> On 01 Jul 2016, at 12:27, Esteban Lorenzano <esteba...@gmail.com> wrote: > > hi, > > this is because you want to get an array with opaque objects. Do not let the > *** confuses you… cwhat you actually want, conceptually is something like > this: > > *((FFIOpaqueObject*)[]) > > means: you pass the address of an array of opaque types (who are always > pointers). > > So, what you need to pass is the address of an array… you will need to work a > bit here, since translation is not automatic. > > 1) you need to declare your type. Let’ say it will be: > > FFIOpaqueObject subclass: USBDevice. > > 2) then you need to get the pointer to this array. You need to rewrite you > code as this: > > arrayPtr := ExternalAddress new. > size := self getDevice: ctx list: arrayPtr. > > getDevice: ctx list: list > ^ self ffiCall: #(size_t libusb_get_device_list (libusb_context *ctx, > void **list)) > > NOTE that we change the type to "void **”. This is because this is what you > actually want: the array of devices > > 3) now you will have size and arrayPtr. Then you declare the array: > > array := FFIExternalArray fromPointer: arrayPtr type: USBDevice sorry, this expression (while possible) does not stops in “size”… it has to be like this, instead:
array := FFIExternalArray fromPointer: arrayPtr type: USBDevice size: size. “you already has the size for the result" > > … and you should be able to iterate this array normally :) > > let me know if this works for you… I’m “coding in mail client”, so it can > fail :P > > cheers, > Esteban > > >> On 01 Jul 2016, at 12:02, Julien Delplanque <jul...@tamere.eu> wrote: >> >> Thanks, it works I get an instance of FFIOpaqueObject. >> >> But how do I get a specific libusb_device object from the list? >> >> Thanks again for you quick answer :-). >> >> Julien >> >> On 01/07/16 11:44, Esteban Lorenzano wrote: >>> Hi, >>> >>> an opaque structure is not an FFIExternalObject but an FFIOpaqueObject. >>> in that case, something like (simplified): >>> >>> ctx := (your context). >>> list := FFIOpaqueObject new. >>> size := self getDevice: ctx list: list. >>> >>> getDevice: ctx list: list >>> ^ self ffiCall: #(size_t libusb_get_device_list (libusb_context *ctx, >>> FFIOpaqueObject ***list)) >>> >>> should work (note that of course you can make libusb_device an alias for >>> your type… that does not matters much, this is just a simplification). >>> >>> if this does not works, if you can provide me code to reproduce it, I can >>> give it a shot and see what happens :) >>> >>> Esteban >>> >>>> On 01 Jul 2016, at 11:19, Julien Delplanque <jul...@tamere.eu> wrote: >>>> >>>> Hello everyone, >>>> >>>> I have a question about the UFFI API. I have the following function: >>>> >>>> ssize_t libusb_get_device_list (libusb_context *ctx, libusb_device ***list) >>>> >>>> where libusb_device is an opaque structure. >>>> >>>> I made a type mapping "ssize_t" -> "int" and an object inheriting >>>> from FFIExternalObject for the "libusb_context" (others methods >>>> using it are working). >>>> >>>> I can not find how to get an array filled with libusb_device using UFFI >>>> from Pharo. :-( >>>> >>>> Thanks in advance, >>>> >>>> Julien >>>> >>> >> >> >
