RtlFindClearRuns function (wdm.h)
The RtlFindClearRuns routine finds the specified number of runs of clear bits within a given bitmap.
Syntax
NTSYSAPI ULONG RtlFindClearRuns(
[in] PRTL_BITMAP BitMapHeader,
[out] PRTL_BITMAP_RUN RunArray,
[in] ULONG SizeOfRunArray,
[in] BOOLEAN LocateLongestRuns
);
Parameters
[in] BitMapHeader
A pointer to the RTL_BITMAP structure that describes the bitmap. This structure must have been initialized by the RtlInitializeBitMap routine.
[out] RunArray
Pointer to the first element in a caller-allocated array for the bit position and length of each clear run found in the given bitmap variable.
[in] SizeOfRunArray
Specifies the maximum number of clear runs to satisfy this request.
[in] LocateLongestRuns
If TRUE, specifies that the routine is to search the entire bitmap for the longest clear runs it can find. Otherwise, the routine stops searching when it has found the number of clear runs specified by SizeOfRunArray.
Return value
RtlFindClearRuns returns the number of clear runs found.
Remarks
If LocateLongestRuns is TRUE, the clear runs indicated at RunArray are sorted from longest to shortest. A clear run can consist of a single bit.
Callers of RtlFindClearRuns 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, RtlFindClearRuns 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) |