[Pharo-users] UFFI counterpart to "C iterate over a arry through a pointer"

May 25, 2020

      Hello, I'm looking for help with the following problem.
I try to get closer from the C point of view to the problem.

//These are the structures
typedef struct {
  unsigned int  NumEntries;      /* number of entries written to the
pModuleData array */
  MODULE_DATA *pModuleData;      /* pointer to array containing module infos
and module handles */
} MODULE;

typedef struct {
   unsigned int ModuleTypeId;    /* ModuleTypeId */
   unsigned int hMod;            /* handle Module assigned */
   char   *pVendorModuleName;    /* Vendor specific information string. */
} MODULE_DATA;

//this is a function that I call via FFI
unsigned int errorCheck GetModuleIds(MODULE  **pModuleIdList)
{
	//memory will be allocated here and the structure will be filled.
}

Now my questions :-)

I solve the pointer pointer problem with ExternalAddress and MODULE
fromHandle:

| result pointerAutoRelease mod|
	pointerAutoRelease := ExternalAddress new pointerAutoRelease.
	result := call ffiGetModuleIds: pointerAutoRelease.
        "inside Methode -> ffiGetModuleIds ^self ffiCall:#(uint32
GetModuleIds( void** pModuleIdList ) )"
	"result is unimportant for understanding the problem"
	mod := MODULE fromHandle: pointerAutoRelease.

Is this a good way? Or is there a better solution?

And now comes my main problem... 
How do I get my array( or Collection) from NumEntries and *pModuleData with
ffi?

So I would do it roughly in C.
main(){

    MODULE_DATA *pModuleData; 
	MODULE *moduleIdList=NULL;	
	unsigned int retval = GetModuleIds(&moduleIdList);

	printf("Number of modules: %d\n\n",moduleIdList->NumEntries);

	for (unsigned int i=0;i<moduleIdList->NumEntries;i++)
	{
		// Set a pointer to the current ModuleData
        pModuleData = &moduleIdList->pModuleData[i];  //is like iterate
through a pointer

		//etc. .....
		...
	}

}

Thanks you for your help.

--
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[Pharo-users] UFFI counterpart to "C iterate over a arry through a pointer"

ASAM