > e)
  			return sourceIllegal;
  
  		end = ((size_t)(targetEnd)) - ((size_t)(*targetStart));
  	}
  
  	while (source < sourceEnd)
  	{
  		DWORD ch = 0;
  		unsigned short extraBytesToRead = trailingBytesForUTF8[*source];
  
  		if ((source + extraBytesToRead) >= sourceEnd)
  		{
  			result = sourceExhausted;
  			break;
  		}
  
  		/* Do this check whether lenient or strict */
  		if (!isLegalUTF8(source, extraBytesToRead + 1))
  		{
  			result = sourceIllegal;
  			break;
  		}
  
  		/*
  		 * The cases all fall through. See "Note A" below.
  		 */
  		switch (extraBytesToRead)
  		{
  			case 5:
  				ch += *source++;
  				ch <<= 6; /* remember, illegal UTF-8 */
  
  			case 4:
  				ch += *source++;
  				ch <<= 6; /* remember, illegal UTF-8 */
  
  			case 3:
  				ch += *source++;
  				ch <<= 6;
  
  			case 2:
  				ch += *source++;
  				ch <<= 6;
  
  			case 1:
  				ch += *source++;
  				ch <<= 6;
  
  			case 0:
  				ch += *source++;
  		}
  
  		ch -= offsetsFromUTF8[extraBytesToRead];
  
  		if ((target * sizeof(WCHAR) >= end) && (!computeLength))
  		{
  			source -= (extraBytesToRead + 1); /* Back up source pointer! */
  			result = targetExhausted;
  			break;
  		}
  
  		if (ch <= UNI_MAX_BMP)
  		{
  			/* Target is a character <= 0xFFFF */
  			/* UTF-16 surrogate values are illegal in UTF-32 */
  			if (ch >= UNI_SUR_HIGH_START && ch <= UNI_SUR_LOW_END)
  			{
  				if (flags == strictConversion)
  				{
  					source -= (extraBytesToRead + 1); /* return to the illegal value itself */
  					result = sourceIllegal;
  					break;
  				}
  				else
  				{
  					if (!computeLength)
  						Data_Write_UINT16(&(*targetStart)[target], UNI_REPLACEMENT_CHAR);
  					target++;
  				}
  			}
  			else
  			{
  				if (!computeLength)
  					Data_Write_UINT16(&(*targetStart)[target], ch); /* normal case */
  				target++;
  			}
  		}
  		else if (ch > UNI_MAX_UTF16)
  		{
  			if (flags == strictConversion)
  			{
  				result = sourceIllegal;
  				source -= (extraBytesToRead + 1); /* return to the start */
  				break;                            /* Bail out; shouldn't continue */
  			}
  			else
  			{
  				if (!computeLength)
  					Data_Write_UINT16(&(*targetStart)[target], UNI_REPLACEMENT_CHAR);
  				target++;
  			}
  		}
  		else
  		{
  			/* target is a character in range 0xFFFF - 0x10FFFF. */
  			if (((target + 1) * sizeof(WCHAR) >= end) && (!computeLength))
  			{
  				source -= (extraBytesToRead + 1); /* Back up source pointer! */
  				result = targetExhausted;
  				break;
  			}
  
  			ch -= halfBase;
  
  			if (!computeLength)
  			{
  				WCHAR wchar;
  				wchar = (WCHAR)((ch >> halfShift) + UNI_SUR_HIGH_START);
  				Data_Write_UINT16(&(*targetStart)[target++], wchar);
  				wchar = (WCHAR)((ch & halfMask) + UNI_SUR_LOW_START);
  				Data_Write_UINT16(&(*targetStart)[target++], wchar);
  			}
  			else
  			{
  				target++;
  				target++;
  			}
  		}
  	}
  
  	*sourceStart = source;
  	if (targetStart && (*targetStart))
  		*targetStart = &(*targetStart)[target];
  	else if (targetStart)
  		*targetStart = (WCHAR*)(target * sizeof(WCHAR));
  	return result;
  }
  
  /* --------------------------------------------------------------------- */
  
  ConversionResult ConvertUTF32toUTF8(const DWORD** sourceStart, const DWORD* sourceEnd,
                                      BYTE** targetStart, BYTE* targetEnd, ConversionFlags flags)
  {
  	ConversionResult result = conversionOK;
  	const DWORD* source = *sourceStart;
  	BYTE* target = *targetStart;
  
  	while (source < sourceEnd)
  	{
  		DWORD ch;
  		unsigned short bytesToWrite = 0;
  		const DWORD byteMask = 0xBF;
  		const DWORD byteMark = 0x80;
  		ch = *source++;
  
  		if (flags == strictConversion)
  		{
  			/* UTF-16 surrogate values are illegal in UTF-32 */
  			if (ch >= UNI_SUR_HIGH_START && ch <= UNI_SUR_LOW_END)
  			{
  				--source; /* return to the illegal value itself */
  				result = sourceIllegal;
  				break;
  			}
  		}
  
  		/*
  		 * Figure out how many bytes the result will require. Turn any
  		 * illegally large UTF32 things (> Plane 17) into replacement chars.
  		 */
  		if (ch < (DWORD)0x80)
  		{
  			bytesToWrite = 1;
  		}
  		else if (ch < (DWORD)0x800)
  		{
  			bytesToWrite = 2;
  		}
  		else if (ch < (DWORD)0x10000)
  		{
  			bytesToWrite = 3;
  		}
  		else if (ch <= UNI_MAX_LEGAL_UTF32)
  		{
  			bytesToWrite = 4;
  		}
  		else
  		{
  			bytesToWrite = 3;
  			ch = UNI_REPLACEMENT_CHAR;
  			result = sourceIllegal;
  		}
  
  		target += bytesToWrite;
  
  		if (target > targetEnd)
  		{
  			--source; /* Back up source pointer! */
  			target -= bytesToWrite;
  			result = targetExhausted;
  			break;
  		}
  
  		switch (bytesToWrite) /* note: everything falls through. */
  		{
  			case 4:
  				*--target = (BYTE)((ch | byteMark) & byteMask);
  				ch >>= 6;
  
  			case 3:
  				*--target = (BYTE)((ch | byteMark) & byteMask);
  				ch >>= 6;
  
  			case 2:
  				*--target = (BYTE)((ch | byteMark) & byteMask);
  				ch >>= 6;
  
  			case 1:
  				*--target = (BYTE)(ch | firstByteMark[bytesToWrite]);
  		}
  
  		target += bytesToWrite;
  	}
  
  	*sourceStart = source;
  	*targetStart = target;
  	return result;
  }
  
  /* --------------------------------------------------------------------- */
  
  ConversionResult ConvertUTF8toUTF32(const BYTE** sourceStart, const BYTE* sourceEnd,
                                      DWORD** targetStart, DWORD* targetEnd, ConversionFlags flags)
  {
  	ConversionResult result = conversionOK;
  	const BYTE* source = *sourceStart;
  	DWORD* target = *targetStart;
  
  	while (source < sourceEnd)
  	{
  		DWORD ch = 0;
  		unsigned short extraBytesToRead = trailingBytesForUTF8[*source];
  
  		if (source + extraBytesToRead >= sourceEnd)
  		{
  			result = sourceExhausted;
  			break;
  		}
  
  		/* Do this check whether lenient or strict */
  		if (!isLegalUTF8(source, extraBytesToRead + 1))
  		{
  			result = sourceIllegal;
  			break;
  		}
  
  		/*
  		 * The cases all fall through. See "Note A" below.
  		 */
  		switch (extraBytesToRead)
  		{
  			case 5:
  				ch += *source++;
  				ch <<= 6;
  
  			case 4:
  				ch += *source++;
  				ch <<= 6;
  
  			case 3:
  				ch += *source++;
  				ch <<= 6;
  
  			case 2:
  				ch += *source++;
  				ch <<= 6;
  
  			case 1:
  				ch += *source++;
  				ch <<= 6;
  
  			case 0:
  				ch += *source++;
  		}
  
  		ch -= offsetsFromUTF8[extraBytesToRead];
  
  		if (target >= targetEnd)
  		{
  			source -= (extraBytesToRead + 1); /* Back up the source pointer! */
  			result = targetExhausted;
  			break;
  		}
  
  		if (ch <= UNI_MAX_LEGAL_UTF32)
  		{
  			/*
  			 * UTF-16 surrogate values are illegal in UTF-32, and anything
  			 * over Plane 17 (> 0x10FFFF) is illegal.
  			 */
  			if (ch >= UNI_SUR_HIGH_START && ch <= UNI_SUR_LOW_END)
  			{
  				if (flags == strictConversion)
  				{
  					source -= (extraBytesToRead + 1); /* return to the illegal value itself */
  					result = sourceIllegal;
  					break;
  				}
  				else
  				{
  					*target++ = UNI_REPLACEMENT_CHAR;
  				}
  			}
  			else
  			{
  				*target++ = ch;
  			}
  		}
  		else /* i.e., ch > UNI_MAX_LEGAL_UTF32 */
  		{
  			result = sourceIllegal;
  			*target++ = UNI_REPLACEMENT_CHAR;
  		}
  	}
  
  	*sourceStart = source;
  	*targetStart = target;
  	return result;
  }
  
  /* ---------------------------------------------------------------------
  
      Note A.
      The fall-through switches in UTF-8 reading code save a
      temp variable, some decrements & conditionals.  The switches
      are equivalent to the following loop:
      {
          int tmpBytesToRead = extraBytesToRead+1;
          do {
          ch += *source++;
          --tmpBytesToRead;
          if (tmpBytesToRead) ch <<= 6;
          } while (tmpBytesToRead > 0);
      }
      In UTF-8 writing code, the switches on "bytesToWrite" are
      similarly unrolled loops.
  
     --------------------------------------------------------------------- */
  #if __GNUC__
  #pragma GCC diagnostic pop
  #endif
  