TweetFollow Us on Twitter

Jun 91 Letters
Volume Number:7
Issue Number:6
Column Tag:Letters

Sorry, no Yerk

By Kirk Chase, Editor

Yerk is NOT on Disk

Kirk Chase

MacTutor

Jörg Langowski, in his March column, indicated that the sources for NEON, now public domain and called “Yerk”, would be put that month’s source code disk. It did not come in with Mr. Langowski’s materials, but we have obtained it. Unfortunately, Yerk is much to large, even after compression to place on anything but a high density floppy. Therefore, Yerk will NOT be distributed on the source code disk. We obtained it on America OnLine. Other BBS and on-line services should be carrying Yerk also. We are sorry that we are not able to distribute it to you.

Animated Cursor Corrections

Rich Lesh

Bridgeton, MO

In my March ’91 article “Animated Color Cursors,” I mentioned that you must be careful to avoid re-entrant conditions with the SetCursor() calls.

Sometimes this is difficult even in the most well behaved programs. I was informed by a reader, Joe Schwartz, that Apple has posted a tidbit of information that can solve this problem. According to the Q&A Stack that Apple distributes, there is a low memory byte, CrsrBusy at 0x8CD, that indicates whether or not the cursor is currently busy, i.e. shouldn’t be changed. The following correction to the code published in March makes use of this global to prevent any calls to SetCursor() when the cursor is busy.

This prevents any cursor fragments from appearing on the screen.

/* 1 */

static pascal void SpinCursorTask()
{
    long oldA5;
 
    oldA5=SetCurrentA5();
    gCursorTask->vblCount=gSpeed;
    if (gSpinCycles && !(*(Byte*)0x8cd)){
        gSpinCycles--;
        (*gCurrentHdl)->index++;
        (*gCurrentHdl)->index%=(*gCurrentHdl)->n;
        if (gColorCursor){
            SetCCursor((*gCurrentHdl)->frame[(*gCurrentHdl)->index].cursorHdl);
        }else{
            SetCursor(*(*gCurrentHdl)->frame[(*gCurrentHdl)->index].cursorHdl);
        }
    }
    SetA5(oldA5);
}

HOTWIRE Labs Address

Kirk Chase

MacTutor

HOTWIRE Labs’ address was inadvertently left off in the April issue. We regret this sincerely as their hardware debugger, Xtrap, is a great developer’s product. Their address is

HOTWIRE Labs

8912 Jamesburg

Witchita, KS 67212

(316) 838-8849

AppleLink: D4527

INIT Mr. Bus Error

Tom Nielsen

Recommended Testing

336 Cernon St.

Vacaville, CA 95688

In February’s issue, Dave Dunham said “I don’t like them (programs) generating bus errors, having to reboot without Mr. Bus Error and rerunning the programs”. Being a programmer and tester myself, I can understand Mr. Dunham’s frustration; however, there is a way to continue the program’s execution as if INIT Mr. Bus Error were not installed.

In MacsBug, examine the registers on the left looking for the characteristic 00F0F0F1 that INIT Mr. Bus Error uses. (Note: Sometimes the register is 00F0F0Fx, where x is some number besides 1. This happens when the application uses the handle as a handle to an array or string). If this value is in register A0, then you would type “A0=0;g.” If it’s in A1, then you’d type “A1=0;g.” That’s it. The program continues as if INIT Mr. Bus Error were not installed. In fact, I type this line so often that I’ve created MacsBug macros to do it for me. These macros clear out register A0, A1 or both and then continue.

[Tom has included three resources that can be added to MacsBug’s prefs file “Debugger Prefs” (found in the System Folder) which may be found on this month’s source disk. Pasting these resources into this file and rebooting, adds the clear Mr Bus Error commands to the list of macros.

Macros Meaning Expansion

azg A Zero Go A0=0;g

aog A One Go A1=0;g

abg A Both Go A0=0;A1=0;g

The template for editing these resources should already be in your Debugger Prefs file.-ed and Tom]

More Debugging Tips

Mike Morton

Honolulu, HI

Some comments on Rex Reinhart’s letter in the March issue:

First, you needn’t use “asm” to drop into the debugger. Think C has a Debugger() trap defined for you, so just put this line in your source:

/* 2 */

Debugger(); /* invoke debugger */

An equally useful trap is the DebugStr(), which takes a single Pascal-string argument. You can “print” simple messages with:

/* 3 */

DebugStr(“\phello, world!”);

or you can print out more useful information to print variables or other values:

/* 4 */

{
 char tempBuf[100];
 sprintf(tempBuf, “x is %d”, x);
 CtoPstr(tempBuf);
 DebugStr(tempBuf);
}

Don’t forget the CtoPstr() call to convert the string from C to Pascal format.

An advantage of this kind of output is that during repeated debugging sessions you needn’t enter your variables into the Data window in the Think C debugger. Or if you don’t have the memory for the debugger, or are debugging a standalone application, this stuff is handy. (of course, if you have a text window for debugging output, you don’t usually need DebugStr().)

Another trick is the equivalent of Think C’s conditional breakpoints. Suppose you have a loop which is locking up after many iterations. If you press the Interrupt switch, you’ll get Macsbug or TMON, not the Think C debugger. Instead, put this line anywhere in the loop:

/* 5 */

if (optionKeyDown()) DeBugger();

(Here, optionKeyDown() is some function you write which tests for the option key.) Run your application until it seems to hang up, then hold down the option key-now you’re in the Think C debugger.

Lastly, be sure to remove all these calls before you distribute your application!

[Still, Think C would definitely be friendlier if its debugger were more like Think Pascal. I feel something like selecting a variable and the a menu command to examine its contents would be nice. I suppose something a little more interactive than DebugStr().-ed]

Call For Articles

Kirk Chase

Editor, MacTutor

Every so often (about five or six times a day), I am asked what I would like to see in the way of articles for MacTutor. At that time, I pull out my editorial calendar (which is scribbled on with a multitude of changes) to read off some of the upcoming topics. Here are a number of requests from readers:

• Programming for modules. This would include such things as given the application’s working directory, a folder name of where the modules are located, and a filter proc, return a path (or directory) and list of filtered files to be used later. Also, we have had articles on external functions/modules in January and February of 1990, but one on file format filters would also be nice.

• Dialog enhancements such as a preview picture.

• A great article or two on the in’s and out’s of the File Manager, Resource Manager, Finder information and MultiFinder information (such as proper use of the SCC ports).

• System 7 quirks, tips and discussions.

• 32-bit QuickDraw, animation (B&W/Color), sound.

• Networking/Groupware articles.

• Neat DEF’s.

And the list goes on and on.

So if you have an elegant solution to a problem, send it in. You’ll gain recognition and inspire others.

GUI Wars

XVT Software, Inc.

1800 30th St., Box 17665

Boulder, CO 80308

(303) 443-4223

One way to reach a bigger market for your product is to publish it on multiple platforms. This is called, “cross development”. This has been growing steadily for the past few years. Even on the Macintosh, there are different platforms such as A/UX to develope for.

The problem with cross development is differing machine architectures and user interfaces. You can reuse some of your code, but it is hard to separate the Mac Toolbox from your code; this makes it difficult to port your code over. You could go to the lowest level of character I/O (PLEASE DON’T!), but that is not why you got started on the Macintosh. You could even rewrite everything from scratch.

Another solution offers an elegant way to port your graphical program over to another windowing environment. Enter XVT, or the Extensible Virtual Toolkit, from XVT Software Inc. With XVT, you can obtain GUI portability. Now you can develope C/C++ code for THINK or MPW. Then, you take that same source over to your other platform environment and compile without a whole lot of changes.

There is a down side to this GUI solution. The first is the cost factor; each library for a particular platform costs about $800; to get the source it is around $5000; also a license is required for distribution. This price does include an annual technical support and update program.

The second problem and third problem are speed degradation and capability limitations. These problems are only natural. One would expect a slight slow down in execution speed because of the higher-level calls. Also, some features beyond the normal ones are not implemented due to the need for cross compatibility.

Still, these factors are probably not large when faced with the potential savings in time/resources and potential gains in new markets. I know now that AppMaker now generates code for XVT. This makes development time go down dramatically. Imagine using AppMaker to get the user interface down, and then generating code that is cross compatible. I imagine dollar signs.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Lyn 1.7.2 - Lightweight image browser an...
Lyn is a fast, lightweight image browser and viewer designed for photographers, graphic artists, and Web designers. Featuring an extremely versatile and aesthetically pleasing interface, it delivers... Read more
Lyn 1.7.2 - Lightweight image browser an...
Lyn is a fast, lightweight image browser and viewer designed for photographers, graphic artists, and Web designers. Featuring an extremely versatile and aesthetically pleasing interface, it delivers... Read more
Tunnelblick 3.6.7beta02 - GUI for OpenVP...
Tunnelblick is a free, open source graphic user interface for OpenVPN on OS X. It provides easy control of OpenVPN client and/or server connections. It comes as a ready-to-use application with all... Read more
jAlbum Pro 13.4 - Organize your digital...
jAlbum Pro has all the features you love in jAlbum, but comes with a commercial license. You can create gorgeous custom photo galleries for the Web without writing a line of code! Beginner-friendly... Read more
calibre 2.65.1 - Complete e-book library...
Calibre is a complete e-book library manager. Organize your collection, convert your books to multiple formats, and sync with all of your devices. Let Calibre be your multi-tasking digital librarian... Read more
jAlbum 13.4 - Create custom photo galler...
With jAlbum, you can create gorgeous custom photo galleries for the Web without writing a line of code! Beginner-friendly, with pro results - Simply drag and drop photos into groups, choose a design... Read more
Backblaze 4.2.0.966 - Online backup serv...
Backblaze is an online backup service designed from the ground-up for the Mac. With unlimited storage available for $5 per month, as well as a free 15-day trial, peace of mind is within reach with... Read more
Backblaze 4.2.0.966 - Online backup serv...
Backblaze is an online backup service designed from the ground-up for the Mac. With unlimited storage available for $5 per month, as well as a free 15-day trial, peace of mind is within reach with... Read more
Tunnelblick 3.6.7beta02 - GUI for OpenVP...
Tunnelblick is a free, open source graphic user interface for OpenVPN on OS X. It provides easy control of OpenVPN client and/or server connections. It comes as a ready-to-use application with all... Read more
calibre 2.65.1 - Complete e-book library...
Calibre is a complete e-book library manager. Organize your collection, convert your books to multiple formats, and sync with all of your devices. Let Calibre be your multi-tasking digital librarian... Read more

Siralim 2 (RPG / Roguelike) (Games)
Siralim 2 (RPG / Roguelike) 1.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0 (iTunes) Description: Siralim 2 is an old-school monster catching RPG. Summon and customize hundreds of creatures to fight for you as... | Read more »
Clean Text (Productivity)
Clean Text 1.0 Device: iOS Universal Category: Productivity Price: $3.99, Version: 1.0 (iTunes) Description: | Read more »
Gemini - A Journey of Two Stars (Games)
Gemini - A Journey of Two Stars 1.0.1 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0.1 (iTunes) Description: *** SPECIAL LAUNCH SALE: $2.99 (25% off) *** "A mesmerizing and unexpectedly emotional journey." -- Los... | Read more »
How to get four NFL superstars for your...
Even though you're probably well on your way to building a top notch squad for the new season in Madden NFL Mobile, let's say you could beef it up by adding Rob Gronkowski, Antonio Brown, Von Miller, and Todd Gurley to your roster. That's... | Read more »
Cartoon Network Superstar Soccer: Goal!!...
Cartoon Network Superstar Soccer: Goal!!! – Multiplayer Sports Game Starring Your Favorite Characters 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: Become a soccer superstar with your... | Read more »
NFL Huddle: What's new in Topps NFL...
Can you smell that? It's the scent of pigskin in the air, which either means that cliches be damned, pigs are flying in your neck of the woods, or the new NFL season is right around the corner. [Read more] | Read more »
FarmVille: Tropic Escape tips, tricks, a...
Maybe farming is passé in mobile games now. Ah, but farming -- and doing a lot of a other things too -- in an island paradise might be a little different. At least you can work on your tan and sip some pina coladas while tending to your crops. [... | Read more »
Become the King of Avalon in FunPlus’ la...
King Arthur is dead. Considering the legend dates back to the 5th century, it would be surprising if he wasn’t. But in the context of real-time MMO game King of Avalon: Dragon Warfare, Arthur’s death plunges the kingdom into chaos. Evil sorceress... | Read more »
Nightgate (Games)
Nightgate 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: *** Launch Sale: 25% OFF for a limited time! *** In the year 2398, after a great war, a network of intelligent computers known as... | Read more »
3 best fantasy football apps to get you...
Last season didn't go the way you wanted it to in fantasy football. You were super happy following your drafts or auctions, convinced you had outsmarted everyone. You were all set to hustle on the waiver wire, work out some sweet trades, and make... | Read more »

Price Scanner via MacPrices.net

Back To School with OtterBox Essentials
Back to school means back to an environment that is tough on tech. OtterBox has the back to school essentials you need to keep tech safe from drops, bumps, scratches and hallway havoc. Check out the... Read more
VRS Design Releases New iPhone 7 Plus Case Li...
With a device as large and costly as the iPhone 7 Plus, it is primal instinct to protect it from potential damage. According to a study by SquareTrade in 2012, iPhone damages cost Americans roughly $... Read more
MacBook Airs on sale for up to $101 off MSRP
Amazon has 11″ and 13″ MacBook Airs on sale for up to $101 off MSRP for a limited time. Shipping is free: - 11″ 1.6GHz/128GB MacBook Air (model MJVM2LL/A): $798 $101 off MSRP - 11″ 1.6GHz/256GB... Read more
Apple certified refurbished iPad mini 4s avai...
Apple has certified refurbished iPad mini 4s now available for up to $120 off the cost of new models. An Apple one-year warranty is included with each iPad, and shipping is free. The following models... Read more
Apple price trackers, updated continuously
Scan our Apple Price Trackers for the latest information on sales, bundles, and availability on systems from Apple’s authorized internet/catalog resellers. We update the trackers continuously: - 15″... Read more
Global Tablet Shipments Projected to Increase...
Digitimes’ Jim Hsiao reports that global tablet shipments will increase by 16.3 percent sequentially to reach nearly 47 million units in 2016′s third quarter, but that volume will still be down over... Read more
Apple’s 2016 Back to School promotion: Free B...
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, and... Read more
Apple refurbished iPad Air 2s available start...
Apple has Certified Refurbished iPad Air 2 available starting at $339. Apple’s one-year warranty is included with each model, and shipping is free: - 128GB Wi-Fi iPad Air 2: $499 - 64GB Wi-Fi iPad... Read more
13-inch 2.5GHz MacBook Pro available for $961...
Overstock has the 13″ 2.5GHz MacBook Pro available for $961.63 including free shipping. Their price is $138 off MSRP. Read more
Clearance 12-inch Retina MacBooks, Apple refu...
Apple has Certified Refurbished 2015 12″ Retina MacBooks available starting at $929. Apple will include a standard one-year warranty with each MacBook, and shipping is free. The following... Read more

Jobs Board

SW Engineer *Apple* TV - Apple Inc. (United...
The Apple TV team is looking for excellent software engineers with experience in hardware, media management, media playback, content delivery and a passion for Read more
*Apple* Retail - Multiple Positions Victor,...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
*Apple* /Mac Support Engineer - GFI Digital,...
FI Digital, Inc. is currently seeking candidates for a full time Apple Support Engineer to add to our Maryland Heights, Missouri IT team. Candidates must be dynamic Read more
SW Engineer *Apple* TV - Apple Inc. (United...
The Apple TV team is looking for excellent software engineers with experience in hardware, media management, media playback, content delivery and a passion for Read more
Senior *Apple* Administrator - Pratt Instit...
POSITION SUMMARY: Directs the coordination and standardization of campus-wide Apple systems, including planning, analysis and implementation of Apple -related Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.