On Fri, Feb 16, 2018 at 9:07 AM, Torsten Bergmann <astares@gmx.de> wrote:

...

but unfortunately its hard to find any docs or examples.

PDF Docu: https://github.com/SquareBracketAssociates/Booklet-uFFI

(this should be added to http://books.pharo.org)

It will be added when it will be completed. And since this is not me that will do it because I cannot then I wait. May be one day someone with enough knowledge will consider that FFI is important enough to document it seriously. Stef

Examples: load OSWindows, OSLinuxUbuntu, ... or GlorpSQlite from catalog They all use UFFI.

On 16 February 2018 at 16:38, Esteban Lorenzano <estebanlm@gmail.com> wrote:

hi,

“casting” is not necessary in general since is just a way to tell the C compiler that a pointer is form a certain type (but is always a pointer, and in machine code is always the same).

So, here you will do something like this:

Iterator >> asCollectionOfType: aTypeName | result address typeClass |

result := OrderedCollection new. address := ExternalAddress new. typeClass := FFIExternalType resolveType: aTypeName. [self iterator_next: address] whileTrue: [ result add: (typeClass fromHandle: address) ].

Perhaps this is a bit about discover-ability. People with C experience may naturally search for "cast". If I Spotter search for..... cast #i it turns up only four... "broadcast" under Socket class If that was instead like... (typeClass castFromHandle: address) then people may be more likely to find it themselves. cheers -ben

^result

Iterator >> iterator_next: data ^ self ffiCall: #(Boolean iterator_next (Iterator self, void** data))

now… you have a problem if your type if your type is an “atomic” type, like int, long, etc. because those values are passed “by value” and not by pointer, so you will need to decode them. in this case, I would implement a method extension (probably it worths to add it to UFFI):

FFIExternalType class >> valueFromHandle: anAddress ^ self new handle: anAddress at: 1 “This is used for structures, but we can reuse them :)"

FFIExternalReference class >> valueFromHandle: anAddress ^ self fromHandle: anAddress

FFIExternalStructure class >> valueFromHandle: anAddress ^ self fromHandle: anAddress

So your function will be like something like this:

Iterator >> asCollectionOfType: aTypeName | result address typeClass |

result := OrderedCollection new. address := ExternalAddress new. typeClass := FFIExternalType resolveType: aTypeName. [self iterator_next: address] whileTrue: [ result add: (typeClass valueFromHandle:: address) ]. ^result

and voilà, you have your cast :)

Esteban

ps: (some errors can be found here, since I’m “programming at mail client”, but you get the idea ;) )

...

On 15 Feb 2018, at 19:59, Egor Scorik <shirofaii@gmail.com> wrote:

Hi,

I'm trying to play with new UFFI system. It looks much easier then NativeBoost, but unfortunately its hard to find any docs or examples. I have problem with casting void* (ExternalAddress) into smalltalk object if there is no hardcoded type in ffi method. And I really dislike the idea of making many ffi methods, one for each required type. In this example i can't understand how to make something like `address castTo: type`

FFIExternalObject subclass: #Iterator

Iterator >> asCollectionOfType: aTypeName | result address type |

result := OrderedCollection new. address := ExternalAddress new. type := FFIExternalType resolveType: aTypeName. [self iterator_next: address] whileTrue: [ result add: (address castTo: type). ]. ^result

Iterator >> iterator_next: data ^ self ffiCall: #(Boolean iterator_next (Iterator self, void** data))

-- Sent from: http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html

On 18 February 2018 at 01:46, Esteban Lorenzano <estebanlm@gmail.com> wrote:

On 17 Feb 2018, at 02:50, Ben Coman <btc@openInWorld.com> wrote:

On 16 February 2018 at 16:38, Esteban Lorenzano <estebanlm@gmail.com> wrote:

...

hi,

“casting” is not necessary in general since is just a way to tell the C compiler that a pointer is form a certain type (but is always a pointer, and in machine code is always the same).

So, here you will do something like this:

Iterator >> asCollectionOfType: aTypeName | result address typeClass |

result := OrderedCollection new. address := ExternalAddress new. typeClass := FFIExternalType resolveType: aTypeName. [self iterator_next: address] whileTrue: [ result add: (typeClass fromHandle: address) ].

Perhaps this is a bit about discover-ability. People with C experience may naturally search for "cast". If I Spotter search for..... cast #i it turns up only four... "broadcast" under Socket class

If that was instead like... (typeClass castFromHandle: address) then people may be more likely to find it themselves.

I was thinking to implement the #castTo: for all the “pointer” classes (ByteArray, FFIExternalReference, FFIExternalStructure).

#[42 0 0 0] castTo: FFIInt32 -> 42

what do you think?

That will be useful, and intuitive for people to find. cheers -ben

Esteban

cheers -ben

...

^result

Iterator >> iterator_next: data ^ self ffiCall: #(Boolean iterator_next (Iterator self, void** data))

now… you have a problem if your type if your type is an “atomic” type, like int, long, etc. because those values are passed “by value” and not by pointer, so you will need to decode them. in this case, I would implement a method extension (probably it worths to add it to UFFI):

FFIExternalType class >> valueFromHandle: anAddress ^ self new handle: anAddress at: 1 “This is used for structures, but we can reuse them :)"

FFIExternalReference class >> valueFromHandle: anAddress ^ self fromHandle: anAddress

FFIExternalStructure class >> valueFromHandle: anAddress ^ self fromHandle: anAddress

So your function will be like something like this:

Iterator >> asCollectionOfType: aTypeName | result address typeClass |

result := OrderedCollection new. address := ExternalAddress new. typeClass := FFIExternalType resolveType: aTypeName. [self iterator_next: address] whileTrue: [ result add: (typeClass valueFromHandle:: address) ]. ^result

and voilà, you have your cast :)

Esteban

ps: (some errors can be found here, since I’m “programming at mail client”, but you get the idea ;) )

...

On 15 Feb 2018, at 19:59, Egor Scorik <shirofaii@gmail.com> wrote:

Hi,

I'm trying to play with new UFFI system. It looks much easier then NativeBoost, but unfortunately its hard to find any docs or examples. I have problem with casting void* (ExternalAddress) into smalltalk object if there is no hardcoded type in ffi method. And I really dislike the idea of making many ffi methods, one for each required type. In this example i can't understand how to make something like `address castTo: type`

FFIExternalObject subclass: #Iterator

Iterator >> asCollectionOfType: aTypeName | result address type |

result := OrderedCollection new. address := ExternalAddress new. type := FFIExternalType resolveType: aTypeName. [self iterator_next: address] whileTrue: [ result add: (address castTo: type). ]. ^result

Iterator >> iterator_next: data ^ self ffiCall: #(Boolean iterator_next (Iterator self, void** data))

-- Sent from: http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html

Hi esteban do you plan to add this explanation to the documentation of uFFI? Stef On Fri, Feb 16, 2018 at 9:38 AM, Esteban Lorenzano <estebanlm@gmail.com> wrote:

hi,

“casting” is not necessary in general since is just a way to tell the C compiler that a pointer is form a certain type (but is always a pointer, and in machine code is always the same).

So, here you will do something like this:

Iterator >> asCollectionOfType: aTypeName | result address typeClass |

result := OrderedCollection new. address := ExternalAddress new. typeClass := FFIExternalType resolveType: aTypeName. [self iterator_next: address] whileTrue: [ result add: (typeClass fromHandle: address) ]. ^result

Iterator >> iterator_next: data ^ self ffiCall: #(Boolean iterator_next (Iterator self, void** data))

now… you have a problem if your type if your type is an “atomic” type, like int, long, etc. because those values are passed “by value” and not by pointer, so you will need to decode them. in this case, I would implement a method extension (probably it worths to add it to UFFI):

FFIExternalType class >> valueFromHandle: anAddress ^ self new handle: anAddress at: 1 “This is used for structures, but we can reuse them :)"

FFIExternalReference class >> valueFromHandle: anAddress ^ self fromHandle: anAddress

FFIExternalStructure class >> valueFromHandle: anAddress ^ self fromHandle: anAddress

So your function will be like something like this:

Iterator >> asCollectionOfType: aTypeName | result address typeClass |

result := OrderedCollection new. address := ExternalAddress new. typeClass := FFIExternalType resolveType: aTypeName. [self iterator_next: address] whileTrue: [ result add: (typeClass valueFromHandle:: address) ]. ^result

and voilà, you have your cast :)

Esteban

ps: (some errors can be found here, since I’m “programming at mail client”, but you get the idea ;) )

...

On 15 Feb 2018, at 19:59, Egor Scorik <shirofaii@gmail.com> wrote:

Hi,

I'm trying to play with new UFFI system. It looks much easier then NativeBoost, but unfortunately its hard to find any docs or examples. I have problem with casting void* (ExternalAddress) into smalltalk object if there is no hardcoded type in ffi method. And I really dislike the idea of making many ffi methods, one for each required type. In this example i can't understand how to make something like `address castTo: type`

FFIExternalObject subclass: #Iterator

Iterator >> asCollectionOfType: aTypeName | result address type |

result := OrderedCollection new. address := ExternalAddress new. type := FFIExternalType resolveType: aTypeName. [self iterator_next: address] whileTrue: [ result add: (address castTo: type). ]. ^result

Iterator >> iterator_next: data ^ self ffiCall: #(Boolean iterator_next (Iterator self, void** data))

-- Sent from: http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html