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man pages section 4: Device and Network Interfaces

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Updated: Thursday, June 13, 2019
 
 

cdio(4I)

Name

cdio - CD-ROM control operations

Synopsis

#include <sys/cdio.h>

Description

The set of ioctl(2) commands described below are used to perform audio and CD-ROM specific operations. Basic to these cdio ioctl requests are the definitions in <sys/cdio.h>.

Several CD-ROM specific commands can report addresses either in LBA (Logical Block Address) format or in MSF (Minute, Second, Frame) format. The READ HEADER, READ SUBCHANNEL, and READ TABLE OF CONTENTS commands have this feature.

LBA format represents the logical block address for the CD-ROM absolute address field or for the offset from the beginning of the current track expressed as a number of logical blocks in a CD-ROM track relative address field. MSF format represents the physical address written on CD-ROM discs, expressed as a sector count relative to either the beginning of the medium or the beginning of the current track.

Ioctls

The following I/O controls do not have any additional data passed into or received from them.

CDROMSTART

This ioctl() spins up the disc and seeks to the last address requested.

CDROMSTOP

This ioctl() spins down the disc.

CDROMPAUSE

This ioctl() pauses the current audio play operation.

CDROMRESUME

This ioctl() resumes the paused audio play operation.

CDROMEJECT

This ioctl() ejects the caddy with the disc.

CDROMCLOSETRAY

This ioctl() closes the caddy with the disc.

The following I/O controls require a pointer to the structure for that ioctl(), with data being passed into the ioctl().

CDROMPLAYMSF

This ioctl() command requests the drive to output the audio signals at the specified starting address and continue the audio play until the specified ending address is detected. The address is in MSF format. The third argument of this ioctl() call is a pointer to the type struct cdrom_msf.

/*
 * definition of play audio msf structure
 */
struct cdrom_msf {
	unsigned char	cdmsf_min0;	/* starting minute*/
	unsigned char	cdmsf_sec0;	/* starting second*/
	unsigned char	cdmsf_frame0;	/*starting frame*/
	unsigned char	cdmsf_min1;	/* ending minute */
	unsigned char	cdmsf_sec1;	/* ending second */
	unsigned char	cdmsf_frame1;	/* ending frame */
};

The CDROMREADTOCENTRY ioctl request may be used to obtain the start time for a track. An approximation of the finish time can be obtained by using the CDROMREADTOCENTRY ioctl request to retrieve the start time of the track following the current track.

The leadout track is the next consecutive track after the last audio track. Hence, the start time of the leadout track may be used as the effective finish time of the last audio track.

CDROMPLAYTRKIND

This ioctl() command is similar to CDROMPLAYMSF. The starting and ending address is in track/index format. The third argument of the ioctl() call is a pointer to the type struct cdrom_ti.

/*
 * definition of play audio track/index structure
 */
struct cdrom_ti {
	unsigned char	cdti_trk0;	/* starting track*/
	unsigned char	cdti_ind0;	/* starting index*/
	unsigned char	cdti_trk1;	/* ending track */
	unsigned char	cdti_ind1;	/* ending index */
};
CDROMVOLCTRL

This ioctl() command controls the audio output level. The SCSI command allows the control of up to four channels. The current implementation of the supported CD-ROM drive only uses channel 0 and channel 1. The valid values of volume control are between 0x00 and 0xFF, with a value of 0xFF indicating maximum volume. The third argument of the ioctl() call is a pointer to struct cdrom_volctrl which contains the output volume values.

/*
 * definition of audio volume control structure
 */
struct cdrom_volctrl {
	unsigned char	channel0;
	unsigned char	channel1;
	unsigned char	channel2;
	unsigned char	channel3;
};


The following I/O controls take a pointer that will have data returned to the user program from the CD-ROM driver.

CDROMREADTOCHDR

This ioctl() command returns the header of the table of contents (TOC). The header consists of the starting tracking number and the ending track number of the disc. These two numbers are returned through a pointer of struct cdrom_tochdr. While the disc can start at any number, all tracks between the first and last tracks are in contiguous ascending order.

/*
 * definition of read toc header structure
 */
struct cdrom_tochdr {
	unsigned char	cdth_trk0;	/* starting track*/
	unsigned char	cdth_trk1;	/* ending track*/
};
CDROMREADTOCENTRY

This ioctl() command returns the information of a specified track. The third argument of the function call is a pointer to the type struct cdrom_tocentry. The caller needs to supply the track number and the address format. This command will return a 4-bit adr field, a 4-bit ctrl field, the starting address in MSF format or LBA format, and the data mode if the track is a data track. The ctrl field specifies whether the track is data or audio.

/*
 * definition of read toc entry structure
 */
struct cdrom_tocentry {
	unsigned char  cdte_track;
	unsigned char  cdte_adr   :4;
	unsigned char  cdte_ctrl   :4;
	unsigned char  cdte_format;
	union {
		struct {
			unsigned char  minute;
			unsigned char  second;
			unsigned char  frame;
		} msf;
		int	lba;
	} cdte_addr;
	unsigned char  cdte_datamode;
};


To get the information from the leadout track, the following value is appropriate for the cdte_track field:

CDROM_LEADOUT

Leadout track

To get the information from the data track, the following value is appropriate for the cdte_ctrl field:

CDROM_DATA_TRACK

Data track

The following values are appropriate for the cdte_format field:

CDROM_LBA

LBA format

CDROM_MSF

MSF format

CDROMSUBCHNL

This ioctl() command reads the Q sub-channel data of the current block. The subchannel data includes track number, index number, absolute CD-ROM address, track relative CD-ROM address, control data and audio status. All information is returned through a pointer to struct cdrom_subchnl. The caller needs to supply the address format for the returned address.

struct cdrom_subchnl {
	unsigned char	cdsc_format;
	unsigned char	cdsc_audiostatus;
	unsigned char	cdsc_adr:	4;
	unsigned char	cdsc_ctrl:	4;
	unsigned char	cdsc_trk;
	unsigned char	cdsc_ind;
	union {
		struct {
			unsigned char 	minute;
			unsigned char 	second;
			unsigned char 	frame;
		} msf;
		int	lba;
	} cdsc_absaddr;
	union {
		struct {
			unsigned char 	minute;
			unsigned char 	second;
			unsigned char 	frame;
		} msf;
		int	lba;
	} cdsc_reladdr;
};


The following values are valid for the audio status field returned from READ SUBCHANNEL command:

CDROM_AUDIO_INVALID

Audio status not supported.

CDROM_AUDIO_PLAY

Audio play operation in progress.

CDROM_AUDIO_PAUSED

Audio play operation paused.

CDROM_AUDIO_COMPLETED

Audio play successfully completed.

CDROM_AUDIO_ERROR

Audio play stopped due to error.

CDROM_AUDIO_NO_STATUS

No current audio status to return.

CDROMREADOFFSET

This ioctl() command returns the absolute CD-ROM address of the first track in the last session of a Multi-Session CD-ROM . The third argument of the ioctl() call is a pointer to an int.

CDROMCDDA

This ioctl() command returns the CD-DA data or the subcode data. The third argument of the ioctl() call is a pointer to the type struct cdrom_cdda. In addition to allocating memory and supplying its address, the caller needs to supply the starting address of the data, the transfer length in terms of the number of blocks to be transferred, and the subcode options. The caller also needs to issue the CDROMREADTOCENTRY ioctl() to find out which tracks contain CD-DA data before issuing this ioctl().

/*
 * Definition of CD-DA structure
 */
struct cdrom_cdda {
	unsigned int	cdda_addr;
	unsigned int	cdda_length;
	caddr_t		cdda_data;
	unsigned char	cdda_subcode;
};

cdda_addr signifies the starting logical block address.

cdda_length signifies the transfer length in blocks. The length of the block depends on the cdda_subcode selection, which is explained below.

To get the subcode information related to CD-DA data, the following values are appropriate for the cdda_subcode field:

CDROM_DA_NO_SUBCODE

CD-DA data with no subcode.

CDROM_DA_SUBQ

CD-DA data with sub Q code.

CDROM_DA_ALL_SUBCODE

CD-DA data with all subcode.

CDROM_DA_SUBCODE_ONLY

All subcode only.

To allocate the memory related to CD-DA and/or subcode data, the following values are appropriate for each data block transferred:

CD-DA data with no subcode

2352 bytes

CD-DA data with sub Q code

2368 bytes

CD-DA data with all subcode

2448 bytes

All subcode only

96 bytes

CDROMCDXA

This ioctl() command returns the CD-ROM XA (CD-ROM Extended Architecture) data according to CD-ROM XA format. The third argument of the ioctl() call is a pointer to the type struct cdrom_cdxa. In addition to allocating memory and supplying its address, the caller needs to supply the starting address of the data, the transfer length in terms of number of blocks, and the format. The caller also needs to issue the CDROMREADTOCENTRY ioctl() to find out which tracks contain CD-ROM XA data before issuing this ioctl().

/*
 * Definition of CD-ROM XA structure
 */
struct cdrom_cdxa {
	unsigned int	cdxa_addr;
	unsigned int	cdxa_length;
	caddr_t		cdxa_data;
	unsigned char	cdxa_format;
};

To get the proper CD-ROM XA data, the following values are appropriate for the cdxa_format field:

CDROM_XA_DATA

CD-ROM XA data only

CDROM_XA_SECTOR_DATA

CD-ROM XA all sector data

CDROM_XA_DATA_W_ERROR

CD-ROM XA data with error flags data

To allocate the memory related to CD-ROM XA format, the following values are appropriate for each data block transferred:

CD-ROM XA data only

2048 bytes

CD-ROM XA all sector data

2352 bytes

CD-ROM XA data with error flags data

2646 bytes

CDROMSUBCODE

This ioctl() command returns raw subcode data (subcodes P ~ W are described in the "Red Book," see SEE ALSO) to the initiator while the target is playing audio. The third argument of the ioctl() call is a pointer to the type struct cdrom_subcode. The caller needs to supply the transfer length in terms of number of blocks and allocate memory for subcode data. The memory allocated should be a multiple of 96 bytes depending on the transfer length.

/*
 * Definition of subcode structure
 */
struct cdrom_subcode {
	unsigned int	cdsc_length;
	caddr_t		cdsc_addr;
};

The next group of I/O controls get and set various CD-ROM drive parameters.

CDROMGBLKMODE

This ioctl() command returns the current block size used by the CD-ROM drive. The third argument of the ioctl() call is a pointer to an integer.

CDROMSBLKMODE

This ioctl() command requests the CD-ROM drive to change from the current block size to the requested block size. The third argument of the ioctl() call is an integer which contains the requested block size.

This ioctl() command operates in exclusive-use mode only. The caller must ensure that no other processes can operate on the same CD-ROM device before issuing this ioctl(). read(2) behavior subsequent to this ioctl() remains the same: the caller is still constrained to read the raw device on block boundaries and in block multiples.

To set the proper block size, the following values are appropriate:

CDROM_BLK_512

512 bytes

CDROM_BLK_1024

1024 bytes

CDROM_BLK_2048

2048 bytes

CDROM_BLK_2056

2056 bytes

CDROM_BLK_2336

2336 bytes

CDROM_BLK_2340

2340 bytes

CDROM_BLK_2352

2352 bytes

CDROM_BLK_2368

2368 bytes

CDROM_BLK_2448

2448 bytes

CDROM_BLK_2646

2646 bytes

CDROM_BLK_2647

2647 bytes

CDROMGDRVSPEED

This ioctl() command returns the current CD-ROM drive speed. The third argument of the ioctl() call is a pointer to an integer.

CDROMSDRVSPEED

This ioctl() command requests the CD-ROM drive to change the current drive speed to the requested drive speed. This speed setting is only applicable when reading data areas. The third argument of the ioctl() is an integer which contains the requested drive speed.

To set the CD-ROM drive to the proper speed, the following values are appropriate:

CDROM_NORMAL_SPEED

150k/second

CDROM_DOUBLE_SPEED

300k/second

CDROM_QUAD_SPEED

600k/second

CDROM_MAXIMUM_SPEED

300k/second (2x drive) 600k/second (4x drive)

Note that these numbers are only accurate when reading 2048 byte blocks. The CD-ROM drive will automatically switch to normal speed when playing audio tracks and will switch back to the speed setting when accessing data.

See Also

ioctl(2), read(2)

N. V. Phillips and Sony Corporation, System Description Compact Disc Digital Audio, ("Red Book").

N. V. Phillips and Sony Corporation, System Description of Compact Disc Read Only Memory, ("Yellow Book").

N. V. Phillips, Microsoft, and Sony Corporation, System Description CD-ROM XA, 1991.

Volume and File Structure of CD-ROM for Information Interchange, ISO 9660:1988(E).

SCSI-2 Standard, document X3T9.2/86-109

SCSI Multimedia Commands, Version 2 (MMC-2)

Notes

The CDROMCDDA, CDROMCDXA, CDROMSUBCODE, CDROMGDRVSPEED, CDROMSDRVSPEED, and some of the block sizes in CDROMSBLKMODE are designed for new Sun-supported CD-ROM drives and might not work on some of the older CD-ROM drives.

CDROMCDDA, CDROMCDXA and CDROMSUBCODE will return error if the transfer length exceeds valid limits as determined appropriate. Example: for MMC-2 drives, length can not exceed 3 bytes (i.e. 0xffffff). The same restriction is enforced for older, pre-MMC-2 drives, as no limit was published for these older drives (and 3 bytes is reasonable for all media). Note that enforcing this limit does not imply that values passed in below this limit will actually be applicable for each and every piece of media.

The interface to this device is preliminary and subject to change in future releases. Programs should be written in a modular fashion so that future changes can be easily incorporated.