[Oberon] [EXT] Re: Emulating interrupts in oberon-risc-emu as in the RISC5 specification

[Skulski, Wojciech]

Joerg:

what is SYSTEM.LDPSR? It does not seem to be present in the language report dated Revision 1.10.2013 / 3.5.2016, which I just downloaded from Paul's website.

Wojtek


________________________________________
From: Oberon [oberon-bounces at lists.inf.ethz.ch] on behalf of Jörg [joerg.straube at iaeth.ch]
Sent: Tuesday, March 30, 2021 8:45 PM
To: ETH Oberon and related systems
Subject: [EXT] Re: [Oberon] Emulating interrupts in oberon-risc-emu as in the RISC5 specification

Although TestInt is low-level, it should use Kernel.Install (SYSTEM.ADR(Int), 4) to make it a little bit less low-level😀

This little wrapper makes interrupts a little bit better consumable:
MODULE Interrupts; (* jr/31mar21 *)
IMPORT S := SYSTEM, Kernel;
PROCEDURE Install*(handler: PROCEDURE);
  BEGIN Kernel.Install(S.ADR(handler), 4) END Install;
PROCEDURE Set*(on: BOOLEAN);
  BEGIN S.LDPSR(ORD(on)) END Set;
END Interrupts.

With it TestInt.Mod gets
MODULE TestInt;
IMPORT Interrupts;
VAR led, cnt: INTEGER;
PROCEDURE* MyInterrupt;
  BEGIN
    INC(cnt); IF cnt = 500 THEN led := 3-led; LED(led); cnt := 0 END
  END MyInterrupt;
PROCEDURE On*; BEGIN Interrupts.Set(TRUE) END On;
PROCEDURE Off*; BEGIN Interrupts.Set(FALSE) END Off;
BEGIN
  led := 1; cnt := 0; Interrupts.Install(MyInterrupt)
END
TestInt.On
TestInt.Off

Interrupts.Mod could be enhanced servicing multiple interrupt handlers. Comparable to the background tasks in Oberon.Mod. This enhancement would install its own interrupt handler doing the scheduling, and the user‘s „interrupt handlers“ are normal procedures without * marking of the procedure. You would then install your handler like this
PROCEDURE MyTask; BEGIN led := 3 - led; LED(led) END MyTask;
BEGIN led := 1; Interrupts.Install(MyTask, 500) END TestInt.

br, Jörg