TweetFollow Us on Twitter

SADE Debugging
Volume Number:5
Issue Number:9
Column Tag:Programmer's Workshop

SADE™ Debugging

By Joe Pillera, Ann Arbor, MI

Debugging In MPW With SADE™

Joe Pillera is a Scientific Staff Member at Bell Northern Research (BNR) in Ann Arbor, Michigan. Prior to this he was a Systems Analyst at the Ford Motor Company. He earned his B.S. in Computer Science from Eastern Michigan University, and is now a Master’s of Computer Science degree candidate at Wayne State University. His primary area of research is object oriented programming and software engineering.

Introduction

A good debugger is a programmer’s best friend. One of the serious drawbacks to MPW (Macintosh Programmer’s Workshop) software development has always been a lack of a source level debugger (no, I don’t consider MacsBug hexadecimal dumps debugging!). Until now. Introducing SADE™ - the Symbolic Application Debugging Environment. This is Apple’s new source level debugger for MPW 3.0 and beyond.

In this article I plan to cover the following:

• An overview of SADE.

• SADE in action - debugging a sample C program.

• A numerical integrator - pushing the SADE script language to the limit.

• Talking straight - the good, the bad and the ugly.

Note that even though this is not a ‘comparison’ article, I will occasionally mention THINK’s Lightspeed™ debuggers (because of their excellent performance), as a frame of reference in discussing SADE.

Figure 1. The SADE Menu System

What Is SADE, Anyway?

SADE is not an MPW tool, nor is it physically part of the MPW shell. It is simply a stand-alone application that communicates with your target program under Multifinder. As in THINK’s Lightspeed C, this debugger must be operated under Multifinder, to allow interprocess communication. Two or more megs of memory are strongly recommended; however, the manual does indicate you can squeeze by with one meg. The only special requirements to run SADE are:

1. You must be using Multifinder 6.1b7 or later.

2. The (Pascal or C) compiler must be instructed to generate ‘symbol’ files during program compiles.

One of the more interesting design decisions Apple made was to make SADE appear almost identical to the MPW Shell. This has both an advantage and a disadvantage: the advantage is that of instant familiarity to existing MPW programmers; the disadvantage is that this precludes the use of a user-friendly, animated interface (such as the debuggers used in THINK’s Lightspeed C and Lightspeed Pascal).

Please refer to Figure 1 for a closer look at SADE’s functionality.

Wade Through Your Code With SADE

The most fundamental operation in using a debugger is setting a breakpoint in the source code. Because SADE is so sophisticated, there are four ways to do this:

1. Enter the break command from the SADE command interpreter. The syntax (for debugging a C program) is:

 break <function name>.(<line number>)

2. Call the function SysError from within the C code itself. The syntax of this approach is:

 #include <Errors.h>
 . . .
 SysError(<integer from 129..32511>).

3. Press the SADEKey (Command-Option-<period>).

4. Open a source code file (as read-only from SADE), and use the mouse to select a line of code. Then execute ‘Break’ from the SourceCmds menu.

Method number 1 is fine if your functions are small, otherwise counting the individual lines of code could prove cumbersome.

Why does method number 2 work? When using version 6.1b7 and above of Multifinder, MC68000 exceptions are passed to SADE, if present; if SADE isn’t a concurrently executing task, then a system exception occurs.

Personally, I think method number 3 is somewhat satirical; trying to guess which machine instruction you are now (ahem, were) executing can cause brain damage.

Method number 4, of course, appears to be the most user-friendly of them all.

So in practice, it would seem that all methods except number three can be easily used to set break points in your own code. Refer to Figure 2 for an example of starting up SADE and setting breakpoints. For an illustration of SADE stopping at a breakpoint, please refer to Figure 3. The MPW C source listings will also provide more information on how to set breakpoints within your own code.

One interesting thing I noticed is that a SysError() breakpoint will stop after that line of code is executed, whereas setting a normal breakpoint will stop before that line of code.

SADE has complete facilities for keeping track of variable values. You can either perform a Show Value, which shows the contents of the variable of your choice, or you can use the Watch feature. This feature is analogous to THINK’s Lightspeed Pascal’s ‘Observe’ window: every time a variable’s value changes, it is updated in a display window for you. Please refer to Figure 4 for an example from the ‘Test’ program.

And of course, you have complete code stepping facilities: single step lines of code, and even control whether or not you step into procedure calls.

Program Your Bugs Away

All of the aforementioned features can be found in most other debuggers. However, the feature that sets SADE apart from any other debugger I’ve used is its internal programming facility (henceforth, I’ll refer to SADE programs as ‘scripts’, to differentiate these from your C & Pascal programs). You can actually write SADE procedures and functions to automate debugging tasks. And if that’s not enough, how about a slew of predefined procedures (even printf ) and reserved system variables? Furthermore, complete expression evaluation is possible, including pointer manipulation, bit-wise operations, and string manipulation.

The script facility of SADE is so extensive, it strongly resembles Pascal. Not only that, SADE procedures and functions are fully capable of recursion. Unlike Pascal, however, all variables are dynamically typed - based on their use in the program; this would appear to be the result of an interpretative implementation of this language.

To execute a SADE script, enter the script name (followed by any arguments) and press ‘enter’ from the numeric keypad. Thus, script invocation is identical to executing MPW tools. Before a SADE subroutine can be run, the file that contains it must first be loaded into memory; this is done as follows:

 execute ‘<Full HFS Path>:<File Name>’

As an example, I’ve developed a general purpose numerical integration script, which when given any arbitrary function f(x), will find the (approximate) integral bounded between two values ‘a’ and ‘b’. The foundation to my algorithm is the SADE eval function; this function takes a string representing an expression, and then proceeds to parse it in search of an answer. For example:

 define x = 5
 eval(‘x * 2’)

When executed at the SADE command line, this would return ‘10’ as the result.

The technique of integration I use is called Simpson’s Rule, which partitions an interval from ‘a’ to ‘b’ an even number of times (i.e. N=2M partitions). We then approximate the graph of f(x) by M segments of parabolas; the technique is shown below:

In my case, I partition each region between n and n+1 four times, giving delta x the value of 0.25; integration then simply becomes a matter of alternating the coefficients of the intermediate data values.

Unfortunately, it wasn’t that easy - because I wanted to be able to integrate any continuous function I could think of, not just the simple ones. As it turns out, simple mathematical functions (such as x**n) are not known to SADE, so I had to write my own.

How did I do this for polynomials? Using something called a Taylor Expansion, it is possible to calculate x**n (x to the nth power), where either ‘x’ or ‘n’ can be floating point values. Taylor Expansions are open-ended functions, so it is necessary to determine a stopping criteria that is both accurate and efficient. The Taylor Expansion for x**n is shown below:

For example: because both ‘x’ and ‘n’ can be floating point numbers, integrating the square root of ‘x’ is simply a matter of integrating x**(1/2) power.

Just one more problem - ln(x) is not known to SADE either, so here’s the approximation for it:

This approximation, of course, is only valid for x > 0. For an example of a simple polynomial integration, please refer to Figure 5.

However, before you throw away your favorite numerical analysis package, I should warn you that I found SADE to have problems maintaining floating point precision. Take a look at my exponent script: I noticed that using tricks such as intermediate variables for subexpressions made the difference between a correct answer and something way out in left field. SADE’s natural habitat seems to be integers, which would make a lot of sense seeing how it’s a debugging environment. Therefore, even though Simpson’s Rule will (theoretically) work on any continuous function, my SADE script will only work in cases when SADE handles floating point calculations correctly. We should remember, that SADE is a debugging environment, so I don't consider this to be a drawback.

If all these features still aren’t enough, SADE even provides high level calls to prompt the user with dialog boxes, add custom menus, and even generate music! In short, SADE has every power-tool a programmer could ever ask for in a debugger.

Straight Talk About SADE

SADE is by far the most sophisticated and user-extendable debugger I’ve ever used - but I do have one complaint: its user interface. This drawback is caused by SADE’s own complexity: at times it seems to offer you too many features. All of these features in turn dictate a user-interface that’s not as elegant as the Lightspeed debuggers. If SADE were made to be more user-friendly, even at the expense of some of its bells and whistles, Apple would have a world-class debugger in their hands.

The End...

MacsBug, MPW, Multifinder and SADE are trademarks of Apple Computer, Inc. Lightspeed is a registered trademark of Lightspeed, Inc.

The opinions expressed here are solely those of the author, and not of Bell Northern Research Inc., or its employees.

BIBLIOGRAPHY

Apple Computer, Inc. (1989) SADE: Symbolic Application Debugging Environment, Apple Programmer’s and Developer’s Association, Cupertino, California.

Beyer, William H., PhD. (1978) “Series Expansion,” p.387 in Standard Mathematical Tables - 25th Edition, CRC Press Inc., Boca Raton, Florida.

Shenk, Al, PhD. (1979) “Techniques of Integration,” pp. 424-425 in Calculus and Analytic Geometry - 2nd Edition, Scott, Foresman and Company, Glenview, Illinois.

Symantec, Inc. (1989) “Debugging Programs,” pp. 103-110 in THINK’s Lightspeed Pascal User’s Manual, The Symantec Corporation, Cupertino, California.

Symantec, Inc. (1989) “The Debugger,” pp. 129-145 in THINK’s Lightspeed C User’s Manual, The Symantec Corporation, Cupertino, California.

========== The Integrator Script ===========

# ----------------------------------------
# A simple but powerful use of the SADE™
# script langauge to perform numercial
# integration on almost any function.
# ----------------------------------------
# Copyright © Joe Pillera, 1989
# All Rights reserved
# ----------------------------------------

# ----------------------------------------
#            func integrate(a,b) 
# ----------------------------------------
# Integrate a global function ‘f(x)’ from 
# a to b.  
# ----------------------------------------
# INPUTS:
# a -> integer or floating point
# b -> integer or floating point
# ----------------------------------------
func integrate(lower,upper)
  define factor, result, index, x
  index := lower
  factor := 2
  result := 0
  while index <= upper
    x := index
    if (index = lower) or (index = upper) then
      result := result + eval(f)
   else
     result := result + (factor * eval(f))
   end
   index := index + 0.25
   if factor = 2 then
     factor := 4
   else
     factor := 2
    end
  end
  return (1.0/12.0) * result
end

# ----------------------------------------
# func ln(x)  -> Compute natural log of x
# ----------------------------------------
# INPUTS:
# x -> integer or floating point
# ----------------------------------------
func ln(x)
  define result, term, index, frac
  term   := (x - 1.0) / (x + 1.0)
  result := term + (0.3333 * power(term,3))
  index := 5
  while index <= 25 do
    frac := 1.0 / index
    result := result + 
              (frac * power(term,index))
    index := index + 2
  end
  return (2.0 * result)
end

# ----------------------------------------
# func exponent(a,x) -> Compute a ** x 
# ----------------------------------------
# INPUTS:
# a -> integer or floating point
# x -> integer or floating point
# ----------------------------------------
# NOTE: Use power(a,x) if ‘x’ is a integer,
#       because that routine is faster.
# ----------------------------------------
func exponent(a,x)
  define result,iteration,term
  define numerator,denominator
  term   := x * ln(a) 
  result := 1.0 + term
  for iteration := 2 to 15 do
    numerator   := power(term,iteration)
   denominator := fact(iteration)
    result := result + 
              (numerator / denominator)
  end
  return result
end 

# ----------------------------------------
# func power(x,n)  -> Compute x ** n
# ----------------------------------------
# INPUTS:
# x -> integer or floating point
# n -> integer
# ----------------------------------------
# NOTE: Use iteration for speed.
# ----------------------------------------
func power(x,n)
  define index, result
  if n = 0 then
    return 1
  elseif n = 1 then
    return x
  else
    result := x
    for index := 2 to n do
     result := result * x
  end
  return result
end

# ----------------------------------------
# func fact(n)  -> Compute n!
# ----------------------------------------
# INPUTS:
# n -> integer 
# ----------------------------------------
func fact(n)
  if n = 0 then
    return 1
  elseif n = 1 then
    return 1
  else
    return ( n * fact(n-1) )
  end
end

================== Main.C ==================

#include <Errors.h>

int  number;

main()
{    
  /* Set breakpoint #1 here (from SADE) */
  number = 1;
  
  /* Now pass control to func, and let */
  /* it alter the “number” variable.   */
  func();
 
  /* Hard code breakpoint #3 here */
  SysError(129); 
}

================== Func.C ==================

extern int number;

void func()
{
  /* Set breakpoint #2 here (from SADE) */
  number = 10;
}

================== Test.R ==================

#include “SysTypes.r”

resource ‘vers’ (1) {
    0x1,
    0x00,
    release,
    0x0,
    verUS,
    “”,
    “1.0 / MacTutor Magazine”
};

resource ‘vers’ (2) {
    0x1,
    0x00,
    release,
    0x0,
    verUS,
    “”,
    “For Use With MPW SADE™ Only!”
};

=============== Make File =================

Test ƒƒ Test.make test.r
 Rez test.r -append -o Test
func.c.o ƒ Test.make func.c
  C -sym on func.c
main.c.o ƒ Test.make main.c
  C -sym on main.c

SOURCES = test.r func.c main.c
OBJECTS = func.c.o main.c.o

Test ƒƒ Test.make {OBJECTS}
 Link -w -t APPL -c ‘????’ -sym on -mf 
 {OBJECTS} 
 “{CLibraries}”CRuntime.o 
 “{Libraries}”Interface.o 
 “{CLibraries}”StdCLib.o 
 “{CLibraries}”CSANELib.o 
 “{CLibraries}”Math.o 
 “{CLibraries}”CInterface.o 
 -o Test

 
AAPL
$119.00
Apple Inc.
+1.40
MSFT
$47.75
Microsoft Corpora
+0.28
GOOG
$540.37
Google Inc.
-0.71

MacTech Search:
Community Search:

Software Updates via MacUpdate

Skype 7.2.0.412 - Voice-over-internet ph...
Skype allows you to talk to friends, family and co-workers across the Internet without the inconvenience of long distance telephone charges. Using peer-to-peer data transmission technology, Skype... Read more
HoudahSpot 3.9.6 - Advanced file search...
HoudahSpot is a powerful file search tool built upon MacOS X Spotlight. Spotlight unleashed Create detailed queries to locate the exact file you need Narrow down searches. Zero in on files Save... Read more
RapidWeaver 6.0.3 - Create template-base...
RapidWeaver is a next-generation Web design application to help you easily create professional-looking Web sites in minutes. No knowledge of complex code is required, RapidWeaver will take care of... Read more
iPhoto Library Manager 4.1.10 - Manage m...
iPhoto Library Manager lets you organize your photos into multiple iPhoto libraries. Separate your high school and college photos from your latest summer vacation pictures. Or keep some photo... Read more
iExplorer 3.5.1.9 - View and transfer al...
iExplorer is an iPhone browser for Mac lets you view the files on your iOS device. By using a drag and drop interface, you can quickly copy files and folders between your Mac and your iPhone or... Read more
MacUpdate Desktop 6.0.3 - Discover and i...
MacUpdate Desktop 6 brings seamless 1-click installs and version updates to your Mac. With a free MacUpdate account and MacUpdate Desktop 6, Mac users can now install almost any Mac app on macupdate.... Read more
SteerMouse 4.2.2 - Powerful third-party...
SteerMouse is an advanced driver for USB and Bluetooth mice. It also supports Apple Mighty Mouse very well. SteerMouse can assign various functions to buttons that Apple's software does not allow,... Read more
iMazing 1.1 - Complete iOS device manage...
iMazing (was DiskAid) is the ultimate iOS device manager with capabilities far beyond what iTunes offers. With iMazing and your iOS device (iPhone, iPad, or iPod), you can: Copy music to and from... Read more
PopChar X 7.0 - Floating window shows av...
PopChar X helps you get the most out of your font collection. With its crystal-clear interface, PopChar X provides a frustration-free way to access any font's special characters. Expanded... Read more
OneNote 15.4 - Free digital notebook fro...
OneNote is your very own digital notebook. With OneNote, you can capture that flash of genius, that moment of inspiration, or that list of errands that's too important to forget. Whether you're at... Read more

Latest Forum Discussions

See All

Raby (Games)
Raby 1.0.3 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0.3 (iTunes) Description: ***WARNING - Raby runs on: iPhone 5, iPhone 5C, iPhone 5S, iPhone 6, iPhone 6 Plus, iPad Mini Retina, iPad Mini 3, iPad 4, iPad Air,... | Read more »
Oddworld: Stranger's Wrath (Games)
Oddworld: Stranger's Wrath 1.0 Device: iOS Universal Category: Games Price: $5.99, Version: 1.0 (iTunes) Description: ** PLEASE NOTE: Oddworld Stranger's Wrath requires at least an iPhone 4S, iPad 2, iPad Mini or iPod Touch 5th gen... | Read more »
Bounce On Back (Games)
Bounce On Back 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: | Read more »
Dwelp (Games)
Dwelp 1.0 Device: iOS Universal Category: Games Price: $.99, Version: 1.0 (iTunes) Description: === 50% off for a limited time, to celebrate release === Dwelp is an elegant little puzzler with a brand new game mechanic. To complete a... | Read more »
Make Way for Fat Chicken, from the Maker...
Make Way for Fat Chicken, from the Makers of Scrap Squad Posted by Jessica Fisher on November 26th, 2014 [ permalink ] Relevant Games has announced they will be releasing their reverse tower defense game, | Read more »
Tripnary Review
Tripnary Review By Jennifer Allen on November 26th, 2014 Our Rating: :: TRAVEL BUCKET LISTiPhone App - Designed for the iPhone, compatible with the iPad Want to create a travel bucket list? Tripnary is a fun way to do exactly that... | Read more »
Ossian Studios’ RPG, The Shadow Sun, is...
Ossian Studios’ RPG, The Shadow Sun, is Now Available for $4.99 Posted by Jessica Fisher on November 26th, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
Mmmm, Tasty – Having the Angry Birds for...
The very first Angry Birds debuted on iOS back in 2009. When you sit back and tally up the number of Angry Birds games out there and the impact they’ve had on pop culture as a whole, you just need to ask yourself: “How would the birds taste... | Read more »
Rescue Quest Review
Rescue Quest Review By Jennifer Allen on November 26th, 2014 Our Rating: :: PATH BASED MATCH-3Universal App - Designed for iPhone and iPad Guide a wizard to safety by matching gems. Rescue Quest might not be an entirely original... | Read more »
You Can Play the Final Chapter of Lone W...
You Can Play the Final Chapter of Lone Wolf: Dawn Over V’taag Right Now Posted by Jessica Fisher on November 26th, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »

Price Scanner via MacPrices.net

Black Friday: 15% off iTunes Gift Cards
Staples is offering 15% off $50 and $100 iTunes Gift Cards on their online store as part of their Black Friday sale. Click here for more information. Shipping is free. Best Buy is offering $100... Read more
BEVL Releases Dock Tailored for iPhone 6 and...
Seattle based BEVL has released their first product: an iPhone dock that is divergent in build quality, rock-solid function and visual simplicity to complement the iPhone. BEVL is now accepting... Read more
Black Friday: $150 off 13-inch Retina MacBook...
 Best Buy has 13-inch 2.6GHz Retina MacBook Pros on sale for $150 off MSRP on their online store as part of their Black Friday sale. Choose free shipping or free local store pickup (if available).... Read more
Black Friday: $300 off 15-inch Retina MacBook...
 B&H Photo has the new 2014 15″ Retina MacBook Pros on sale for $300 off MSRP as part of their Black Friday sale. Shipping is free, and B&H charges NY sales tax only: - 15″ 2.2GHz Retina... Read more
Black Friday: Up to $140 off MacBook Airs, fr...
 B&H Photo has 2014 MacBook Airs on sale for up to $140 off MSRP as part of their Black Friday sale. Shipping is free, and B&H charges NY sales tax only: - 11″ 128GB MacBook Air: $799 $100... Read more
Black Friday: 13-inch 2.5GHz MacBook Pro on s...
 Best Buy has the 13″ 2.5GHz MacBook Pro on sale for $899.99 on their online store as part of their Black Friday sale. Choose free shipping or free instant local store pickup (if available). Their... Read more
Black Friday: 21-inch 1.4GHz iMac on sale for...
 Best Buy has the 21″ 1.4GHz iMac on sale for $899.99 on their online store as part of their Black Friday sale. Their price is $200 off MSRP. Choose free shipping or free local store pick up. Price... Read more
Black Friday iPad Air 2 sale prices, $100 off...
 Best Buy has iPad Air 2s on sale for $100 off MSRP on their online store for Black Friday. Choose free shipping or free local store pickup (if available). Sale prices available for online orders... Read more
2014 1.4GHz Mac mini on sale for $449, save $...
 B&H Photo has the new 1.4GHz Mac mini on sale for $449.99 including free shipping plus NY tax only. Their price is $50 off MSRP, and it’s the lowest price available for this new model. Adorama... Read more
Early Black Friday pricing on 27-inch 5K iMac...
 B&H Photo continues to offer Black Friday sale prices on the 27″ 3.5GHz 5K iMac, in stock today and on sale for $2299 including free shipping plus NY sales tax only. Their price is $200 off MSRP... Read more

Jobs Board

*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
Senior Event Manager, *Apple* Retail Market...
…This senior level position is responsible for leading and imagining the Apple Retail Team's global event strategy. Delivering an overarching brand story; in-store, Read more
*Apple* Retail - Multiple Positions (US) - A...
Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the 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.