Autodocs
Devices:
trackdisk.device
CMD_CLEAR
CMD_READ
CMD_UPDATE
CMD_WRITE
TD_ADDCHANGEINT
TD_CHANGENUM
TD_CHANGESTATE
TD_EJECT
TD_FORMAT
TD_GETDRIVETYPE
TD_GETGEOMETRY
TD_GETNUMTRACKS
TD_MOTOR
TD_PROTSTATUS
TD_RAWREAD
TD_RAWWRITE
TD_REMCHANGEINT
TD_SEEK
Include
GuruMeditation
|
Docs » Autodocs » trackdisk.device » CMD_READ
CMD_READ/ETD_READ -- read sectors of data from a disk.
These commands transfer data from the track buffer to a supplied
buffer. If the desired sector is already in the track buffer, no disk
activity is initiated. If the desired sector is not in the buffer, the
track containing that sector is automatically read in. If the data in
the current track buffer has been modified, it is written out to the
disk before a new track is read. ETD_READ will read the sector label
area if the iotd_SecLabel is non-NULL.
IO REQUEST INPUT
io_Device preset by the call to OpenDevice()
io_Unit preset by the call to OpenDevice()
io_Command CMD_READ or ETD_READ
io_Flags 0 or IOF_QUICK
io_Data pointer to the buffer where the data should be put
io_Length number of bytes to read, must be a multiple of
TD_SECTOR.
io_Offset byte offset from the start of the disk describing
where to read data from, must be a multiple of
TD_SECTOR.
iotd_Count (ETD_READ only) maximum allowable change counter
value.
iotd_SecLabel (ETD_READ only) NULL or sector label buffer pointer.
If provided, the buffer must be a multiple of
TD_LABELSIZE.
IO REQUEST RESULT
io_Error - 0 for success, or an error code as defined in
<devices/trackdisk.h>
Under versions of Kickstart earlier than V36, the io_Data had to
point to a buffer in chip memory. This restriction is no longer
present as of Kickstart V36 and beyond.
CMD_WRITE()
|
