[linux-audio-dev] strange jack ringbuffer problem

I've been banging my head against this one all evening. Now I'm going to go to sleep on it, but I throw it out for the wiser and more experienced to see if you can see my error. The code is at http://fugal.net/~fugalh/src/alex which you are welcome to refer to and critique. It segfaults on line 171 of jack.cc, but not if I comment out line 158 (or use 0 for the second argument). It seems to segfault once input_rb is nearly or completely to the end (not full, since it is being drained by the other thread; it's just as it would wrap around). The autopsy shows that it is segfaulting because output_rb and consequentially vec is completely hosed. What I don't understand is how jack_ringbuffer_write_advance(input_rb, something_plenty_small) could possibly hose output_rb. something_plenty_small is usually on the order of 160 bytes. I'm running jackd with a 512 byte buffer at 48000Hz. (gdb) bt #0 0xb7f91253 in src_short_to_float_array () from /usr/lib/libsamplerate.so.0 #1 0x0804a01c in Jack::jack_process (this=0xbffff300, nframes=512, arg=0xbffff300) at jack.cc:171 #2 0x08049d87 in Jack::jack_process_wrapper (nframes=512, arg=0xbffff300) at jack.cc:114 #3 0xb7fb255d in jack_stop_freewheel () from /usr/lib/libjack-0.80.0.so.0 #4 0xb7d639b4 in start_thread () from /lib/tls/libpthread.so.0 #5 0x00000000 in ?? () (gdb) up #1 0x0804a01c in Jack::jack_process (this=0xbffff300, nframes=512, arg=0xbffff300) at jack.cc:171 171 src_short_to_float_array((short*)vec[i].buf, buf, vframes); (gdb) p *output_rb $1 = {buf = 0xd0b0c860 <Address 0xd0b0c860 out of bounds>, write_ptr = 92858992, read_ptr = 88669736, size = 4291362712, size_mask = 13171512, mlocked = 3735008} (gdb) p vec $2 = {{buf = 0xd5f9c688 <Address 0xd5f9c688 out of bounds>, len = 4189256}, { buf = 0x804d028 "����", len = 0}} (gdb) p *input_rb $3 = {buf = 0x804d028 "����", write_ptr = 16266, read_ptr = 16266, size = 16384, size_mask = 16383, mlocked = 0} I hope someone can see what I'm doing wrong. Consider the code under the GPL. -- .O. Hans Fugal | De gustibus non disputandum est. ..O http://hans.fugal.net | Debian, vim, mutt, ruby, text, gpg OOO | WindowMaker, gaim, UTF-8, RISC, JS Bach --------------------------------------------------------------------- GnuPG Fingerprint: 6940 87C5 6610 567F 1E95 CB5E FC98 E8CD E0AA D460