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MMIOINFO structure

The MMIOINFO structure contains the current state of a file opened by using the mmioOpen function.

Syntax


typedef struct {
  DWORD      dwFlags;
  FOURCC     fccIOProc;
  LPMMIOPROC pIOProc;
  UINT       wErrorRet;
  HTASK      hTask;
  LONG       cchBuffer;
  HPSTR      pchBuffer;
  HPSTR      pchNext;
  HPSTR      pchEndRead;
  HPSTR      pchEndWrite;
  LONG       lBufOffset;
  LONG       lDiskOffset;
  DWORD      adwInfo[4];
  DWORD      dwReserved1;
  DWORD      dwReserved2;
  HMMIO      hmmio;
} MMIOINFO;

Members

dwFlags

Flags specifying how a file was opened. The following values are defined:

NameDescription
MMIO_ALLOCBUF

File's I/O buffer was allocated by the mmioOpen or mmioSetBuffer function.

MMIO_CREATE

The mmioOpen function was directed to create the file (or truncate it to zero length if it already existed).

MMIO_DIRTY

The I/O buffer has been modified.

MMIO_EXIST

Checks for the existence of the file.

MMIO_GETTEMP

A temporary name was retrieved by the mmioOpen function.

MMIO_PARSE

The new file's path is returned.

 

The following values may be set when the file is opened in share mode (identified by using the MMIO_SHAREMODE bit mask):

NameDescription
MMIO_COMPAT

File was opened with compatibility mode, allowing any process on a given machine to open the file any number of times.

MMIO_DENYNONE

Other processes are not denied read or write access to the file.

MMIO_DENYREAD

Other processes are denied read access to the file.

MMIO_DENYWRITE

Other processes are denied write access to the file.

MMIO_EXCLUSIVE

Other processes are denied read and write access to the file.

 

The following values may be set when the file is opened in read/write mode (identified by using the MMIO_RWMODE bit mask):

NameDescription
MMIO_READ

File was opened only for reading.

MMIO_READWRITE

File was opened for reading and writing.

MMIO_WRITE

File was opened only for writing.

 

fccIOProc

Four-character code identifying the file's I/O procedure. If the I/O procedure is not an installed I/O procedure, this member is NULL.

pIOProc

Pointer to file's IO procedure.

wErrorRet

Extended error value from the mmioOpen function if it returns NULL. This member is not used to return extended error information from any other functions.

hTask

Handle to a local I/O procedure. Media Control Interface (MCI) devices that perform file I/O in the background and need an I/O procedure can locate a local I/O procedure with this handle.

cchBuffer

Size, in bytes, of the file's I/O buffer. If the file does not have an I/O buffer, this member is zero.

pchBuffer

Pointer to the file's I/O buffer. If the file is unbuffered, this member is NULL.

pchNext

Pointer to the next location in the I/O buffer to be read or written. If no more bytes can be read without calling the mmioAdvance or mmioRead function, this member points to the pchEndRead member. If no more bytes can be written without calling the mmioAdvance or mmioWrite function, this member points to the pchEndWrite member.

pchEndRead

Pointer to the location that is 1 byte past the last location in the buffer that can be read.

pchEndWrite

Pointer to the location that is 1 byte past the last location in the buffer that can be written.

lBufOffset

Reserved.

lDiskOffset

Current file position, which is an offset, in bytes, from the beginning of the file. I/O procedures are responsible for maintaining this member.

adwInfo

State information maintained by the I/O procedure. I/O procedures can also use these members to transfer information from the application to the I/O procedure when the application opens a file.

dwReserved1

Reserved.

dwReserved2

Reserved.

hmmio

Handle to the open file, as returned by the mmioOpen function. I/O procedures can use this handle when calling other multimedia file I/O functions.

Requirements

Minimum supported client

Windows 2000 Professional [desktop apps only]

Minimum supported server

Windows 2000 Server [desktop apps only]

Header

Mmsystem.h (include Windows.h)

See also

mmioAdvance
mmioOpen
mmioRead
mmioSetBuffer
mmioWrite

 

 

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