LONG mmioSendMessage(hmmio, wMsg, lParam1, lParam2)
This function sends a message to the I/O procedure associated with the specified file.
HMMIO hmmio
Specifies the file handle for a file opened with mmioOpen.
WORD wMsg
Specifies the message to send to the I/O procedure.
LONG lParam1
Specifies a parameter for the message.
LONG lParam2
Specifies a parameter for the message.
The return value depends on the message. If the I/O procedure does not recognize the message, the return value is zero.
Use this function to send custom user-defined messages. Do not use it to send the MMIOM_OPEN, MMIOM_CLOSE, MMIOM_READ, MMIOM_WRITE, MMIOM_WRITEFLUSH, or MMIOM_SEEK messages. Define custom messages to be greater than or equal to the MMIOM_USER constant.
mmioInstallIOProc