I declared a void pointer
void *ptr;
and a typedef struct named testStructure, with a member 'unsigned int a'.
Now I will cast this pointer to a struct pointer:
ptr=(testStructure*)malloc(sizeof(testStructure));
Now I try to access the member of the struct...
ptr->a=5;
...and I get an error "expression must have a pointer-to-struct-or-union type"... Why is 'ptr' still void? It seems, a void pointer cannot be casted to any other pointer type... How I can do this properly? I just need ONE pointer, which can point to different structures, that means, I need to cast a void pointer...
You have 2 conflicting goals. The kernel accessing data, and you not wanting to have an understanding of what it is accessing because it is in a DLL. If the Kernel merely needs to pass the data (pointer) I suppose this works.
Erstwhile making a macro is likely the 'cleanest' route. IE
typedef struct insect { float value; char *name; uint32_t count; } insect; #define INSECT(VPTR) ((insect *)(VPTR)) #define INSECT_VALUE(VPTR) INSECT(VPTR)->value #define INSECT_NAME(VPTR) INSECT(VPTR)->name #define INSECT_COUNT(VPTR) INSECT(VPTR)->count
etc
"Erstwhile (sic?) making a macro is likely the 'cleanest' route."
Is that really the word you were looking for:
www.dictionary.cambridge.org/define.asp