HidP_UsageAndPageListDifference (Windows Embedded CE 6.0)

1/6/2010

This function returns the difference between two arrays of HID extended usages.

Syntax

NTSTATUS HidP_UsageAndPageListDifference(
  PUSAGE_AND_PAGE PreviousUsageList,
  PUSAGE_AND_PAGE CurrentUsageList,
  PUSAGE_AND_PAGE BreakUsageList,
  PUSAGE_AND_PAGE MakeUsageList,
  ULONG UsageListLength
);

Parameters

• PreviousUsageList
  [in] Pointer to a list of usages that the function compares with the list of usages in CurrentUsageList.

• CurrentUsageList
  [in] Pointer to a list of usages that the function compares with the list of usages in PreviousUsageList.

• BreakUsageList
  [out] Pointer to a caller-allocated buffer that, on return, contains a list of the usages that are in PreviousUsageList, but not in CurrentUsageList.

• MakeUsageList
  [out] Pointer to a caller-allocated buffer that, on return, contains a list of the usages that are in CurrentUsageList, but not in PreviousUsageList.

• UsageListLength
  [in] Length, in array elements, of the buffers provided at CurrentUsageList and PreviousUsageList.

Return Value

HidP_UsageAndPageListDifference returns HIDP_STATUS_SUCCESS.

Remarks

The terms button and usage are used synonymously.

A HID client can use this function to compare two lists of extended usages, for example, to determine the change in button state between two usage lists returned by two HidP_GetButtons.

If the input usage lists have different lengths, an application or driver should set UsageListLength to the length of the larger list.

The function interprets a zero usage in an input usage list as a delimiter that ends the list. Any usages after a zero in a list are not processed. The function sets unused usages at the end of the output lists to zero.

Requirements

See Also

Reference

HID Parser Functions
HidP_GetButtons
HidP_UsageListDifference