/*

 * 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>

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* targetEnd, ConversionFlags flags)

{

	BYTE* target;

	const WCHAR* source;

	BOOL computeLength;

	ConversionResult result;

	computeLength = (!targetEnd) ? TRUE : FALSE;

	source = *sourceStart;

	target = *targetStart;

	result = conversionOK;

	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;

		}

		target += bytesToWrite;

		if ((target > targetEnd) && (!computeLength))

		{

			source = oldSource; /* Back up source pointer! */

			target -= bytesToWrite;

			result = targetExhausted;

			break;

		}

		if (!computeLength)

		{

			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]);

			}

		}

		else

		{

			switch (bytesToWrite)

			{

				/* note: everything falls through. */

				case 4:

					--target;

				case 3:

					--target;

				case 2:

					--target;

				case 1:

					--target;

			}

		}

		target += bytesToWrite;

	}

	*sourceStart = source;

	*targetStart = target;

	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)

{

	WCHAR* target;

	const BYTE* source;

	BOOL computeLength;

	ConversionResult result;

	computeLength = (!targetEnd) ? TRUE : FALSE;

	result = conversionOK;

	source = *sourceStart;

	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; /* 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 >= targetEnd) && (!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(target, UNI_REPLACEMENT_CHAR);

						target++;

					}

					else

						target++;

				}

			}

			else

			{

				if (!computeLength)

				{

					Data_Write_UINT16(target, ch); /* normal case */

					target++;

				}

				else

					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(target, UNI_REPLACEMENT_CHAR);

					target++;

				}

				else

					target++;

			}

		}

		else

		{

			/* target is a character in range 0xFFFF - 0x10FFFF. */

			if ((target + 1 >= targetEnd) && (!computeLength))

			{

				source -= (extraBytesToRead + 1); /* Back up source pointer! */

				result = targetExhausted;

				break;

			}

			ch -= halfBase;

			if (!computeLength)

			{

				WCHAR wchar;

				wchar = (ch >> halfShift) + UNI_SUR_HIGH_START;

				Data_Write_UINT16(target, wchar);

				target++;

				wchar = (ch & halfMask) + UNI_SUR_LOW_START;

				Data_Write_UINT16(target, wchar);

				target++;

			}

			else

			{

				target++;

				target++;

			}

		}

	}

	*sourceStart = source;

	*targetStart = target;

	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.

   --------------------------------------------------------------------- */