PCMETHOD_ITEM structure

The PCMETHOD_ITEM structure describes a method supported by a filter, pin, or node.

Syntax


typedef struct {
  const GUID          *Set;
  ULONG               Id;
  ULONG               Flags;
  PCPFNMETHOD_HANDLER Handler;
} PCMETHOD_ITEM, *PPCMETHOD_ITEM;

Members

Set

Specifies the method set. This member is a pointer to a GUID that uniquely identifies the method set.

Id

Specifies the method ID. This member identifies a method item in the method set. If the method set contains n items, valid method IDs are integers in the range 0 to n-1.

Flags

Specifies the type of parameter passing and memory access that a method uses. This member can be set to the bitwise OR of one or more of the flag bits in the following table.

Flag bitMeaning

PCMETHOD_ITEM_FLAG_MODIFY

The method reads from and writes to the parameter buffer.

PCMETHOD_ITEM_FLAG_NONE

The method does not use the parameter buffer.

PCMETHOD_ITEM_FLAG_READ

The method reads from the parameter buffer.

PCMETHOD_ITEM_FLAG_SOURCE

The method probes and locks memory pages before attempting memory access.

PCMETHOD_ITEM_FLAG_WRITE

The method writes to the parameter buffer.

 

Handler

Pointer to the method-handler routine. This member is a function pointer of type PCPFNMETHOD_HANDLER, which is defined as follows:


  typedef NTSTATUS (*PCPFNMETHOD_HANDLER)
  (
      IN PPCMETHOD_REQUEST  MethodRequest
  );

When calling the Handler routine, the caller passes in a single call parameter, which is a pointer to a structure of type PCMETHOD_REQUEST.

Remarks

The WDM audio subsystem does not currently support methods on either filter instances or pin instances. This restriction also precludes support for methods on nodes.

The PCAUTOMATION_TABLE structure contains a pointer to an array of PCMETHOD_ITEM structures.

Requirements

Header

Portcls.h (include Portcls.h)

See also

PCMETHOD_REQUEST

 

 

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