TheAmazingAudioEngine (TAAE) is a popular ObjC library for working with Audio on iOS and OSX. There is one aspect of this that doesn't quite work with RubyMotion yet.
As discussed here https://groups.google.com/forum/#!topic/rubymotion/WoAk0esOMbs one of the methods of generating audio is to run a block of code several thousand times a second which writes waveforms more or less directly to the speakers. This sounds crazy, and probably is, but its also one of the best ways to organise sample-accurate triggering of audio files and recordings.
The problems seem to be happening with the block used as a callback.
Firstly this failed as RubyMotion wasn't able to infer the type that
the block should have. I've patched this with the code in
vendor/TAAERubyMotion using the example given by Eloy Duran here:
https://gist.github.com/alloy/8452461
Now onto the second bug - the one I need help with.
The code for this app will run but crash after calling our block 512 times. You can see this in the crashlog:
hread 0 Crashed:: Dispatch queue: com.apple.main-thread
0 motion-taae-test 0x000000010001eda8 +[AEBlockChannel(RubyMotionBlockTypeWrapper) channelWithBlock:] + 8 (TAAERubyMotion.m:8)
1 motion-taae-test 0x000000010001edc8 +[AEBlockChannel(RubyMotionBlockTypeWrapper) channelWithBlocklock:] + 40 (TAAERubyMotion.m:11)
2 motion-taae-test 0x000000010001edc8000000010001edc8 +[AEBlockChannel(RubyMotionBlockTypeWrapper) channelWithBlock:] + 40 (TAAERubyMotion.m:11)
3 motion-taae-test 0x000000010001edc8000000010001edc80000010001edc8 +[AEBlockChannel(RubyMotionBlockTypeWrapper) channelWithBlock:] + 40 (TAAERubyMotion.m:11)
...
509 motion-taae-test 0x000000010001edc8 +[AEBlockChannelChannel(RubyMotionBlockTypeWrapper) channelWithBlock:] + 40 (TAAERubyMotion.m:11)
510 motion-taae-test 0x000000010001edc8 +[AEBlockChannel(RubyMotionBlockTypeWrapperyMotionBlockTypeWrapper) channelWithBlock:] + 40 (TAAERubyMotion.m:11)
511 motion-taae-test 0x000000010001edc8 +[AEBlockChannel(RubyMotionBlockTypeWrapperyMotionBlockTypeWrappereWrapper) channelWithBlock:] + 40 (TAAERubyMotion.m:11)
Thread 1:: Dispatch queue: com.apple.libdispatch-manager
It doesn't seem to matter what happens inside the block. It can be empty and it doesn't make a difference. Also, if you uncomment the NSLog in the ObjC patch you can see that the patch code is being run.
I've noticed that the crashlog seems to be saying something about STACK GUARD
being called for thread 0
Exception Type: EXC_BAD_ACCESS (SIGSEGV)
Exception Codes: KERN_PROTECTION_FAILURE at 0x00007fff5f3ffff8
VM Regions Near 0x7fff5f3ffff8:
mapped file 0000000110089000-000000011020d000 [ 1552K] r--/rwx SM=COW /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator7.1.sdk/System/Library/.lilid/.lilic/ymROEw3kGk
--> STACK GUARD 00007fff5bc00000-00007fff5f400000 [ 56.0M] ---/rwx SM=NUL stack guard for thread 0
Stack 00007fff5f400000-00007fff5fc00000 [ 8192K] rw-/rwx SM=COW thread 0
How would I go about telling RubyMotion forget about this block in terms of the stack trace?