RtlAreBitsClear function (wdm.h)

Article
02/22/2024

The RtlAreBitsClear routine determines whether a given range of bits within a bitmap variable is clear.

Syntax

NTSYSAPI BOOLEAN RtlAreBitsClear(
  [in] PRTL_BITMAP BitMapHeader,
  [in] ULONG       StartingIndex,
  [in] ULONG       Length
);

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] StartingIndex

Specifies the start of the bit range to be tested. This is a zero-based value indicating the position of the first bit in the range.

[in] Length

Specifies how many bits to test.

Return value

RtlAreBitsClear returns TRUE if Length consecutive bits beginning at StartingIndex are clear (that is, all the bits from StartingIndex to (StartingIndex + Length) -1). It returns FALSE if any bit in the given range is set, if the given range is not a proper subset of the bitmap, or if the given Length is zero.

Remarks

Callers of RtlAreBitsClear 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, RtlAreBitsClear 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)