> On Sep 22, 2015, at 8:32 AM, Stéphane Letz <l...@grame.fr> wrote: > > Hi, > > We have the following project of using JavaScriptCore framework on iOS in an > audio context : > > - we generate optimized asm.js code from a Domain Specific Language (actually > an asm.js module for the audio code itself + some additional standard JS > functions) > > - the asm.js module contains a "compute" function that receive an array of > input float buffers, process them, and returns an array of output float > buffers. > > - the array of input float buffers is typically got from a realtime CoreAudio > audio callback, and the array of output float buffers has to be given back to > the callback. So we would basically need to transfer C float arrays to the > asm.js code and back. > > Now the questions : > > - since the asm.js code does not allocate memory, we hope calling the asm.js > "compute" function directly form the CoreAudio callback will work, so > basically that asm.js code can be called from a real-time callback. Is that a > correct assumption?
It's true that in steady state, asm.js code probably won't allocate memory. But I order to execute the code the engine will parse things, compile things, and generate code - all of which requires memory allocation and may acquire locks held by lower priority threads. So, using JSC from a real time callback seems dangerous even if you're using asm.js. > > - what would be the most efficient manner to transfer C float arrays to the > asm.js code and back? Is there a way to completely avoid copies during the > process? Since JavaScriptCore can be used using a Objective C API (but not > pure C API right?) do we need to use intermediate Objective C arrays to > transfer data? Would this help: https://bugs.webkit.org/show_bug.cgi?id=120112 > > Thanks for any advance or code example to look at. > > Stéphane Letz > _______________________________________________ > webkit-dev mailing list > webkit-dev@lists.webkit.org > https://lists.webkit.org/mailman/listinfo/webkit-dev _______________________________________________ webkit-dev mailing list webkit-dev@lists.webkit.org https://lists.webkit.org/mailman/listinfo/webkit-dev
