Hi Annick ! I'll explain first why you got the error. The assignment time: ’05:45’ failed because you tried to put an array of char (of size 5*sizeof(char)) inside an address. At some point, you need to allocate the memory that will hold the data. In your case, you can do it quite easily with the class-side method #fromString: of class NBExternalAdress. This will return a pointer, which you can assign to the field of your struct. Regarding what you really want to do, having a char[5] field in your struct, I'm not totaly sure how you can do it with NativeBoost. A C struc is just a chunk of memory with a well defined size, so if you want to specify a field as a char[5], you must have a type that match that size. It does not look like the field parser of NBExternalStruct can do it dynamicaly. You could maybe hard code it by subclassing NBExternalType into NBExternalArrayOf5Char, with a valueSize of 5. As a final word, be wary of where you have allocated your objects, whether it is in object-space (#new), or in C heap (#externalNew). The first is garbage collected so the address are volatile, but you bare the duty of freeing the memory in the second. 2014-10-29 12:18 GMT+01:00 stepharo <stepharo@free.fr>:

did you read the NativeBoost tutorial on the PharoForTheEntreprise book? If you do please report potential mistakes so that we can improve.

On 29/10/14 05:59, Annick Fron wrote:

...

I I have a C struct with a char*

struct result { char* time }

I define an ExternalStructure in FFI , with one field of type char* (note that the syntax char [5] is not accepted ! ).

defineFields generates the accessors time and time:

If I use time: ’05:45’

I get an error. How do I set a string value in an ExternalStructure ?

Annick

Oops, sorry, I was misslead by Steph reply. Some of the comments might still hold. For the *time: ’05:45’* code to work, you would need FFI to handle all the hassle of memory management and actually allocate the memory for 5 characters and copying it. I never used FFI but I doubt it does this. Looking at FFI library, you both have ExternalAddress (for the struct with char*) and ExternalType (for the struct with char[5]) that you can use. For the later solution, it still looks like you should define a specific 5 bytes ArrayOf5Char type. 2014-10-29 18:34 GMT+01:00 Annick Fron <list@afceurope.com>:

I can’t use NativeBoost on the Raspberry, I would be glad if I could !!!

Le 29 oct. 2014 à 12:18, stepharo <stepharo@free.fr> a écrit :

...

did you read the NativeBoost tutorial on the PharoForTheEntreprise book? If you do please report potential mistakes so that we can improve.

On 29/10/14 05:59, Annick Fron wrote:

...

I I have a C struct with a char*

struct result { char* time }

I define an ExternalStructure in FFI , with one field of type char* (note that the syntax char [5] is not accepted ! ).

defineFields generates the accessors time and time:

If I use time: ’05:45’

I get an error. How do I set a string value in an ExternalStructure ?

Annick

That is cool. Doru On Thu, Oct 30, 2014 at 11:37 PM, stepharo <stepharo@free.fr> wrote:

Ronie is working on unifying all the api and proposing one syntax mechanism for - nativeBoost back-end - FFI and may be Alien

The FFI situation is not good and we know we should improve it.

On 29/10/14 20:18, Thomas Bany wrote:

Oops, sorry, I was misslead by Steph reply.

Some of the comments might still hold. For the *time: ’05:45’* code to work, you would need FFI to handle all the hassle of memory management and actually allocate the memory for 5 characters and copying it. I never used FFI but I doubt it does this.

Looking at FFI library, you both have ExternalAddress (for the struct with char*) and ExternalType (for the struct with char[5]) that you can use. For the later solution, it still looks like you should define a specific 5 bytes ArrayOf5Char type.

2014-10-29 18:34 GMT+01:00 Annick Fron <list@afceurope.com>:

...

I can’t use NativeBoost on the Raspberry, I would be glad if I could !!!

Le 29 oct. 2014 à 12:18, stepharo <stepharo@free.fr> a écrit :

...

did you read the NativeBoost tutorial on the PharoForTheEntreprise book? If you do please report potential mistakes so that we can improve.

On 29/10/14 05:59, Annick Fron wrote:

...

I I have a C struct with a char*

struct result { char* time }

I define an ExternalStructure in FFI , with one field of type char* (note that the syntax char [5] is not accepted ! ).

defineFields generates the accessors time and time:

If I use time: ’05:45’

I get an error. How do I set a string value in an ExternalStructure ?

Annick

-- www.tudorgirba.com "Every thing has its own flow"

This is good news ! Annick Le 30 oct. 2014 à 23:37, stepharo <stepharo@free.fr> a écrit :

Ronie is working on unifying all the api and proposing one syntax mechanism for - nativeBoost back-end - FFI and may be Alien

The FFI situation is not good and we know we should improve it.

On 29/10/14 20:18, Thomas Bany wrote:

...

Oops, sorry, I was misslead by Steph reply.

Some of the comments might still hold. For the time: ’05:45’ code to work, you would need FFI to handle all the hassle of memory management and actually allocate the memory for 5 characters and copying it. I never used FFI but I doubt it does this.

Looking at FFI library, you both have ExternalAddress (for the struct with char*) and ExternalType (for the struct with char[5]) that you can use. For the later solution, it still looks like you should define a specific 5 bytes ArrayOf5Char type.

2014-10-29 18:34 GMT+01:00 Annick Fron <list@afceurope.com>: I can’t use NativeBoost on the Raspberry, I would be glad if I could !!!

Le 29 oct. 2014 à 12:18, stepharo <stepharo@free.fr> a écrit :

...

did you read the NativeBoost tutorial on the PharoForTheEntreprise book? If you do please report potential mistakes so that we can improve.

On 29/10/14 05:59, Annick Fron wrote:

...

I I have a C struct with a char*

struct result { char* time }

I define an ExternalStructure in FFI , with one field of type char* (note that the syntax char [5] is not accepted ! ).

defineFields generates the accessors time and time:

If I use time: ’05:45’

I get an error. How do I set a string value in an ExternalStructure ?

Annick

Ronie is working on unifying all the api and proposing one syntax mechanism for - nativeBoost back-end - FFI and may be Alien

I had a skype session with Eliot the last. He taught me about the callback mechanism and I am actually going to use Alien for the callbacks, by adapting it to perform the marshalling into the UFFI/NativeBoost types. In the future, I am planning in using Lowcode to perform the whole callback process, but now for simplicity I am just going to piggy back in Alien. I still have to finish the callout by fixing a complicated bug. With Eliot we discussed a workaround for this bug. I haven't implemented those workaround yet, because I have been a bit busy with my university studies. As long as we keep what is working, ahem, working. I now depend on quite a

couple of FFI related libs.

What I need is an easy FFI wrapping tool, like https://github.com/ronsaldo/swig. Is UFFI going that way?

Well, I made the swig adaptation for NativeBoost. Making it for the UFFI is actually something trivial. So, we are going to have a powerful FFI and a binding generator for it. The only problem with Swig, is that the bindings generated by it are not perfect, because it exposes the exact same C API. A C library that uses some kind of object model, cannot be exposed in a clean object oriented way cleanly by a generic automatic tool. The FFI situation is not good and we know we should improve it. For the record, the current FFI situation can be traced to the historical origins of Smalltalk and even Squeak. The original Smalltalk was an actual operating system, and Squeak was also made as an operating system. Because of this, they were not designed to interact with other languages. Getting a perfect FFI is going to take a lot of time, because of other problems, such as Multi-threading and the mandatory use of non-blocking IO. Fortunately, Eliot made a way to have a threaded FFI, in which a single thread owns the VM at a single time. With this threaded FFI we can have things such as a callback from a different thread, which is required by some libraries such as the sound API of SDL2. Of course the UFFI is going to support this threaded FFI in some point of time. To support the threaded FFI I only have to pin/unpin some object, and call two VM functions, disownVM() and ownVM(). As for getting some actual parallelism in Pharo, this is something that I think is going to take a big amount of time. For now the best thing we can do is to use OpenCL. This week I have been doing some experimenting in making an API for linear algebra, that uses OpenCL to perform computations in parallel. Later I will publish a video. Greetings, Ronie 2014-10-31 19:23 GMT-03:00 Alain Rastoul <alf.mmm.cat@gmail.com>:

Hi Annick,

you can't pass smalltalk strings or objects to ffi as parameters, you have to allocate the buffer member of your structure on the external heap ( plus to avoid being gc'd before ffi call) with ExternalAddress allocate: <your buffer/string size +1 for string null termination> fill your buffer with byteAt:put: method, and release this memory with free when you have finished.

not sure, but you could try something like:

s := '05:45' copyWith: (Character value: 0). a := ExternalAddress allocate: s size. s asByteArray withIndexDo: [ :b :i | a byteAt: i put: b ]. myStruct time: a. ... call your ffi ... a free

Regards,

Alain

Le 29/10/2014 11:59, Annick Fron a écrit :

I I have a C struct with a char*

...

struct result { char* time }

I define an ExternalStructure in FFI , with one field of type char* (note that the syntax char [5] is not accepted ! ).

defineFields generates the accessors time and time:

If I use time: ’05:45’

I get an error. How do I set a string value in an ExternalStructure ?

Annick