8.Function specification-2

8.2 File operations

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Title function specification

Function Open file

Function name GFS_Open

No 2.1

Format

GfsHn GFS_Open(Sint32 fid)

input

fid: file identifier

output

none

function value

file handle. Returns NULL in case of error.

function

Opens the specified file and returns a file handle.

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Title function specification

Function Close file

Function name GFS_Close

No 2.2

Format

void GFS_Close(GfsHn gfs)

input

gfs: file handle

output

none

function value

none

function

Closes the specified file handle.

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Title function specification

Function Moving the access point

Function name GFS_Seek

No 2.3

Format

Sint32 GFS_Seek(GfsHn gfs, Sint32 off, Sint32 org)

input

gfs	: file handle
off	:Amount of access pointer movement (in sector units)
org	: Movement criteria (seek mode: GFS_SEEK_~)

output

none

function value

The position of the access pointer after the move. A negative error code if there was an error.

function

Move the access pointer off sector away from org.
Access pointers cannot be specified outside the scope of the file.

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Title function specification

Function Get access pointer

Function name GFS_Tell

No 2.4

Format

Sint32 GFS_Tell(GfsHn gfs)

input

gfs: file handle

output

none

function value

Location of access pointer. Negative error code in case of error.

function

Get the location of the access pointer.

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Title function specification

Function Check for end of file

Function name GFS_IsEof

No 2.5

Format

Bool GFS_IsEof(GfsHn gfs)

input

gfs: file handle

output

none

function value

End of file flag.

function

Checks whether the access pointer has reached the end of the file. Function values have the following meanings:

TRUE	: The end of the file has been reached.
FALSE	: The end of the file has not been reached.

If an invalid file handle is input, it is assumed that the end of the file has been reached.

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Title function specification

Function Conversion from byte size to sector length

Function name GFS_ByteToSct

No 2.6

Format

Sint32 GFS_ByteToSct(GfsHn gfs, Sint32 nbyte)

input

gfs	: file handle
nbyte	: Number of bytes

output

none

function value

Number of sectors. Negative error code in case of error.

function

Converts units from bytes to sectors (nsct). The length in sectors, nsct, is calculated using the following formula.

nsct = (nbyte + file sector length - 1) / file sector length;

If the sector length is undefined (Form1 and Form2 are mixed), 0 is the function value.

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Title function specification

Function Get file size

Function name GFS_GetFileSize

No 2.7

Format

void GFS_GetFileSize(GfsHn gfs, Sint32 *sctsize, Sint32 *nsct,Sint32 *lastsize)

input

gfs: file handle

output

sctsize	:Sector length
nsct	: Number of sectors (including the last sector)
last size	:Number of bytes occupied by file data in the last sector

function value

none

function

Gets information for determining the file size. By specifying NULL for sctsize, nsct, and lastsize, you can suppress the output of that information. The file size (fsize) can be calculated using the following formula.
fsize=sctsize*(nsct−1)+lastsize;

remarks

In a file containing both Form1 and Form2, both sctsize and lastsize will be 0.

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Title function specification

Function Get file information

Function name GFS_GetFileInfo

No 2.8

Format

void GFS_GetFileInfo(GfsHn gfs, Sint32 *fid, Sint32 *fn, Sint32 *fsize,Sint32 *atr)

input

gfs: file handle

output

fid	:File identifier
fn	:File number
fsize	: File size (unit: bytes)
atr	:File attributes

function value

none

function

Get file information. By specifying NULL for fid, fn, fsize, and atr, you can suppress the output of that information. The file size is the value recorded in the directory information, so the size of 1 sector is calculated as 2048 bytes.

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Title function specification

Function Obtaining the number of sectors in the CD buffer partition

Function name GFS_GetNumCdbuf

No 2.9

Format

Sint32 GFS_GetNumCdbuf(GfsHn gfs)

input

gfs: file handle

output

none

function value

Number of sectors in CD buffer partition

function

Gets the number of sectors present in the CD buffer partition.