$Id: README.aztcd,v 1.90 1995/10/21 17:52:16 root Exp root $
Readme-File README.aztcd
for Aztech CD-ROM CDA268-01A, ORCHID CD-3110,
OKANO/WEARNES CDD110, Conrad TXC
CD-ROM Driver
Version 1.9 and newer
(for other drives see 6.-8.)
NOTE: THIS DRIVER WILL WORK WITH THE CD-ROM DRIVES LISTED, WHICH HAVE
A PROPRIETARY INTERFACE (implemented on a sound card or on a
ISA-AT-bus card).
IT WILL DEFINITELY NOT WORK WITH CD-ROM DRIVES WITH *IDE*-INTERFACE,
such as the Aztech CDA269-031SE !!! IF YOU'RE USING A CD-ROM DRIVE
WITH IDE-INTERFACE, SOMETIMES ALSO CALLED ATAPI-COMPATIBLE, PLEASE
USE THE ide-cd.c DRIVER, WRITTEN BY MARK LORD AND SCOTT SNYDER !
THE STANDARD-KERNEL 1.2.x NOW ALSO SUPPORTS IDE-CDROM-DRIVES, SEE THE
HARDDISK (!) SECTION OF make config, WHEN COMPILING A NEW KERNEL!!!
----------------------------------------------------------------------------
Contents of this file:
1. NOTE
2. INSTALLATION
3. CONFIGURING YOUR KERNEL
4. RECOMPILING YOUR KERNEL
4.1 AZTCD AS A RUN-TIME LOADABLE MODULE
4.2 CDROM CONNECTED TO A SOUNDCARD
5. KNOWN PROBLEMS, FUTURE DEVELOPMENTS
5.1 MULTISESSION SUPPORT
5.2 STATUS RECOGNITION
5.3 DOSEMU's CDROM SUPPORT
6. BUG REPORTS
7. OTHER DRIVES
8. IF YOU DON'T SUCCEED ... DEBUGGING
9. TECHNICAL HISTORY OF THE DRIVER
10. ACKNOWLEDGMENTS
11. PROGRAMMING ADD ONS: CDPLAY.C
APPENDIX: Source code of cdplay.c
----------------------------------------------------------------------------
1. NOTE
This software has been successfully in alpha and beta test and is part of
the standard kernel since kernel 1.1.8x since December 1994. It works with
time with AZTECH CDA268-01A, ORCHID CDS-3110, ORCHID/WEARNES CDD110 and
CONRAD TXC (Nr.99 31 23 -series 04) and has proven to be stable with kernel
versions 1.0.9 to 1.3.35. But with any software there still may be bugs in it.
So if you encounter problems, you are invited to help us improve this software.
Please send me a detailed bug report (see chapter BUG REPORTS). You are also
invited in helping us to increase the number of drives, which are supported.
Please read the README-files carefully and always keep a backup copy of your
old kernel, in order to reboot if something goes wrong!
2. INSTALLATION
The driver consists of a header file 'aztcd.h', which normally should reside
in /usr/include/linux and the source code 'aztcd.c', which normally resides in
/usr/src/linux/drivers/block. It uses /dev/aztcd (/dev/aztcd0 in some distri-
butions), which must be a valid block device with major number 29 and reside
in directory /dev. To mount a CD-ROM, your kernel needs to have the ISO9660-
filesystem support included.
PLEASE NOTE: aztcd.c has been developped in parallel to the linux kernel,
which had and is having many major and minor changes which are not backward
compatible. Quite definitely aztcd.c version 1.80 and newer will NOT work
in kernels older than 1.3.33. So please always use the most recent version
of aztcd.c with the appropriate linux-kernel.
3. CONFIGURING YOUR KERNEL
If your kernel is already configured for using the AZTECH driver you will
see the following message while Linux boots:
Aztech CD-ROM Init: DriverVersion=<version number> BaseAddress=<baseaddress>
Aztech CD-ROM Init: FirmwareVersion=<firmware version id of your I/O-card>>>
Aztech CD-ROM Init: <drive type> detected
Aztech CD-ROM Init: End
If the message looks different and you are sure to have a supported drive,
it may have a different base address. The Aztech driver does look for the
CD-ROM drive at the base address specified in aztcd.h at compile time. This
address can be overwritten by boot parameter aztcd=....You should reboot and
start Linux with boot parameter aztcd=<base address>, e.g. aztcd=0x320. If
you do not know the base address, start your PC with DOS and look at the boot
message of your CD-ROM's DOS driver. If that still does not help, use boot
parameter aztcd=<base address>,0x79 , this tells aztcd to try a little harder.
If the message looks correct, as user 'root' you should be able to mount the
drive by
mount -t iso9660 -r /dev/aztcd0 /mnt
and use it as any other filesystem. (If this does not work, check if
/dev/aztcd0 and /mnt do exist and create them, if necessary by doing
mknod /dev/aztcd0 b 29 0
mkdir /mnt
If you still get a different message while Linux boots or when you get the
message, that the ISO9660-filesystem is not supported by your kernel, when
you try to mount the CD-ROM drive, you have to recompile your kernel.
If you do *not* have an Aztech/Orchid/Okano/Wearnes/TXC drive and want to
bypass drive detection during Linux boot up, start with boot parameter aztcd=0.
Most distributions nowadays do contain a boot disk image containing aztcd.
Please note, that this driver will not work with IDE/ATAPI drives! With these
you must use ide-cd.c instead.
4. RECOMPILING YOUR KERNEL
If your kernel is not yet configured for the AZTECH driver and the ISO9660-
filesystem, you have to recompile your kernel:
- Edit aztcd.h to set the I/O-address to your I/O-Base address (AZT_BASE_ADDR),
the driver does not use interrupts or DMA, so if you are using an AZTECH
CD268, an ORCHID CD-3110 or ORCHID/WEARNES CDD110 that's the only item you
have to set up. If you have a soundcard, read chapter 4.2.
Users of other drives should read chapter OTHER DRIVES of this file.
You also can configure that address by LILO boot parameter aztcd=...
- There are some other points, which may be configured, e.g. auto-eject the
CD when umounting a drive, tray locking etc., see aztcd.h for details.
- Build a new kernel, configure it for 'Aztech/Orchid/Okano/Wearnes support'
(if you want aztcd to be part of the kernel). Do not configure it for
'Aztech... support', if you want to use aztcd as a run time loadable module.
But in any case you must have the ISO9660-filesystem included in your
kernel.
- Activate the new kernel, normally this is done by running lilo (don't for-
get to configure it before and to keep a copy of your old kernel in case
something goes wrong!).
- Reboot
- If you've included aztcd in your kernel, you now should see during boot
some messages like
Aztech CD-ROM Init: DriverVersion=<version number> BaseAddress=<baseaddress>
Aztech CD-ROM Init: FirmwareVersion=<firmware version id of your I/O-card>
Aztech CD-ROM Init: <drive type> detected
Aztech CD-ROM Init: End
- If you have not included aztcd in your kernel, but want to load aztcd as a
run time loadable module see 4.1.
- If the message looks correct, as user 'root' you should be able to mount
the drive by
mount -t iso9660 -r /dev/aztcd0 /mnt
and use it as any other filesystem. (If this does not work, check if
/dev/aztcd0 and /mnt do exist and create them, if necessary by doing
mknod /dev/aztcd0 b 29 0
mkdir /mnt
- If this still does not help, see chapters OTHER DRIVES and DEBUGGING.
4.1 AZTCD AS A RUN-TIME LOADABLE MODULE
If you do not need aztcd permanently, you can also load and remove the driver
during runtime via insmod and rmmod. To build aztcd as a loadable module you
must configure your kernel for AZTECH module support (answer 'm' when con-
figuring the kernel). Anyhow, you may run into problems, if the version of
your boot kernel is not the same than the source kernel version, from which
you create the modules. So rebuild your kernel, if necessary.
Now edit the base address of your AZTECH interface card in
/usr/src/linux/include/linux/aztcd.h to the appropriate value. There are
also some special features which may be configured, e.g. auto-eject a CD
when unmounting the drive etc; see aztcd.h for details. Then change
to /usr/src/linux and do a
make modules
make modules_install
After that you can run-time load the driver via
insmod /lib/modules/X.X.X/misc/aztcd.o
and remove it via rmmod aztcd.
If you did not set the correct base address in aztcd.h, you can also supply the
base address when loading the driver via
insmod /lib/modules/X.X.X/misc/aztcd.o aztcd=<base address>
If you do not have the iso9660-filesystem in your boot kernel, you also have
to load it before you can mount the CDROM:
insmod /lib/modules/X.X.X/fs/isofs.o
The mount procedure works as described in 4. above.
(In all commands 'X.X.X' is the current linux kernel version number. For details
see file README.modules in /usr/src/linux.)
4.2 CDROM CONNECTED TO A SOUNDCARD
Most soundcards do have a bus interface to the CDROM-drive. In many cases
this soundcard needs to be configured, before the CDROM can be used. This
configuration procedure consists of writing some kind of initialization
data to the soundcard registers. The AZTECH-CDROM driver in the moment does
only support one type of soundcard (SoundWave32). Users of other soundcards
should try to boot DOS first and let their DOS drivers initialize the
soundcard and CDROM, then warm boot (or use loadlin) their PC to start
Linux.
Support for the CDROM-interface of SoundWave32-soundcards is directly
implemented in the AZTECH driver. Please edit /usr/src/linux/include/aztdc.h,
uncomment line '#define AZT_SW32' and set the appropiate value for
AZT_BASE_ADDR and AZT_SW32_BASE_ADDR. This support was tested with an Orchid
CDS-3110 connected to a SoundWave32.
If you want your soundcard to be supported, find out, how it needs to be
configured and mail me (see 6.) the appropriate information.
5. KNOWN PROBLEMS, FUTURE DEVELOPMENTS
5.1 MULTISESSION SUPPORT
Multisession support for CD's still is a myth. I implemented and tested a basic
support for multisession and XA CDs, but I still have not enough CDs and appli-
cations to test it rigourously. So if you'd like to help me, please contact me
(Email address see below). As of version 1.4 and newer you can enable the
multisession support in aztcd.h by setting AZT_MULTISESSION to 1. Doing so
will cause the ISO9660-filesystem to deal with multisession CDs, ie. redirect
requests to the Table of Contents (TOC) information from the last session,
which contains the info of all previous sessions etc.. If you do set
AZT_MULTISESSION to 0, you can use multisession CDs anyway. In that case the
drive's firmware will do automatic redirection. For the ISO9660-filesystem any
multisession CD will then look like a 'normal' single session CD. But never-
theless the data of all sessions are viewable and accessible. So with practical-
ly all real world applications you won't notice the difference. But as future
applications may make use of advanced multisession features, I've started to
implement the interface for the ISO9660 multisession interface via ioctl
CDROMMULTISESSION.
5.2 STATUS RECOGNITION
The drive status recognition does not work correctly in all cases. Changing
a disk or having the door open, when a drive is already mounted, is detected
by the Aztech driver itself, but nevertheless causes multiple read attempts
by the different layers of the ISO9660-filesystem driver, which finally timeout,
so you have to wait quite a little... But isn't it bad style to change a disk
in a mounted drive, anyhow ?!
The driver uses busy wait in most cases for the drive handshake (macros
STEN_LOW and DTEN_LOW). I tested with a 486/DX2 at 66MHz and a Pentium at
60MHz and 90MHz. Whenever you use a much faster machine you are likely to get
timeout messages. In that case edit aztcd.h and increase the timeout value
AZT_TIMEOUT.
For some 'slow' drive commands I implemented waiting with a timer waitqueue
(macro STEN_LOW_WAIT). If you get this timeout message, you may also edit
aztcd.h and increase the timeout value AZT_STATUS_DELAY. The waitqueue has
shown to be a little critical. If you get kernel panic messages, edit aztcd.c
and substitute STEN_LOW_WAIT by STEN_LOW. Busy waiting with STEN_LOW is more
stable, but also causes CPU overhead.
5.3 DOSEMU's CD-ROM SUPPORT
With release 1.20 aztcd was modified to allow access to CD-ROMS when running
under dosemu-0.60.0 aztcd-versions before 1.20 are most likely to crash
Linux, when a CD-ROM is accessed under dosemu. This problem has partly been
fixed, but still when accessing a directory for the first time the system
might hang for some 30sec. So be patient, when using dosemu's CD-ROM support
in combination with aztcd :-) !
This problem has now (July 1995) been fixed by a modification to dosemu's
CD-ROM driver. The new version came with dosemu-0.60.2, see dosemu's
README.CDROM.
6. BUG REPORTS
Please send detailed bug reports and bug fixes via EMail to
zimmerma@rz.fht-esslingen.de
Please include a description of your CD-ROM drive type and interface card,
the exact firmware message during Linux bootup, the version number of the
AZTECH-CDROM-driver and the Linux kernel version. Also a description of your
system's other hardware could be of interest, especially microprocessor type,
clock frequency, other interface cards such as soundcards, ethernet adapter,
game cards etc..
I will try to collect the reports and make the necessary modifications from
time to time. I may also come back to you directly with some bug fixes and
ask you to do further testing and debugging.
Editors of CD-ROMs are invited to send a 'cooperation' copy of their
CD-ROMs to the volunteers, who provided the CD-ROM support for Linux. My
snail mail address for such 'stuff' is
Prof. Dr. W. Zimmermann
Fachhochschule fuer Technik Esslingen
Fachbereich NT
Flandernstrasse 101
D-73732 Esslingen
Germany
7. OTHER DRIVES
The following drives ORCHID CDS3110, OKANO CDD110, WEARNES CDD110 and Conrad
TXC Nr. 993123-series 04 nearly look the same as AZTECH CDA268-01A, especially
they seem to use the same command codes. So it was quite simple to make the
AZTECH driver work with these drives.
Unfortunately I do not have any of these drives available, so I couldn't test
it myself. But I've got reports, that it works with ORCHID CDS3110 and Game-
Wave32 sound cards and also with WEARNES CDD110 and Conrad TXC in some different
combinations. In some installations, it seems necessary to initialize the drive
with the DOS driver before (especially if combined with a sound card) and then
do a warm boot (CTRL-ALT-RESET) or start Linux from DOS, e.g. with 'loadlin'.
If you do not succeed, read chapter DEBUGGING. Thanks in advance!
Sorry for the inconvenience, but it is difficult to develop for hardware,
which you don't have available for testing. So if you like, please help us.
8. DEBUGGING : IF YOU DON'T SUCCEED, TRY THE FOLLOWING
-reread the complete README file
-make sure, that your drive is hardware configured for
transfer mode: polled
IRQ: not used
DMA: not used
Base Address: something like 300, 320 ...
You can check this, when you start the DOS driver, which came with your
drive. By appropriately configuring the drive and the DOS driver you can
check, whether your drive does operate in this mode correctly under DOS. If
it does not operate under DOS, it won't under Linux.
If your drive's base address is something like 0x170 or 0x1F0 you most
likely are having a IDE/ATAPI-compatible drive, which is not supported by
aztcd.c, use ide-cd.c instead.
Make sure the Base Address is configured correctly in aztcd.h, also make
sure, that /dev/aztcd0 exists with the correct major number (compare it with
the entry in file /usr/include/linux/major.h for the Aztech drive).
-insert a CD-ROM and close the tray
-cold boot your PC (i.e. via the power on switch or the reset button)
-if you start Linux via DOS, e.g. using loadlin, make sure, that the DOS
driver for the CD-ROM drive is not loaded (comment out the calling lines
in DOS' config.sys!)
-look for the aztcd: init message during Linux init and note them exactly
-log in as root and do a mount -t iso9660 /dev/aztcd0 /mnt
-if you don't succeed in the first time, try several times. Try also to open
and close the tray, then mount again. Please note carefully all commands
you typed in and the aztcd-messages, which you get.
-if you get an 'Aztech CD-ROM init: aborted' message, read the remarks about
the version string below.
If this does not help, do the same with the following differences
-start DOS before; make now sure, that the DOS driver for the CD-ROM is
loaded under DOS (i.e. uncomment it again in config.sys)
-warm boot your PC (i.e. via CTRL-ALT-DEL)
if you have it, you can also start via loadlin (try both).
...
Again note all commands and the aztcd-messages.
If you see STEN_LOW or STEN_LOW_WAIT error messages, increase the timeout
values.
If this still does not help,
-look in aztcd.c for the lines #if 0
#define AZT_TEST1
...
#endif
and substitute '#if 0' by '#if 1'.
-recompile your kernel and repeat the above two procedures. You will now get
a bundle of debugging messages from the driver. Again note your commands
and the appropriate messages. If you have syslogd running, these messages
may also be found in syslogd's kernel log file. Nevertheless in some
installations syslogd does not yet run, when init() is called, thus look for
the aztcd-messages during init, before the login-prompt appears.
Then look in aztcd.c, to find out, what happened. The normal calling sequence
is: aztcd_init() during Linux bootup procedure init()
after doing a 'mount -t iso9660 /dev/aztcd0 /mnt' the normal calling sequence is
aztcd_open() -> Status 2c after cold reboot with CDROM or audio CD inserted
-> Status 8 after warm reboot with CDROM inserted
-> Status 2e after cold reboot with no disk, closed tray
-> Status 6e after cold reboot, mount with door open
aztUpdateToc()
aztGetDiskInfo()
aztGetQChannelInfo() repeated several times
aztGetToc()
aztGetQChannelInfo() repeated several times
a list of track informations
do_aztcd_request() }
azt_transfer() } repeated several times
azt_poll }
Check, if there is a difference in the calling sequence or the status flags!
There are a lot of other messages, eg. the ACMD-command code (defined in
aztcd.h), status info from the getAztStatus-command and the state sequence of
the finite state machine in azt_poll(). The most important are the status
messages, look how they are defined and try to understand, if they make
sense in the context where they appear. With a CD-ROM inserted the status
should always be 8, except in aztcd_open(). Try to open the tray, insert a
audio disk, insert no disk or reinsert the CD-ROM and check, if the status
bits change accordingly. The status bits are the most likely point, where
the drive manufacturers may implement changes.
If you still don't succeed, a good point to start is to look in aztcd.c in
function aztcd_init, where the drive should be detected during init. Do the
following:
-reboot the system with boot parameter 'aztcd=<your base address>,0x79'. With
parameter 0x79 most of the drive version detection is bypassed. After that
you should see the complete version string including leading and trailing
blanks during init.
Now adapt the statement
if ((result[1]=='A')&&(result[2]=='Z' ...)
in aztcd_init() to exactly match the first 3 or 4 letters you have seen.
-Another point is the 'smart' card detection feature in aztcd_init(). Normally
the CD-ROM drive is ready, when aztcd_init is trying to read the version
string and a time consuming ACMD_SOFT_RESET command can be avoided. This is
detected by looking, if AFL_OP_OK can be read correctly. If the CD-ROM drive
hangs in some unknown state, e.g. because of an error before a warm start or
because you first operated under DOS, even the version string may be correct,
but the following commands will not. Then change the code in such a way,
that the ACMD_SOFT_RESET is issued in any case, by substituting the
if-statement 'if ( ...=AFL_OP_OK)' by 'if (1)'.
If you succeed, please mail may the exact version string of your drive and
the code modifications, you have made together with a short explanation.
If you don't succeed, you may mail me the output of the debugging messages.
But remember, they are only useful, if they are exact and complete and you
describe in detail your hardware setup and what you did (cold/warm reboot,
with/without DOS, DOS-driver started/not started, which Linux-commands etc.)
9. TECHNICAL HISTORY OF THE DRIVER
The AZTECH-Driver is a rework of the Mitsumi-Driver. Four major items had to
be reworked:
a) The Mitsumi drive does issue complete status information acknowledging
each command, the Aztech drive does only signal that the command was
processed. So whenever the complete status information is needed, an extra
ACMD_GET_STATUS command is issued. The handshake procedure for the drive
can be found in the functions aztSendCmd(), sendAztCmd() and getAztStatus().
b) The Aztech Drive does not have a ACMD_GET_DISK_INFO command, so the
necessary info about the number of tracks (firstTrack, lastTrack), disk
length etc. has to be read from the TOC in the lead in track (see function
aztGetDiskInfo()).
c) Whenever data is read from the drive, the Mitsumi drive is started with a
command to read an indefinite (0xffffff) number of sectors. When the appropriate
number of sectors is read, the drive is stopped by a ACDM_STOP command. This
does not work with the Aztech drive. I did not find a way to stop it. The
stop and pause commands do only work in AUDIO mode but not in DATA mode.
Therefore I had to modify the 'finite state machine' in function azt_poll to
only read a certain number of sectors and then start a new read on demand. As I
have not completely understood, how the buffer/caching scheme of the Mitsumi
driver was implemented, I am not sure, if I have covered all cases correctly,
whenever you get timeout messages, the bug is most likely to be in that
function azt_poll() around switch(cmd) .... case ACD_S_DATA.
d) I did not get information about changing drive mode. So I doubt, that the
code around function azt_poll() case AZT_S_MODE does work. In my test I have
not been able to switch to reading in raw mode. For reading raw mode, Aztech
uses a different command than for cooked mode, which I only have implemen-
ted in the ioctl-section but not in the section which is used by the ISO9660-
The driver was developed on an AST PC with Intel 486/DX2, 8MB RAM, 340MB IDE
hard disk and on an AST PC with Intel Pentium 60MHz, 16MB RAM, 520MB IDE
running Linux kernel version 1.0.9 from the LST 1.8 Distribution. The kernel
was compiled with gcc.2.5.8. My CD-ROM drive is an Aztech CDA268-01A. My
drive says, that it has Firmware Version AZT26801A1.3. It came with a ISA-bus
interface card and works with polled I/O without DMA and without interrupts.
The code for all other drives was 'remote' tested and debugged by a number of
volunteers on the Internet.
Points, where I feel that possible problems might be and all points where I
did not completely understand the drive's behaviour or trust my own code are
marked with /*???*/ in the source code. There are also some parts in the
Mitsumi driver, where I did not completely understand their code.
10. ACKNOWLEDGMENTS
Without the help of P.Bush, Aztech, who delivered technical information
about the Aztech Drive and without the help of E.Moenkeberg, GWDG, who did a
great job in analyzing the command structure of various CD-ROM drives, this
work would not have been possible. E.Moenkeberg was also a great help in
making the software 'kernel ready' and in answering many of the CDROM-related
questions in the newsgroups. He really is *the* Linux CD-ROM guru. Thanks
also to all the guys on the Internet, who collected valuable technical
information about CDROMs.
Joe Nardone (joe@access.digex.net) was a patient tester even for my first
trial, which was more than slow, and made suggestions for code improvement.
Especially the 'finite state machine' azt_poll() was rewritten by Joe to get
clean C code and avoid the ugly 'gotos', which I copied from mcd.c.
Robby Schirmer (schirmer@fmi.uni-passau.de) tested the audio stuff (ioctls)
and suggested a lot of patches for them.
Joseph Piskor and Peter Nugent were the first users with the ORCHID CD3110
and also were very patient with the problems which occurred.
Reinhard Max delivered the information for the CDROM-interface of the
SoundWave32 soundcards.
Jochen Koch and Olaf ? delivered the information for supporting Conrad's TXC
drive.
Anybody, who is interested in these items should have a look at 'ftp.gwdg.de',
directory 'pub/linux/cdrom' and at 'ftp.cdrom.com', directory 'pub/cdrom'.
11. PROGRAMMING ADD ONs: cdplay.c
You can use the ioctl-functions included in aztcd.c in your own programs. As
an example on how to do this, you will find a tiny CD Player for audio CDs
named 'cdplay.c'. It allows you to play audio CDs. You can play a specified
track, pause and resume or skip tracks forward and backwards. If you quit the
program without stopping the drive, playing is continued. You can also
(mis)use cdplay to read and hexdump data disks.
'cdplay.c' can be found as a separate file in package AZTECH.CDROM.Vxx.tgz.
If you don't have it, you can find the code in the APPENDIX of this file,
which you should cut out with an editor and store in a separate file
'cdplay.c'. To compile it and make it executable, do
gcc -s -Wall -O2 -L/usr/lib cdplay.c -o /usr/local/bin/cdplay # compiles it
chmod +755 /usr/local/bin/cdplay # makes it executable
ln -s /dev/aztcd0 /dev/cdrom # creates a link
(for /usr/lib substitute the top level directory, where your include files
reside, and for /usr/local/bin the directory, where you want the executable
binary to reside )
You have to set the correct permissions for cdplay *and* for /dev/mcd0 or
/dev/aztcd0 in order to use it. Remember, that you should not have /dev/cdrom
mounted, when you're playing audio CDs.
This program is just a hack for testing the ioctl-functions in aztcd.c, I will
not maintain it, so if you run into problems, discard it or have a look into
the source code 'cdplay.c'. The program does only contain a minimum of user
protection and input error detection. If you use the commands in the wrong
order or if you try to read a CD at wrong addresses, you may get error messages
or even hang your machine. If you get STEN_LOW, STEN_LOW_WAIT or segment violation
error messages when using cdplay, after that, the system might not be stable
any more, so you'd better reboot. As the ioctl-functions run in kernel mode,
most normal Linux-multitasking protection features do not work. By using
uninitialized 'wild' pointers etc., it is easy to write to other users data and
program areas, destroy kernel tables etc.. So if you experiment with ioctls
as always when you are doing systems programming and kernel hacking, you
should have a backup copy of your system in a safe place (and you also
should try before, how to restore from a backup copy)!
Werner Zimmermann
Fachhochschule fuer Technik Esslingen
(EMail: zimmerma@rz.fht-esslingen.de)
October 21, 1995
---------------------------------------------------------------------------
APPENDIX: Source code of cdplay.c
/* Tiny Audio CD Player
Copyright 1994, 1995 Werner Zimmermann (zimmerma@rz.fht-esslingen.de)
This program originally was written to test the audio functions of the
AZTECH.CDROM-driver, but it should work with every CD-ROM drive. Before
using it, you should set a symlink from /dev/cdrom to your real CDROM
device.
The GNU General Public License applies to this program.
History: V0.1 W.Zimmermann: First release. Nov. 8, 1994
V0.2 W.Zimmermann: Enhanced functionality. Nov. 9, 1994
V0.3 W.Zimmermann: Additional functions. Nov. 28, 1994
V0.4 W.Zimmermann: fixed some bugs. Dec. 17, 1994
V0.5 W.Zimmermann: clean 'scanf' commands without compiler warnings
Jan. 6, 1995
V0.6 W.Zimmermann: volume control (still experimental). Jan. 24, 1995
V0.7 W.Zimmermann: read raw modified. July 26, 95
*/
#include <stdio.h>
#include <ctype.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <fcntl.h>
#include <unistd.h>
#include <linux/cdrom.h>
#include <linux/aztcd.h>
void help(void)
{ printf("Available Commands: STOP s EJECT/CLOSE e QUIT q\n");
printf(" PLAY TRACK t PAUSE p RESUME r\n");
printf(" NEXT TRACK n REPEAT LAST l HELP h\n");
printf(" SUB CHANNEL c TRACK INFO i PLAY AT a\n");
printf(" READ d READ RAW w VOLUME v\n");
}
int main(void)
{ int handle;
unsigned char command=' ', ini=0, first=1, last=1;
unsigned int cmd, i,j,k, arg1,arg2,arg3;
struct cdrom_ti ti;
struct cdrom_tochdr tocHdr;
struct cdrom_subchnl subchnl;
struct cdrom_tocentry entry;
struct cdrom_msf msf;
union { struct cdrom_msf msf;
unsigned char buf[CD_FRAMESIZE_RAW];
} azt;
struct cdrom_volctrl volctrl;
printf("\nMini-Audio CD-Player V0.71 (C) 1994,1995 W.Zimmermann\n");
handle=open("/dev/cdrom",O_RDWR);
ioctl(handle,CDROMRESUME);
if (handle<=0)
{ printf("Drive Error: already playing, no audio disk, door open\n");
printf(" or no permission (you must be ROOT in order to use this program)\n");
}
else
{ help();
while (1)
{ printf("Type command (h = help): ");
scanf("%s",&command);
switch (command)
{ case 'e': cmd=CDROMEJECT;
ioctl(handle,cmd);
break;
case 'p': if (!ini)
{ printf("Command not allowed - play track first\n");
}
else
{ cmd=CDROMPAUSE;
if (ioctl(handle,cmd)) printf("Drive Error\n");
}
break;
case 'r': if (!ini)
{ printf("Command not allowed - play track first\n");
}
else
{ cmd=CDROMRESUME;
if (ioctl(handle,cmd)) printf("Drive Error\n");
}
break;
case 's': cmd=CDROMPAUSE;
if (ioctl(handle,cmd)) printf("Drive error or already stopped\n");
cmd=CDROMSTOP;
if (ioctl(handle,cmd)) printf("Drive error\n");
break;
case 't': cmd=CDROMREADTOCHDR;
if (ioctl(handle,cmd,&tocHdr)) printf("Drive Error\n");
first=tocHdr.cdth_trk0;
last= tocHdr.cdth_trk1;
if ((first==0)||(first>last))
{ printf ("--could not read TOC\n");
}
else
{ printf("--first track: %d --last track: %d --enter track number: ",first,last);
cmd=CDROMPLAYTRKIND;
scanf("%i",&arg1);
ti.cdti_trk0=arg1;
if (ti.cdti_trk0<first) ti.cdti_trk0=first;
if (ti.cdti_trk0>last) ti.cdti_trk0=last;
ti.cdti_ind0=0;
ti.cdti_trk1=last;
ti.cdti_ind1=0;
if (ioctl(handle,cmd,&ti)) printf("Drive Error\n");
ini=1;
}
break;
case 'n': if (!ini++)
{ if (ioctl(handle,CDROMREADTOCHDR,&tocHdr)) printf("Drive Error\n");
first=tocHdr.cdth_trk0;
last= tocHdr.cdth_trk1;
ti.cdti_trk0=first-1;
}
if ((first==0)||(first>last))
{ printf ("--could not read TOC\n");
}
else
{ cmd=CDROMPLAYTRKIND;
if (++ti.cdti_trk0 > last) ti.cdti_trk0=last;
ti.cdti_ind0=0;
ti.cdti_trk1=last;
ti.cdti_ind1=0;
if (ioctl(handle,cmd,&ti)) printf("Drive Error\n");
ini=1;
}
break;
case 'l': if (!ini++)
{ if (ioctl(handle,CDROMREADTOCHDR,&tocHdr)) printf("Drive Error\n");
first=tocHdr.cdth_trk0;
last= tocHdr.cdth_trk1;
ti.cdti_trk0=first+1;
}
if ((first==0)||(first>last))
{ printf ("--could not read TOC\n");
}
else
{ cmd=CDROMPLAYTRKIND;
if (--ti.cdti_trk0 < first) ti.cdti_trk0=first;
ti.cdti_ind0=0;
ti.cdti_trk1=last;
ti.cdti_ind1=0;
if (ioctl(handle,cmd,&ti)) printf("Drive Error\n");
ini=1;
}
break;
case 'c': subchnl.cdsc_format=CDROM_MSF;
if (ioctl(handle,CDROMSUBCHNL,&subchnl))
printf("Drive Error\n");
else
{ printf("AudioStatus:%s Track:%d Mode:%d MSF=%d:%d:%d\n", \
subchnl.cdsc_audiostatus==CDROM_AUDIO_PLAY ? "PLAYING":"NOT PLAYING",\
subchnl.cdsc_trk,subchnl.cdsc_adr, \
subchnl.cdsc_absaddr.msf.minute, subchnl.cdsc_absaddr.msf.second, \
subchnl.cdsc_absaddr.msf.frame);
}
break;
case 'i': if (!ini)
{ printf("Command not allowed - play track first\n");
}
else
{ cmd=CDROMREADTOCENTRY;
printf("Track No.: ");
scanf("%d",&arg1);
entry.cdte_track=arg1;
if (entry.cdte_track<first) entry.cdte_track=first;
if (entry.cdte_track>last) entry.cdte_track=last;
entry.cdte_format=CDROM_MSF;
if (ioctl(handle,cmd,&entry))
{ printf("Drive error or invalid track no.\n");
}
else
{ printf("Mode %d Track, starts at %d:%d:%d\n", \
entry.cdte_adr,entry.cdte_addr.msf.minute, \
entry.cdte_addr.msf.second,entry.cdte_addr.msf.frame);
}
}
break;
case 'a': cmd=CDROMPLAYMSF;
printf("Address (min:sec:frame) ");
scanf("%d:%d:%d",&arg1,&arg2,&arg3);
msf.cdmsf_min0 =arg1;
msf.cdmsf_sec0 =arg2;
msf.cdmsf_frame0=arg3;
if (msf.cdmsf_sec0 > 59) msf.cdmsf_sec0 =59;
if (msf.cdmsf_frame0> 74) msf.cdmsf_frame0=74;
msf.cdmsf_min1=60;
msf.cdmsf_sec1=00;
msf.cdmsf_frame1=00;
if (ioctl(handle,cmd,&msf))
{ printf("Drive error or invalid address\n");
}
break;
#ifdef AZT_PRIVATE_IOCTLS /*not supported by every CDROM driver*/
case 'd': cmd=CDROMREADCOOKED;
printf("Address (min:sec:frame) ");
scanf("%d:%d:%d",&arg1,&arg2,&arg3);
azt.msf.cdmsf_min0 =arg1;
azt.msf.cdmsf_sec0 =arg2;
azt.msf.cdmsf_frame0=arg3;
if (azt.msf.cdmsf_sec0 > 59) azt.msf.cdmsf_sec0 =59;
if (azt.msf.cdmsf_frame0> 74) azt.msf.cdmsf_frame0=74;
if (ioctl(handle,cmd,&azt.msf))
{ printf("Drive error, invalid address or unsupported command\n");
}
k=0;
getchar();
for (i=0;i<128;i++)
{ printf("%4d:",i*16);
for (j=0;j<16;j++)
{ printf("%2x ",azt.buf[i*16+j]);
}
for (j=0;j<16;j++)
{ if (isalnum(azt.buf[i*16+j]))
printf("%c",azt.buf[i*16+j]);
else
printf(".");
}
printf("\n");
k++;
if (k>=20)
{ printf("press ENTER to continue\n");
getchar();
k=0;
}
}
break;
case 'w': cmd=CDROMREADRAW;
printf("Address (min:sec:frame) ");
scanf("%d:%d:%d",&arg1,&arg2,&arg3);
azt.msf.cdmsf_min0 =arg1;
azt.msf.cdmsf_sec0 =arg2;
azt.msf.cdmsf_frame0=arg3;
if (azt.msf.cdmsf_sec0 > 59) azt.msf.cdmsf_sec0 =59;
if (azt.msf.cdmsf_frame0> 74) azt.msf.cdmsf_frame0=74;
if (ioctl(handle,cmd,&azt))
{ printf("Drive error, invalid address or unsupported command\n");
}
k=0;
for (i=0;i<147;i++)
{ printf("%4d:",i*16);
for (j=0;j<16;j++)
{ printf("%2x ",azt.buf[i*16+j]);
}
for (j=0;j<16;j++)
{ if (isalnum(azt.buf[i*16+j]))
printf("%c",azt.buf[i*16+j]);
else
printf(".");
}
printf("\n");
k++;
if (k>=20)
{ getchar();
k=0;
}
}
break;
#endif
case 'v': cmd=CDROMVOLCTRL;
printf("--Channel 0 Left (0-255): ");
scanf("%d",&arg1);
printf("--Channel 1 Right (0-255): ");
scanf("%d",&arg2);
volctrl.channel0=arg1;
volctrl.channel1=arg2;
volctrl.channel2=0;
volctrl.channel3=0;
if (ioctl(handle,cmd,&volctrl))
{ printf("Drive error or unsupported command\n");
}
break;
case 'q': if (close(handle)) printf("Drive Error: CLOSE\n");
exit(0);
case 'h': help();
break;
default: printf("unknown command\n");
break;
}
}
}
return 0;
}
![[bottom]](../icons/bottom.png){kind=icon}
![[previous]](../icons/n_left.png){kind=icon}
![[next]](../icons/n_right.png){kind=icon}
![[first]](../icons/n_first.png){kind=icon}
![[last]](../icons/n_last.png){kind=icon}
![[top]](../icons/n_top.png){kind=icon}
![[index]](../icons/index.png){kind=icon}
![[help]](../icons/help.png){kind=icon}
*/
![[top]](../icons/top.png){kind=icon}
![[bottom]](../icons/n_bottom.png){kind=icon}