UTF-32 to UTF-8 conversion

UTF bits1st UTF-8 byte2nd UTF-8 byte3rd UTF-8 byte4th UTF-8 byte
0aaaaaaa 0aaaaaaa    
00000bbb baaaaaaa 110bbbba10aaaaaa   
ccccbbbb baaaaaaa 1110cccc10bbbbba10aaaaaa  
000ddddd ccccbbbb baaaaaaa11110ddd10ddcccc10bbbbba10aaaaaa