}

/*
 *---------------------------------------------------------------------------
 *
 * Tcl_UniCharToUtf --
 *
 *	Stores the given Tcl_UniChar as a sequence of UTF-8 bytes in the
 *	provided buffer. Equivalent to Plan 9 runetochar().
 *	Stores the given Tcl_UniChar as a sequence of UTF-8 bytes in the provided
 *	buffer. Equivalent to Plan 9 runetochar().
 *
 *	Surrogate pairs are handled as follows: When ch is a high surrogate,
 *	the first byte of the 4-byte UTF-8 sequence is stored in the buffer and
 *	the function returns 1. If the function is called again with a low
 *	surrogate and the same buffer, the remaining 3 bytes of the 4-byte
 *	UTF-8 sequence are produced.
 *
 *	If no low surrogate follows the high surrogate (which is actually
 *	If no low surrogate follows the high surrogate (which is actually illegal),
 *	illegal), this can be handled reasonably by calling Tcl_UniCharToUtf
 *	again with ch = -1. This produces a 3-byte UTF-8 sequence
 *	representing the high surrogate.
 *	calling Tcl_UniCharToUtf again with ch being -1 produces a 3-byte UTF-8
 *	sequence representing the high surrogate.
 *
 * Results:
 *	Returns the number of bytes stored into the buffer.
 *
 * Side effects:
 *	None.
 *
 *---------------------------------------------------------------------------
 */

#undef Tcl_UniCharToUtf
size_t
Tcl_UniCharToUtf(
    int ch,			/* The Tcl_UniChar to be stored in the
				 * buffer. Can be or'ed with flag TCL_COMBINE */
    char *buf)			/* Buffer in which the UTF-8 representation of
    int ch,	/* The Tcl_UniChar to be stored in the
		 * buffer. Can be or'ed with flag TCL_COMBINE
		 */
    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 4 bytes). */
		 * ch is stored. Must be large enough to hold the UTF-8
		 * character (at most 4 bytes).
		 */
{
#if TCL_UTF_MAX > 3
    int flags = ch;
#endif

    if (ch >= TCL_COMBINE) {
	ch &= (TCL_COMBINE - 1);

			buf[2]  = (char) (0x80 | (0x3F & ch));
			buf[1] |= (char) (0x80 | (0x0F & (ch >> 6)));
			return 3;
		    }
		    /* Previous Tcl_UniChar was not a high surrogate, so just output */
		} else {
		    /* High surrogate */

		    /* Add 0x10000 to the raw number encoded in the surrogate
		     * pair in order to get the code point.
		    */
		    ch += 0x40;

		    /* Fill buffer with specific 3-byte (invalid) byte combination,
		       so following low surrogate can recognize it and combine */
		    buf[2] = (char) ((ch << 4) & 0x30);
		    buf[1] = (char) (0x80 | (0x3F & (ch >> 2)));
		    buf[0] = (char) (0xF0 | (0x07 & (ch >> 8)));
		    return 1;
		}