HelenOS sources

hda_get_subnc     516 uspace/drv/audio/hdaudio/codec.c 	rc = hda_get_subnc(codec, 0, &sfg, &nfg);
hda_get_subnc     548 uspace/drv/audio/hdaudio/codec.c 		rc = hda_get_subnc(codec, fg, &saw, &naw);
HelenOS homepage, sources at GitHub