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

VirtualBox 5.1.10 - x86 virtualization s...
VirtualBox is a family of powerful x86 virtualization products for enterprise as well as home use. Not only is VirtualBox an extremely feature rich, high performance product for enterprise customers... Read more
Pixa 1.1.9 - Quickly and easily organize...
Pixa is an image-organizing application. The new app functions well, is easy to use, and helps people organize their images quickly and easily on their computers. For those who prefer not to use the... Read more
Civilization VI 1.0.1 - Next iteration o...
Sid Meier’s Civilization VI is the next entry in the popular Civilization franchise. Originally created by legendary game designer Sid Meier, Civilization is a strategy game in which you attempt to... Read more
Google Chrome 55.0.2883.75 - Modern and...
Google Chrome is a Web browser by Google, created to be a modern platform for Web pages and applications. It utilizes very fast loading of Web pages and has a V8 engine, which is a custom built... Read more
Chromium 55.0.2883.75 - Fast and stable...
Chromium is an open-source browser project that aims to build a safer, faster, and more stable way for all Internet users to experience the web. Version 55.0.2883.75: Security fixes: High CVE-2016... Read more
Luminar 1.0.2 - Powerful, adaptive, conf...
Luminar is the new full-featured image editor that adapts to the way you edit photos. Over 300 essential tools to fix, edit, and enhance your photos with comfort. The future of photo editing is here... Read more
Slack 2.3.3 - Collaborative communicatio...
Slack is a collaborative communication app that simplifies real-time messaging, archiving, and search for modern working teams. Version 2.3.3: Fixed window zoom jumping back-and-forth OS X 10.9... Read more
WhatRoute 2.0.10 - Geographically trace...
WhatRoute is designed to find the names of all the routers an IP packet passes through on its way from your Mac to a destination host. It also measures the round-trip time from your Mac to the router... Read more
Luminar 1.0.2 - Powerful, adaptive, conf...
Luminar is the new full-featured image editor that adapts to the way you edit photos. Over 300 essential tools to fix, edit, and enhance your photos with comfort. The future of photo editing is here... Read more
WhatRoute 2.0.10 - Geographically trace...
WhatRoute is designed to find the names of all the routers an IP packet passes through on its way from your Mac to a destination host. It also measures the round-trip time from your Mac to the router... Read more

Latest Forum Discussions

See All

Amateur Surgeon 4 Guide: Become the worl...
It's time to wield your trusty pizza cutter again, as Amateur Surgeon has returned with a whole fresh set of challenges (and some old, familiar ones, too). Starting anew isn't easy, especially when all you have at your disposal is a lighter, the... | Read more »
Le Parker: Sous Chef Extraordinaire (Ga...
Le Parker: Sous Chef Extraordinaire 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: | Read more »
Telltale Games really is working on a Gu...
Telltale Games' next episodic adventure is indeed Guardians of the Galaxy. A document tied to the voice actors strike suggested that the project was in the work, but now we have direct confirmation following an announcement at the Game Awards that... | Read more »
Amateur Surgeon returns to iOS and Andro...
Amateur Surgeon and its two sequels disappeared from the App Store some time and it was sad days for all. But now, just in time for the holidays, the Adult Swim favorite makes its joyous return in the shape of Amateur Surgeon 4, a remake with... | Read more »
The best board games on mobile
Sometimes you need to ditch all of the high speed, high action games in favor of something a little more traditional. If you don't feel like parting ways from your mobile device, though, there are still plenty of ways to get that old-school fix.... | Read more »
The best Facebook Messenger Instant Game...
Facebook's new Instant Games is now here, meaning you can play games with your friends directly via Facebook. It's a fun new way to connect with friends, of course, but it's also proving to be a solid gaming experience in its own right, with a... | Read more »
You can now play game's on Facebook...
Facebook launched its new Instant Games platform in an exciting new attempt to engage its user base. As a result, you can now play a number of different games directly through Facebook Messenger. All of these games run with HTML5, meaning you play... | Read more »
Apollo Justice Ace Attorney (Games)
Apollo Justice Ace Attorney 1.00.00 Device: iOS Universal Category: Games Price: $.99, Version: 1.00.00 (iTunes) Description: Court Is Back In Session Star as rookie defense attorney, Apollo Justice, as he visits crime scenes,... | Read more »
KORG iWAVESTATION (Music)
KORG iWAVESTATION 1.0 Device: iOS Universal Category: Music Price: $19.99, Version: 1.0 (iTunes) Description: A revolutionary new world of sound.The Wave Sequence Synthesizer for iPad - KORG iWAVESTATION | Read more »
Don't Grind Guide: Tips for becomin...
Don’t Grind is a surprising, derpy little one touch game with fun hand-drawn graphics. The goal is simple -- get the high score without being chopped to bits. That can be tough when you’re not used to the game, and that’s compounded by the fact... | Read more »

Price Scanner via MacPrices.net

13-inch Silver Touch Bar MacBook Pro in stock...
Amazon has the new 2016 13″ 2.9GHz/256GB Silver Touch Bar MacBook Pro (MLVP2LL/A) in stock today and on sale for $1749 including free shipping. That’s $50 off MSRP, and it’s the lowest price... Read more
Parallels Toolbox 1.3 for Mac Offers 25 Singl...
Parallels has launched Parallels Toolbox 1.3 for Mac, an upgrade that adds five new utilities to the stand-alone application which was released in August and is available exclusively online at http... Read more
OWC Mercury Elite Pro Dual mini Ultra-Portabl...
OWC has introduced the new OWC Mercury Elite Pro Dual mini, a powerful yet ultra-portable dual-drive RAID solution. The new Mercury Elite Pro Dual mini packs phenomenal performance into a small... Read more
Clearance 13-inch Retina MacBook Pros availab...
B&H Photo has clearance 2015 13″ Retina Apple MacBook Pros available for up to $200 off original MSRP. Shipping is free, and B&H charges NY tax only: - 13″ 2.7GHz/128GB Retina MacBook Pro: $... Read more
Roundup of 2016 13-inch 2.0GHz MacBook Pro sa...
B&H has the non-Touch Bar 13″ MacBook Pros in stock today for $50-$100 off MSRP. Shipping is free, and B&H charges NY sales tax only: - 13″ 2.0GHz MacBook Pro Space Gray (MLL42LL/A): $1449 $... Read more
New 13-inch 2.0GHz Space Gray MacBook Pro in...
Adorama has the new 13″ 2.0GHz Space Gray MacBook Pro (non-Touch Bar, MLL42LL/A) in stock for $1499 including a free 3-year AppleCare Protection Plan. Shipping is free, and Adorama charges sales tax... Read more
Finnair Adopts iOS Enterprise iPad Apps from...
Finnair and IBM have announced a first-of-its-kind agreement to utilize iOS enterprise apps from IBM to support the airline’s overall digital transformation. Finnair is focused on Asia-Europe traffic... Read more
Tech21 Launches Evo Go iPhone 7 Case Availabl...
Tech21 has announced the launch of the Evo Go case for Apple iPhone 7 and iPhone 7 Plus, exclusively at T-Mobile. Available online and at participating T-Mobile stores nationwide, Evo Go cases start... Read more
Apple Turns (RED) with More Ways to Join the...
In recognition of World AIDS Day, Apple is offering more ways than ever for customers to join (RED) in its mission to create an AIDS-free generation. Apple is the worlds largest corporate contributor... Read more
Deals on new 15-inch Touch Bar MacBook Pros,...
B&H Photo has new 2016 Apple 15″ Touch Bar MacBook Pro models in stock today with some available for $50 off MSRP, each including free shipping plus NY sales tax only: - 15″ 2.7GHz Touch Bar... Read more

Jobs Board

*Apple* Brand Ambassador (Macy's) - The...
…(T-ROC), is proud of its unprecedented relationship with our partner and client, APPLE ,in bringing amazing" APPLE ADVOCATES"to "non" Apple store locations. Read more
US- *Apple* Store Leader Program - Apple (Un...
…Summary Learn and grow as you explore the art of leadership at the Apple Store. You'll master our retail business inside and out through training, hands-on Read more
*Apple* Retail - Multiple Positions- White P...
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
Automotive Detailer - *Apple* Used Autos -...
We are currently conductinginterviews and will be accepting applications for a part-time detailer. Apple Used Autos is a great place to work andstart a career. We Read more
*Apple* Retail - Multiple Positions - Apple,...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.