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

/* Since TCL_ENCODING_MODIFIED is only used for utf-8/cesu-8 and
 * TCL_ENCODING_LE is only used for  utf-16/utf-32/ucs-2. re-use the same value */
#define TCL_ENCODING_LE		TCL_ENCODING_MODIFIED	/* Little-endian encoding */
#define ENCODING_UTF	0x200	/* For UTF-8 encoding, allow 4-byte output sequences */
#define ENCODING_INPUT	0x400 /* For UTF-8/CESU-8 encoding, means external -> internal */

void
TclInitEncodingSubsystem(void)
{
    Tcl_EncodingType type;
    TableEncodingData *dataPtr;
    unsigned size;

    tclIdentityEncoding = Tcl_CreateEncoding(&type);

    type.encodingName	= "utf-8";
    type.toUtfProc	= UtfToUtfProc;
    type.fromUtfProc	= UtfToUtfProc;
    type.freeProc	= NULL;
    type.nullSize	= 1;
    type.clientData	= INT2PTR(ENCODING_UTF);
    Tcl_CreateEncoding(&type);
    type.clientData	= INT2PTR(TCL_ENCODING_NOCOMPLAIN);
    type.encodingName	= "cesu-8";
    Tcl_CreateEncoding(&type);

    type.toUtfProc	= Utf16ToUtfProc;
    type.fromUtfProc    = UtfToUcs2Proc;

	srcLen = 0;
    } else if (srcLen < 0) {
	srcLen = encodingPtr->lengthProc(src);
    }

    flags |= TCL_ENCODING_START | TCL_ENCODING_END;
    if (encodingPtr->toUtfProc == UtfToUtfProc) {
	flags |= ENCODING_INPUT;
    }

    while (1) {
	result = encodingPtr->toUtfProc(encodingPtr->clientData, src, srcLen,
		flags, &state, dst, dstLen, &srcRead, &dstWrote, &dstChars);
	soFar = dst + dstWrote - Tcl_DStringValue(dstPtr);

	 * the actual \0 at the end of the destination buffer, we need to
	 * append it manually.  First make room for it...
	 */

	dstLen--;
    }
    if (encodingPtr->toUtfProc == UtfToUtfProc) {
	flags |= ENCODING_INPUT;
    }
    do {
	Tcl_EncodingState savedState = *statePtr;

	result = encodingPtr->toUtfProc(encodingPtr->clientData, src, srcLen,
		flags, statePtr, dst, dstLen, srcReadPtr, dstWrotePtr,
		dstCharsPtr);

int
Tcl_UtfToExternalDStringEx(
    Tcl_Encoding encoding,	/* The encoding for the converted string, or
				 * NULL for the default system encoding. */
    const char *src,		/* Source string in UTF-8. */
    int srcLen,			/* Source string length in bytes, or < 0 for
				 * strlen(). */
    int flags,			/* Conversion control flags. */
    Tcl_DString *dstPtr)	/* Uninitialized or free DString in which the
				 * converted string is stored. */
{
    char *dst;
    Tcl_EncodingState state;
    const Encoding *encodingPtr;
    int dstLen, result, soFar, srcRead, dstWrote, dstChars;

    }
    if (flags & TCL_ENCODING_CHAR_LIMIT) {
	charLimit = *dstCharsPtr;
    }

    dstStart = dst;
    flags |= PTR2INT(clientData);
    dstEnd = dst + dstLen - ((flags & ENCODING_UTF) ? TCL_UTF_MAX : 6);

    for (numChars = 0; src < srcEnd && numChars <= charLimit; numChars++) {
	if ((src > srcClose) && (!Tcl_UtfCharComplete(src, srcEnd - src))) {
	    /*
	     * If there is more string to follow, this will ensure that the
	     * last UTF-8 character in the source buffer hasn't been cut off.
	     */

	    size_t len = TclUtfToUCS4(src, &ch);
	    if ((len < 2) && (ch != 0) && (flags & TCL_ENCODING_MODIFIED)
		    && (((flags & TCL_ENCODING_STRICT) == TCL_ENCODING_STRICT))) {
		result = TCL_CONVERT_SYNTAX;
		break;
	    }
	    src += len;
	    if (!(flags & ENCODING_UTF) && (ch > 0x3FF)) {
		if (ch > 0xFFFF) {
		    /* CESU-8 6-byte sequence for chars > U+FFFF */
		    ch -= 0x10000;
		    *dst++ = 0xED;
		    *dst++ = (char) (((ch >> 16) & 0x0F) | 0xA0);
		    *dst++ = (char) (((ch >> 10) & 0x3F) | 0x80);
		    ch = (ch & 0x0CFF) | 0xDC00;