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PCMETHOD_ITEM structure (portcls.h)

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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 bit Meaning
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

Requirement Value
Header portcls.h (include Portcls.h)

See also

PCMETHOD_REQUEST