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The RtlFindSetBitsAndClear routine searches for a range of set bits of a requested size within a bitmap and clears all bits in the range when it has been located.
Syntax
NTSYSAPI ULONG RtlFindSetBitsAndClear(
[in] PRTL_BITMAP BitMapHeader,
[in] ULONG NumberToFind,
[in] ULONG HintIndex
);
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] NumberToFind
Specifies how many contiguous set bits will satisfy this request.
[in] HintIndex
Specifies a zero-based bit position around which to start looking for a set bit range of the given size.
Return value
RtlFindSetBitsAndClear either returns the zero-based starting bit index for a set bit range of the requested size that it cleared, or it returns 0xFFFFFFFF if it cannot find such a range within the given bitmap variable.
Remarks
For a successful call, the returned bit position is not necessarily equivalent to the given HintIndex. If necessary, RtlFindSetBitsAndClear searches the whole bitmap to locate a set bit range of the requested size. However, it starts searching for the requested range near HintIndex, so callers can clear such a range more quickly when they can supply appropriate hints about where to start looking.
Callers of RtlFindSetBitsAndClear 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, RtlFindSetBitsAndClear 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) |