May 2021 - Oberon - mailman3.inf.ethz.ch

Should hidden re-imports be able to coexist with identifiers
by Andreas Pirklbauer 13 May '21

13 May '21

The following reports a “mult def” error in PO 2013 when compiling M2 MODULE M0; TYPE T0* = RECORD i: INTEGER END ; END M0. MODULE M1; IMPORT M0; TYPE T1* = RECORD (M0.T0) j: INTEGER END ; END M1. MODULE M2; IMPORT M1; (*re-imports M0.T0*) VAR M0: INTEGER; (* <--- "mult def” error message*) END M2. In PO2013 this error is reported because the symbol table headed by topScope *also* contains the re-imported module M0 (which is a bit unfortunate) -- but ORB.NewObj does not check that fact. I my mind, M2 should compile with no error message. i.e. hidden re-imports should be able to coexist with regular identifiers (since one cannot refer to re-imported objects by name anyway). Comments?

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Email; was Streams.
by peter＠easthope.ca 13 May '21

13 May '21

From: Liam Proven <lproven(a)gmail.com> Date: Thu, 13 May 2021 14:26:13 +0200 > I personally use Thunderbird, and this enables offline replies, > composition, editing etc. You only need to go online to send and > receive. An old topic repeated too often; IMAP is also available in A2 and POP3 is in Oberon. Messages can be retrieved by POP3. Messages can be read offline. Replies can be composed offline. Connect and send by SMTP. =8~) The discussion always reminds me of a comment by a developer of molecular graphics software. Paraphrasing: one tends to have more confidence in software which the developer is willing to use. Generalized slightly, applicable here: one tends to have more confidence in software used by people claiming it to be good software. =8~) Regards, ... P.L. -- tel: +1 604 670 0140 Bcc: peter at easthope. ca

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Re (2): Re (2): Re (2): Streams.
by peter＠easthope.ca 13 May '21

13 May '21

From: eas lab <lab.eas(a)gmail.com> Date: Tue, 4 May 2021 00:18:55 -0400 > Can aos do: > list the 22 most recentcy-ordered > including <dotted files> in /tmp ? > eg.*nix: ls -ta /tmp | head -22 Your *nix system should be firewalled. If not install Shorewall. In /etc/inetd.conf comment out #telnet stream tcp nowait telnetd /usr/sbin/tcpd /usr/sbin/in.telnetd and add this. telnet stream tcp nowait eas /usr/sbin/tcpd /usr/sbin/telnetd -E bin/bash In the Oberon subsystem, a console is opened without a password. Desktops.OpenDoc telnet://localhost There do the linux command. ls -ta /tmp | head -22 ls -ta /path/to/any/directory | head -22 Etc. A2 also has Tools > Serial Terminal which should connect to localhost and accept commands. Regards, ... P.L. -- tel: +1 604 670 0140 Bcc: peter at easthope. ca

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Re (2): Re (2): Re (2): Re (2): Streams.
by peter＠easthope.ca 13 May '21

13 May '21

> P.E's reply to my query makes no sence ? I suggested a means to have a host console in A2. Also in the Oberon subsystem. Ref. here. https://en.wikibooks.org/wiki/Oberon/A2#User_Level_Applications In the host console you can execute any linux command. Then copy the results to an Oberon viewer using MR+MM. Or save the host result to a file and open the file in the Oberon system. That's your objective? No? ... P. -- tel: +1 604 670 0140 Bcc: peter at easthope. ca

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Michael Franz receives 2020 ACM Chuck Thacker Breakthrough Award
by Andreas Pirklbauer 10 May '21

10 May '21

Just FYI: https://www.acm.org/media-center/2021/april/thacker-award-2020 PS: Michael was my assistant in the course Informatik 3/4 given by Niklaus Wirth in the late 80s. He also showed me many tricks in compiler design.. - - - - - - ACM Chuck Thacker Breakthrough Award Goes to Innovator Who Transformed Web Applications UC Irvine's Michael Franz Made Just-In-Time Compilation Practical for Billions of Web Users Daily New York, NY, April 28, 2021 – ACM, the Association for Computing Machinery, today announced that Michael Franz of the University of California, Irvine is the recipient of the ACM Charles P. “Chuck” Thacker Breakthrough in Computing Award. Franz is recognized for the development of just-in-time compilation techniques that enable fast and feature-rich web services on the internet. Every day, millions of people around the world use online applications such as Gmail and Facebook. These web applications would not have been possible without the groundbreaking compilation technique Franz developed in the mid-1990s. Beginning with the PhD thesis he completed in 1994, Franz has been exploring the use of just-in-time (JIT) dynamic compilation and optimization, focusing not only on static languages such as Java, but also on dynamically-typed languages. Initially such dynamic languages were primarily used in research and academic settings, but that changed when JavaScript was adopted for creating web services. JavaScript enabled the creation of websites that had application-like behavior, rather than the more static websites enabled by HTML. JavaScript, like other dynamic languages, was initially interpreted, and that led to poor performance. By inventing a new compilation technique, developing a JIT compiler for JavaScript based on this new technique, and then collaborating with Mozilla to incorporate it into the Firefox browser, Franz enabled massive growth in the use of JavaScript, now one of the world’s most heavily used programming languages. “We all use web-based applications every day and they are now so prevalent that we often forget how revolutionary they were when they were first introduced,” said ACM President Gabriele Kotsis. “Whether we’re connecting with friends or colleagues on a social media platform, preparing our taxes using online software, or booking an accommodation at a hotel, we are using a web-based application. Michael Franz’s work certainly fits the Thacker Award’s criteria for ‘leapfrog contributions to computing ideas and technologies.’ Franz displayed foresight in working with Mozilla to implement his ideas on their browser and in making his technology open source so that it could be continually refined and adapted by developers worldwide.” The idea of JIT dynamic compilation goes back decades and was initially used for a variety of statically-typed-languages. In the 1970s, researchers at the Xerox Palo Alto Research Center used JIT compilation for Smalltalk, a dynamically-typed language. In the 1980s, researchers at Stanford and Sun explored the use of JITs for Self, a dynamically typed, prototype-based language similar to JavaScript. Franz made several important contributions beyond this earlier work that greatly increased the practicality of JIT compilation. First, rather than optimizing entire functions, he introduced a technique that optimizes only the loops of a program, using a structure called a “trace tree” to represent alternative paths through a loop that are discovered and subsequently translated incrementally. Second, Franz developed a JIT compiler that could be applied in a variety of settings, including those with more limited CPU or memory resources. With these techniques, Franz’s JIT compiler could often achieve performance improvements of 5-10x on JavaScript, which was critical to its wide-ranging adoption and the transformation of web applications. Most websites today use JavaScript, and all browsers include a JavaScript execution engine. Franz’s technology helped make this transformation possible. “Microsoft is proud to fund the Breakthrough in Computing Award, named after Chuck Thacker, one of the computing field’s true visionaries,” said Eric Horvitz, Microsoft’s Chief Scientific Officer. “Chuck had a magical ability to transform over-the-horizon computing dreams into world-changing realities. Michael Franz’s work on just-in-time compilation is a great choice for the Breakthrough in Computing honor. His work has been transformative, enabling today’s rich web experiences by allowing websites to execute sophisticated, interactive programs nearly instantaneously. Michael Franz’s insights, and his successful application of those insights, have had tremendous real-world impact.” Biographical Background Michael Franz is a Chancellor's Professor in the Department of Computer Science at the University of California (UC), Irvine, where he also directs the Secure Systems and Software Laboratory. His current research emphasis is in software systems, particularly focusing on compiler, virtual machine, and related system-level techniques for making software safer, or faster, or both. Franz received a Doctor of Technical Sciences degree in Computer Science and a Diplomingenieur, Informatik-Ing. ETH degree, both from the Swiss Federal Institute of Technology (ETH Zurich). His honors include receiving a Humboldt Research Award from the Alexander von Humboldt Foundation, a National Science Foundation CAREER Award, an IEEE Computer Society Technical Achievement Award, and a Distinguished Mid-Career Faculty Award for Research from the University of California, Irvine. Franz is a Fellow of ACM, the Institute of Electrical and Electronics Engineers (IEEE), the American Association for the Advancement of Science (AAAS), and the International Federation for Information Processing (IFIP). About the ACM Charles P. "Chuck" Thacker Breakthrough in Computing Award The ACM Breakthrough Award celebrates Thacker's pioneering contributions in computing and his long-term inspirational mentorship of generations of computer scientists. The award recognizes individuals or groups with the same out-of-the-box thinking and “can-do” approach to solving the unsolved that Thacker exhibited. The award is accompanied by a prize of $100,000 and is presented at the annual ACM Awards Banquet. Recipients are expected to give the ACM Breakthrough Lecture at a major ACM conference of their choosing during the year following the announcement. Financial support of the ACM Breakthrough Award is provided by Microsoft. About ACM ACM, the Association for Computing Machinery, is the world's largest educational and scientific computing society, uniting educators, researchers and professionals to inspire dialogue, share resources and address the field's challenges. ACM strengthens the computing profession's collective voice through strong leadership, promotion of the highest standards, and recognition of technical excellence. ACM supports the professional growth of its members by providing opportunities for life-long learning, career development, and professional networking.

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Stimulus driven interrupts?
by Jeff Maggio 07 May '21

07 May '21

Gray - that would be fantastic! I'd love to look more into it Jorg - thank you, that module simplifies things a lot. Would it be possible for you to walk me through how it works in more detail? I'm not following every line - for instance what does SYSTEM.LDPSR do? Adding to Jörg's post, below, I have a simple eight channel interrupt controller in the FPGA hardware as "front end" to the single interrupt of the RISC5 CPU, including the corresponding Oberon driver of course. It adds one clock cycle of latency, IIRC. Let me know if you're interested. It requires some minor changes to the RISC5 CPU, though. > -- gray On Thu, 6 May 2021, at 19:53, Joerg wrote: > >* Hi Jeff > * > > > >* The interrupt signal is handed over by the HW to the RISC5 CPU in RISC5Top.v. > * > >* The interrupt signal in the CPU is called .irq, and the current RISC5Top.v hands over periodic interrupts with the Verilog code below > * > >* RISC5 riscx(.clk(clk), .rst(rst), *.irq(limit),* > *>* .rd(rd), .wr(wr), .ben(ben), .stallX(vidreq), > * > >* .adr(adr), .codebus(codebus), .inbus(inbus), > * > >* .outbus(outbus)); > * > > >* assign limit = (cnt0 == 24999); > *> > >* But you are totally free to set the CPU’s .irq signal on other HW conditions, e.g. a packet on the Ethernet board arrived or the temperature sensor says the meat is tender. > * > > > >* Below I attached an older mail on an “simple” API to facilitate programming with interrupts. Instead of Kernel.Install you would call Interrupt.Install to install the interrupt handler. > * > > > >* br > * > >* Jörg > *

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Re: [Oberon] Stimulus driven interrupts?
by Jeff Maggio 07 May '21

07 May '21

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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Stimulus driven interrupts?
by Jeff Maggio 06 May '21

06 May '21

Hi all, I'm using Oberon on an embedded RISC5 system, and am able to modify both firmware and software. In this Oberon-1 paper (*http://norayr.am/papers/WirthTasksVersusThreads.pdf <http://norayr.am/papers/WirthTasksVersusThreads.pdf>*) from 1996, Wirth discusses a method of "real-time tasks". *(Page 10)*. In which I believe interrupt handlers installed with *Kernel.Install(Handler, N)* are triggered when a device or buffer is updated? The details are unclear in the paper. I see that *Kernel.Install* still exists in the RISC5 source. Can this method still be used for "real-time tasks" in which a procedure is run when an external stimulus changes? So far all the interrupt examples I've seen make use of interrupts triggered periodically by the millisecond timer. My end goal is to trigger an interrupt (from firmware or otherwise) in reaction to stimulus without having to wait for the millisecond timer best, Jeff

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INC(i) vs i := i + 1
by Jeff Maggio 05 May '21

05 May '21

Thanks everyone! That was very helpful

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Re: [Oberon] INC(i) vs i := i + 1
by Chris Burrows 05 May '21

05 May '21

> > From: Oberon [mailto:oberon-bounces@lists.inf.ethz.ch] On Behalf Of Joerg > Sent: Wednesday, 5 May 2021 6:00 PM > To: ETH Oberon and related systems > Subject: Re: [Oberon] INC(i) vs i := i + 1 > > Just as an example, find below the output of the RISC5 compiler: > > The statements i := i+1; and INC(i); generate exactly the same output, That is true if i is a local or global variable or a value parameter. However, if i is a VAR parameter, the INC version generates one less instruction. Regards, Chris Burrows CFB Software https://www.astrobe.com

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