/* aend character c with ZMODEM escape sequence encoding.  */
void zsend_zdle_char(rt_uint16_t ch)
/* aend character c with ZMODEM escape sequence encoding.  */
void zsend_zdle_char(rt_uint16_t ch)
{
    rt_uint16_t	res;
	res = ch & 0377;
	switch (res) 
	{
	case 0377:
		zsend_byte(res);
		break;
	case ZDLE:
		zsend_byte(ZDLE);  
		res ^= 0100;
		zsend_byte(res);
		break;
	case 021: 
	case 023:
	case 0221: 
	case 0223:
		zsend_byte(ZDLE);  
		res ^= 0100;  
		zsend_byte(res);
		break;
	default:
		zsend_byte(res);
	}
}