Not sure about the hang, but that code looks wrong. You first malloc() memory, then create 'dataHeap' to be a view into that allocated memory, then free() the memory, and finally return a pointer 'dataHeap.byteOffset' that points to the just freed memory. Accessing memory in dataHeap.byteOffset after the free() is not safe, since the memory has already been freed. You should free() the malloc()ed memory only after you are finished using it.
2014-08-26 10:52 GMT+03:00 awt <[email protected]>: > JJ, thanks for your clear and prompt reply. I tried to free the memory for > dataPtr as follows: > > var nDataBytes = array.length * array.BYTES_PER_ELEMENT; > var dataPtr = Module._malloc(nDataBytes); > > // Copy data to Emscripten heap (directly accessed from Module.HEAPU8) > var dataHeap = new Uint8Array(Module.HEAPU8.buffer, dataPtr, nDataBytes); > dataHeap.set(new Uint8Array(array.buffer)); > > Module._free(dataPtr); > > return dataHeap.byteOffset; > > Unfortunately, my code hangs after passing thru the above code twice and I > didn't manage to see any error messages. Do you have any idea on what might > have gone wrong? Thanks for your help. > > On Monday, August 25, 2014 8:16:21 PM UTC+8, jj wrote: > >> Yes, each malloc() call must be matched with a call to free(). If you >> create a typed array view to the memory area you allocated with malloc(), >> you should not reference that view after you free() the underlying memory, >> or you will be writing to a memory area you have already freed. >> >> Typed array views that you have allocated with a 'new Uint8Array' or >> similar do not need to be deleted, since they are subject to JS VM garbage >> collection. >> >> >> 2014-08-25 13:53 GMT+03:00 awt <[email protected]>: >> >> Hi, >>> >>> I have allocated memory for a Uint8Array in JS using the following code: >>> >>> >>> var nDataBytes = array.length * array.BYTES_PER_ELEMENT; >>> var dataPtr = Module._malloc(nDataBytes); >>> >>> // Copy data to Emscripten heap (directly accessed from Module.HEAPU8) >>> var dataHeap = new Uint8Array(Module.HEAPU8.buffer, dataPtr, >>> nDataBytes); >>> dataHeap.set(new Uint8Array(array.buffer)); >>> >>> return dataHeap.byteOffset; >>> >>> I then return the pointer to the memory thru dataHeap.byteOffset to my >>> C++ code. Do I have to free the memory in dataPtr and dataHeap >>> .byteOffset in my C++ code explicitly using the free and delete calls >>> respectively? >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "emscripten-discuss" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to [email protected]. >>> For more options, visit https://groups.google.com/d/optout. >>> >> >> -- > You received this message because you are subscribed to the Google Groups > "emscripten-discuss" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "emscripten-discuss" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
