OpenEuphoria

cffi

• Posted by petelomax Aug 31, 2015
• 2295 views

I've written a simple cffi implementation.

The intro reads:

-- 
--  cffi.e 
--  ====== 
-- 
--      Eliminates most of the byte-counting needed when interfacing to C routines. 
--      The motivation behind this was that while I had many of the windows API 
--      structures laboriously translated to offsets for 32-bit from many years 
--      ago, they would all have otherwise needed re-doing for 64-bit. 
-- 
--      I must stress that any savings are limited to converting C header (.h) files, 
--      or more accurately fragments copied verbatim from said, which would otherwise  
--      have to be done line-by-line manually. There is no new fancy slick syntax to  
--      help with the code that follows, or anything remotely like that. Although it 
--      knows the names, offsets and sizes of fields, that does not mean that you no  
--      longer have to fill them in! But there is less chance of being out-by-2 or 
--      whetever on the 4th field and therefore all the rest. 
-- 
--      Structures: 
--      =========== 
--          id = define_struct(s) parses C struct definitions into sizes/offsets etc. 
--          pStruct = allocate_struct(id)   -- (invoke free(pStruct) when done) 
--          set_struct_field(id,pStruct,"name",value) 
--          value = get_struct_field(id,pStruct,"name") 
--          {offset,size,sign} = get_field_details(id,"name") 
--          size = get_struct_size(id) 
-- 
--      Routine definition: 
--      =================== 
--          integer rid = define_cfunc(object lib, string cdef) 
--          integer rid = define_cproc(object lib, string cdef) 

A little test, works on Phix and OE 4.1.0.

include builtins\cffi.e 
constant tMB=""" 

int WINAPI MessageBox( 
  _In_opt_  HWND hWnd, 
  _In_opt_  LPCTSTR lpText, 
  _In_opt_  LPCTSTR lpCaption, 
  _In_      UINT uType 
); 
""" 

set_unicode(0) 
constant xMessageBox = define_cfunc("user32.dll",tMB,0) 
--?c_func(xMessageBox,{0,"text","caption",0}) 
atom pText = allocate_string("text"), 
     pCaption = allocate_string("caption") 
if 01 then 
?c_func(xMessageBox,{0,pText,pCaption,0}) 
end if 
 
constant tMBP=""" 

typedef struct { 
  UINT           cbSize; 
  HWND           hwndOwner; 
  HINSTANCE      hInstance; 
  LPCTSTR        lpszText; 
  LPCTSTR        lpszCaption; 
  DWORD          dwStyle; 
  LPCTSTR        lpszIcon; 
  DWORD_PTR      dwContextHelpId; 
  MSGBOXCALLBACK lpfnMsgBoxCallback; 
  DWORD          dwLanguageId; 
} MSGBOXPARAMS, *PMSGBOXPARAMS; 
""" 

constant tMBI = """ 

int WINAPI MessageBoxIndirect( 
  _In_ const LPMSGBOXPARAMS lpMsgBoxParams 
); 
""" 

integer idMBP = define_struct(tMBP) 
integer xMBI = define_cfunc("user32.dll",tMBI) 
atom pMBP = allocate_struct(idMBP) 
    set_struct_field(idMBP,pMBP,"cbSize",get_struct_size(idMBP)) 
    set_struct_field(idMBP,pMBP,"lpszText",pText) 
    set_struct_field(idMBP,pMBP,"lpszCaption",pCaption) 
    ?c_func(xMBI,{pMBP}) 
 

Just in case you need it you can get the current version of pcolumn.e from http://openeuphoria.org/pastey/274.wc

I even got a version to work on RDS Eu 2.4, but it turned out a bit grubby.

I am thinking that things like MAX_PATH are probably best handled manually, unless someone has a better idea.

Let me know what you think,

Pete

PS The triple-quoted constants do not seem to be working.