RtlFindLastBackwardRunClear function (wdm.h)
The RtlFindLastBackwardRunClear routine searches a given bitmap for the preceding clear run of bits, starting from the specified index position.
Syntax
NTSYSAPI ULONG RtlFindLastBackwardRunClear(
[in] PRTL_BITMAP BitMapHeader,
[in] ULONG FromIndex,
[out] PULONG StartingRunIndex
);
Parameters
[in] BitMapHeader
A pointer to the RTL_BITMAP structure that describes the bitmap. This structure must have been initialized by the RtlInitializeBitMap routine.
[in] FromIndex
Specifies a zero-based bit position at which to start looking for a clear run of bits.
[out] StartingRunIndex
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.
Requirements
| Requirement | Value |
|---|---|
| Minimum supported client | Available starting with Windows 2000. |
| Target Platform | Universal |
| Header | wdm.h (include Wdm.h, Ntddk.h, Ntifs.h) |
| Library | NtosKrnl.lib |
| DLL | NtosKrnl.exe |
| IRQL | <= APC_LEVEL (see Remarks section) |