T-Kernel Specification (1.B0.02)

230 CHAPTER 5. T-KERNEL/SM
TD NOLOCK Lock (making resident) not necessary
Indicates that a memory space (buf) designated in IO operations (tk rea dev and tk wri dev)
has already been locked (made resident) on the calling side and does not have to be locked
by the device driver. In this case the device driver does not (must not) lock the area. One
use of this designation is to perform disk access for page in/page out in a virtual memory
system. Generally it does not have to be designated.
The device descriptor belongs to the resource group of the task that opened the device.
When a physical device is opened, the logical devices belonging to it are all treated as having been
opened in the same mode, and are processed as exclusive open.
E BUSY
E NOEXS
E LIMIT
Other
Device busy (exclusive open)
Device does not exist
Open count exceeds the limit
Errors returned by device driver
• ER tk_cls_dev( ID dd, UINT option )
dd
option
return code
Device descriptor
Close option
Error
Closes device descriptor dd.
If a request is being processed, the processing is aborted and the device is closed.
option := [TD_EJECT]
#define TD_EJECT 0x0001 /* eject media */
TD EJECT Eject media
If the same device has not been opened by another task, the media is ejected. In the case of
devices that cannot eject their media, the request is ignored.
The subsystem cleanup processing (tk cln ssy) closes all the device descriptors belonging to the
resource group.
E ID
Other
dd is invalid or not open
Errors returned by device driver
• ID tk_rea_dev( ID dd, INT start, VP buf, INT size, TMO tmout )
dd
start
buf
size
tmout
return code
Device descriptor
Read start location (≥ 0: Device-specific data, < 0: Attribute data)
Buffer location for putting the read data
Read size
Request acceptance timeout (ms)
Request ID or error
Starts reading device-specific data or attribute data from the designated device. This function
starts reading only, returning to its caller without waiting for the read operation to finish. The
space designated in buf must be retained until the read operation completes. Read completion is
waited for by tk wai dev.
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T-Kernel 1.B0.02