TweetFollow Us on Twitter

Mar 93 Tips, Tidbits
Volume Number:9
Issue Number:3
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 2 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

Writing code that will walk your array instead of using a standard loop to access the array elements will improve the speed of the code 40-400% depending on the compiler you use.

Standard array access:

FOR index := 1 TO kNumOfElements DO
    theArray[index] := someNumber;

Optimized access:
{--elementSize is the size of one array element. This is an example }
{  of an array of long integers, therefore SizeOf(LongInt)}
   elementSize := SizeOf(LongInt);
   elementPtr := LongIntPtr(arrayHandle^); {--Ptr to 1st array elmnt.}
   endArrayAddress := ORD4(elementPtr) + elementSize * kNumOfElements;
   WHILE ORD(elementPtr) < endArrayAddress DO
   BEGIN
   elementPtr^ := someNumber;  {--elementPtr^ accesses the array }
  {elements.  Increment the elementPtr }
  {to point to the next elt in the array.}
   elementPtr := LongIntPtr(ORD(elementPtr) + elementSize);
   END;

Essentially, you're forcing the compiler to generate more efficient code for your loop.

-- Marek Hajek, Reno, Nevada

Self Documenting Code

Do yourself a favor: write self-documented code. Have you ever looked over source code that makes no sense whatsoever? Worse yet, have you ever looked at your own code six months later and you can't make heads or tails of it?

Try self-documented code. This is where you name functions and variables so well that there is no mistake about what they do.

Consider a function you are writing that, say, strips off all the trailing space characters from a string. The WRONG names to give this function are "String1," "StrStrip," "FixString," to name a few. A far better name would be:

  remove_trailing_spaces_from_string

Yes, the name is long, but it pays off in a big way! If you came back a year later and looked at the code, well, what does this function do? Duh! Does it remove trailing spaces from a string, perhaps?!

The same rule applies to variable declarations. Instead of the ol' fashion "i," "k," etc., start naming your variables real English names that make sense. Example:

length_of_text instead if "i" or "len"

number_of_records instead of "r"

users_name instead of "UserStr" or "str"

You will find this system is worth far more than pages of (meaningless?) comments!

- Gar, DataPak Software

DrawPicture Bug

There is a crashing bug in DrawPicture that can happen when you draw pictures that contain very wide PixMaps. DTS has verified that this is a bug in QuickDraw (on machines with IIci ROMs or later running 7.0 or later. Currently, that means the IIci, IIfx, LC, IIsi, Classic II, PowerBook 140 and 170, and the Quadras all have this bug). Thanks to Forrest Tanaka for the following information.

The problem happens with pictures that contain direct PixMaps that have been compressed using run-length encoding. The bug is that DrawPicture allocates two times the rowBytes value of the direct PixMap on the stack without first checking to make sure that there’s enough space to grow the stack that big. For wide PixMaps, two times the rowBytes can be very big, and so the stack can easily overflow when you try to draw a picture that contains a wide PixMap.

A reasonable work-around for this bug is to increase the size of the area of memory that’s reserved for your stack, which is just above your application’s heap. By default, Color QuickDraw machines provide you with a 24K stack. The widest possible PixMap has 16K per row, so multiply that by two and you get 32K as a maximum amount of stack space DrawPicture needs to draw the direct PixMap. Add to this a lot of slop for all the other stuff that you’ll have on the stack when you call DrawPicture, and a 48K to 64K stack becomes reasonable, in my opinion at least.

Increasing the size of the area of memory for the stack is done by setting the address of the top of your heap farther down from where it is by default. The SetApplLimit routine lets you set this address, and the GetApplLimit routine gives you the current address of the top of your heap. To add space to the memory that’s set aside for your stack, you can use something like the following line of code:

SetApplLimit(Ptr(Ord4(GetApplLimit) - kAdditionalStackRequirements));

kAdditionalStackRequirements is the number of bytes of stack space you’d like above and over the default stack size. Make sure you call this before calling any other routine - before MaxApplZone, MoreMasters, and InitGraf.

If you want to find the existing size of area of memory for the stack, you can get the address of the bottom of the stack (the part that’s highest in memory) from the low-memory global called CurStackBase which is located at $0908. Subtract from this the return value of GetApplLimit, and you get the current size of the area of memory for your stack.

- Mike Scanlin, Mountain View, CA

Excerpt taken from DTS answer

The Easy way to store disks

I have looked far and wide for a way to store hundreds of diskettes. Most of the vendors want big dollars for custom disk holders. They look great in plastic or metal. Holding hundreds of disks though can get very expensive.

I have found that a three-drawer kit can be assembled easily. These kits are found in the hardware section of your local retailer. They are in the place where the furniture is sold for garages and children's rooms.

These drawers are made out of particle board and masonite. Each drawer is 4 1/2" high by 15" deep by 13" wide. I can put in 3 rows or 100 disks per row in these with plenty of room to thumb through the diskettes. That is 300 diskettes per drawer.

They can be assembled even by me or my kids in about 20 minutes. And instead of paying $100's to hold the disks, I have less than $25 into holding 900+ diskettes.

The disk holders are 15" High x 15" wide x 15" deep. They are manufactured by SturdiCraft, 2742 Homdale Rd., Klamath Falls, OR 97603 phone (503) 882-4406. They are available through Fred Meyer, Sears catalog sales, HomeBase and many local hardware stores. Or they are available direct from SturdiCraft for $34.30 including shipping and handling. Ask for Model S-350. Some assembly required.

- Bruce Kyle, Beaverton, Oregon

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

coconutBattery 3.9.14 - Displays info ab...
With coconutBattery you're always aware of your current battery health. It shows you live information about your battery such as how often it was charged and how is the current maximum capacity in... Read more
Keynote 13.2 - Apple's presentation...
Easily create gorgeous presentations with the all-new Keynote, featuring powerful yet easy-to-use tools and dazzling effects that will make you a very hard act to follow. The Theme Chooser lets you... Read more
Apple Pages 13.2 - Apple's word pro...
Apple Pages is a powerful word processor that gives you everything you need to create documents that look beautiful. And read beautifully. It lets you work seamlessly between Mac and iOS devices, and... Read more
Numbers 13.2 - Apple's spreadsheet...
With Apple Numbers, sophisticated spreadsheets are just the start. The whole sheet is your canvas. Just add dramatic interactive charts, tables, and images that paint a revealing picture of your data... Read more
Ableton Live 11.3.11 - Record music usin...
Ableton Live lets you create and record music on your Mac. Use digital instruments, pre-recorded sounds, and sampled loops to arrange, produce, and perform your music like never before. Ableton Live... Read more
Affinity Photo 2.2.0 - Digital editing f...
Affinity Photo - redefines the boundaries for professional photo editing software for the Mac. With a meticulous focus on workflow it offers sophisticated tools for enhancing, editing and retouching... Read more
SpamSieve 3.0 - Robust spam filter for m...
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
WhatsApp 2.2338.12 - Desktop client for...
WhatsApp is the desktop client for WhatsApp Messenger, a cross-platform mobile messaging app which allows you to exchange messages without having to pay for SMS. WhatsApp Messenger is available for... Read more
Fantastical 3.8.2 - Create calendar even...
Fantastical is the Mac calendar you'll actually enjoy using. Creating an event with Fantastical is quick, easy, and fun: Open Fantastical with a single click or keystroke Type in your event details... Read more
iShowU Instant 1.4.14 - Full-featured sc...
iShowU Instant gives you real-time screen recording like you've never seen before! It is the fastest, most feature-filled real-time screen capture tool from shinywhitebox yet. All of the features you... Read more

Latest Forum Discussions

See All

The iPhone 15 Episode – The TouchArcade...
After a 3 week hiatus The TouchArcade Show returns with another action-packed episode! Well, maybe not so much “action-packed" as it is “packed with talk about the iPhone 15 Pro". Eli, being in a time zone 3 hours ahead of me, as well as being smart... | Read more »
TouchArcade Game of the Week: ‘DERE Veng...
Developer Appsir Games have been putting out genre-defying titles on mobile (and other platforms) for a number of years now, and this week marks the release of their magnum opus DERE Vengeance which has been many years in the making. In fact, if the... | Read more »
SwitchArcade Round-Up: Reviews Featuring...
Hello gentle readers, and welcome to the SwitchArcade Round-Up for September 22nd, 2023. I’ve had a good night’s sleep, and though my body aches down to the last bit of sinew and meat, I’m at least thinking straight again. We’ve got a lot to look at... | Read more »
TGS 2023: Level-5 Celebrates 25 Years Wi...
Back when I first started covering the Tokyo Game Show for TouchArcade, prolific RPG producer Level-5 could always be counted on for a fairly big booth with a blend of mobile and console games on offer. At recent shows, the company’s presence has... | Read more »
TGS 2023: ‘Final Fantasy’ & ‘Dragon...
Square Enix usually has one of the bigger, more attention-grabbing booths at the Tokyo Game Show, and this year was no different in that sense. The line-ups to play pretty much anything there were among the lengthiest of the show, and there were... | Read more »
Valve Says To Not Expect a Faster Steam...
With the big 20% off discount for the Steam Deck available to celebrate Steam’s 20th anniversary, Valve had a good presence at TGS 2023 with interviews and more. | Read more »
‘Honkai Impact 3rd Part 2’ Revealed at T...
At TGS 2023, HoYoverse had a big presence with new trailers for the usual suspects, but I didn’t expect a big announcement for Honkai Impact 3rd (Free). | Read more »
‘Junkworld’ Is Out Now As This Week’s Ne...
Epic post-apocalyptic tower-defense experience Junkworld () from Ironhide Games is out now on Apple Arcade worldwide. We’ve been covering it for a while now, and even through its soft launches before, but it has returned as an Apple Arcade... | Read more »
Motorsport legends NASCAR announce an up...
NASCAR often gets a bad reputation outside of America, but there is a certain charm to it with its close side-by-side action and its focus on pure speed, but it never managed to really massively break out internationally. Now, there's a chance... | Read more »
Skullgirls Mobile Version 6.0 Update Rel...
I’ve been covering Marie’s upcoming release from Hidden Variable in Skullgirls Mobile (Free) for a while now across the announcement, gameplay | Read more »

Price Scanner via MacPrices.net

New low price: 13″ M2 MacBook Pro for $1049,...
Amazon has the Space Gray 13″ MacBook Pro with an Apple M2 CPU and 256GB of storage in stock and on sale today for $250 off MSRP. Their price is the lowest we’ve seen for this configuration from any... Read more
Apple AirPods 2 with USB-C now in stock and o...
Amazon has Apple’s 2023 AirPods Pro with USB-C now in stock and on sale for $199.99 including free shipping. Their price is $50 off MSRP, and it’s currently the lowest price available for new AirPods... Read more
New low prices: Apple’s 15″ M2 MacBook Airs w...
Amazon has 15″ MacBook Airs with M2 CPUs and 512GB of storage in stock and on sale for $1249 shipped. That’s $250 off Apple’s MSRP, and it’s the lowest price available for these M2-powered MacBook... Read more
New low price: Clearance 16″ Apple MacBook Pr...
B&H Photo has clearance 16″ M1 Max MacBook Pros, 10-core CPU/32-core GPU/1TB SSD/Space Gray or Silver, in stock today for $2399 including free 1-2 day delivery to most US addresses. Their price... Read more
Switch to Red Pocket Mobile and get a new iPh...
Red Pocket Mobile has new Apple iPhone 15 and 15 Pro models on sale for $300 off MSRP when you switch and open up a new line of service. Red Pocket Mobile is a nationwide service using all the major... Read more
Apple continues to offer a $350 discount on 2...
Apple has Studio Display models available in their Certified Refurbished store for up to $350 off MSRP. Each display comes with Apple’s one-year warranty, with new glass and a case, and ships free.... Read more
Apple’s 16-inch MacBook Pros with M2 Pro CPUs...
Amazon is offering a $250 discount on new Apple 16-inch M2 Pro MacBook Pros for a limited time. Their prices are currently the lowest available for these models from any Apple retailer: – 16″ MacBook... Read more
Closeout Sale: Apple Watch Ultra with Green A...
Adorama haș the Apple Watch Ultra with a Green Alpine Loop on clearance sale for $699 including free shipping. Their price is $100 off original MSRP, and it’s the lowest price we’ve seen for an Apple... Read more
Use this promo code at Verizon to take $150 o...
Verizon is offering a $150 discount on cellular-capable Apple Watch Series 9 and Ultra 2 models for a limited time. Use code WATCH150 at checkout to take advantage of this offer. The fine print: “Up... Read more
New low price: Apple’s 10th generation iPads...
B&H Photo has the 10th generation 64GB WiFi iPad (Blue and Silver colors) in stock and on sale for $379 for a limited time. B&H’s price is $70 off Apple’s MSRP, and it’s the lowest price... Read more

Jobs Board

Optometrist- *Apple* Valley, CA- Target Opt...
Optometrist- Apple Valley, CA- Target Optical Date: Sep 23, 2023 Brand: Target Optical Location: Apple Valley, CA, US, 92308 **Requisition ID:** 796045 At Target Read more
Senior *Apple* iOS CNO Developer (Onsite) -...
…Offense and Defense Experts (CODEX) is in need of smart, motivated and self-driven Apple iOS CNO Developers to join our team to solve real-time cyber challenges. Read more
*Apple* Systems Administrator - JAMF - Activ...
…**Public Trust/Other Required:** None **Job Family:** Systems Administration **Skills:** Apple Platforms,Computer Servers,Jamf Pro **Experience:** 3 + years of Read more
Child Care Teacher - Glenda Drive/ *Apple* V...
Child Care Teacher - Glenda Drive/ Apple ValleyTeacher Share by Email Share on LinkedIn Share on Twitter Share on Facebook Apply Read more
Machine Operator 4 - *Apple* 2nd Shift - Bon...
Machine Operator 4 - Apple 2nd ShiftApply now " Apply now + Start apply with LinkedIn + Apply Now Start + Please wait Date:Sep 22, 2023 Location: Swedesboro, NJ, US, Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.