[Oberon] Stimulus driven interrupts?

[Jeff Maggio]

Thank you Jörg - this clears a lot up


In the paper from N Wirth that I linked (
http://norayr.am/papers/WirthTasksVersusThreads.pdf), he mentions an
"interrupt vector" (page 10). Does this mean that multiple interrupts can
be setup in a priority order?

much obliged,
Jeff

In addition to Chris’ reply. Here a minimum implementation of
> Install*(handler: PROCEDURE);
> SYSTEM.LDPSR(0);
> (* disable/clear interrupt *) Kernel.Install(SYSTEM.VAL(INTEGER, handler),
> 4);      (* install the interrupt handler at memory address 4 *)
> SYSTEM.LDPSR(1);
> (* enable/set interrupt *) LDPSR is the abbreviation for “load processor
> status register”. The last bit of this status register is “interrupt:
> on/off” As interrupts begin and end differently than “normal” procedures,
> and it has bad consequences if you install a “normal” procedure as
> interrupt handler, I decided to check that the parameter “handler” is
> really an interrupt procedure. To do this I check the procedure’s prolog.
> Here the start of the prolog (=the code the compiler generates when it sees
> a BEGIN)
>  normal proc:                  interrupt proc:
>   SUB SP SP localsize       SUB SP SP localsize
>   STW LNK SP 0                STW R0 SP 0
>  ….                                    … The first instruction is the same
> but the second instruction differs.
> SYSTEM.LDPSR(0);
> (* disable/clear interrupt *) Kernel.Install(SYSTEM.ADR(Empty),
> 4);                                           (* see below *)
> SYSTEM.GET(SYSTEM.VAL(INTEGER, handler)+4, instr);           (* get second
> instruction of the “handler” code. If “handler” is NIL the check below is
> never true *) IF instr = 0A0E00000H THEN (* valid interrupt handler
> *)       (* check for STW R0 SP 0 *) Kernel.Install(SYSTEM.VAL(INTEGER,
> handler), 4);                   (* install interrupt handler at memory
> address 4 *)
> SYSTEM.LDPSR(1)
> (* enable/set interrupt *) END The “Empty” interrupt is a precaution in
> case the programmer’s interrupt handler is not valid or NIL and the
> programmer would code a SYSTEM.LDPSR(1) on his own after Install(). I could
> put this code in the ELSE. Instead of SYSTEM.GET(SYSTEM.VAL(INTEGER,
> handler)+4, instr);  the compiler would also accept the shorter
> SYSTEM.GET(ORD(handler)+4, instr); As the Oberon report does not define
> ORD() on procedure variables, I use the “official” way of doing it. br Jörg
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