[pypy-dev] RPython function callback from C

[Hart's Antler]

I have the PortAudio blocking API working, simple reading and writing to the sound card works.  PortAudio also has an async API where samples are fed to a callback as they stream in.  But i'm not sure how to define a RPython function that will be called as a callback from C, is this even possible?  I see some references in the source of rffi that seems to suggest it is possible.  Full source code is here http://pastebin.com/6YHbT7CU


I'm passing the callback like this:

def stream_callback( *args ):
	print 'stream callback'
	return 0		# 0=continue, 1=complete, 2=abort

stream_callback_ptr = rffi.CCallback([], rffi.INT)

OpenDefaultStream = rffi.llexternal(	'Pa_OpenDefaultStream', 
	[
		StreamRefPtr,		# PaStream** 
		rffi.INT, 		# numInputChannels
		rffi.INT, 		# numOutputChannels
		rffi.INT, 		# sampleFormat
		rffi.DOUBLE, 		# double sampleRate
		rffi.INT, 		# unsigned long framesPerBuffer
		#rffi.VOIDP,		#PaStreamCallback *streamCallback
		stream_callback_ptr,
		rffi.VOIDP,		#void *userData
	],	
	rffi.INT,		# return
	compilation_info=eci,
	_callable=stream_callback
)

entrypoint():
   ...
   callback = lltype.nullptr( stream_callback_ptr.TO )
   ok = OpenDefaultStream( streamptr, 2, 2, Int16, 22050.0, 512, callback, userdata )