Home / Autodocs / trackdisk.device
NAME
- TD_ADDCHANGEINT
-
add a disk change software interrupt handler.
FUNCTION
This command lets you add a software interrupt handler to the disk device that gets invoked whenever a disk insertion or removal occurs.
You must pass in a properly initialized Exec Interrupt structure and be prepared to deal with disk insertions/removals immediately. From within the interrupt handler, you may only call the status commands that can use IOF_QUICK.
To set up the handler, an Interrupt structure must be initialized. This structure is supplied as the io_Data to the TD_ADDCHANGEINT command. The handler then gets linked into the handler chain and gets invoked whenever a disk change happens. You must eventually remove the handler before you exit.
This command only returns when the handler is removed. That is, the device holds onto the IO request until the TD_REMCHANGEINT command is executed with that same IO request. Hence, you must use SendIO() with this command.
You must pass in a properly initialized Exec Interrupt structure and be prepared to deal with disk insertions/removals immediately. From within the interrupt handler, you may only call the status commands that can use IOF_QUICK.
To set up the handler, an Interrupt structure must be initialized. This structure is supplied as the io_Data to the TD_ADDCHANGEINT command. The handler then gets linked into the handler chain and gets invoked whenever a disk change happens. You must eventually remove the handler before you exit.
This command only returns when the handler is removed. That is, the device holds onto the IO request until the TD_REMCHANGEINT command is executed with that same IO request. Hence, you must use SendIO() with this command.
INPUTS
- io_Device
-
preset by the call to OpenDevice()
- io_Unit
-
preset by the call to OpenDevice()
- io_Command
-
TD_ADDCHANGEINT
- io_Flags
-
0
- io_Length
-
sizeof(struct Interrupt)
- io_Data
-
pointer to Interrupt structure
RESULT
- io_Error
-
0 for success, or an error code as defined in <devices/trackdisk.h>
SEE ALSO
BUGS
As this command is issued with SendIO(), the issuer will not be notified when exactly the change interrupt becomes active, and in particular, when TD_REMCHANGEINT can be issued to remove the interrupt again. If TD_ADDCHANGEINT and TD_REMCHANGEINT are send shortly after each other without a task switch taking place, the TD_REMCHANGEINT could have caused bad side effects in V45 and before. While the trackdisk.device became aware of this race condition in V47, it is still advisable to perform any other command via DoIO(), e.g. TD_MOTOR, to ensure that the interrupt is really queued in, and is safe to remove.