/*
     * UTF-8 string length in bytes will be <= Unicode string length *
     * TCL_UTF_MAX.
     */

    oldLength = Tcl_DStringLength(dsPtr);
    Tcl_DStringSetLength(dsPtr, oldLength + (uniLength + 1) * TCL_UTF_MAX);
    string = Tcl_DStringValue(dsPtr) + oldLength;

    p = string;
    wEnd = uniStr + uniLength;
    for (w = uniStr; w < wEnd; ) {
	p += Tcl_UniCharToUtf(*w, p);
	w++;

    /*
     * Unicode string length in Tcl_UniChars will be <= UTF-8 string length in
     * bytes.
     */

    oldLength = Tcl_DStringLength(dsPtr);

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

    w = wString;
    p = src;
    end = src + length - TCL_UTF_MAX;
    while (p < end) {
	p += TclUtfToUniChar(p, &ch);
	*w++ = ch;
    }
    end += TCL_UTF_MAX;
    while (p < end) {
	if (Tcl_UtfCharComplete(p, end-p)) {
	    p += TclUtfToUniChar(p, &ch);
	} else {
	    ch = UCHAR(*p++);
	}
	*w++ = ch;
    }
    *w = '\0';
    Tcl_DStringSetLength(dsPtr,
	    (oldLength + ((char *) w - (char *) wString)));

    return wString;