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CDROM_WRITE_SPEED_DESCRIPTOR structure (ntddcdrm.h)

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The CDROM_WRITE_SPEED_DESCRIPTOR structure is returned for the IOCTL_CDROM_GET_PERFORMANCE IOCTL when the request type is CdromWriteSpeedRequest. The IOCTL returns the CDROM_PERFORMANCE_HEADER followed by one or more descriptors of type CDROM_WRITE_SPEED_DESCRIPTOR.

Syntax

typedef struct _CDROM_WRITE_SPEED_DESCRIPTOR {
  UCHAR MixedReadWrite : 1;
  UCHAR Exact : 1;
  UCHAR Reserved1 : 1;
  UCHAR WriteRotationControl : 2;
  UCHAR Reserved2 : 3;
  UCHAR Reserved3[3];
  UCHAR EndLba[4];
  UCHAR ReadSpeed[4];
  UCHAR WriteSpeed[4];
} CDROM_WRITE_SPEED_DESCRIPTOR, *PCDROM_WRITE_SPEED_DESCRIPTOR;

Members

MixedReadWrite

The MixedReadWrite (MRW) field corresponds to the MRW bit of the Write Speed Descriptor in the MultiMedia Command Set - 6 (MMC-6) specification. This field indicates that it is suitable for a mixture of streaming read and write requests (overwrite mode). The STREAMING_CONTROL_REQUEST_TYPE enumeration specifies the type of request.

Exact

The Exact field indicates whether the logical unit can perform the recording operation specified by CDM_WRITE_SPEED_DESCRIPTOR on the whole medium mounted. This field corresponds to the Exact bit of the Write Speed Descriptor.

Reserved1

Reserved fields.

WriteRotationControl

The WriteRotationControl (WRC) field specifies the type of the rotation control for the medium.

Reserved2

Reserved fields.

Reserved3[3]

Reserved fields.

EndLba[4]

The End Logical Block Address (EndLBA) field indicates the capacity of the medium if a medium is mounted. It corresponds to the EndLBA field of the Write Speed Descriptor.

ReadSpeed[4]

The ReadSpeed field indicates the lowest read performance data of all blocks (in kilobytes per second).

WriteSpeed[4]

The WriteSpeed field indicates the lowest write performance data of all blocks (in kilobytes per second).

Remarks

The fields in the CDROM_WRITE_SPEED_DESCRIPTOR structure correspond to the fields defined in the MultiMedia Command Set - 6 (MMC-6) specification for the Write Speed Descriptor.

Requirements

Requirement Value
Header ntddcdrm.h (include Ntddcdrm.h)

See also

IOCTL_CDROM_GET_PERFORMANCE

STREAMING_CONTROL_REQUEST_TYPE