Sorry, I forgot to answer and now I'm in movement. Look in LibC memcpy method (is not called exactly like that) and his uses. That's the faster you can move things inside the image.
And remember: an EA is a pointer and a ByteArray is an array who will be passed as pointer too. Esteban > On 23 Feb 2017, at 17:21, raffaello.giulie...@lifeware.ch wrote: > > Hi, > > browsing through ByteArray's and ExternalAddress's code, I'm getting the > impression that copying *portions* of ByteArrays from/to the C heap can > be quite costly. > > Copying *to* the C heap sometimes requires first copying the portion of > the ByteArray into a newly instantiated temporary ByteArray, then > copying the latter to the C heap. > > Copying *from* the C heap might require explicitly looping over the > single bytes. I say "might" because I still cannot find more direct way, > as using ByteArray>>replaceFrom:to:with:startingAt: doesn't seem to work. > > Any suggestion on more effective copy operations? > > Thanks > Raffaello > > > > > > >> On 22/02/17 15:08, Raffaello Giulietti wrote: >> Hi Esteban, >> >> not sure I'm understanding your snippet correctly. >> >> Below is my try. It throws a SubscriptOutOfBounds exception in the last >> line. The reason is that the implementation of ByteArray >> replaceFrom:to:with:startingAt: does not consider that ea is meant to be >> a pointer to a C byte array, not an object whose content is to be copied >> directly. >> >> >> | ea ba | >> ea := ExternalAddress gcallocate: 200. >> ba := ByteArray new: 100. >> ba replaceFrom: 1 to: 50 with: ea startingAt: 51. >> >> >> Am I missing some point? >> >> >> >> >>> On 2017-02-21 17:20, Esteban Lorenzano wrote: >>> usually, something more or less like this: >>> >>> sourceByteArrayOrExternalAddress := … some ... >>> destEnternalAddressOrByteArray >>> replaceFrom: 1 >>> to: sourceByteArrayOrExternalAddress size >>> with: sourceByteArrayOrExternalAddress >>> startingAt: 1 >>> >>> and or course you can play with the starting points and sizes. >>> >>> cheers, >>> Esteban >>> >>> >>>> On 21 Feb 2017, at 17:13, Raffaello Giulietti >>>> <raffaello.giulie...@lifeware.ch> wrote: >>>> >>>> Hi, >>>> >>>> I'm having a hard time finding documentation on how to copy a portion >>>> of a ByteArray to/from another portion of a heap allocated C byte >>>> array with UFFI. >>>> >>>> My current reference is >>>> https://ci.inria.fr/pharo-contribution/view/Books/job/PharoBookWorkInProgress/lastSuccessfulBuild/artifact/book-result/UnifiedFFI/UnifiedFFI.pdf >>>> >>>> >>>> Thanks for directing me at relevant docs or examples and sorry in >>>> advance if I missed some important point in the docs. >>>> >>>> RG >>>> >>>> >>> >>> >> >> > >
