RtlFindClearBitsAndSet function (wdm.h)
The RtlFindClearBitsAndSet routine searches for a range of clear bits of a requested size within a bitmap and sets all bits in the range when it has been located.
Syntax
NTSYSAPI ULONG RtlFindClearBitsAndSet(
[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 clear bits will satisfy this request.
[in] HintIndex
Specifies a zero-based bit position from which to start looking for a clear bit range of the given size.
Return value
RtlFindClearBitsAndSet either returns the zero-based starting bit index for a clear bit range of the requested size that it set, 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, RtlFindClearBitsAndSet searches the whole bitmap to locate a clear bit range of the requested size. However, it starts searching for the requested range from HintIndex, so callers can have such a range reset more quickly when they can supply appropriate hints about where to start looking.
Callers of RtlFindClearBitsAndSet 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, RtlFindClearBitsAndSet 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) |