13df2l2.txt
;**************************************************************************************************
; LISTING 2 - DISPATCH ROUTINE
;
; "Get those boards talking under Linux," EDN, June 22, 2000, pg 153
;
; http://www.ednmag.com/ednmag/reg/2000/06222000/13df2.htm
;****************************************************************************************************

//============ ioctl dispatch routine ===================
static int pd_ioctl(
   struct inode *inode,
   struct file *file,
   unsigned int command,
   unsigned long argument
) {
    int real_minor, board, board_minor, iRes;
    // calculate board# and subsystem
    real_minor = MINOR(file->f_dentry->d_inode->i_rdev);
    board = real_minor / PD_MINOR_RANGE;
    board_minor = real_minor % PD_MINOR_RANGE;
    // check if this process owns the subsystem
    if (!pd_CheckOwnerPID(board, board_minor, current->pid))
       return -EBUSY;
    // dispatch the ioctl() call to board-dependent routine
    iRes = pd_dispatch_ioctl(board,     // adapter number
                          board_minor,  // adapter subsystem
                          command,      // command
  			   argument,     // input/output buffer ptr
                          argument      // output buffer ptr
                         );
    // convert board-dependent error code into OS-dependent code
    return  pd_ConvertErrorCode(iRes); 
}