A92: Re: Thanks David
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A92: Re: Thanks David
> I tried your idea of disabling the interrupts before reading the keypresses.
> It works perfectly. Thanks for the help. Also, At one point I tried to
> create a custom interrupt for handling the keypresses (so it would all be
> done automatically) but it failed. I couldn't get the old interrupt out
> and the new one in. It kept crashing and stuff. Maybe you have something
> that could help me here. If anyone has any ideas to help please send them.
The interrupt vector table is protected from writing. You have to disable
the protection first before you right to the table. Then reenable it when
you're done. Unfortunately you will also need to mask out the particular
interrupt you are modifiying. This cannot be done as Fargo programs are all
run in user mode. Ellsworth wrote a "function" to help you and it is tied
in as a TRAP vector. This piece of code will disable the protection, mess
with the interrupts, and reenable the protection.
; INITIALIZATION
move.w #$0700,d0 ; Change SR (Status Register)
trap #1 ;
move.l $64,old_int_1 ; Store old interrupt vector
bclr.b #2,$600001 ; Disable write protection
move.l #int_1,$64 ; Replace with our interrupt
bset.b #2,$600001 ; Enable write protection
trap #1 ; Restore SR
. . .
; CLEAN UP
move.w #$0700,d0 ; Change SR
trap #1 ;
bclr.b #2,$600001 ; Disable write protection
move.l #old_int1,$64 ; Restore the old interrupt
bset.b #2,$600001 ; Enable write protection
trap #1 ; Restore SR
. . .
; INTERRUPT CODE
int_1:
; some code here
move.l old_int_1,-(sp) ; Also execute the old interrupt
rts
. . .
; DATA SECTION
old_int_1 dc.l 0
The %fargo%\doc\traps.txt file explains the interrupts. It also explains how
to use the TRAP #1 function. This should help you get some interrupt-based
programs working. Enjoy.
====
Aaron Hill (Redmond, Wash.)
Electronic Mail: serac@lightmail.com
IRC Nickname: serac (on EF-Net)
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