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:

  Name	Description
  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):

  Name	Description
  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):

  Name	Description
  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

See also

mmioAdvance

mmioOpen

mmioRead

mmioSetBuffer

mmioWrite