RtlFindLastBackwardRunClear function

Description

The RtlFindLastBackwardRunClear routine searches a given bitmap for the preceding clear run of bits, starting from the specified index position.

Parameters

BitMapHeader [in]

A pointer to the RTL_BITMAP structure that describes the bitmap. This structure must have been initialized by the RtlInitializeBitMap routine.

FromIndex [in]

Specifies a zero-based bit position at which to start looking for a clear run of bits.

StartingRunIndex [out]

Pointer to a variable in which the starting index of the clear run found in the bitmap is returned. This is a zero-based value indicating the bit position of the first clear bit in the run preceding the given FromIndex. Its value is meaningless if RtlFindLastBackwardRunClear cannot find a run of clear bits.

Return value

RtlFindLastBackwardRunClear returns the number of bits in the run beginning at StartingRunIndex, or zero if it cannot find a run of clear bits preceding FromIndex in the bitmap.

Remarks

Callers of RtlFindLastBackwardRunClear must be running at IRQL <= APC_LEVEL if the memory that contains the bitmap variable is pageable or the memory at BitMapHeader is pageable. Otherwise, RtlFindLastBackwardRunClear can be called at any IRQL.

See also

RTL_BITMAP

RtlAreBitsClear

RtlFindClearBits

RtlFindClearRuns

RtlFindFirstRunClear

RtlFindLastBackwardRunClear

RtlFindLongestRunClear

RtlFindNextForwardRunClear

RtlInitializeBitMap