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

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Apple Security Update 2015-001 - For OS...
Apple Security Update 2015-001 is recommended for all users and improves the security of OS X. For detailed information about the security content of this update, please visit: http://support.apple.... Read more
Drive Genius 4.0.1 - Powerful system uti...
Drive Genius 4 gives you faster performance from your Mac while also protecting it. The award-winning and improved DrivePulse feature alerts you to hard drive issues before they become major problems... Read more
OS X Yosemite 10.10.2 - Apple's lat...
OS X Yosemite is Apple's newest operating system for Mac. An elegant design that feels entirely fresh, yet inherently familiar. The apps you use every day, enhanced with new features. And a... Read more
Apple iOS 8.1.3 - The latest version of...
The latest version of iOS can be downloaded through iTunes. Apple iOS 8 comes with big updates to apps you use every day, like Messages and Photos. A whole new way to share content with your family.... Read more
SpamSieve 2.9.19 - Robust spam filter fo...
SpamSieve is a robust spam filter for major email clients that uses powerful Bayesian spam filtering. SpamSieve understands what your spam looks like in order to block it all, but also learns what... Read more
RapidWeaver 6.0.5 - 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
Duet 1.2.2 - Use your iPad as an externa...
Duet is the first app that allows you to use your iDevice as an extra display for your Mac using the Lightning or 30-pin cable. Note: This app requires a $14.99 iOS companion app. Version 1.2.2:... Read more
Alfred 2.6 - Quick launcher for apps and...
Alfred is an award-winning productivity application for OS X. Alfred saves you time when you search for files online or on your Mac. Be more productive with hotkeys, keywords, and file actions at... Read more
1Password 5.1 - Powerful password manage...
1Password is a password manager that uniquely brings you both security and convenience. It is the only program that provides anti-phishing protection and goes beyond password management by adding Web... Read more
GarageSale 6.9.2 - Create outstanding eB...
GarageSale is a slick, full-featured client application for the eBay online auction system. Create and manage your auctions with ease. With GarageSale, you can create, edit, track, and manage... Read more

New WOTA: U-Boat Compass ‘Wets’ Your App...
New WOTA: U-Boat Compass ‘Wets’ Your Appetite for WOTA: Wolves of the Atlantic. Posted by Jessica Fisher on January 27th, 2015 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
Warship Solitaire Review
Warship Solitaire Review By Nadia Oxford on January 27th, 2015 Our Rating: :: A WAR OF NUMBERSUniversal App - Designed for iPhone and iPad Warship Solitaire might lack frills and looks, but it offers some thought provoking... | Read more »
Keep Track of Your Hectic Work Schedule...
Keep Track of Your Hectic Work Schedule With Shifts Posted by Jessica Fisher on January 27th, 2015 [ permalink ] iPhone App - Designed for the iPhone, compatible with the iPad | Read more »
All Star Quarterback Review
All Star Quarterback Review By Campbell Bird on January 27th, 2015 Our Rating: :: PLAY YOUR PARTUniversal App - Designed for iPhone and iPad Train your way to the Super Bowl in this free-to-play sports management game.   | Read more »
Sentinel 4: Dark Star Adds New Campaign...
Sentinel 4: Dark Star Adds New Campaign and More Posted by Ellis Spice on January 27th, 2015 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
Wheel & Deal Review
Wheel & Deal Review By Tre Lawrence on January 27th, 2015 Our Rating: :: SIMPLE FUNUniversal App - Designed for iPhone and iPad A simple arcade shooter that has a retro feel.   | Read more »
Join the NAVY in a Big New Update for WW...
Join the NAVY in a Big New Update for WW2: Sandbox. Strategy & Tactics Posted by Jessica Fisher on January 27th, 2015 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
Earthworm Alchemy Review
Earthworm Alchemy Review By Campbell Bird on January 27th, 2015 Our Rating: :: FEED THE WORMUniversal App - Designed for iPhone and iPad Feed this funny looking worm and dodge bombs in this charming, free-to-play arcade game.   | Read more »
Graphic Novel App netwars – The Butterfl...
Graphic Novel App netwars – The Butterfly Attack has Received Some New Episodes Posted by Jessica Fisher on January 27th, 2015 [ permalink ] | Read more »
DataVault Password Manager Review
DataVault Password Manager Review By Jennifer Allen on January 27th, 2015 Our Rating: :: SECURE DATA STORAGEUniversal App - Designed for iPhone and iPad Store your passwords and other sensitive information safely, thanks to... | Read more »

Price Scanner via MacPrices.net

Apple Releases New Tranche Of OS Updates For...
Apple has released incremental bugfix and security updates for its most recent Mac and iOS versions. OS X Yosemite 10.10.2 Update Apple says this update includes the following improvements: Resolves... Read more
Samsung To Be Main Supplier Of A9 Chips For i...
Korea’s Maeil Business Newspaper reports that Samsung has beat out its chipmaking rivals, Taiwan’s Qualcomm and TSMC, as supplier of chipsets for the next generations of both its own Galaxy S6 and... Read more
Save up to $340 on iMacs with Apple Certified...
The Apple Store has Apple Certified Refurbished iMacs available for up to $340 off the cost of new models. Apple’s one-year warranty is standard, and shipping is free. These are the best prices on... Read more
AppleCare Protection Plans on sale for up to...
B&H Photo has 3-Year AppleCare Warranties on sale for up to $105 off MSRP including free shipping plus NY sales tax only: - Mac Laptops 15″ and Above: $244 $105 off MSRP - Mac Laptops 13″ and... Read more
Apple refurbished Time Capsules available sta...
The Apple Store has certified refurbished Time Capsules available for up to $60 off MSRP. Apple’s one-year warranty is included with each Time Capsule, and shipping is free: - 2TB Time Capsule: $255... Read more
3TB AirPort Time Capsule on sale for $349, $5...
B&H Photo has 3TB AirPort Time Capsules on sale for $349 including free shipping plus NY sales tax only. Their price is $50 off MSRP, and it’s the lowest price available for this model (except... Read more
16GB iPad Air 2 on sale for $446, save $53
Walmart has 16GB WiFi iPad Air 2s on sale for $53 off MSRP on their online store. Choose free shipping or free local store pickup (if available). Sale prices available for online orders only, in-... Read more
Save up to $300 on a new Mac, $30 on an iPad,...
Purchase a new Mac or iPad at The Apple Store for Education and take up to $300 off MSRP. All teachers, students, and staff of any educational institution qualify for the discount. Shipping is free,... Read more
MasterCard Brings Contactless Payment, Apple...
MasterCard, the official card of the Waste Management Phoenix Open, and the PGA TOUR are bringing the latest payment technology to the spectator experience with the introduction of contactless... Read more
Petitioning Dropbox For Mac OS X 10.4 and 10....
Last week Dropbox announced to its users that app support for Mac OS X 10.4 and 10.5 will end May 18 — disappointing news for those of us who are still getting useful service out of older PPC Macs... Read more

Jobs Board

*Apple* Solutions Consultant - Retail Sales...
As an ambassador of the Apple brand, the ASC is accountable for driving sales performance by: Connecting with customers. Discovering customers' needs and values. Showing Read more
*Apple* Tree Children's Center is hirin...
Apple Tree Learning Center is Hiring Preschool Teachers! Phoenix Childrens Academy is a national leader in the early childhood education industry and we are currently Read more
*Apple* Solutions Consultant - Retail Sales...
**Job Summary** As an Apple Solutions Consultant (ASC) you are the link between our customers and our products. Your role is to drive the Apple business in a retail Read more
*Apple* Solutions Consultant - Retail Sales...
As an ambassador of the Apple brand, the ASC is accountable for driving sales performance by: Connecting with customers. Discovering customers' needs and values. Showing Read more
*Apple* Solutions Consultant- Retail Sales -...
**Job Summary** The ASC is an Apple employee who serves as an Apple brand ambassador and influencer in a Resellers store. The ASCs role is to grow Apple product Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.