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RtlNumberOfSetBits function (wdm.h)

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The RtlNumberOfSetBits routine returns a count of the set bits in a given bitmap variable.

Syntax

NTSYSAPI ULONG RtlNumberOfSetBits(
  [in] PRTL_BITMAP BitMapHeader
);

Parameters

[in] BitMapHeader

A pointer to the RTL_BITMAP structure that describes the bitmap. This structure must have been initialized by the RtlInitializeBitMap routine.

Return value

RtlNumberOfSetBits returns a count of the bits that are currently set.

Remarks

Callers of RtlNumberOfSetBits 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, RtlNumberOfSetBits 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 (kernel mode); Ntdll.dll (user mode)
IRQL <= APC_LEVEL (See Remarks section)

See also

RTL_BITMAP

RtlFindSetBits

RtlInitializeBitMap

RtlNumberOfClearBits