HidP_UsageListDifference function (hidpi.h)

The HidP_UsageListDifference routine returns the differences between two arrays of HID usages.

Syntax

NTSTATUS HidP_UsageListDifference(
  [in]  PUSAGE PreviousUsageList,
  [in]  PUSAGE CurrentUsageList,
  [out] PUSAGE BreakUsageList,
  [out] PUSAGE MakeUsageList,
  [in]  ULONG  UsageListLength
);

Parameters

[in] PreviousUsageList

Pointer to a list of usages that the routine compares with the list of usages in CurrentUsageList.

[in] CurrentUsageList

Pointer to a list of usages that the routine compares with the list of usages in PreviousUsageList.

[out] BreakUsageList

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

[out] MakeUsageList

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

[in] UsageListLength

Specifies the length, in array elements, of the buffers provided at CurrentUsageList and PreviousUsageList.

Return value

HidP_UsageListDifference returns HIDP_STATUS_SUCCESS.

Remarks

A user-mode application or kernel-mode driver can use this routine to compare two usage lists, for example, to determine the change in button state between two usage lists returned by two HidP_GetButtons calls.

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

The routine 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. Unused usages in an output list are set to zero.

For more information, see HID Collections.

Requirements

See also

HidP_UsageAndPageListDifference