TweetFollow Us on Twitter

Modula-2 Compiler
Volume Number:1
Issue Number:6
Column Tag:Modula-2

Modula-2 Compiler by Modula Corporation

By Jörg Langowski

The ‘almost released’ beta version of the Modula-2 compiler by Modula Corporation has been around for some time now on several peoples’ desks, including mine. I feel it is time to report some of my experiences with this product.

Modula 2 is in some way the successor of Pascal, created by the same author, Niklaus Wirth from Zürich. Simple Modula 2 programs almost look like Pascal programs. Supposedly some of the inconveniences of Pascal have been straightened out in Modula 2, e.g., the rigid order in which declarations are made in Pascal has been relaxed. The most important new concept is that of modular compilation, which means that external (library) definitions can be ‘imported’ from separately compiled ‘modules’ at compile time and checked for correct passing of parameters, type mismatches etc

But I do not want to talk about language differences here. There has been a whole issue of BYTE dealing with Modula recently, and if you plan to use the Modula-2 compiler, you will have to get the standard reference book, ‘Programming in Modula-2’, by Niklaus Wirth, anyway.

The Modula-2 version that I received from Modula Corporation came on one Macintosh disk with a three-ring binder manual. The disk contains:

- The Modula-2 compiler and linker. Both are compiled Modula-2 programs, which means (for this system) that they are not native 68000 code, but rather M-code for a virtual machine, which has to be interpreted.

- The interpreter. The disk contains two versions, one of which is used to run the compiler and linker, the other one to run your compiled Modula-2 program.

- System libraries with precompiled modules for I/O, file handling, number conversion, string manipulation and - most important of all - toolbox access.

- a Decode utility to disassemble M-code. I found this of little use since I had no definition of the M-code instructions available.

- source code of a Graphics Demo and the Edit sample application that is also part of the IM manual.

- Edit, the same editor as in the Asm/Edit system.

- Rmaker, the (in)famous resource maker.

The manual gives a rather concise introduction on how to use the compiler and linker if you want to write a simple program or create a separately compiled module. Beside these instructions, it contains a listing of all the predefined modules that come with the system.

If you want to write a program that does just simple I/O and do not care about the user interface, you can use the standard GrafPort that the system comes up with when you start your application. Unfortunately, this is the full screen, not a nicely set up window like some other compilers have. You merely get a blank screen terminal emulation; if you want to use a window, you will have to define it through toolbox calls. You might want to take a look at the sample program in Listing 1 now.

This is a short matrix multiplication routine that initializes two matrices and determines the product matrix, then types out one element of the product as a check. You see that the actual calculation comprises about 25% of the total program, the rest is definitions and setting up of the window. Having read some of the other examples in MacTutor, you might not be surprised at that kind of overhead. The main parts of the program are:

- the IMPORT declarations, which get routines out of precompiled modules; note that not even simple I/O is defined by default, you have to import procedures for any kind of I/O that you want to do.

- some TYPE and VAR declarations - similar to Pascal. Integers (signed) and Cardinals (unsigned) are 16 bit by default. If you need a 32 bit integer, you have to use the LongCard TYPE, which is a record with the fields h and l, both CARDINAL. You have to assign them separately.

- toolbox PROCEDURE declarations. Unfortunately, there is no way to access a toolbox routine through its trap number directly; the routines are called (presumably) through numbers in another module, and the definitions that you have to use are given in the manual. Most of the toolbox routines (no - not all of them) are included. The definitions make as much sense to me as they make to you, but they seem to work.

- the actual program. You will notice there that the string format has to be converted from Modula (zero byte at the end) to Macintosh (character count in front) format.

The program is edited using the well-known Edit program, then passed as a file with the extension .MOD to the compiler. Compilation of this sample program takes 2 min 58 secs, add to that 25 secs to bring up the compiler. The reason for the system being so slow is of course that the compiler is written in M-code, too, and is interpreted. You quickly learn to examine your code very carefully for errors before you call up the compiler! One rather annoying feature of Modula-2 did not make things easier, either: Upper and lower case are distinguished, and it makes a difference whether you write WindowPtr or windowptr. Oh well Debugging the example, after it ‘almost’ ran, took me one hour, most of that time waiting for the compiler to finish.

The compiled program is then linked with the library modules (no linker errors here, since external references are already checked for completeness by the compiler) and you get a .LOD file, which, when double clicked, is executed by the Modula runtime interpreter.

Even though the compiler is slow, the generated code is rather fast. The example takes 21 seconds to execute. This is faster as you can ever do with the built-in 80-bit floating point package (judged from a similar program in Forth, which took over 40 seconds, most of that being floating point time). Modula-2 has its own 32-bit floating point package built in, which is precise enough for most applications. The Sieve runs 9 seconds per iteration, making a total of 90 secs for the standard 10 iterations. This, in turn, is slower than Forth (probably because the ratio M-code to built-in 68000 routines is higher in this case).

The timing results, in my opinion, make the Modula-2 system a very satisfactory choice for scientific and engineering applications. If Modula Corporation could come up with a compiler written in machine code, program development would be much more fun, too.

MODULE Matmul;

FROM InOut  IMPORT ReadCard, WriteCard, WriteString, WriteLn;
FROM Terminal  IMPORT ClearScreen;
FROM RealInOut   IMPORT ReadReal, GWriteReal;
FROM QuickDrawTypes  IMPORT Rect, GrafPtr, Str255, LongCard;
FROM ToolBoxTypes  IMPORT WindowPtr, WindowRecord;
FROM Strings   IMPORT StrModToMac;
FROM SYSTEM IMPORT ADDRESS;

CONST   CX = 355B;  QuickDrawModNum = 1; ToolBoxModNum = 2;

TYPE  Ptr = ADDRESS;

VAR   i,j,k : CARDINAL;
 sum,p,q : REAL;
 a : ARRAY [1..20] OF ARRAY [1..30] OF REAL;
 b : ARRAY [1..30] OF ARRAY [1..20] OF REAL;
 c : ARRAY [1..30] OF ARRAY [1..30] OF REAL;
 Wbounds : Rect;
 Wtitle : Str255;
 Wnew : WindowPtr;
 WrefCon, behind, OnHeap: LongCard;
 
PROCEDURE SetPort (port : WindowPtr); 
   CODE CX; QuickDrawModNum; 4 END SetPort;
 
PROCEDURE PortSize (width, height : INTEGER); 
   CODE CX; QuickDrawModNum; 8 END PortSize;
  
PROCEDURE TextFont (font : INTEGER); 
   CODE CX; QuickDrawModNum; 32 END TextFont;
   
PROCEDURE TextSize (size : INTEGER); 
   CODE CX; QuickDrawModNum; 35 END TextSize;
   
PROCEDURE NewWindow (wStorage : Ptr;  boundsRect : Rect;
                     title : Str255;  visible : BOOLEAN;
      theProc:INTEGER; behind : WindowPtr;
      goAwayFlag:BOOLEAN; refCon:LongCard) : WindowPtr; 
   CODE CX; ToolBoxModNum; 50 END NewWindow;

PROCEDURE DrawGrowIcon (theWindow : WindowPtr); 
   CODE CX; ToolBoxModNum; 64 END DrawGrowIcon;
   
PROCEDURE SelectWindow (theWindow : WindowPtr); 
   CODE CX; ToolBoxModNum; 56 END SelectWindow;

BEGIN
WITH WrefCon DO h := 0; l := 0 END;
WITH behind DO h := 65535; l := 65535 END;
WITH OnHeap DO h := 0; l := 0 END;
WITH Wbounds DO top := 50; left := 20; bottom := 300; right := 500 END;
StrModToMac (Wtitle, “Demo Window”); TextFont(0); TextSize(12);
Wnew := NewWindow(Ptr(OnHeap),Wbounds,Wtitle,TRUE,0,
                  WindowPtr(behind),TRUE,WrefCon);
SetPort(Wnew); SelectWindow(Wnew); DrawGrowIcon(Wnew);
PortSize(464,234); ClearScreen; TextFont(3); TextSize(9);
WriteString(“Initialization values for a: “); ReadReal(p);
WriteString(“, and b: “); ReadReal(q); WriteLn;

FOR i:= 1 TO 20 DO
 FOR j:= 1 TO 30 DO
 a[i][j] := p; b[j][i] := q 
 END
END;
WriteString (“Initialization done.”); WriteLn;

FOR i:= 1 TO 30 DO
 FOR j:= 1 TO 30 DO
 sum := 0.0;
 FOR k := 1 TO 20 DO sum:=sum + a[k][i]*b[j][k]  END;
 c[i][j] := sum
 END
END;

WriteString (“Multiplication completed.”); WriteLn;
WriteString (“ C[15,16] = “); GWriteReal (c[15][16],10);
ReadReal(p)

END Matmul.

 
AAPL
$99.02
Apple Inc.
+0.00
MSFT
$43.97
Microsoft Corpora
+0.00
GOOG
$590.60
Google Inc.
+0.00

MacTech Search:
Community Search:

Software Updates via MacUpdate

OS X Yosemite Wallpaper 1.0 - Desktop im...
OS X Yosemite Wallpaper is the gorgeous new background image for Apple's upcoming OS X 10.10 Yosemite. This wallpaper is available for all screen resolutions with a source file that measures 5,418... Read more
Acorn 4.4 - Bitmap image editor. (Demo)
Acorn is a new image editor built with one goal in mind - simplicity. Fast, easy, and fluid, Acorn provides the options you'll need without any overhead. Acorn feels right, and won't drain your bank... Read more
Bartender 1.2.20 - Organize your menu ba...
Bartender lets you organize your menu bar apps. Features: Lets you tidy your menu bar apps how you want. See your menu bar apps when you want. Hide the apps you need to run, but do not need to... Read more
TotalFinder 1.6.2 - Adds tabs, hotkeys,...
TotalFinder is a universally acclaimed navigational companion for your Mac. Enhance your Mac's Finder with features so smart and convenient, you won't believe you ever lived without them. Tab-based... Read more
Vienna 3.0.0 RC 2 :be5265e: - RSS and At...
Vienna is a freeware and Open-Source RSS/Atom newsreader with article storage and management via a SQLite database, written in Objective-C and Cocoa, for the OS X operating system. It provides... Read more
VLC Media Player 2.1.5 - Popular multime...
VLC Media Player is a highly portable multimedia player for various audio and video formats (MPEG-1, MPEG-2, MPEG-4, DivX, MP3, OGG, ...) as well as DVDs, VCDs, and various streaming protocols. It... Read more
Default Folder X 4.6.7 - Enhances Open a...
Default Folder X attaches a toolbar to the right side of the Open and Save dialogs in any OS X-native application. The toolbar gives you fast access to various folders and commands. You just click... Read more
TinkerTool 5.3 - Expanded preference set...
TinkerTool is an application that gives you access to additional preference settings Apple has built into Mac OS X. This allows to activate hidden features in the operating system and in some of the... Read more
Audio Hijack Pro 2.11.0 - Record and enh...
Audio Hijack Pro drastically changes the way you use audio on your computer, giving you the freedom to listen to audio when you want and how you want. Record and enhance any audio with Audio Hijack... Read more
Intermission 1.1.1 - Pause and rewind li...
Intermission allows you to pause and rewind live audio from any application on your Mac. Intermission will buffer up to 3 hours of audio, allowing users to skip through any assortment of audio... Read more

Latest Forum Discussions

See All

Traps n’ Gemstones Review
Traps n’ Gemstones Review By Campbell Bird on July 28th, 2014 Our Rating: :: CASTLEVANIA JONESUniversal App - Designed for iPhone and iPad Fight mummies, dig tunnels, and ride a runaway minecart to discover ancient secrets in this... | Read more »
The Phantom PI Mission Apparition Review
The Phantom PI Mission Apparition Review By Jordan Minor on July 28th, 2014 Our Rating: :: GHOSTS BUSTEDUniversal App - Designed for iPhone and iPad The Phantom PI is an exceedingly clever and well-crafted adventure game.   | Read more »
More Stubies Are Coming Your Way in a Ne...
More Stubies Are Coming Your Way in a New Update Posted by Jessica Fisher on July 28th, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
The Great Prank War Review
The Great Prank War Review By Nadia Oxford on July 28th, 2014 Our Rating: :: PRANKING IS SERIOUS BUSINESSUniversal App - Designed for iPhone and iPad Though short, The Great Prank War offers an interesting and fun mix of action and... | Read more »
Marvel Contest of Champions Announced at...
Marvel Contest of Champions Announced at Comic-Con Posted by Jennifer Allen on July 28th, 2014 [ permalink ] Announced over the weekend at San Diego Comic-Con was the fairly exciting looking Marvel Contest of Champions. | Read more »
Teenage Mutant Ninja Turtles Review
Teenage Mutant Ninja Turtles Review By Jennifer Allen on July 28th, 2014 Our Rating: :: DULL SWIPINGUniversal App - Designed for iPhone and iPad The pizza power is weak when it comes to this Teenage Mutant Ninja Turtles game.   | Read more »
Exploration Focused Puzzle Game Beatbudd...
Exploration Focused Puzzle Game Beatbuddy Set to Make Transition from PC to iOS this September Posted by Jennifer Allen on July 28th, 2014 [ permalink ] | Read more »
PlanetHD
PlanetHD By Nadia Oxford on July 28th, 2014 Our Rating: :: SPACE MADNESSUniversal App - Designed for iPhone and iPad PlanetHD will keep players busy for a while, though its unpredictable physics are a handful to deal with.   | Read more »
This Week at 148Apps: July 21-25, 2014
Another Week of Expert App Reviews   At 148Apps, we help you sort through the great ocean of apps to find the ones we think you’ll like and the ones you’ll need. Our top picks become Editor’s Choice, our stamp of approval for apps with that little... | Read more »
Reddme for iPhone - The Reddit Client (...
Reddme for iPhone - The Reddit Client 1.0 Device: iOS iPhone Category: News Price: $.99, Version: 1.0 (iTunes) Description: Reddme for iPhone is an iOS 7-optimized Reddit client that offers a refreshing new way to experience Reddit... | Read more »

Price Scanner via MacPrices.net

Apple updates MacBook Pros with slightly fast...
Apple updated 13″ and 15″ Retina MacBook Pros today with slightly faster Haswell processors. 13″ models now ship with 8GB of RAM standard, while 15″ MacBook Pros ship with 16GB across the board. Most... Read more
iOS 8 and OS X 10.10 To Support DuckDuckGo As...
Writing for Quartz, Dan Frommer reports that Apple’s forthcoming iOS 8 and OS X 10.10 operating systems version updates will allow users to select DuckDuckGo as their default search engine. He notes... Read more
U.K. Hospital Using iPods and iPads To Record...
British news journal GazetteLive’s. Ian McNeal notes that the old “an apple a day keeps the doctor away” proverb is being turned on its head at http://southtees.nhs.uk/hospitals/james-cook/ James... Read more
13-inch 2.5GHz MacBook Pro on sale for $1099,...
Best Buy has the 13″ 2.5GHz MacBook Pro available for $1099.99 on their online store. Choose free shipping or free instant local store pickup (if available). Their price is $100 off MSRP. Price is... Read more
Roundup of Apple refurbished MacBook Pros, th...
The Apple Store has Apple Certified Refurbished 13″ and 15″ MacBook Pros available for up to $400 off the cost of new models. Apple’s one-year warranty is standard, and shipping is free. Their prices... Read more
Record Mac Shipments In Q2/14 Confound Analys...
A Seeking Alpha Trefis commentary notes that Apple’s fiscal Q3 2014 results released July 22, beat market predictions on earnings, although revenues were slightly lower than anticipated. Apple’s Mac’... Read more
Intel To Launch Core M Silicon For Use In Not...
Digitimes’ Monica Chen and Joseph Tsai, report that Intel will launch 14nm-based Core M series processors specifically for use in fanless notebook/tablet 2-in-1 models in Q4 2014, with many models to... Read more
Apple’s 2014 Back to School promotion: $100 g...
 Apple’s 2014 Back to School promotion includes a free $100 App Store Gift Card with the purchase of any new Mac (Mac mini excluded), or a $50 Gift Card with the purchase of an iPad or iPhone,... Read more
iMacs on sale for $150 off MSRP, $250 off for...
Best Buy has iMacs on sale for up to $160 off MSRP for a limited time. Choose free home shipping or free instant local store pickup (if available). Prices are valid for online orders only, in-store... Read more
Mac minis on sale for $100 off MSRP, starting...
Best Buy has Mac minis on sale for $100 off MSRP. Choose free shipping or free instant local store pickup. Prices are for online orders only, in-store prices may vary: 2.5GHz Mac mini: $499.99 2.3GHz... Read more

Jobs Board

Sr Software Lead Engineer, *Apple* Online S...
Sr Software Lead Engineer, Apple Online Store Publishing Systems Keywords: Company: Apple Job Code: E3PCAK8MgYYkw Location (City or ZIP): Santa Clara Status: Full Read more
*Apple* Solutions Consultant (ASC) - Apple (...
**Job Summary** The ASC is an Apple employee who serves as an Apple brand ambassador and influencer in a Reseller's store. The ASC's role is to grow Apple Read more
Sr. Product Leader, *Apple* Store Apps - Ap...
**Job Summary** Imagine what you could do here. At Apple , great ideas have a way of becoming great products, services, and customer experiences very quickly. Bring Read more
*Apple* Solutions Consultant (ASC) - Apple (...
**Job Summary** The ASC is an Apple employee who serves as an Apple brand ambassador and influencer in a Reseller's store. The ASC's role is to grow Apple Read more
*Apple* Solutions Consultant (ASC) - Apple (...
**Job Summary** The ASC is an Apple employee who serves as an Apple brand ambassador and influencer in a Reseller's store. The ASC's role is to grow Apple Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.