mmioInstallIOProcW function (mmiscapi.h)

Article
02/22/2024

The mmioInstallIOProc function installs or removes a custom I/O procedure. This function also locates an installed I/O procedure, using its corresponding four-character code.

Syntax

LPMMIOPROC mmioInstallIOProcW(
  FOURCC     fccIOProc,
  LPMMIOPROC pIOProc,
  DWORD      dwFlags
);

Parameters

fccIOProc

Four-character code identifying the I/O procedure to install, remove, or locate. All characters in this code should be uppercase.

pIOProc

Pointer to the I/O procedure to install. To remove or locate an I/O procedure, set this parameter to NULL. For more information about the I/O procedure, see MMIOProc.

dwFlags

Flag indicating whether the I/O procedure is being installed, removed, or located. The following values are defined.

Value	Meaning
MMIO_FINDPROC	Searches for the specified I/O procedure.
MMIO_GLOBALPROC	This flag is a modifier to the MMIO_INSTALLPROC flag and indicates the I/O procedure should be installed for global use. This flag is ignored if MMIO_FINDPROC or MMIO_REMOVEPROC is specified.
MMIO_INSTALLPROC	Installs the specified I/O procedure.
MMIO_REMOVEPROC	Removes the specified I/O procedure.

Return value

Returns the address of the I/O procedure installed, removed, or located. Returns NULL if there is an error.

Remarks

Note

The mmiscapi.h header defines mmioInstallIOProc as an alias that automatically selects the ANSI or Unicode version of this function based on the definition of the UNICODE preprocessor constant. Mixing usage of the encoding-neutral alias with code that is not encoding-neutral can lead to mismatches that result in compilation or runtime errors. For more information, see Conventions for Function Prototypes.

Requirements

Requirement	Value
Minimum supported client	Windows 2000 Professional [desktop apps only]
Minimum supported server	Windows 2000 Server [desktop apps only]
Target Platform	Windows
Header	mmiscapi.h (include Mmiscapi.h, Windows.h)
Library	Winmm.lib
DLL	Winmm.dll

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