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[Libcdio-devel] MMC source code changes

From: Rocky Bernstein
Subject: [Libcdio-devel] MMC source code changes
Date: Sun, 7 Feb 2010 22:06:00 -0500

It looks like mmc code will be expanding a bit. Furthermore, I think we want
to turn this into a library. From my standpoint, a library inside libcdio is
the easiest. But even if it is moved out, making it a library inside libcdio
is a useful and easier step.

Still it is more involved than I want to directly undertake right now. So
first some smaller changes.

A little background about things in lib/driver. Files that are related and
form a unit I have been putting in its own directory. For example the
various image drivers (BIN/CUE, TOC, Nero) located in lib/driver/image. So
mmc-related things are now in lib/driver/mmc. The individual files in that
directory start mmc_, but of course when this becomes its own library then I
can drop the mmc_ prefix which I hope to do.

Previously there was just one source code file here mmc.c. However it looks
like we want to layer the code at least 3 files.

One file contains low-level stuff like things that turn enumerations/indices
into strings, like mmc_sense_key2str[] or Frank's mmc_is_... routines. That
currently remains in mmc.c, but under directory mmc.c now. If this were a
library I might call it core.c or something like that. There is code in
mmc.c that should probably be moved to one of the other files, but I haven't
gotten around to it.

A second file contains the largely 1-1 SCSI-MMC commands. That is now called
mmc/mmc_ll_cmds.c for "low-level commands". Please note that I've spend some
effort to reduce the boilerplate code that appears everywhere in issuing MMC

In some of the original tests that Thomas wrote, he duplicated cod to issue
MMC commands that already was in mmc.c. In other cases where the MMC command
needed in a test didn't previously exist, I have now created them. In
particular mmc_mode_select() and mmc_test_unit_ready().

A third file contains the higher-level MMC functions mmc/mmc_hl_cmds.c (hl
for "higher level"). The thought is that they would largely call the
lower-level routines to get things done. Important is the fact that you
shouldn't have to issue an MMC command directly.

So consider Frank's mmc_get_disctype() routine. It issues a MMC GET
CONFIGURATION command, customized for its particular needs and then it
parses the profiles returned. Probably the profile parsing part is something
that will be used over and over in different situations so that aspect of it
would probably be a function in what is now called mmc.c.

But rather than issue a MMC GET CONFIGURATION in mmc_get_disctype by
declaring and initializing a CDB variable, I added the more generic GET
CONFIGURATION routine in mmc_ll_cmds.c. It is called

I am not thrilled about the choice of file names mmc.c, mmc_ll_cmds.c and
mmc_hl_cmds.c. It is likely that these file names when we come up with
better ones.

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