AVC_FUNCTION_SEND_RESPONSE

The AVC_FUNCTION_SEND_RESPONSE function code is used to respond to AV/C unit and subunit requests.

I/O Status Block

If successful, the AV/C protocol driver may set Irp->IoStatus.Status to either:

• STATUS_SUCCESS if the response is discarded due to one or more bus resets since original request, or

• STATUS_PENDING if the response is successfully delivered to 61883.sys (implies successful delivery to the request initiator)

Possible other return values include:

Return value	Description
STATUS_INSUFFICIENT_RESOURCES	An internal buffer allocation failed.

Comments

This function uses the AVC_COMMAND_IRB structure as shown below.

typedef struct _AVC_COMMAND_IRB {
  AVC_IRB  Common;
  UCHAR  SubunitAddrFlag : 1;
  UCHAR  AlternateOpcodesFlag : 1;
  UCHAR  TimeoutFlag : 1;
  UCHAR  RetryFlag : 1;
  union {
    UCHAR  CommandType;
    UCHAR  ResponseCode;
  };
  PUCHAR  SubunitAddr;
  PUCHAR  AlternateOpcodes;
  LARGE_INTEGER  Timeout;
  UCHAR  Retries;
  UCHAR  Opcode;
  ULONG  OperandLength;
  UCHAR  Operands[MAX_AVC_OPERAND_BYTES];
  NODE_ADDRESS  NodeAddress;
  ULONG  Generation;
} AVC_COMMAND_IRB, *PAVC_COMMAND_IRB;

Requirements

Header: Avc.h (include Avc.h)

AVC_COMMAND_IRB Input

Common
The Function submember of this member must be set to AVC_FUNCTION_SEND_RESPONSE from the AVC_FUNCTION enumeration.

SubunitAddrFlag
Set to the value obtained from the AVC_FUNCTION_GET_REQUEST completion.

AlternateOpcodesFlag
Ignored.

TimeoutFlag
Ignored.

RetryFlag
Ignored.

CommandType
Ignored for responses.

ResponseCode
This member must be set to one of the values from the AvcResponseCode enumeration.

SubunitAddr
Set to the value obtained from the AVC_FUNCTION_GET_REQUEST completion.

AlternateOpcodes
Ignored.

Timeout
Ignored.

Retries
Ignored.

Opcode
This must contain the AV/C unit opcode appropriate for the response (may be different than the opcode provided in the original request).

OperandLength
Set to the number of bytes in the operand list of the response.

Operands
The operand list of the response.

NodeAddress
The node address of the source of the original request.

Generation
The generation ID obtained from the original request.

In the context of the GUID_AVC_CLASS device interface, the AVC_FUNCTION_SEND_RESPONSE function code is used to respond only to AV/C unit requests.

In the case of virtual instances of avc.sys (that is, instances that register the GUID_VIRTUAL_AVC_CLASS device interface), the AVC_FUNCTION_SEND_RESPONSE function code is used to respond to AV/C unit and subunit requests.

If the first response uses the AVC_RESPONSE_INTERIM response code (from the AvcResponseType enumeration), then follow-up processing is expected. The NodeAddress and Generation members, obtained by the completion of the AVC_FUNCTION_GET_REQUEST original function, must be used in subsequent responses. In any case, the next AVC_FUNCTION_GET_REQUEST function should be submitted before returning from the initial AVC_FUNCTION_SEND_RESPONSE completion routine, so that the next unit request may be received.

The recommended use of this structure is to use the contents of the original request, and update the Opcode, OperandLength, and Operands members as appropriate for the response.

This function code may be called at IRQL >= DISPATCH_LEVEL.

See Also

AVC_FUNCTION_GET_REQUEST

AvcResponseCode

AVC_FUNCTION