The batchlib library io.cmd is part of the batchlib package. It provides the following subroutines:

:PRINT: Prints all arguments into one line without new line.
:PRINTLN: Prints all arguments into one line with delimiting new line.
:ISDIR: Tests for exisiting directory.
:CREATE_TEMPFILE: Creates an empty temporary file within the user's temp directory.


void :PRINT varargs
Prints all arguments into one line without new line.
Parameters:

1. variable number of arguments

Since: 1.0


void :PRINTLN varargs
Prints all arguments into one line with delimiting new line.
Parameters:

1. variable number of arguments

Since: 1.0


Boolean :ISDIR String
Tests for exisiting directory.
Parameters:

1. path to directory or file

Returns:
"true" if input is an existing directory, otherwise "false"
Since: 1.0


String :CREATE_TEMPFILE
Creates an empty temporary file within the user's temp directory.
Returns:
full path to temp file
Since: 1.0

The batchlib library number.cmd is part of the batchlib package. It provides the following subroutines:

:IS_NUMBER: Checks if the first parameter is a number.
:NEAREST: Returns the nearest matching number from a sorted list of numbers.
:NEAREST_LESS: Returns the nearest matching number from a sorted list of numbers that is equal or less.
:NEAREST_GREATER: Returns the nearest matching number from a sorted list of numbers that is equal or greater.
:DEC2HEX: Converts a decimal number to hex.


Boolean :IS_NUMBER String
Checks if the first parameter is a number. That is it only contains the characters 0 to 9 and additionally the minus as the first character.
Parameters:

1. string to test for number

Returns:
"true" if string is a valid number, "false" otherwise
Since: 1.0


Integer :NEAREST Integer[] Integer
Returns the nearest matching number from a sorted list of numbers.
Parameters:

1. list of integers sorted ascending
2. number to match

Returns:
nearest matching number of list
Since: 1.0


Integer :NEAREST_LESS Integer[] Integer
Returns the nearest matching number from a sorted list of numbers that is equal or less. If no such number can be found, the smallest from the list will be returned.
Parameters:

1. list of integers sorted ascending
2. number to match

Returns:
nearest matching number of list
Since: 1.0


Integer :NEAREST_GREATER Integer[] Integer
Returns the nearest matching number from a sorted list of numbers that is equal or greater. If no such number can be found, the greatest from the list will be returned.
Parameters:

1. list of integers sorted ascending
2. number to match

Returns:
nearest matching number of list
Since: 1.0


String :DEC2HEX Integer
Converts a decimal number to hex. Currently only numbers 0 <= x <= 255 are supported (0x00 <= x <= 0xFF). The result will NOT be prefixed with 0x!
Parameters:

1. decimal number 0 <= x <= 255

Returns:
hex representation of number
Since: 1.0

Though hex numbers can be converted to decimals using SET /A MY_DECIMAL=0xFF, the other way around is not natively supported in Windows batch. However, the following subroutine does this job for numbers 0 <= x <= 255 (8bit).

:: Converts a decimal number to hex. Currently only numbers 0 <= x <= 255 are 
:: supported (0x00 <= x <= 0xFF). The result will NOT be prefixed with 0x!
:: 
:: @PARAM Integer decimal number 0 <= x <= 255
:: @RETURN String hex representation of number
:: @SINCE 1.0
:DEC2HEX
SETLOCAL ENABLEEXTENSIONS ENABLEDELAYEDEXPANSION
SET HEX=0123456789ABCDEF
SET /A T1=%1 / 16
SET /A T2=%1 %% 16
SET RESULT=!HEX:~%T1%,1!!HEX:~%T2%,1!
ENDLOCAL & SET RESULT=%RESULT%
GOTO :EOF

Note: This subroutine is part of the number.cmd library contained in the batchlib package since version 1.0.

I needed a command line tool for automatic extraction (ripping) of CDDA discs (CD Digital Audio). After long hours of searching the only tool that came up was AKRip. However, AKRip is a library (DLL) and only a demo application providing a command line interface exists. As the link on the AKRip homepage is dead, I downloaded it from Sonic Spot. It's not working though, and always fails with an exception when trying to list the drives available in my system.

So I finally fell back to the ported linux application cdda2wav, running under windows using cygwin. Unfortunately cdda2wav accesses CD-ROM drives using (emulated and virtual) SCSI devices in the form of Bus,ID,Lun, e.g. 0,3,0. Here is what cdda2wav.exe -scanbus tells me what I have:

scsibus0:
        0,0,0     0) *
        0,1,0     1) *
        0,2,0     2) 'HL-DT-ST' 'CD-RW GCE-8320B ' '1.04' Removable CD-ROM
        0,3,0     3) 'LG (KOR)' 'DVD-ROM DRD8120B' '1e05' Removable CD-ROM
        0,4,0     4) *
        0,5,0     5) *
        0,6,0     6) *
        0,7,0     7) HOST ADAPTOR
scsibus1:
        1,0,0   100) 'KB9081Z ' 'YHQ276H         ' '1.0 ' Removable CD-ROM
        1,1,0   101) *
        1,2,0   102) *
        1,3,0   103) *
        1,4,0   104) *
        1,5,0   105) *
        1,6,0   106) *
        1,7,0   107) HOST ADAPTOR

Note that running cdda2wav with and without Administrator priviledges might return different results! Now I need to find a way to map these virtual SCSI devices to the drive letters Windows uses. It should look like this:

X: -> 1,0,0
Y: -> 0,3,0
Z: -> 0,2,0

I figured out a solution in three varying ways that should work on Windows 2000 systems and newer (XP, 2003). I will start to explain these with the easyest, most simple yet most specific solution, and fall back step by step to the most complicated but compatible one.

WMIC

WMIC, the Windows Management Instrumentation Console, is a native tool since Windows XP Professional and 2003 Server. Although I only need it to query information, it needs Administrator priviledges. Okay, what information does WMIC provide for my CD-ROM drives? Using the command WMIC.EXE Path Win32_CDROMDrive GET * /VALUE /format:list tells me this (output shortened to one drive only):

Availability=3
Capabilities={3,7}
CapabilityDescriptions=
Caption=HL-DT-ST CD-RW GCE-8320B
CompressionMethod=
ConfigManagerErrorCode=0
ConfigManagerUserConfig=FALSE
CreationClassName=Win32_CDROMDrive
DefaultBlockSize=
Description=CD-ROM Drive
DeviceID=IDE\CDROMHL-DT-ST_CD-RW_GCE-8320B________________1.04____\4&2EA472A
E&0&1.0.0
Drive=Z:
DriveIntegrity=
ErrorCleared=
ErrorDescription=
ErrorMethodology=
FileSystemFlags=
FileSystemFlagsEx=
Id=Z:
InstallDate=
LastErrorCode=
Manufacturer=(Standard CD-ROM drives)
MaxBlockSize=
MaximumComponentLength=
MaxMediaSize=
MediaLoaded=FALSE
MediaType=CD-ROM
MfrAssignedRevisionLevel=
MinBlockSize=
Name=HL-DT-ST CD-RW GCE-8320B
NeedsCleaning=
NumberOfMediaSupported=
PNPDeviceID=IDE\CDROMHL-DT-ST_CD-RW_GCE-8320B________________1.04____\4&2EA4
72AE&0&1.0.0
PowerManagementCapabilities=
PowerManagementSupported=
RevisionLevel=
SCSIBus=0
SCSILogicalUnit=0
SCSIPort=0
SCSITargetId=2
Size=
Status=OK
StatusInfo=
SystemCreationClassName=Win32_ComputerSystem
SystemName=CYPRESSOR
TransferRate=
VolumeName=
VolumeSerialNumber=

I marked the important information. There seems to be some information in SCSI writing, namely SCSIBus, SCSITargetId and SCSILogicalUnit. Using these I get 0,2,0 for drive Z: which is exactly what I wanted (see beginning). But how bad - looking at Drive X:, WMIC says 0,0,0 which is obviously wrong. AFAIK only happy guessing could lead to the correct Bus number, but I don't like guessing in automated scripts. That's why I marked the drive name, too, because it seems to be similar to the name cdda2wav told me. Let's compare drive names. First, extract the information from cdda2wav's output to return the device for a specified name:

:: Returns the cygwin SCSI CD-ROM device Bus,ID,Lun (e.g. 1,3,0) for the
:: provided drive name (e.g. "HL-DT-ST CD-RW GCE-8320B").
::
:: @PARAM String drive name
:: @RETURN String cygwin SCSI device
:: @REQUIRES tools\cdda2wav.exe
:: @REQUIRES lib\string.cmd
:GET_SCSI_CDROM_DEVICE_FOR_NAME
SETLOCAL ENABLEEXTENSIONS ENABLEDELAYEDEXPANSION
FOR /F "usebackq tokens=1,3,5,7 delims='	" %%A IN (`^
    %~dps0tools\cdda2wav.exe -scanbus 2^>^&1 ^| FIND "Removable CD-ROM"`) DO (
  :: A=device, B=vendor, C=model, D=version
  CALL %~dps0lib\string.cmd :TRIM "%%B"
  SET VENDOR=!RESULT!
  CALL %~dps0lib\string.cmd :TRIM "%%C"
  SET MODEL=!RESULT!
  SET NAME=!VENDOR! !MODEL!
  IF "!NAME!" == "%~1" (
    ENDLOCAL & SET RESULT=%%A
    GOTO :EOF
  )
)
ECHO ERROR: No CD-ROM device by the name '%~1' could be found. >&2
ENDLOCAL & SET RESULT=
GOTO :EOF

Now, I can query the drive name for a specific drive letter using the command WMIC.EXE Path Win32_CDROMDrive WHERE Drive='X:' GET Name /format:csv >NUL. SCSI drive name's will be postfixed with "SCSI CdRom Device", so that string has to be manually removed from the name. Here is all what it takes to get the device for a specific drive letter:

:: Returns the cygwin SCSI device Bus,ID,Lun (e.g. 1,3,0) for the provided
:: Windows drive letter (e.g. D:) using WMIC.EXE.
:: NOTE: WMIC is natively available since Windows XP/2003 and requires
:: Administrator priviledges.
::
:: @INTERNAL use :GET_SCSI_CDROM_DEVICE_FOR_DRIVE instead
:: @PARAM String Windows drive letter including colon
:: @RETURN String cygwin SCSI device
:GET_SCSI_CDROM_DEVICE_FOR_DRIVE_BY_WMIC
SETLOCAL ENABLEEXTENSIONS ENABLEDELAYEDEXPANSION
FOR /F "usebackq skip=2 tokens=2 delims=," %%N IN (`^
    WMIC.EXE Path Win32_CDROMDrive ^
        WHERE Drive^='%~1' GET Name /format:csv 2^>NUL`) DO (
  SET DRIVENAME=%%N
  SET DRIVENAME=!DRIVENAME: SCSI CdRom Device=!
)
IF DEFINED DRIVENAME (
  CALL :GET_SCSI_CDROM_DEVICE_FOR_NAME "!DRIVENAME!"
) ELSE (
  ECHO ERROR: No CD-ROM drive could be found for drive letter '%~1'. >&2
  SET RESULT=
)
ENDLOCAL & SET RESULT=%RESULT%
GOTO :EOF

REG

Unfortunately WMIC need Administrator priviledges as stated above. So I thought about another method for retrieving data about CD-ROM drives. All the information that WMIC returns is available in the registry.
First, the used drive letters can be found in HKLM\SYSTEM\MountedDevices, named like \DosDevices\X:. The value is a 16bit little-endian hex string, storing something like \??\SCSI#CdRom&Ven_KB9081Z&Prod_YHQ276H&Rev_1.0#5&3a3a60d9&0&000#{53f5630d-b6bf-11d0-94f2-00a0c91efb8b}. Replace the # through backslashes, remove the first 4 characters and the last element \{53f5630d-b6bf-11d0-94f2-00a0c91efb8b} and you get the registry path below HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\. And here I find the FriendlyName of our drive, in that case KB9081Z YHQ276H SCSI CdRom Device. From here on it's the very same as with WMIC.

Three simple steps to be taken:

1. Query the drive letter from registry, convert the hex value to an ASCII string, and fix the registry path.
2. Open the registry path and check if device's Class is CDROM.
3. Query the FriendlyName.

:: Returns the cygwin SCSI CD-ROM device Bus,ID,Lun (e.g. 1,3,0) for the 
:: provided Windows drive letter (e.g. D:) using REG.EXE.
:: NOTE: REG.EXE is natively available since Windows XP/2003.
::
:: @INTERNAL use :GET_SCSI_CDROM_DEVICE_FOR_DRIVE instead
:: @PARAM String Windows drive letter including colon
:: @RETURN String cygwin SCSI device
:: @REQUIRES lib\string.cmd
:GET_SCSI_CDROM_DEVICE_FOR_DRIVE_BY_REG
SETLOCAL ENABLEEXTENSIONS ENABLEDELAYEDEXPANSION
FOR /F "usebackq tokens=3 delims=	" %%B IN (`^
    REG.EXE QUERY "HKLM\SYSTEM\MountedDevices" ^| ^
    FINDSTR /R "\\DosDevices\\%~1.*REG_BINARY.*5C00"`) DO (
  SET LINE=%%B
  :: remove high bytes (reduce 16bit hex to 8bit hex numbers)
  SET LINE=!LINE:000=0,!
  SET LINE=!LINE:00=,!
  :: extract registry path
  CALL %~dps0lib\string.cmd :HEX2ASC "!LINE:~0,-1!" ","
  SET REGPATH=!RESULT:~4,-39!
  SET REGPATH=HKLM\SYSTEM\CurrentControlSet\Enum\!REGPATH:#=\!
)
SET CDROM_DEVICE=
IF DEFINED REGPATH (
  FOR /F "tokens=1,2* delims=	 " %%C IN ('^
      REG.EXE QUERY "!REGPATH!" ^| ^
      FINDSTR /R "Class[^^A-Za-z0-9_-].*REG_SZ"') DO (
    IF "%%C" == "Class" IF "%%E" == "CDROM" (
      FOR /F "tokens=2* delims=	" %%M IN ('^
          REG.EXE QUERY "!REGPATH!" ^| FINDSTR /R "FriendlyName.*REG_SZ"') DO (
        SET DRIVENAME=%%N
        CALL :GET_SCSI_CDROM_DEVICE_FOR_NAME "!DRIVENAME: SCSI CdRom Device=!"
        SET CDROM_DEVICE=!RESULT!
      )
    )
  )
)
IF NOT DEFINED CDROM_DEVICE (
  ECHO ERROR: No CD-ROM drive could be found for drive letter '%~1'. >&2
)
ENDLOCAL & SET RESULT=%CDROM_DEVICE%
GOTO :EOF

Instead of converting little endian to big endian on the hex string, I simply remove all high bytes - which are always 00. Additionally I insert a comma as a delimiter as needed by the :HEX2ASC method. At first, I walked through the string, copying every first and second character, inserting a comma and simply omitting every third and fourth character. As this method was veeeery slow, I switched to the quick and dirty solution. Nevertheless, here is the good one:

:: remove high bytes and replace by comma
SET LINE_FIXED=
CALL %~dps0lib\string.cmd :STRLEN "!LINE!"
SET /A MAX=!RESULT! - 1
FOR /L %%I IN (0,2,!MAX!) DO (
  SET /A MOD=%%I%%4
  IF !MOD! == 0 (
    CALL %~dps0lib\string.cmd :SUBSTR "!LINE!" %%I 2
    SET LINE_FIXED=!LINE_FIXED!!RESULT!,
  )
)

REGEDIT

The last solution that should also work on Windows 2000 systems is much more complex. It works basically the same way as the REG.EXE one, however I have to export the registry keys to a file and work on that one. The problem is that long keys are spanned over multiple lines, indicated by a backslash at the end of the line. So I have to scan the file until finding my drive, and then starting concatenating the string until the last backslash. However I am using a little performance tweak here: Instead of checking each read line for my drive letter, I first retrieve the line where it is using FINDSTR, then start scanning until that line and begin concatenation. Testing each line was way to slow...

:: Returns the cygwin SCSI CD-ROM device Bus,ID,Lun (e.g. 1,3,0) for the 
:: provided Windows drive letter (e.g. D:) using REGEDIT.EXE.
::
:: @INTERNAL use :GET_SCSI_CDROM_DEVICE_FOR_DRIVE instead
:: @PARAM String Windows drive letter including colon
:: @RETURN String cygwin SCSI device
:: @REQUIRES lib\io.cmd
:: @REQUIRES lib\string.cmd
:GET_SCSI_CDROM_DEVICE_FOR_DRIVE_BY_REGEDIT
SETLOCAL ENABLEEXTENSIONS ENABLEDELAYEDEXPANSION
:: export registry key HKLM\SYSTEM\MountedDevices to a file
CALL %~dps0lib\io.cmd :CREATE_TEMPFILE
SET REG_FILENAME=!RESULT!
REGEDIT.EXE /E "!REG_FILENAME!" "HKEY_LOCAL_MACHINE\SYSTEM\MountedDevices"
:: parse registry file excluding empty lines
SET HEX=
FOR /F "usebackq tokens=1 delims=:" %%I IN (`^
    TYPE "!REG_FILENAME!" ^| FINDSTR /R /V "^^$" ^| ^
    FINDSTR /R /N "^^.\\\\DosDevices\\\\%~1.=hex:5c,00"`) DO (
  :: %%I is the line number where the searched key starts
  SET CURRENTLINE=
  SET LINESTR=
  SET LINENR=0
  :: as a key might span over multiple lines, concat these lines
  FOR /F "usebackq tokens=1,2* delims=: " %%M IN (`TYPE data.reg ^| FINDSTR /R /V "^^$"`) DO (
    SET /A LINENR=!LINENR! + 1
    :: found the key, check for spanning (line ending with backslash "\")
    IF !LINENR! == %%I (
      SET CURRENTLINE=%%O
      IF "!CURRENTLINE:~-1!" == "\" (
        SET LINESTR="!CURRENTLINE:~0,-1!"
      ) ELSE (
        SET HEX=!CURRENTLINE!
	GOTO :GET_SCSI_CDROM_DEVICE_FOR_DRIVE_BY_REGEDIT_GET_NAME
      )
    ) ELSE IF DEFINED LINESTR (
      SET CURRENTLINE=%%M
      IF "!CURRENTLINE:~-1!" == "\" (
        SET LINESTR="!LINESTR:~1,-1!!CURRENTLINE:~0,-1!"
      ) ELSE (
        SET HEX=!LINESTR:~1,-1!!CURRENTLINE!
	SET LINESTR=
	GOTO :GET_SCSI_CDROM_DEVICE_FOR_DRIVE_BY_REGEDIT_GET_NAME
      )
    )
  )
)
:GET_SCSI_CDROM_DEVICE_FOR_DRIVE_BY_REGEDIT_GET_NAME
SET CDROM_DEVICE=
IF DEFINED HEX (
  :: quick fix: convert 16bit hex to 8bit by removing high byte
  SET HEX=!HEX:,00=!
  CALL %~dps0lib\string.cmd :HEX2ASC "!HEX!" ","
  SET REGPATH=!RESULT:~4,-39!
  SET REGPATH=HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\!REGPATH:#=\!
  REGEDIT.EXE /E "!REG_FILENAME!" "!REGPATH!"
  FOR /F %%X IN ('TYPE "!REG_FILENAME!" ^| FINDSTR /R "^^.Class.=.CDROM"') DO (
    FOR /F "tokens=2 delims==" %%N IN ('TYPE "!REG_FILENAME!" ^| FINDSTR /R "^^.FriendlyName.=."') DO (
      SET DRIVENAME=%%N
      CALL :GET_SCSI_CDROM_DEVICE_FOR_NAME !DRIVENAME: SCSI CdRom Device=!
      SET CDROM_DEVICE=!RESULT!
    )
  )
)
IF NOT DEFINED CDROM_DEVICE (
  ECHO ERROR: No CD-ROM drive could be found for drive letter '%~1'. >&2
)
DEL /F "!REG_FILENAME!"
ENDLOCAL & SET RESULT=%CDROM_DEVICE%
GOTO :EOF

Finally, here is my main method that checks what solution is available and selectes that one:

:: Returns the cygwin SCSI CD-ROM device Bus,ID,Lun (e.g. 1,3,0) for the 
:: provided Windows drive letter (e.g. D:).
::
:: @PARAM String Windows drive letter including colon
:: @RETURN String cygwin SCSI device
:GET_SCSI_CDROM_DEVICE_FOR_DRIVE
:: Provides 3 internal methods to detect the device with auto-fallback.
:: 1) WMIC.EXE (since Windows XP/2003, requires Administrator priviledges)
:: 2) Registry through REG.EXE (since Windows XP/2003)
:: 3) Registry through REGEDIT.EXE (since Windows NT)
WMIC.EXE ALIAS /? >NUL 2>&1 || GOTO :GET_SCSI_CDROM_DEVICE_FOR_DRIVE_REG_LABEL
FOR /F "skip=2 tokens=2 delims=:" %%T IN ('WMIC.EXE ALIAS /? 2^>^&1') DO (
  IF "%%T" == "Win32 Error" GOTO :GET_SCSI_CDROM_DEVICE_FOR_DRIVE_REG_LABEL
  GOTO :GET_SCSI_CDROM_DEVICE_FOR_DRIVE_WMIC_LABEL
)
:GET_SCSI_CDROM_DEVICE_FOR_DRIVE_WMIC_LABEL
CALL :GET_SCSI_CDROM_DEVICE_FOR_DRIVE_BY_WMIC "%~1"
GOTO :EOF
:GET_SCSI_CDROM_DEVICE_FOR_DRIVE_REG_LABEL
REG.EXE EXPORT /? >NUL 2>&1 || GOTO :GET_SCSI_CDROM_DEVICE_FOR_DRIVE_REGEDIT_LABEL
CALL :GET_SCSI_CDROM_DEVICE_FOR_DRIVE_BY_REG "%~1"
GOTO :EOF
:GET_SCSI_CDROM_DEVICE_FOR_DRIVE_REGEDIT_LABEL
CALL :GET_SCSI_CDROM_DEVICE_FOR_DRIVE_BY_REGEDIT "%~1"
GOTO :EOF

Copy that stuff into one file, copy my libraries to lib\io.cmd, lib\string.cmd and lib\number.cmd and add tools\cdda2wav.exe including the tools\cygwin1.dll. Now by typing CALL :GET_SCSI_CDROM_DEVICE_FOR_DRIVE "X:" you will receive the SCSI device in the variable %RESULT%.