Topic       : TOS - The Operating System
Author      : 
Version     : tos.hyp (December 19, 2008)
Subject     : Programmieren/Atari
Nodes       : 3010
Index Size  : 93790
HCP-Version : 5
Compiled on : Atari
@charset    : atarist
@lang       : 
@default    : Title
@help       : 
@options    : +g -i -s +x +zz -t4
@width      : 70
View Ref-File14.8.1  XHDI cookie                                                TOS

Cookie ID: 'XHDI'. The contents of the cookie points to the start 
address of a function which provides procedures for dealing with block 
storage devices. As an additional check, the function is preceded by 
the LONG constant 0x27011992.

The contents of the XHDI cookie may change (because it can be used by 
more than one driver). Therefore, in some applications (example: Desk 
accessories) the cookie contents must be inquired each time before the 
handler is called.

How to install more than one XHDI driver:

 (1)  During the installation, check whether the cookie is already 
      set. If so:

 (2)  For XHGetVersion first jump through the old vector and return 
      the minimum of this and your own version number.

 (3)  For XHDrvMap first jump through the old vector and then OR in 
      the drive bits for the devices supported by you.

 (4)  For all other functions: Check whether it is one of your 
      devices. If not, jump through the old vector.

See Also: XHDI specification   About the GEMDOS   About the BIOS 
Cookie jar   SCSI specification