Function details-8

8.2.8 CD block file system

List

Title Function specifications

Function Move directory

Function Name [SR] CDC_ChgDir

No 8.1

Form

Sint32 CDC_ChgDir (Sint32 filtno, Sint32 fid)

input

filtno	: Aperture number
fid	: File identifier of directory file (CDC_NUL_FID: root directory)

output

none

Function value

Returns an error code.

End flag

EFLS flag

function

Moves the current directory to the directory indicated by the specified file identifier. Specifying CDC_NUL_FID for the file identifier will take you to the root directory. When moved, it reads the directory record and holds up to 254 file information from the beginning. (Maximum 256 including yourself and parent) Returns REJECT if the file identifier does not point to a directory.

remarks

The CD block file system uses selectors for work. The work selector is specified by the aperture number.

List

Title Function specifications

Function Retention of file information

Function Name [SR] CDC_ReadDir

No 8.2. 8.2

Form

Sint32 CDC_ReadDir (Sint32 filtno, Sint32 fid)

input

filtno: Aperture number

output

none

Function value

Returns an error code.

End flag

EFLS flag

function

Reads the directory record of the current directory and holds up to 254 file information after the specified file identifier. (Always keep yourself and your parents)

remarks

The CD block file system uses selectors for work. The work selector is specified by the aperture number.

List

Title Function specifications

Function Acquisition of retained file information range

Function Name [S-] CDC_GetFileScope

No 8.3

Form

Sint32 CDC_GetFileScope (Sint32 * fid, Sint32 * infnum, Bool * drend)

input

none

output

fid	: Retained first file identifier
infnum	: Number of file information held
drend	: Last directory record retention flag

Function value

Returns an error code.

function

Returns the range of file information currently held by the CD block.

(1) Last directory record retention flag

Tells you if the current retained file information range contains the last directory record in the directory block. This allows you to determine if there are any subsequent directory records.

Constant name	explanation
TRUE	Holds the last directory record.
FALSE	Does not hold the last directory record.

remarks

It is not included in the number of file information because it always keeps its own and its parent directories.

List

Title Function specifications

Function Acquisition of retained file information

Function Name [S-] CDC_TgetFileInfo

No 8.4

Form

Sint32 CDC_TgetFileInfo (Sint32 fid, CdcFile * file)

input

fid: File identifier (CDC_NUL_FID: Indicates all file information)

output

file: File information

Function value

Returns an error code.

function

The file information (12 bytes) is acquired by specifying the file identifier from the retained file information range.
If CDC_NUL_FID is specified as the file identifier, all file information held by the CD block (up to 254 excluding yourself and the parent) will be acquired.

caution

Immediately after issuing the file read (CDC_ReadFile) command, be sure to leave at least 16.7 ms to prevent the command from being overwritten.

example

CdcFile file; / * 1 Secure file information storage area * /
ret = CDC_TgetFileInfo (fid, & file);

CdcFile allfile [254]; / * All file information storage area secured * /
ret = CDC_TgetFileInfo (CDC_NUL_FID, allfile);

List

Title Function specifications

Function Read file

Function Name [SR] CDC_ReadFile

No 8.5

Form

Sint32 CDC_ReadFile (Sint32 filtno, Sint32 fid, Sint32 offset)

input

filtno	: Aperture number
fid	: File identifier
offset	: Logical offset from the beginning of the file (in sector units)

output

none

Function value

Returns an error code.

End flag

EFLS flag

function

Reads the specified file into the CD buffer. The selector to read to is specified by the aperture number.

List

Title Function specifications

Function Stop file access

Function Name [SR] CDC_AbortFile

No 8.6

Form

Sint32 CDC_AbortFile (void)

input

none

output

none

Function value

Returns an error code.

End flag

EFLS flag (only 0 is cleared) …… Can be executed regardless of the EFLS value

function

Stops file access by the CD block file system (features below).

• Move directory ( CDC_ChgDir )
• Retain file information ( CDC_ReadDir )
• Read file ( CDC_ReadFile )

When file access is aborted, the CD drive is paused and the EFLS flag in the interrupt cause register is set to 1.
If you are not accessing a file, just set the EFLS flag to 1.

remarks

Even if file access is stopped, the buffer partition is not cleared and the selector is not initialized.
When the execution of the CDC_ChgDir and CDC_ReadDir functions is stopped, all the stored file information is cleared.
File access is also stopped when the tray is opened.