utf8_to_utf16.lsp

; utf8_to_utf16.lsp
; http://www.newlispfanclub.alh.net/forum/viewtopic.php?f=9&t=3656&p=18353#p18353
;
; Example:
;  (import "user32.dll" "MessageBoxW")
;  (MessageBoxW 0 (utf8->16 "中文") (utf8->16 "title") 0)

(constant 'SIZEOF_WCHAR 2) ; assumption
(constant 'CP_UTF8 65001)

(define (utf8->16 lpMultiByteStr , cchWideChar lpWideCharStr ret)
   (if (not MultiByteToWideChar)
      (begin
      (import "kernel32.DLL" "MultiByteToWideChar")
      )
   )
   ; calculate the size of buffer (in WCHAR's)
   (setq cchWideChar 
      (
      MultiByteToWideChar
      CP_UTF8 ; from UTF-8
      0       ; no flags necessary
      lpMultiByteStr
      -1      ; convert until NULL is encountered
      0
      0
      )
   )
   
   ; allocate the buffer
   (setq lpWideCharStr (dup " " (* cchWideChar SIZEOF_WCHAR)))
   
   ; convert
   (setq ret 
      (
      MultiByteToWideChar
      CP_UTF8 ; from UTF-8
      0       ; no flags necessary
      lpMultiByteStr
      -1      ; convert until NULL is encountered
      lpWideCharStr
      cchWideChar
      )
   )
   (if (> ret 0) lpWideCharStr nil)
)