August 2014 - Oberon - mailman3.inf.ethz.ch

Spartan 6 Kickstarter project
by Aubrey.McIntosh＠Alumni.UTexas.Net 12 Oct '14

12 Oct '14

There is a Kickstarter project to produce a Spartan 6 board. This reached its funding goal in 4 days and will run for about 3 more weeks. https://www.kickstarter.com/projects/1812459948/minispartan6-a-powerful-fpg… -- Aubrey McIntosh, Ph.D. 1502 Devon Circle Austin TX 78723-1814 (512)-348-7401

6 5

Nimrod is not Oberon
by Stefan Salewski 02 Oct '14

02 Oct '14

Yes, I am still subscribed to this list... And I noticed that "Oberon on FPGA" project, but have not read much about it. Recently, when I was looking about some news about Mozillas Rust language, I discovered Nimrod, a language which looks similar to Modula/Oberon, with some interesting new features. Nimrod is not very popular now, some people simple do not like the Wirthian style syntax. (And of course there are many other interesting new languages available now, Mozillas Rust with C syntax, Julia for numerical computing, Haskell -- not really new, but still modern...) But maybe someone of you may be interested in Nimrod. Of course it is no operating system, just a modern language. Keywords: Wirthian syntax, with Python indentation, system- and high-level programming, garbage-collector which still allows time critical applications, advanced generics, templates, high-level macros. Good support for parallel processing. Speed seems to be close to C. Currently Compiler generates C intermediate code. Currently there is no wikipedia entry (was rejected) so it is difficult to discover it. There was an article in DrDobbs Journal recently, and of course there is a homepage with a tutorial. http://nimrod-lang.org/ http://www.drdobbs.com/open-source/nimrod-a-new-systems-programming-languag… Not a high rank at http://langpop.corger.nl/ but Oberon is not listed at all ;-) Best regards Stefan Salewski

3 3

ALO usage Log/Query ?
by eas lab 07 Sep '14

07 Sep '14

This rambling journey exposes some exercising of the current ALO version. A reason for making/keeping detailed logs, is confirmed by my difficulty to 'pick up the threads' of ... Tue, Jan 29, 2013 at 2:39 PM Subject: [Oberon] HOW2 get Token at cursor? <paulreed(a)paddedcell.com> ] Have a look at TextFrames.Call(), which calls Oberon.Call() after setting ] up the parameters to the command. ... Yes, as advised I've consulted PO.System.pdf, and even [listen while sleeping, via wily, which is a killer-ap for linux-ETHO-users] to: 4.4.3. Cursor management. === A certain project needs the user to be able to roam-the-screen with the mouse-in-right-hand and left-hand-press-any-key when the cursor is on specific tokens/words. BTW, I'm writing this all in ALO [in color - of course]:--------------- Real task to exercise ALO140731Z Trace co-ordinates of cursor <- Find "ursor" in *.Mod, where *.Mod is <loaded>. ?! but ALO will use *nix-X cursor control !? Binary file ./ALO.DisplayX11.Mod matches Binary file ./ARM.Display.Mod matches Display loaded. Display3 loaded. Display3.Mod <--no mention of "ursor" GfxDisplay.Mod <--no mention of "ursor" =?=> why/what difference: ARM.Display.Mod : Display.Mod =nX ARM.Display.Mod == ... (** Move hardware cursor to (x,y) *) PROCEDURE MoveSprite*(x,y : LONGINT); (** non-portable *) ... SYSTEM.PUT(index,51X); SYSTEM.PUT(data, CHR(x DIV 100H)); SYSTEM.PUT(index,53X); SYSTEM.PUT(data, CHR(y MOD 100H)); spriteX:=x; spriteY:=y END MoveSprite; =?=> HOW2 trace spriteX:=x; = Check Hello.Mod = Out.String("spriteX:=x"); Out.Int(spriteX,8); Out.Ln; BACKUP: ARM.Display.Mod => ARM.Display.ModORGNL =?=> Can't compile a running/used module ? -> ARMCompiler.Compile * == compiling Display pos 1055 err 152 symbol file of imported module not found -> System.Directory *Display* == Display.Sym -> System.Free Display == Display reference count not zero <- being USED ?!! !!!!!!!!!! Since the present system's compiler can't run except when the Display is active, how can this problem be solved ? Last year, to finally get output from <cusorPikToken>, I made a module, similar to an existing one that gave the X,Y values -- IIRC? == Chris Glur.

2 7

Re: [Oberon] EXIT statement?
by Diego Sardina 30 Aug '14

30 Aug '14

> Hi, Hi > Does anyone know the reasoning behind [..] the EXIT statement? > Why does it only work inside a LOOP statement [..]? These forms of iteration in Oberon have a precise semantic: In the WHILE statement the termination condition is checked each time *before* the execution of the statement sequence. In the REPEAT statement the termination condition is checked each time *after* the execution of the statement sequence. The LOOP statement can have multiple termination conditions (with EXIT) *within* the statement sequence. WHILE/REPEAT/FOR statements do not expect to have arbitrary exit points, but they can have a premature RETURN (that is more evil than EXIT) in the previous Oberon report. > why is there no CONTINUE statement [..]? The LOOP statement with arbitrary exit points, CONTINUE statement and RETURN statement are forms of unstructured control flow. They are like goto and the result is spaghetti code: harder to read and to mantain. > Is there some inherent drawback/downside in adding this to the language? In general an unstructured control flow is harder to optimise. Generation of SSA form is also hard for these forms of unstructured statement, in particular in a single-pass compiler. A suggested reading about this: Brandis - Single-Pass Generation of SSA Form for Structured Languages. > I'm looking [..] if I can add a few features that [..] seem quite useful. There is always an alternative formulation that doesn't require any of those forms and they are often surprisingly better in look, code quality and maintenance. For example I converted Sets.Mod to Oberon-07. In particular the major change was the removal of a premature return in the function procedure. This was the original procedure: PROCEDURE Includes*(VAR s1, s2: ARRAY OF SET): BOOLEAN; VAR i: INTEGER; BEGIN i := 0; WHILE i < LEN(s1) DO IF s1[i] + s2[i] # s1[i] THEN RETURN FALSE END; INC(i) END; RETURN TRUE; END Includes; Without the premature return, it became: PROCEDURE Includes*(s1, s2: ARRAY OF SET): BOOLEAN; VAR i: INTEGER; BEGIN i := 0; WHILE (i < LEN(s1)) & (s1[i] + s2[i] = s1[i]) DO INC(i) END; RETURN i = LEN(s1); END Subset; The code is not only shorter than the previous one, but the termination condition makes the result more visible from an algorithmic point of view. The expression (i = LEN(s1)) OR (s1[i] + s2[i] # s1[i]) is your resulting condition after the execution of the WHILE statement and it is also the result of your algorithm (in this case i = LEN(s1) suffice). What is the resulting condition of the algorithm in the previous one? It's hard to say, it's spaghetti code. Although not very visible, the condition is the same. But just imagine a very complex algorithm in a procedure with a lot of premature returns, it will be a challenge for you. It is a nightmare to postulate pre/post conditions of an algorithm with spaghetti code. -- Diego Sardina

3 2

EXIT statement?
by Matic Kukovec 29 Aug '14

29 Aug '14

Hi, Does anyone know the reasoning behind functionality of the EXIT statement? Why does it only work inside a LOOP statement and not inside WHILE and FOR? And also why is there no CONTINUE statement (as in C, Python, ...) , to skip to the next iteration of a loop? Is there some inherent drawback/downside in adding this to the language? I'm looking into the OP2 compiler to see if I can add a few features that I like or that seem quite useful for my needs. Matic

3 2

OPCL Portable Oberon-2 compiler help?
by Matic Kukovec 25 Aug '14

25 Aug '14

Hi guys, Does anyone know of any detailed documentation for the OPCL - Oberon Portable Compiler and Linker. (http://sourceforge.net/projects/opcl/) I have Régis Crelier's "OP2: A PORTABLE OBERON–2 COMPILER" paper, is there any other documentation on it? Thanks, Matic

2 3

Re: [Oberon] OPCL Portable Oberon-2 compiler help?
by Chris Burrows 23 Aug '14

23 Aug '14

> > From: Matic Kukovec [mailto:kukovecmatic@hotmail.com] > Sent: Friday, 22 August 2014 7:38 PM > To: Oberon Mailing List > Subject: [Oberon] OPCL Portable Oberon-2 compiler help? > > Hi guys, > > Does anyone know of any detailed documentation for the OPCL - Oberon Portable > Compiler and Linker. > (http://sourceforge.net/projects/opcl/) > > I have Régis Crelier's "OP2: A PORTABLE OBERON2 COMPILER" paper, is there > any other documentation on it? > See Diss. ETH No 10650 'Separate Compilation and Module Extension', Régis Crelier, ETH Zurich 1994: http://e-collection.library.ethz.ch/view/eth:39386?q=10650 Regards, Chris Burrows CFB Software Astrobe: Oberon for Cortex-M4, Cortex-M3 and ARM7 http://www.astrobe.com

1 0

Open Verilog Code for the Propeller processor and all its tools!
by greim 18 Aug '14

18 Aug '14

Hi, i know its not directly related to Oberon, but very closed related to Oberons philosophy. http://www.parallax.com/microcontrollers/propeller-1-open-source Parallax gave there processor design (Verilog) and their development tools free under the GNU GPL 3.0! The Propeller is a very clever but simply designed 8 core 32bit round robin multi processor with no interrupts. Beneath others it has a (8) VGA outputs, different timers and counters, free pin assignment, etc. And nearly everything, incl. the serial interface, I2C etc. was in done in software. It has an integrated interpreter (SPIN) with a very clear and simple Pascal/Python similar syntax. It should be, for example, not so difficult to integrate an Oberon RISC machine (for example as master) and a Propeller as (for example I/O slave) on one single FPGA. Or to write an Oberon Compiler for the Propeller ;-) Regards Markus

1 0

VNC.Open inconsistency
by Yaroslav Romanchenko 07 Aug '14

07 Aug '14

Hi Oberon Comunity! There is a small inconsistency in A2's VNC.Open command. It actually makes impossible for A2 newbies to use both of VNC examples present in system (VNCTetrisServer and WMVNCView). Both examples by default does not require password for connection establishing, but VNC.Open at first incorrectly handles password omission in command line and at second on password omission requests password through the dialog and finishes with error if user will omit it again in the dialog. And at third this behaviour even does not correspond to syntax presented to user by message "Error: expected server[ pwd] port". Correct code, probably, will be following: PROCEDURE Open*(context : Commands.Context); (** server[ pwd] port *) VAR server: IP.Adr; res, port: LONGINT; c: Connection; pwd: ARRAY 32 OF CHAR; svr, title: ARRAY 128 OF CHAR; BEGIN context.arg.SkipWhitespace; context.arg.String(svr); context.arg.SkipWhitespace; IF (context.arg.Peek() < "0") OR (context.arg.Peek() > "9") THEN context.arg.String(pwd) END; context.arg.SkipWhitespace; context.arg.Int(port, FALSE); IF (context.arg.res = Streams.Ok) OR (context.arg.res = Streams.EOF) THEN DNS.HostByName(svr, server, res); IF (res = Ok) & (port # 0) THEN NEW(c); OpenVNC(c, server, port, pwd); IF c.res = Ok THEN pool.Add(c); COPY(svr, title); Files.AppendStr(" Port ", title); Files.AppendInt(port, title); Files.AppendStr(" - VNC ", title); Files.AppendInt(c.id, title); c.w.SetTitle(WMWindowManager.NewString(title)); Show(context) ELSE context.error.String("Error "); context.error.Int(c.res, 1); context.error.Ln END ELSE context.error.String("Error: not found"); context.error.Ln END ELSE context.error.String("Error: expected server[ pwd] port"); context.error.Ln END; END Open; --- Cheers, SAGE http://sage.com.ua/

2 2