VCR_RequestResponse (Windows CE 5.0)
This structure is primarily a union of the details of all the command parameters and results processed.
typedef struct {BYTE CommandType;BYTE Command;BYTE ResponseCode; union { // sub-structure for each supported command } u;} VCR_RequestResponse;
Members
- CommandType
This member must be filled in with AVC_VCR_CommandType_Status or AVC_VCR_CommandType_Control. Other types of commands, such as Notify or Inquiries are also legitimate, but undocumented and not supported. Status commands are typically those functions that obtain data from the VCR, and control commands are typically those that cause or request the VCR to perform an action. - Command
Caller must complete the Command member with the specific command they request. In general, status commands are typically those functions that obtain data from the VCR, and control commands are typically those that cause or request the VCR to perform an action. - ResponseCode
After the command executes, the ResponseCode field will contain a result value from the VCR itself. The DeviceIoControl function succeeding does not imply that the specific command succeeded, only that the transaction with the VCR itself completed correctly. The ResponseCode member contains information that explains whether the VCR itself understood and processed the command. In general, if the command was unsupported, this field will return a value of AVC_RESPONSE_NOTIMPL. For Status commands, successful completion typically results in a response of AVC_RESPONSE_STABLE. For control commands, successful completion typically results in a response of AVC_RESPONSE_ACCEPTED.Response Description AVC_RESPONSE_NOTIMPL This VCR does not implement the command requested. This might be specific to the form of the command; that is, some commands have subparameters, of which only a subset are implemented. AVC_RESPONSE_ACCEPTED The control command was completed as requested. AVC_RESPONSE_REJECTED The control command was rejected and cannot be processed as requested. AVC_RESPONSE_IN_TRANSITION The status value requested is in the process of changing, and should be queried again. AVC_RESPONSE_STABLE The status value requested has been returned. AVC_RESPONSE_IMPLEMENTED The command queried is implemented. AVC_RESPONSE_CHANGED See the AVC Digital Interface General Specification, Rev 3.0. AVC_RESPONSE_INTERIM See the AVC Digital Interface General Specification, Rev 3.0.
The VCR Subunit Specification, mentioned above, can be a useful resource in understanding some of the intricate details in what a specific command is intended to do. However, data described within the document, especially in the topic of range values, may be overridden by this documentation. The VCR subunit driver automatically manages decimal to BCD conversion for many of the supported commands, for example.
Requirements
OS Versions: Windows CE .NET 4.0 and later.
Header: Avc_vcr.h.
See Also
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