Drawing circles: DOHFX

       Name: DOHFX                                                   [Show more]
       Type: Subroutine
   Category: Drawing circles
    Summary: Implement the #DOHFX <flag> command (update the hyperspace effect
             flag)
    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * JMPTAB calls DOHFX


 This routine is run when the parasite sends a #DOHFX <flag> command. It
 updates the hyperspace effect flag in HFX.


 Arguments:

   A                    The new value of the hyperspace effect flag:

                          * 0 = no colour effect

                          * Non-zero = enable hyperspace colour effect


.DOHFX

 STA HFX                \ Store the new hyperspace effect flag in HFX

 JMP PUTBACK            \ Jump to PUTBACK to restore the USOSWRCH handler and
                        \ return from the subroutine using a tail call