On 10 Sep 2008, at 15:47, Marcel Kilgus wrote:
George Gwilt wrote:
I have never before used this trap but have just now tried it out. It
appears that you have to put the return address on the (user) stack
before Trap #1 otherwise the return is to whatever happens to be on
the user stack which can be rather nasty.
Yes, the normal schema to use it is
bsr.s something_nasty
; normal stuff
rts
something_nasty
moveq #sms.xtop,d0
trap #1
; nasty stuff here
rts
You could also do
pea after
moveq #sms.xtop,d0
trap #1
; nasty stuff
rts
after:
; normal stuff
However, I think the documentation is very slightly misleading. I
would not expect to have to use PEA or BSR to load the return address.
George
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