8.Function specification-4

8.4 Read with immediate return

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Title function specification

Function Start loading data

Function name GFS_NwFread

No 4.1

Format

Sint32 GFS_NwFread(GfsHn gfs, Sint32 nsct, void *buf, Sint32 bsize)

input

gfs	: file handle
nsct	: Number of sectors to read
bsize	: Size of read area (unit: number of bytes)

output

buf: Read area

function value

Error code.

function

Issue a request to read data to the server function. When the requested access operation is completed, the access pointer advances by nsct sectors.

remarks

The same precautions as those for GFS_Fread are required regarding buf address boundaries.

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Title function specification

Function Start reading ahead into CD buffer

Function name GFS_NwCdRead

No 4.2

Format

Sint32 GFS_NwCdRead(GfsHn gfs, Sint32 nsct)

input

gfs	: file handle
nsct	: Number of sectors to read

output

none

function value

Error code.

function

Issues a read-ahead request to the server function to read data into the CD buffer.
The access pointer does not change upon completion of the requested read process. If the following conditions are not met, the access operation for the specified file handle will not be completed.

• The data in the nsct sector is transferred to the host area by the GFS_Fread function or GFS_NwFread function.
• The access operation is stopped by the GFS_NwStop function.

remarks

To check that the transfer to the host area using the GFS_NwFread function after starting read ahead is complete, perform the following process.

• Get the number of transferred bytes with GFS_NwGetStat.
• Check whether the number of bytes transferred is equal to the desired number of bytes.
  (If it is equal to the desired number of bytes, the transfer is complete.)

If you read ahead with the GFS_NwCdRead function, you must be careful because you cannot check whether the GFS_NwFread function has completed with the GFS_NwIsComplete function.

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Title function specification

Function Checking for completion of access operation

Function name GFS_NwIsComplete

No 4.3

Format

Bool GFS_NwIsComplete(GfsHn gfs)

input

gfs: file handle

output

none

function value

Status of access operation.

function

Checks whether the access operation of the server function is completed. Function values have the following meanings:

TRUE	:Access completed
FALSE	:in action

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Title function specification

Function Canceling access operation

Function name GFS_NwStop

No 4.4

Format

Sint32 GFS_NwStop(GfsHn gfs)

input

gfs: file handle

output

none

function value

Access pointer at the time of cancellation. Negative error code in case of error.

function

Aborts the access operation of the server function. GFS_NwExecServer continues accessing the next file.

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Title function specification

Function Get current access status

Function name GFS_NwGetStat

No 4.5

Format

void GFS_NwGetStat(GfsHn gfs, Sint32 *stat, Sint32 *ndata)

input

gfs: file handle

output

stat	:Current access status
data	:The number of data

function value

none

function

Used to obtain access status of server functions.
The meaning of the data for each access state is shown below.

access status	process	Meaning of number of data
GFS_NWSTAT_NOACT	none	meaningless
GFS_NWSTAT_FREAD	Loading from CD to host area	Number of bytes read into host area
GFS_NWSTAT_CDREAD	Read ahead to CD buffer	Number of sectors read into CD buffer

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Title function specification

Function Executing access operations on a file-by-file basis

Function name GFS_NwExecOne

No 4.6

Format

Sint32 GFS_NwExecOne(GfsHn gfs)

input

gfs: file handle

output

none

function value

Execution status (GFS_SVR_~). Negative error code in case of error.

function

This is an access server function for a single file. Performs the following processing according to the most recently called access operation for the file handle.

• GFS_NwFread
  Performs loading into the CD buffer and transferring to the host.
• GFS_NwCdRead
  Performs the loading process to the CD buffer.

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Title function specification

Function Performing multiple file access operations

Function name GFS_NwExecServer

No 4.7

Format

Sint32GFS_NwExecServer(GfsHn *now_gfs)

input

none

output

now_gfs: File handle to be executed

function value

Access server status (GFS_SVR_~). Negative error code in case of error.

function

This is an access server function for multiple files. Actual access (GFS_NwExecOne) is performed in the order in which requests are issued.
After the access operation for one file is completed, it moves on to the next process.
When processing of multiple files is completed, it becomes GFS_SVR_COMPLETED.