mmioAdvance
The mmioAdvance
function advances the I/O buffer of a file set up for direct I/O buffer access
with the mmioGetInfo
function.
MMRESULT mmioAdvance(
|
HMMIO hmmio, |
|
|
LPMMIOINFO
lpmmioinfo, |
|
|
UINT wFlags |
|
|
); |
|
Parameters
hmmio
File handle
of a file opened by using the mmioOpen function.
lpmmioinfo
Address of
the MMIOINFO
structure obtained by using the mmioGetInfo function. This structure is used to set the
current file information, and then it is updated after the buffer is advanced.
This parameter is optional.
wFlags
Flags for the
operation. It can be one of the following:
MMIO_READ
Buffer is
filled from the file.
MMIO_WRITE
Buffer is
written to the file.
Return Values
Returns
MMSYSERR_NOERROR if successful or an error otherwise. Possible error values
include the following:
|
MMIOERR_CANNOTEXPAND |
The
specified memory file cannot be expanded, probably because the adwInfo
member of the MMIOINFO
structure was set to zero in the initial call to the mmioOpen function. |
|
MMIOERR_CANNOTREAD |
An error
occurred while refilling the buffer. |
|
MMIOERR_CANNOTWRITE |
The
contents of the buffer could not be written to disk. |
|
MMIOERR_OUTOFMEMORY |
There was
not enough memory to expand a memory file for further writing. |
|
MMIOERR_UNBUFFERED |
The
specified file is not opened for buffered I/O. |
Remarks
If the file
is opened for reading, the I/O buffer is filled from the disk. If the file is
opened for writing and the MMIO_DIRTY flag is set in the dwFlags member
of the MMIOINFO
structure, the buffer is written to disk. The pchNext, pchEndRead,
and pchEndWrite members of the MMIOINFO structure are updated to
reflect the new state of the I/O buffer.
If the
specified file is opened for writing or for both reading and writing, the I/O
buffer is flushed to disk before the next buffer is read. If the I/O buffer
cannot be written to disk because the disk is full, mmioAdvance returns
MMIOERR_CANNOTWRITE.
If the
specified file is open only for writing, the MMIO_WRITE flag must be specified.
If you have
written to the I/O buffer, you must set the MMIO_DIRTY flag in the dwFlags
member of the MMIOINFO structure before calling mmioAdvance.
Otherwise, the buffer will not be written to disk.
If the end of
file is reached, mmioAdvance still returns successfully even though no
more data can be read. To check for the end of the file, check if the pchNext
and pchEndRead members of the MMIOINFO structure are equal after
calling mmioAdvance.
See Also