TweetFollow Us on Twitter

Aug 93 Tips, Tidbits
Volume Number:9
Issue Number:8
Column Tag:Tips & Tidbits

Tips & Tidbits

By Neil Ticktin, Editor-in-Chief

This column is your opportunity to spread the word about little bits of information that you find out about. These tidbits can be programming related or they can be user tips that are particularly useful to programmers.

MacTech Magazine will pay $25 for every tip used, and $50 for the Tip of the Month. Or you can take your award in orders or subscriptions.

To submit a tip, send in a letter to the magazine. E-mail is our preferred method, but feel free to send something via the US Mail. See page two for all addresses. If you do send snail mail, enclose a printed copy and a disk copy of the letter so that it does not have to be retyped.

Tip of the Month

If you log a MacsBug disassembly to a file the instructions are saved in the form:

     +0000  40809A7C   MOVEC    CACR,D1  | 4E7A 1002
     +0004  40809A80   ADDQ.W   #$8,D1   | 5041

One day I got sick of editing disassembled code, especially the code I wanted to recompile later. I wrote an MPW script to edit MacsBug disassembly log file into code that is easy to read and recompile, like this:

 MOVEC  CACR,D1
 ADDQ.W #$8,D1

Here is the script to do this. For those of you who don't know, the "#" character indicates a comment to be ignored by MPW.

#STEP1
format -f geneva -s 9 -t 26 #Set font, font size, tab size
find •  #Go to beginning of file
Loop    #Execute lines within loop repeatedly

 # Next line makes a selection of: spaces that are followed 
 # by a "+" all text between that and the next several 
 # spaces, And all text between the previous two and the next 
 # several spaces. Selects everything in front of the Opcode 
 # (MOVEC). Example - Selection between "" 
 # "  +0000 40809A7C "MOVEC CACR,D1 | 4E7A 1002
find  /" "++/:/" "+/:/" "+/
replace § "t"   #Replace the selection with a tab
find /" "+/ #Select the spaces after the Opcode
replace § "t"   #Replace the selection with a tab
find /" "+/:/ /  #Selection starts after the Operand 
 #(CACR,D1) and ends at the end of the line
replace § ""#Replace above selection with nothing
End#Loop if not at the end of the file

#STEP 2 - Clean up all RTS instructions
find •
Loop    #Loop until end of file reached
find /RTS/#Find an "RTS" string
find /t/:/ /    #Select all text after "RTS" to end of line
replace § ""#Replace with nothing
End

Execute STEP1 and STEP2 separately! In MPW, make the window that contains your disassemble routine the target window - click on it and then click back to the window that contains the above script. Select the lines following STEP1 and hit the "Enter" key. Then select STEP2 and hit Enter again. Your code should nicely align into the format shown above. The formatted code needs little editing before it can be recompiled.

- Greg Pribyl

Incline Village, Nevada

An Anonymouse Tip

According to Inside Macintosh Volume VI, the Macintosh File Manager is fully implemented in A/UX. This may be true when accessing Macintosh volumes. However, if you are writing to a Unix partition there is a subtle difference in behavior which can cause headaches.

If you set the logical end-of-file to zero, using a call such as "PBSetEOF", you might assume that the file position would automatically be set to zero as well, so that if you subsequently write to the file the data will be written starting at the zero position. This is in fact what happens if the file is on a Mac volume.

However, if it's on a UNIX volume, you get a nasty surprise. The file position is evidently NOT changed by the call to "PBSetEOF". Thus, subsequent writing will begin at the old position, which may not be zero. Example: You have a file of 1 megabyte which you want to overwrite with new data and the position happens to be at the end of the file. You set the logical end-of-file to zero, the File Manager reports no error, and so you go ahead and write the new data (again with no error reported). You discover that the file now contains a megabyte of null characters followed by the new data! This is a quick way to fill a disk with garbage!

MORAL: Explicitly set the file position to zero whenever you set the logical end-of-file to zero. And in general, always set the position to less than or equal to the logical end-of-file whenever you reduce the latter.

- Anonymous(e)

Hiding from MacsBug

Under System 7, if you place MacsBug's resources in the system sub-folder called Preferences, Macsbug will ignore the resource file during startup. Place the MacsBug resources in the system folder only!

This is useful if you want to hide these resources from MacsBug.

- Greg Pribyl

Incline Village, Nevada

Making use of a fast Tool

The StreamEdit tool introduced with MPW 3.2 doesn’t actually add a great deal of functionality to MPW. However, its main advantage is that it’s fast. If you have any shell scripts that do repetitive string manipulations, you can usually speed them up by rewriting them to use StreamEdit.

For example, in one of my projects, I have a special shell script to construct the makefile. Among other things, this script scans a dependencies file, with lines that look like

Module1 Module2 Type

to indicate that “Module1” imports something from “Module2” (“Type” indicates whether the dependency is in the definition or implementation module).

The script used to scan this file by opening it in the editor and using Find commands, followed by Catenate commands to read from the current selection. It used to take about 15 minutes to execute. After I rewrote it to use StreamEdit, it took 90 seconds.

Even a simple thing like generating a rule to compile all the source files in the current directory can benefit from StreamEdit. Here’s the old way I used to build the object library:

Set Ident '[A-Za-z0-9]+'
Echo -n 'MyModLib.o ƒ'
For ThisModule in "{Mods}" .mod
 (Evaluate "{ThisModule}" =~ 
 / :({Ident})®1.mod/) 
 >Dev:Null
 Echo -n 
' 'ntt'"{Objs}"'{®1}'.mod.o'
End # For

And here’s the new way:

# 2
Set Ident '[A-Za-z0-9]+'
Echo -n 'MyModLib.o ƒ'
Files "{Mods}" .mod | 
 StreamEdit -d -e 
 "/:({Ident})®1.mod/ "
"print ' '; print -n"
" 'tt"{Objs}"'®1'.mod.o'"

Another advantage of StreamEdit is that, by avoiding use of editor commands like Open and Find, your script can execute in the background under ToolServer.

- Lawrence D’Oliveiro

Computer Services Dept.

University of Waikato

Hamilton, New Zealand

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

1Password 6.8.6 - Powerful password mana...
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
File Juicer 4.66 - $18.00
File Juicer is a drag-and-drop can opener and data archaeologist. Its specialty is to find and extract images, video, audio, or text from files which are hard to open in other ways. In computer... Read more
DEVONthink Pro 2.9.17 - Knowledge base,...
Save 10% with our exclusive coupon code: MACUPDATE10 DEVONthink Pro is your essential assistant for today's world, where almost everything is digital. From shopping receipts to important research... Read more
GraphicConverter 10.5.4 - $39.95
GraphicConverter is an all-purpose image-editing program that can import 200 different graphic-based formats, edit the image, and export it to any of 80 available file formats. The high-end editing... Read more
SoftRAID 5.6.4 - High-quality RAID manag...
SoftRAID allows you to create and manage disk arrays to increase performance and reliability. SoftRAID allows the user to create and manage RAID 4 and 5 volumes, RAID 1+0, and RAID 1 (Mirror) and... Read more
Opera 50.0.2762.58 - High-performance We...
Opera is a fast and secure browser trusted by millions of users. With the intuitive interface, Speed Dial and visual bookmarks for organizing favorite sites, news feature with fresh, relevant content... Read more
OmniGraffle Pro 7.6 - Create diagrams, f...
OmniGraffle Pro helps you draw beautiful diagrams, family trees, flow charts, org charts, layouts, and (mathematically speaking) any other directed or non-directed graphs. We've had people use... Read more
OmniGraffle 7.6 - Create diagrams, flow...
OmniGraffle helps you draw beautiful diagrams, family trees, flow charts, org charts, layouts, and (mathematically speaking) any other directed or non-directed graphs. We've had people use Graffle to... Read more
Dash 4.1.3 - Instant search and offline...
Dash is an API documentation browser and code snippet manager. Dash helps you store snippets of code, as well as instantly search and browse documentation for almost any API you might use (for a full... Read more
MacFamilyTree 8.2.7 - Create and explore...
MacFamilyTree gives genealogy a facelift: modern, interactive, convenient and fast. Explore your family tree and your family history in a way generations of chroniclers before you would have loved.... Read more

Latest Forum Discussions

See All

The 7 best games that came out for iPhon...
Well, it's that time of the week. You know what I mean. You know exactly what I mean. It's the time of the week when we take a look at the best games that have landed on the App Store over the past seven days. And there are some real doozies here... | Read more »
Popular MMO Strategy game Lords Mobile i...
Delve into the crowded halls of the Play Store and you’ll find mobile fantasy strategy MMOs-a-plenty. One that’s kicking off the new year in style however is IGG’s Lords Mobile, which has beaten out the fierce competition to receive Google Play’s... | Read more »
Blocky Racing is a funky and fresh new k...
Blocky Racing has zoomed onto the App Store and Google Play this week, bringing with it plenty of classic kart racing shenanigans that will take you straight back to your childhood. If you’ve found yourself hooked on games like Mario Kart or Crash... | Read more »
Cytus II (Games)
Cytus II 1.0.1 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0.1 (iTunes) Description: "Cytus II" is a music rhythm game created by Rayark Games. It's our fourth rhythm game title, following the footsteps of three... | Read more »
JYDGE (Games)
JYDGE 1.0.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0.0 (iTunes) Description: Build your JYDGE. Enter Edenbyrg. Get out alive. JYDGE is a lawful but awful roguehate top-down shooter where you get to build your... | Read more »
Tako Bubble guide - Tips and Tricks to S...
Tako Bubble is a pretty simple and fun puzzler, but the game can get downright devious with its puzzle design. If you insist on not paying for the game and want to manage your lives appropriately, check out these tips so you can avoid getting... | Read more »
Everything about Hero Academy 2 - The co...
It's fair to say we've spent a good deal of time on Hero Academy 2. So much so, that we think we're probably in a really good place to give you some advice about how to get the most out of the game. And in this guide, that's exactly what you're... | Read more »
Everything about Hero Academy 2: Part 3...
In the third part of our Hero Academy 2 guide we're going to take a look at the different modes you can play in the game. We'll explain what you need to do in each of them, and tell you why it's important that you do. [Read more] | Read more »
Everything about Hero Academy 2: Part 2...
In this second part of our guide to Hero Academy 2, we're going to have a look at the different card types that you're going to be using in the game. We'll split them up into different sections too, to make sure you're getting the most information... | Read more »
Everything about Hero Academy 2: Part 1...
So you've started playing Hero Academy 2, and you're feeling a little bit lost. Don't worry, we've got your back. So we've come up with a series of guides that are going to help you get to grips with everything that's going on in the game. [Read... | Read more »

Price Scanner via MacPrices.net

How to find the lowest prices on 2017 Apple M...
Apple has Certified Refurbished 13″ and 15″ 2017 MacBook Pros available for $200 to $420 off the cost of new models. Apple’s refurbished prices are the lowest available for each model from any... Read more
The lowest prices anywhere on Apple 12″ MacBo...
Apple has Certified Refurbished 2017 12″ Retina MacBooks available for $200-$240 off the cost of new models. Apple will include a standard one-year warranty with each MacBook, and shipping is free.... Read more
Apple now offering a full line of Certified R...
Apple is now offering Certified Refurbished 2017 10″ and 12″ iPad Pros for $100-$190 off MSRP, depending on the model. An Apple one-year warranty is included with each model, and shipping is free: –... Read more
27″ iMacs on sale for $100-$130 off MSRP, pay...
B&H Photo has 27″ iMacs on sale for $100-$130 off MSRP. Shipping is free, and B&H charges sales tax for NY & NJ residents only: – 27″ 3.8GHz iMac (MNED2LL/A): $2199 $100 off MSRP – 27″ 3.... Read more
2.8GHz Mac mini on sale for $899, $100 off MS...
B&H Photo has the 2.8GHz Mac mini (model number MGEQ2LL/A) on sale for $899 including free shipping plus NY & NJ sales tax only. Their price is $100 off MSRP. Read more
Apple offers Certified Refurbished iPad minis...
Apple has Certified Refurbished 128GB iPad minis available today for $339 including free shipping. Apple’s standard one-year warranty is included. Their price is $60 off MSRP. Read more
Amazon offers 13″ 256GB MacBook Air for $1049...
Amazon has the 13″ 1.8GHz/256B #Apple #MacBook Air on sale today for $150 off MSRP including free shipping: – 13″ 1.8GHz/256GB MacBook Air (MQD42LL/A): $1049.99, $150 off MSRP Read more
9.7-inch 2017 WiFi iPads on sale starting at...
B&H Photo has 9.7″ 2017 WiFi #Apple #iPads on sale for $30 off MSRP for a limited time. Shipping is free, and pay sales tax in NY & NJ only: – 32GB iPad WiFi: $299, $30 off – 128GB iPad WiFi... Read more
Wednesday deal: 13″ MacBook Pros for $100-$15...
B&H Photo has 13″ #Apple #MacBook Pros on sale for up to $100-$150 off MSRP. Shipping is free, and B&H charges sales tax for NY & NJ residents only: – 13-inch 2.3GHz/128GB Space Gray... Read more
Apple now offering Certified Refurbished 2017...
Apple has Certified Refurbished 9.7″ WiFi iPads available for $50-$80 off the cost of new models. An Apple one-year warranty is included with each iPad, and shipping is free: – 9″ 32GB WiFi iPad: $... Read more

Jobs Board

*Apple* Solutions Consultant - Apple (United...
# Apple Solutions Consultant Job Number: 113384559 Brandon, Florida, United States Posted: 10-Jan-2018 Weekly Hours: 40.00 **Job Summary** Are you passionate about Read more
Art Director, *Apple* Music + Beats1 Market...
# Art Director, Apple Music + Beats1 Marketing Design Job Number: 113258081 Santa Clara Valley, California, United States Posted: 05-Jan-2018 Weekly Hours: 40.00 Read more
*Apple* Pay & Wallet Engineering Manager...
# Apple Pay & Wallet Engineering Manager, Apple Watch Job Number: 83769531 Santa Clara Valley, California, United States Posted: 06-Nov-2017 Weekly Hours: 40.00 Read more
UI Tools and Automation Engineer, *Apple* M...
# UI Tools and Automation Engineer, Apple Media Products Job Number: 113136387 Santa Clara Valley, California, United States Posted: 11-Jan-2018 Weekly Hours: 40.00 Read more
Senior Product Architect, *Apple* Pay - App...
# Senior Product Architect, Apple Pay Job Number: 58046427 Santa Clara Valley, California, United States Posted: 04-Jan-2018 Weekly Hours: **Job Summary** Apple , Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.