RtlFindNextForwardRunClear function (wdm.h)

Article
02/22/2024

The RtlFindNextForwardRunClear routine searches a given bitmap variable for the next clear run of bits, starting from the specified index position.

Syntax

NTSYSAPI ULONG RtlFindNextForwardRunClear(
  [in]  PRTL_BITMAP BitMapHeader,
  [in]  ULONG       FromIndex,
  [out] PULONG      StartingRunIndex
);

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] FromIndex

Specifies a zero-based bit position at which to start looking for a clear run of bits.

[out] StartingRunIndex

Pointer to a variable in which the starting index of the clear run found in the bitmap is returned. This is a zero-based value indicating the bit position of the first clear bit in the run. Its value is meaningless if RtlFindNextForwardRunClear cannot find a run of clear bits.

Return value

RtlFindNextForwardRunClear returns either the number of bits in the run beginning at StartingRunIndex, or zero if it cannot find a run of clear bits following FromIndex in the bitmap.

Remarks

Callers of RtlFindNextForwardRunClear 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, RtlFindNextForwardRunClear 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)