[squeak-dev] FFI - structure pointer
bschwab at anest.ufl.edu
Sat Apr 3 13:36:56 UTC 2010
Andreas, John, anybody,
I need to find the address of a "function" (it is in fact a global structure pointer somewhere in memory) and pass it to another function.
Suppose the structure is called Type and the function allocate_one(). I call the function something like
<cdecl: SomeOtherStruct* 'allocate_one' ( Type* long ) >
but I am having an awful time getting the pointer to Type. Given that dlsym() will return a pointer to it, how can I represent that in Smalltalk? I have tried variations on
"Indirectly call dlsym()"
address := Library default getProcAddress:'name_of_global_struct'.
"try to create Type* from the resulting address"
type := Type fromHandle:address.
type := Type fromHandle:address getHandle.
type := ExternalData fromHandle:address type:Type externalType asPointerType.
Something := Library default allocateOne:type size:2.
and it either complains about bad arguments during the call or segment faults. Any ideas or similar examples?
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