Lucent Technologies USS-720 manual WriteFile, 3 I/O File Functions continued, USB Device Driver

USS-720	Preliminary User Guide, Rev. 2
USB Device Driver	February 1999

3 I/O File Functions (continued)

3.3 WriteFile

The WriteFile I/O file function writes data to the Bulk Out pipe and returns TRUE if the function is successful and FALSE if it fails. Details regarding the syntax, parameters, return values, and error codes are listed below.

3.3.1 Syntax
BOOL
WriteFile(
HANDLE	hDev,
LPVOID	lpBuffer,
DWORD	nNumberOfBytesToWrite,
LPDWORD	lpNumberOfBytesWritten,
LPOVERLAPPED	lpOverlapped
);

3.3.2 Parameters

Input:

hDev—Handle returned from a successful CreateFile.

nNumberOfBytesToWrite—Specifies the number of bytes to be written.

lpOverlapped—Pointer to OVERLAPPED structure. This is an optional parameter that can be “NULL” if overlapping I/O is not required.

Output:

lpBuffer—Pointer to the buffer containing the data to be written to the Bulk Out pipe of the device. This buffer is assumed to be in locked system memory allocated from the nonpaged pool.

lpNumberOfBytesWritten—Pointer to the number of bytes written.

3.3.3 Return Values

If the function succeeds, the return value is TRUE (1).

If the function fails, the return value is FALSE (0). To get extended error information, call GetLastError.

3.3.4 Notes

See the Win32 SDK documentation for complete definitions.

3.3.5 Error Codes

ERROR_DEVICE_REMOVE—The device instance has been removed.

ERROR_DEVICE_STOP—The device instance has been stopped.

ERROR_INVALID_ALTERNATESETTING—The current alternate interface setting for this device instance does not support the Bulk Out pipe.

ERROR_PIPE_ALREADY_OPEN—The Bulk Out pipe for this device instance is already open.

STATUS_INVALID_HANDLE—The Bulk Out pipe handle is invalid for this device instance.

STATUS_INVALID_PARAMETER—The pipe type is invalid for this device instance.

STATUS_INSUFFICIENT_RESOURCES—This is an internal error resulting from insufficient memory available to perform a required USB request.

7-6 Lucent Technologies Inc.