(I'm a big paged out today and not really keeping up, but wanted to comment quickly since I was asked.)
"Thomas Schmitt" <scdbac...@gmx.net> writes: > Edd Barrett wrote: >> Is it important, though, to offer up both addressing modes for consumers >> of libcdio? Or is it not exposed that way? >> Put differently, if the underlying OS supports both addressing modes, >> should we implement both callbacks in the driver. > > The libcdio API has functions for LBA addressing and for MSF addressing. > > On operating system level, only one of both address modes would need to > be supported, because the implementation of libcdio seems to expect > this and uses the supported format with subsequent conversion to the > desired format. See in track.c cdio_get_track_lba(), cdio_get_track_msf(). > > I.e in > static cdio_funcs_t _funcs > at least one of > .get_track_lba > .get_track_msf > must be non-NULL. Not much benefit seems gained if both are non-NULL. > > Important is that the functions of the netbsd.c driver know which format > they get from their interface to the operating system, _cdio_read_toc(). > The netbsd.c driver assumes that MSF is delivered. > But the OpenBSD driver from which you take code obviously assumes that > LBA adresses are delivered. > > You need to unify this. My proposal is to let _cdio_read_toc() deliver MSF > on both systems. If OpenBSD cannot deliver MSF to _cdio_read_toc(), then > let it deliver LBA and convert the result to MSF. (See mail of yesterday.) > > If you decide to keep get_track_lba_netbsd(), then you need to adapt it > to _cdio_read_toc() delivering MSF. This all sounds sensible to me. Definitely the code needs to keep track of which is which especially with unions. Going out on a limb maybe more than I should, it seems like the CD world prefers MSF as the main thing, so trying to be in that format as much as possible seems good. If so having OpenBSD-specific code to use LBA if that's needed and get back to MSF as fast as possible seems like it will cause the least confusion long term. > (I still doubt that OpenBSD cannot deliver MSF. In the end it is about > a field in SCSI command READ TOC/PMA/ATIP. But exploring this is a new > adventure which we can easily avoid by result conversion.) Agreed on both counts, and I have zero clue about the actual details.
