Function details-8

8.2.8 CD Block File System

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Title function specification

Function Move directory

Function Name［SR］ CDC_ChgDir

No 8.1

Format

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 as the file identifier moves you to the root directory. When moving, it reads directory records and retains up to 254 file information from the beginning. (Up to 256 including self and parent) Returns REJECT if the file identifier does not point to a directory.

remarks

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

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Title function specification

Function Retaining file information

Function Name［SR］ CDC_ReadDir

No 8.2

Format

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 retains information on up to 254 files starting from the specified file identifier. (Always retained by myself and parents)

remarks

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

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Title function specification

Function Obtaining the retained file information range

Function Name［S-］ CDC_GetFileScope

No 8.3

Format

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

input

none

output

fid	: First file identifier held
infnum	: Number of retained file information
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

Notifies whether the current retained file information range includes 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 final directory record.
FALSE	Not keeping the final directory record.

remarks

Since the self and parent directories are always retained, they are not included in the number of file information.

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Title function specification

Function Get retained file information

Function Name［S-］ CDC_TgetFileInfo

No 8.4

Format

Sint32 CDC_TgetFileInfo(Sint32 fid, CdcFile *file)

input

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

output

file: File information

function value

Returns an error code.

function

Obtain file information (12 bytes) by specifying a file identifier from the retained file information range.
If you specify CDC_NUL_FID as the file identifier, all file information held by the CD block (up to 254 files excluding self and parent) will be retrieved.

Note

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

example

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

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

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Title function specification

Function Load file

Function Name［SR］ CDC_ReadFile

No 8.5

Format

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 sectors)

output

none

function value

Returns an error code.

end flag

EFLS flag

function

Reads the specified file into the CD buffer. The load destination selector is specified by the aperture number.

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Title function specification

Function Aborting file access

Function Name［SR］ CDC_AbortFile

No 8.6

Format

Sint32 CDC_AbortFile(void)

input

none

output

none

function value

Returns an error code.

end flag

EFLS flag (only cleared to 0)...Can be executed regardless of the EFLS value

function

Stops accessing files using the CD block file system (features described below).

• Move directory ( CDC_ChgDir )
• Maintaining 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 factor register becomes 1.
If the file is not being accessed, just set the EFLS flag to 1.

remarks

Aborting file access does not clear the buffer partition or initialize the selector.
If you stop executing the CDC_ChgDir or CDC_ReadDir functions, all retained file information will be cleared.
File access is also aborted if the tray is opened.