RtlClearBits function (wdm.h)

Article
02/22/2024

The RtlClearBits routine sets all bits in the specified range of bits in the bitmap to zero.

Syntax

NTSYSAPI VOID RtlClearBits(
  [in] PRTL_BITMAP BitMapHeader,
  [in] ULONG       StartingIndex,
  [in] ULONG       NumberToClear
);

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

The index of the first bit in the bit range that is to be cleared. If the bitmap contains N bits, the bits are numbered from 0 to N-1.

[in] NumberToClear

Specifies how many bits to clear. If the bitmap contains N bits, this parameter can be a value in the range 1 to (N - StartingIndex).

Return value

This routine does not return a value.

Remarks

If the NumberToClear parameter is zero, RtlClearBits simply returns control without clearing any bits.

The sum (StartingIndex + NumberToClear) must not exceed the SizeOfBitMap parameter value specified in the RtlInitializeBitMap call that initialized the bitmap.

Callers of RtlClearBits must be running at IRQL <= APC_LEVEL if the memory that contains the bitmap is pageable or the memory at BitMapHeader is pageable. Otherwise, RtlClearBits 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.)