TD_FORMAT/ETD_FORMAT - format a track on a disk.

These commands are used to write data to a track that either has not yet been formatted or has had a hard error on a standard write command. TD_FORMAT completely ignores all data currently on a track and does not check for disk change before performing the command. The io_Data field must point to at least one track worth of data. The io_Offset field must be track aligned, and the io_Length field must be in units of track length (that is, NUMSEC*TD_SECTOR).

The device will format the requested tracks, filling each sector with the contents of the buffer pointed to by io_Data. You should do a read pass to verify the data.

If you have a hard write error during a normal write, you may find it possible to use the TD_FORMAT command to reformat the track as part of your error recovery process. Note that the mfm.device does not write sector label information.

io_Device

preset by the call to OpenDevice()

io_Unit

preset by the call to OpenDevice()

io_Command

TD_FORMAT or ETD_FORMAT

io_Flags

0 or IOF_QUICK

io_Data

points to a buffer containing the data to write to the track, must be at least as large as io_Length.

io_Length

number of bytes to format, must be a multiple of (TD_SECTORS * NUMSEC).

io_Offset

byte offset from the start of the disk for the track to format, must be a multiple of (TD_SECTORS * NUMSEC).

iotd_Count

(ETD_FORMAT only) maximum allowable change counter value.

iotd_SecLabel

ignored

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, TD_RAWWRITE