passing to a dll

how do I fill and pass a c struct to a dll from max

in c:
typedef struct dsFunctions {
Int version; /* put DS_VERSION here */
/* version 1 data */
void (*start)(); /* called before sim loop starts */
void (*doStep) (Int pause); /* called before every frame */
void (*command) (Int cmd); /* called If a command key is pressed */
void (*stop)(); /* called after sim loop exits */
/* version 2 data */
char *path_to_textures; /* If nonzero, path To texture files */

max:
extern
Function dsSimulationLoop(argc:Int,argv:BytePtr,window_width:Int,window_height:Int,dsFunctions:Byte Ptr)
end extern



filling up a type and sending a pointer to it doesnt seem to work, the dll function
runs but doesnt get the right version number


typedef dsFunct
field ver:int
field start_p:var ptr
..
..
enddef
dsf:dsFunctions=New dsFunctions
dsf.ver=2
..
..
dsSimulationLoop (0,Null,352,288,Varptr dsf)

I believe that BlitzMAX types have several other 'internal' fields in addition to those you specify in the code.

The easiest option would probably to create a block of memory using MemAlloc and then insert the data there.

It would be nice to have a function which converts BlitzMAX types to C Structs though.

notice the first byte(2) this is the first int
in the structure and the dll does get the value of 2
how would i get a function pointer into
dsf[4..7]


Global dsf:Byte[]=[Byte(2),Byte(0),Byte(0),Byte(0)..
,Byte(0),Byte(0),Byte(0),Byte(0)..
,Byte(0),Byte(0),Byte(0),Byte(0)..
,Byte(0),Byte(0),Byte(0),Byte(0)..
,Byte(0),Byte(0),Byte(0),Byte(0)..
,Byte(0),Byte(0),Byte(0),Byte(0)]

st=Int(Byte Ptr start)

Local pnt:byte
pnt=var(dsf+5)
pnt=st

Print "st="+Hex(st)
Print "d4="+dsf[4]
Print "d5="+dsf[5]
Print "d6="+dsf[6]
Print "d7="+dsf[7]

I think they changed it. You can see several cases in their modules where they define a C++ struct direclty within bmax.
(I.e to recieve c++ made structures.)

It seems it's ok to use a type as a C struct substitute:

http://www.blitzbasic.com/Community/posts.php?topic=41809