FSReadFileWithPos

Syntax

#include <cafe/fs.h>

FSStatus FSReadFileWithPos(
                FSClient                        *client,
                FSCmdBlock                      *block,
                void                            *dest,
                FSSize                          size,
                FSCount                         count,
                FSFilePosition                  fpos,
                FSFileHandle                    fileHandle,
                FSFlag                          flag,
                FSRetFlag                       errHandling
                );
FSStatus FSReadFileWithPosAsync(
                FSClient                        *client,
                FSCmdBlock                      *block,
                void                            *dest,
                FSSize                          size,
                FSCount                         count,
                FSFilePosition                  fpos,
                FSFileHandle                    fileHandle,
                FSFlag                          flag,
                FSRetFlag                       errHandling,
                const FSAsyncParams             *asyncParams
                );

Parameters

client Pointer to the client buffer.
block Command block.
dest Pointer to data array to read into. This must be aligned properly. See description.
size Size of one array member [bytes].
count Number of array members to read.
fpos Stating file position.
fileHandle Handle of the file to read from.
flag Bitfield of flag values. No effective flag is defined yet.
errHandling Auto error handling flag. Only indicated errors are returned.
asyncParams (Async API only) Notification parameters for an asynchronous call.

Return Values

Sync API : Return values / Async API: Callback return values

Non-negative value ( ≥ 0 ) Number of elements read.
FS_STATUS_CANCELED The command was canceled.
FS_STATUS_ACCESS_ERROR Access mode is invalid (e.g. Opened file is not readable mode).
FS_STATUS_MEDIA_NOT_READY (Only for manually mounted devices) Media is not present.
FS_STATUS_MEDIA_ERROR (Only for manually mounted devices) Media is in some inaccessible condition.
FS_STATUS_DATA_CORRUPTED (Only for manually mounted devices) The data is corrupted beyond repair. The volume needs format.

Async API: Immediate return values

FS_STATUS_OK Successfully issued request.
FS_STATUS_FATAL_ERROR The argument is invalid.

Description

Reads data from the file stream designated by fileHandle into the data array designated by dest, specifying the starting file position designated by fpos. The file position of the stream is advanced from the specified file position by the number of characters read. If an error occurs, the file position is indeterminate. If a partial element is read, its value is indeterminate.

If size or count is zero, this function returns zero (=FS_STATUS_OK) without reading anything, but it will be followed by physical seek motion on the device to the requested location if the device supports it (e.g. optical disc drive moving the pickup head). NULL can be specified to dest if and only if size or count is zero.

Alignment of the address and size of data buffer are constrained by FS_IO_BUFFER_ALIGN as same as FSReadFile.

For good performance, allocate the dest buffer on the heap.

Large file read transaction will be automatically paused when a command with higher priority is queued to the same client.

Both a sync and async style API are provided. To use the async API, set the user callback and parameters in asyncParams. For more information, see FSAsyncParams.

Do Not Call From

FSReadFileWithPos

Thread that displays graphics Do not call this function from a thread that displays graphics. This function may block indefinitely in error cases and the application must be able to display appropriate messages.
Thread that handles system messages Do not call this function from a thread that handles system messages. This function may block indefinitely in error cases and the application must be able to handle system events such as shutdown.
Callbacks Do not call this function from any callback function.
Interrupt handler Do not call this function from any interrupt handler.
Exception handler Do not call this function from any exception handler.

FSReadFileWithPosAsync

None.

See Also

File/Directory operations
Rules and Conventions
FSOpenFile
FSWriteFileWithPos
FSCloseFile

Revision History

2014/09/16 Added "Thread that displays graphics" and "Thread that handles system messages" to "Do not call from".
2013/05/23 Added FS_STATUS_DATA_CORRUPTED to return values.
2013/05/20 Added FS_STATUS_MEDIA_NOT_READY to return values.
2013/05/08 Automated cleanup pass.
2013/01/19 Added description that NULL can be specified to dest if and only if size or count is zero.
2013/01/10 Added "Do not call from".
2012/07/20 Readability and correctness cleanup.
2012/02/20 Initial version.
2011/07/31 Noted about command priority.
2010/03/30 Fixed type name FSNotificationParams -> FSAsyncParams.


CONFIDENTIAL