*
 * Side effects:
 *	None.
 *
 *---------------------------------------------------------------------------
 */

INLINE int
int
Tcl_UniCharToUtf(
    int ch,			/* The Tcl_UniChar to be stored in the
				 * buffer. */
    char *buf)			/* Buffer in which the UTF-8 representation of
				 * the Tcl_UniChar is stored. Buffer must be
				 * large enough to hold the UTF-8 character
				 * (at most TCL_UTF_MAX bytes). */

 *	The caller must ensure that the source buffer is long enough that this
 *	routine does not run off the end and dereference non-existent memory
 *	looking for trail bytes. If the source buffer is known to be '\0'
 *	terminated, this cannot happen. Otherwise, the caller should call
 *	Tcl_UtfCharComplete() before calling this routine to ensure that
 *	enough bytes remain in the string.
 *
 *	If TCL_UTF_MAX == 4, special handling of Surrogate pairs is done:
 *	For any UTF-8 string containing a character outside of the BMP, the
 *	first call to this function will fill *chPtr with the high surrogate
 *	and generate a return value of 0. Calling Tcl_UtfToUniChar again
 *	will produce the low surrogate and a return value of 4. Because *chPtr
 *	is used to remember whether the high surrogate is already produced, it
 *	is recommended to initialize the variable it points to as 0 before
 *	the first call to Tcl_UtfToUniChar is done.
 *
 * Results:
 *	*chPtr is filled with the Tcl_UniChar, and the return value is the
 *	number of bytes from the UTF-8 string that were consumed.
 *
 * Side effects:
 *	None.
 *
 *---------------------------------------------------------------------------
 */

int
Tcl_UtfToUniChar(
    register const char *src,	/* The UTF-8 string. */
    register Tcl_UniChar *chPtr)/* Filled with the Tcl_UniChar represented by
				 * the UTF-8 string. */
{
    register int byte;

    /*
     * Unroll 1 to 3 byte UTF-8 sequences, use loop to handle longer ones.
     * Unroll 1 to 3 (or 4) byte UTF-8 sequences.
     */

    byte = *((unsigned char *) src);
    if (byte < 0xC0) {
	/*
	 * Handles properly formed UTF-8 characters between 0x01 and 0x7F.
	 * Also treats \0 and naked trail bytes 0x80 to 0xBF as valid

    }
#if TCL_UTF_MAX > 3
    else if (byte < 0xF8) {
	if (((src[1] & 0xC0) == 0x80) && ((src[2] & 0xC0) == 0x80) && ((src[3] & 0xC0) == 0x80)) {
	    /*
	     * Four-byte-character lead byte followed by three trail bytes.
	     */
#if TCL_UTF_MAX == 4
	    Tcl_UniChar surrogate;

	    byte = (((byte & 0x07) << 18) | ((src[1] & 0x3F) << 12)
		    | ((src[2] & 0x3F) << 6) | (src[3] & 0x3F)) - 0x10000;
	    surrogate = (Tcl_UniChar) (0xD800 + (byte >> 10));
	    if (byte & 0x100000) {
		/* out of range, < 0x10000 or > 0x10ffff */
	    } else if (*chPtr != surrogate) {
		/* produce high surrogate, but don't advance source pointer */
		*chPtr = surrogate;
		return 0;
	    } else {
		/* produce low surrogate, and advance source pointer */
		*chPtr = (Tcl_UniChar) (0xDC00 | (byte & 0x3FF));
		return 4;
	    }
#else
	    *chPtr = (Tcl_UniChar) (((byte & 0x07) << 18) | ((src[1] & 0x3F) << 12)
		    | ((src[2] & 0x3F) << 6) | (src[3] & 0x3F));
	    if ((unsigned)(*chPtr - 0x10000) <= 0xFFFFF) {
		return 4;
	    }
#endif
	}

	/*
	 * A four-byte-character lead-byte not followed by two trail-bytes
	 * represents itself.
	 */
    }

    const char *src,		/* UTF-8 string to convert to Unicode. */
    int length,			/* Length of UTF-8 string in bytes, or -1 for
				 * strlen(). */
    Tcl_DString *dsPtr)		/* Unicode representation of string is
				 * appended to this previously initialized
				 * DString. */
{
    Tcl_UniChar *w, *wString;
    Tcl_UniChar ch, *w, *wString;
    const char *p, *end;
    int oldLength;

    if (length < 0) {
	length = strlen(src);
    }

    Tcl_DStringSetLength(dsPtr,
	    (int) ((oldLength + length + 1) * sizeof(Tcl_UniChar)));
    wString = (Tcl_UniChar *) (Tcl_DStringValue(dsPtr) + oldLength);

    w = wString;
    end = src + length;
    for (p = src; p < end; ) {
	p += TclUtfToUniChar(p, w);
	w++;
	p += TclUtfToUniChar(p, &ch);
	*w++ = ch;
    }
    *w = '\0';
    Tcl_DStringSetLength(dsPtr,
	    (oldLength + ((char *) w - (char *) wString)));

    return wString;
}

int
Tcl_UtfCharComplete(
    const char *src,		/* String to check if first few bytes contain
				 * a complete UTF-8 character. */
    int length)			/* Length of above string in bytes. */
{
    int ch;
    int ch = *((unsigned char *) src);

    ch = *((unsigned char *) src);
    return length >= totalBytes[ch];
}

/*
 *---------------------------------------------------------------------------
 *
 * Tcl_NumUtfChars --

int
Tcl_NumUtfChars(
    register const char *src,	/* The UTF-8 string to measure. */
    int length)			/* The length of the string in bytes, or -1
				 * for strlen(string). */
{
    Tcl_UniChar ch;
    Tcl_UniChar ch = 0;
    register Tcl_UniChar *chPtr = &ch;
    register int i;

    /*
     * The separate implementations are faster.
     *
     * Since this is a time-sensitive function, we also do the check for the
     * single-byte char case specially.
     */

    i = 0;
    if (length < 0) {
	while (*src != '\0') {
	    src += TclUtfToUniChar(src, chPtr);
	    src += TclUtfToUniChar(src, &ch);
	    i++;
	}
    } else {
	register int n;

	while (length > 0) {
	    if (UCHAR(*src) < 0xC0) {
		length--;
		src++;
	    } else {
		n = Tcl_UtfToUniChar(src, chPtr);
		n = Tcl_UtfToUniChar(src, &ch);
		length -= n;
		src += n;
	    }
	    i++;
	}
    }
    return i;

const char *
Tcl_UtfFindFirst(
    const char *src,		/* The UTF-8 string to be searched. */
    int ch)			/* The Tcl_UniChar to search for. */
{
    int len;
    Tcl_UniChar find;
    Tcl_UniChar find = 0;

    while (1) {
	len = TclUtfToUniChar(src, &find);
	if (find == ch) {
	    return src;
	}
	if (*src == '\0') {

const char *
Tcl_UtfFindLast(
    const char *src,		/* The UTF-8 string to be searched. */
    int ch)			/* The Tcl_UniChar to search for. */
{
    int len;
    Tcl_UniChar find;
    Tcl_UniChar find = 0;
    const char *last;

    last = NULL;
    while (1) {
	len = TclUtfToUniChar(src, &find);
	if (find == ch) {
	    last = src;

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

const char *
Tcl_UtfNext(
    const char *src)		/* The current location in the string. */
{
    Tcl_UniChar ch;
    Tcl_UniChar ch = 0;
    int len = TclUtfToUniChar(src, &ch);

#if TCL_UTF_MAX == 4
    if (len == 0) {
    return src + TclUtfToUniChar(src, &ch);
      len = TclUtfToUniChar(src, &ch);
    }
#endif
    return src + len;
}

/*
 *---------------------------------------------------------------------------
 *
 * Tcl_UtfPrev --
 *

    const char *src,		/* The current location in the string. */
    const char *start)		/* Pointer to the beginning of the string, to
				 * avoid going backwards too far. */
{
    const char *look;
    int i, byte;

    src--;
    look = src;
    look = --src;
    for (i = 0; i < TCL_UTF_MAX; i++) {
	if (look < start) {
	    if (src < start) {
		src = start;
	    }
	    break;
	}

 */

const char *
Tcl_UtfAtIndex(
    register const char *src,	/* The UTF-8 string. */
    register int index)		/* The position of the desired character. */
{
    Tcl_UniChar ch;
    Tcl_UniChar ch = 0;

    while (index > 0) {
	index--;
	src += TclUtfToUniChar(src, &ch);
    }
    return src;
}