RtlCmEncodeMemIoResource function (wdm.h)

Article
02/22/2024

The RtlCmEncodeMemIoResource routine updates a CM_PARTIAL_RESOURCE_DESCRIPTOR structure to describe a range of memory or I/O port addresses.

Syntax

NTSYSAPI NTSTATUS RtlCmEncodeMemIoResource(
  [in] PCM_PARTIAL_RESOURCE_DESCRIPTOR Descriptor,
  [in] UCHAR                           Type,
  [in] ULONGLONG                       Length,
  [in] ULONGLONG                       Start
);

Parameters

[in] Descriptor

A pointer to the CM_PARTIAL_RESOURCE_DESCRIPTOR structure to update.

[in] Type

The resource type of the memory. This parameter can be CmResourceTypeMemory, CmResourceTypeMemoryLarge, or CmResourceTypePort.

[in] Length

The length, in bytes, of the range of allocated addresses.

[in] Start

The starting address of the range of memory or I/O port addresses.

Return value

RtlCmEncodeMemIoResource returns an NTSTATUS value. This routine might return one of the following values:

Return code	Description
STATUS_SUCCESS	The CM_PARTIAL_RESOURCE_DESCRIPTOR structure has been updated.
STATUS_UNSUCCESSFUL	The specified value for Length cannot be encoded in a CM_PARTIAL_RESOURCE_DESCRIPTOR structure.
STATUS_INVALID_PARAMETER	One or more of the specified parameters are invalid.

Remarks

Addresses that are larger than 32 bits in length must satisfy certain alignment restrictions or else the routine returns STATUS_UNSUCCESSFUL.

Address length	Alignment restriction
40 bits	Lowest 8 bits must be zero.
48 bits	Lowest 16 bits must be zero.
64 bits	Lowest 32 bits must be zero.

Requirements

Requirement	Value
Minimum supported client	Available in Windows Vista and later versions of Windows.
Target Platform	Universal
Header	wdm.h (include Wdm.h, Ntddk.h, Ntifs.h)
Library	NtosKrnl.lib
DLL	NtosKrnl.exe
IRQL	Any level