RtlNumberOfClearBits function (wdm.h)
The RtlNumberOfClearBits routine returns a count of the clear bits in a given bitmap variable.
C++
NTSYSAPI ULONG RtlNumberOfClearBits(
[in] PRTL_BITMAP BitMapHeader
);
[in] BitMapHeader
A pointer to the RTL_BITMAP structure that describes the bitmap. This structure must have been initialized by the RtlInitializeBitMap routine.
RtlNumberOfClearBits returns the number of bits that are currently clear.
Callers of RtlNumberOfClearBits 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, RtlNumberOfClearBits can be called at any IRQL.
| 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) |