Re: [Libcdio-help] reading the whole 2352 bytes from every type of sector

[R. Bernstein]

Matheus Izvekov writes:
 > Well to simplify things, imagine i want to implement a cdrom drive
 > emulator, like daemon-tools, using libcdio.
 > Do you see the issues now? 

No. 

If you find as you go along that some things are missing and/or better
suited in libcdio, it can be put in. (It will go a lot faster though
if you submit a patch and a regression tests ;-) One thing others have
done is put the support in their packages first to test things out and
before suggesting addition to libcdio.

 > What I am doing is just implementing the
 > playstation cdrom drive. Some times the user
 > (a game for example, not the guy on the control pad) will issue a
 > command to read the whole 2352 bytes of a sector,
 > and the real psx just accepts and does that correctly, no matter what
 > kind of sector it is.

Okay. Just keep in mind that a raw read, that is, a MMC GP_CMD_READ
issued via mmc_read_sectors() with a read type CDIO_MMC_READ_TYPE_ANY,
isn't the same as a redbook cd-audio read. I probably need to add
another "mode" to cd-read which will help make this more explicit.

 > >  The mmc_* routines issue multimedia commands to a CD-ROM drive. Some
 > >  support for simulating CD-ROM behavior is tolerated but there is only
 > >  so far one can go pretending an image file is a CD-ROM. With some
 > >  effort, possibly one can jimmy up routines to always return false if
 > >  you ask if the media has been changed, but what does it mean to
 > >  "eject" a CD image file? (I think here libcdio returns a status like
 > >  "not supported")
 > 
 > It seems like a good compromise, although I dont see a dilemma here.

Not a dilemma so much as something that can be painstakingly difficult
with vanishingly small returns. You want to fake up the 3 or so
versions of the MMC INQUIRY commands?

 > For the operations that dont make sense, just dont implement them like you 
 > said.
 > And for a CD image file, almost everything makes sense, except maybe
 > in case of libcdio eject itself.
 > For an example of this take a look at daemon-tools. And they even
 > implement ejecting....
 > 
 > >
 > >   >
 > >   > The weird thing is that doing the same thing on a image file, 
 > > cddio_read_sector
 > >   > doesnt return an error, but gives some garbage instead.
 > >
 > >  Perhaps an error should be returned. The weird thing to me is that you
 > >  seem to want to just try any a read of a sector in audio format,
 > >  whether it makes sense or not. There is a saying: garbage in, garbage
 > >  out.
 > >
 > >
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 > >
 >