TweetFollow Us on Twitter

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

Related Into: Standard File Memory Manager

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

The toolbox call BlockMove is quite efficient and smart, especially for large chunks of data. In moving smaller pieces of memory, a very simple macro can do as well and execute much faster:

/* 1 (/
#define BLOCKMOVE(source,dest,len) \
{ typedef struct { char s[len] ; } _sss ;  \
  *(_sss*) (dest) = *(_sss*) (source) ;\
}

This macro generates a temporary structure of size 'len', and assigns the source structure to the destination structure. In this case the compiler will generate a tight loop moving 2 or 4 bytes of data whenever possible. There is no space penalty, i.e., it compiles to exactly the same number of bytes as a normal BlockMove.

Two restrictions apply in using BLOCKMOVE:

• the parameter 'len' must be a constant.

• the source and destinations cannot overlap.

Some performance comparisons:

Bytes BlockMove memcpy BLOCKMOVE

50 9 9 2

100 11 15 4

150 12 21 7

200 14 28 8

250 15 34 11

300 17 41 13

350 18 49 14

400 20 55 16

450 21 61 19

500 22 68 21

These comparisons were done on a PowerBook Duo 230 using Think C 6.0. Times are all measured in ticks for 5000 samples.

- Jan Bruyndonckx, Wave Research, Belgium

[If you are interested in more information on BlockMove, you might want to check out an article by Mike Scanlin in the May, 1993 issue of MacTech Magazine. The article is about writing a more efficient 68040 BlockMove. - Ed.]

Dump obj formatter

The MPW command 'dumpobj SomeLibrary > LibraryObjectCode.a' disassembles compiled library code into the form:

Module: Flags=$00=(Local Code) Module="SomeProcedure"(8) Segment="Main"(7)

Reference: Flags=$90=(A5Relative 16BitPatch 16BitOffsets FromCode)

Ref="arrow"(12)

0006

Content: Flags $08

Contents offset $0000 size $003A

00000000: 4E56 FFFC 'NV..' LINK A6,#$FFFC

00000004: 4AAE 0008 'J...' TST.L $0008(A6)

00000008: 6606 'f.' BNE.S *+$0008 ;00000010

The script below modifies the disassembled code into the form:

Module="SomeProcedure"(8) Segment="Main"(7)
 LINK   A6,#$FFFC
 TST.L  $0008(A6)
 BNE.S  *+$0008

The script:

          #2
format -f geneva -s 9 -t 26  #Set font, font size, tab size

#STEP1 - removes code comments 
find •
Loop
  #Find ; preceded by spaces & select to
  #  the end of line
find /" "+;/:/ /
  #Replace selection with nothing
replace § ""
End

#STEP2 - removes routine text header
find •
Loop
#Selects all lines between Reference &
#  second word Content
#end of line to the.
find /Reference/:/Content/:/Content/:/ /
replace § ""#Replace selection with nothing
End

#STEP3 - Delete everything before exprssn
#"Module="
find •
Loop
#Select everything in front of
#Module= to the beginning of the line
find /"Module="/:\•\
replace § ""#Replace with nothing
find !1 #Select next line
End

#STEP4 - Formats instruction lines
find •
Loop
#Find the line that starts with 4 0's
find /"0000"????/
 #followed by any 4 characters.
find /?«43»/#Select 43 characters from beginning of line
replace § "t"   #Replace selection w/tab
#Select spaces between Opcode and operand
find /" "+/ 
replace § "t"   #Replace with a tab
End#Repeat the Loop until done

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 under each step separately and hit the "Enter" key. Your code should align nicely into the format shown above.

- Greg Pribyl, Incline Village, NV

Customgetfile customization

I recently had to customize a CustomGetFile dialog to select folders. The returned StandardFileReply record contains the file specificatins of the target folder. But I needed to create files inside that folder while the directory ID in the specifications refers to its parent directory.

A simple method for getting a FSSpec record having as parID the directory ID of the selected folder, thus allowing to put the name of the new file into FSSpec.name without further actions, uses FSMakeFSSpec, documented in Inside Macintosh VI (25-30):

FUNCTION FSMakeFSSpec  (vRefNum:Integer;  dirID: LongInt; fileName: Str255; 
VAR spec: FSSpec): OSErr;

The first two parameters will be the same as in the file specifications of the target folder while fileName will contain a partial path.

/* 3 */

function  FileInFolderSpec (theSpec: 
 FSSpec): FSSpec;
var
 target:  FSSpec;
 fn: Str255;
 error:  OSErr;
begin
{theSpec: folder specifications}
 fn:=Concat(':' ,theSpec.name,': ');

 {create a partial path}
 error:=FSMakeFSSpec(theSpec.vRefNum,
 theSpec.parID, fn, target);
 FileInFolderSpec:= target;
end;

A fnfErr (file or directory does not exist) error will be returned because the partial path was incomplete, ending with ':' instead of a filename, but target is nonetheless valid.

- Luigi Belverato, Milano, Italy

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Posterino 3.3.6 - Create posters, collag...
Posterino offers enhanced customization and flexibility including a variety of new, stylish templates featuring grids of identical or odd-sized image boxes. You can customize the size and shape of... Read more
Together 3.8.3 - Store and organize all...
Together helps you organize your Mac, giving you the ability to store, edit and preview your files in a single clean, uncluttered interface. Features Smart storage. With simple drag-and-drop... Read more
iClock Pro 3.4.9 - Customize your menuba...
iClock Pro is a menu bar replacement clock for Apple's default clock. iClock Pro is an update, total rewrite and improvement to the popular iClock. Have the day, date and time in different fonts and... Read more
Things 2.8.12 - Elegant personal task ma...
Things is a task management solution that helps to organize your tasks in an elegant and intuitive way. Things combines powerful features with simplicity through the use of tags and its intelligent... Read more
Typinator 7.2 - Speedy and reliable text...
Typinator turbo-charges your typing productivity. Type a little. Typinator does the rest. We've all faced projects that require repetitive typing tasks. With Typinator, you can store commonly used... Read more
Spotify 1.0.53.758. - Stream music, crea...
Spotify is a streaming music service that gives you on-demand access to millions of songs. Whether you like driving rock, silky R&B, or grandiose classical music, Spotify's massive catalogue puts... Read more
beaTunes 4.6.14 - Organize your music co...
beaTunes is a full-featured music player and organizational tool for music collections. How well organized is your music library? Are your artists always spelled the same way? Any R.E.M. vs REM?... Read more
Vienna 3.1.10 :d05d7a5d: - RSS and Atom...
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
Day One 2.1.8 - Maintain a daily journal...
Day One is the easiest and best-looking way to use a journal / diary / text-logging application for the Mac. Day One is well designed and extremely focused to encourage you to write more through... Read more
iDefrag 5.1.8 - Disk defragmentation and...
iDefrag helps defragment and optimize your disk for improved performance. Features include: Supports HFS and HFS+ (Mac OS Extended). Supports case sensitive and journaled filesystems. Supports... Read more

Latest Forum Discussions

See All

Fantasy MMORPG MU Origin adds new modes,...
MU Origin, Webzen’s highly popular fantasy MMORPG is getting ready to shake things up for the second time this year, as a new update makes its way to the Google Play and App Store from today. Introducing new systems, modes, and events, the land of... | Read more »
Blizzard is looking to hire a mobile dev...
A new thread on the popular video game rumor forum, NeoGAF, uncovered an interesting job listing over at Blizzard Entertainment. It appears the studio behindStarCraft, World of WarCraft, Hearthstone,andOverwatch is looking to bring on a new hire... | Read more »
Legend of Zelda meets Cooking Mama in ne...
Dungeon Chef is what happens when you mix the RPG elements (and style) of a Legend of Zelda game, with cooking elements. Although, now that The Legend of Zelda: Breath of the Wild also has cookingelements, so maybe the gameplay is not so novel.... | Read more »
ChordFlow (Music)
ChordFlow 1.0.0 Device: iOS Universal Category: Music Price: $6.99, Version: 1.0.0 (iTunes) Description: ChordFlow is a chord sequencer with a unique 4-track polyphonic arpeggiator, extensive chord library, MIDI out and Ableton Link... | Read more »
The Walking Dead: A New Frontier is out...
The newest season of Telltale Games'The Walking Dead is well underway. After the release of the third episode, "Above the Law" about a month ago, episode four, "Thicker Than Water" is hot and ready for more zombies and gut-wrenching emotional... | Read more »
Best games we played this week
Another week, another new wave of mobile games do dive into. We've dug through the list of apps that came out this week to tell you which apps are worth your sweet time. And while there weren't too many games this week, there were some big ones.... | Read more »
Vignettes (Games)
Vignettes 1.0.1 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0.1 (iTunes) Description: Vignettes is a casual but unique exploration game without text or characters, where objects shapeshift as you spin them around... | Read more »
Get Me Outta Here is an 80s retro shoote...
Are you ready to fight some aliens? Because Crescent Moon Games has released the retro shooter Get Me Outta Here on iOS devices today. [Read more] | Read more »
Get a bunch of Apple productivity apps f...
If you're an Apple Mac owner, you're probably aware of the host of Apple productivity apps the company includes in all new Mac purchases. Apps like iMovie, Keynote, and of course, GarageBand. While you used to be able to also buy these apps... | Read more »
Terra Mystica (Games)
Terra Mystica 1.03 Device: iOS Universal Category: Games Price: $9.99, Version: 1.03 (iTunes) Description: Short Summary:≈≈≈≈≈≈≈≈≈≈≈≈≈ | Read more »

Price Scanner via MacPrices.net

Use Apple’s Education discount to save up to...
Purchase a new Mac or iPad using Apple’s Education Store 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
Apple refurbished Apple Watches available sta...
Apple is now offering Certified Refurbished Series 1 and Series 2 Apple Watches for 14-16% off MSRP, starting at $229. An Apple one-year warranty is included with each watch. Shipping is free: Series... Read more
15-inch Touch Bar MacBook Pros, Apple refurbi...
Apple is offering Certified Refurbished 2016 15″ Touch Bar MacBook Pros for $360 to $420 off original MSRP. An Apple one-year warranty is included with each model, and shipping is free: - 15″ 2.6GHz... Read more
13-inch MacBook Airs on sale for up to $150 o...
Overstock.com has 13″ MacBook Airs on sale for up to $150 off MSRP including free shipping: - 13″ 1.6GHz/128GB MacBook Air (sku MMGF2LL/A): $869.99 $130 off MSRP - 13″ 1.6GHz/256GB MacBook Air (sku... Read more
15-inch Touch Bar MacBook Pros on sale for $1...
B&H Photo has the new 2016 15″ Apple Touch Bar MacBook Pros in stock today and on sale for up to $200 off MSRP. Shipping is free, and B&H charges NY sales tax only: - 15″ 2.7GHz Touch Bar... Read more
15-inch 2.7GHz Touch Bar MacBook Pros on sale...
Amazon has 2016 15″ 2.7GHz Apple Touch Bar MacBook Pros in stock today and on sale for $150-$200 off MSRP. Shipping is free: - 15″ 2.7GHz Touch Bar MacBook Pro Space Gray (sku MLH42LL/A): $2599 $200... Read more
Apple now offering Certified Refurbished 13-i...
Apple is now offering Certified Refurbished 2016 13″ Touch Bar MacBook Pros for $270-$300 off original MSRP. An Apple one-year warranty is included with each model, and shipping is free: - 13″ 2.9GHz... Read more
MyGiHealth Digestive Symptom Tracker Version...
My Total Health, Inc. has announced the release of MyGiHealth 2.1, an important update to their digestive symptom tracker developed exclusively for iPhone, iPad and iPod touch devices. MyGiHealth is... Read more
Galaxy S8 Materials Costs Highest by Far Comp...
The new Samsung Galaxy S8 equipped with 64 gigabytes (GB) of NAND flash memory carries a bill of materials (BOM) cost that comes out to US$301.60, much higher than for previous versions of the... Read more
iCarMode 4.0 Car Dashboard App For iOS Integr...
Indie developer Diego Resnik has announced the release of iCarMode 4.0, an update to his productivity app developed for iOS devices. iCarMode has positioned itself as a true car dashboard app,... Read more

Jobs Board

*Apple* Mac Computer Technician - GeekHampto...
…complex computer issues over the phone and in person? GeekHampton, Long Island's Apple Premium Service Provider, is looking for you! Come work with our crew 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
Music Marketing Lead, iTunes & *Apple*...
# Music Marketing Lead, iTunes & Apple Music Job Number: 56868140 Culver City, California, United States Posted: Apr. 17, 2017 Weekly Hours: 40.00 **Job Summary** Read more
*Apple* Media Products - Commerce Engineerin...
Apple Media Products - Commerce Engineering Manager Job Number: 57037480 Santa Clara Valley, California, United States Posted: Apr. 18, 2017 Weekly Hours: 40.00 Job Read more
*Apple* Mac Computer Technician - GeekHampto...
…complex computer issues over the phone and in person? GeekHampton, Long Island's Apple Premium Service Provider, is looking for you! Come work with our crew Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.