TweetFollow Us on Twitter

GoodbyE Kiss
Volume Number:3
Issue Number:2
Column Tag:Tech Notes

GoodbyE Kiss

by Dan Weston

I'd like to inform the Mac community of a bug in the generic desk accessories that appear in my book, The Complete Book of Macintosh Assembly Language Programming, Vol I. Kirk Austin pointed out to me that the desk accessories crashed when receiving a goodbye kiss. The goodbye kiss is supposed to let your desk accessory clean up after itself if the application over which the accessory is running is terminated. For example, if your DA maintained open disk files or messed with low memory globals, you would normally close the files and reset the globals when a user closed the desk accessory. The goodbye kiss is provided by the Mac system software for those cases where the user quits an application without first closing the desk accessories. The underlying application doesn't need to be concerned with the goodbye kiss; it is handled totally by the Mac system software as it reinitializes the heap for the next program.

If you want your desk accessory to receive the goodbye kiss you must set bit #12 of the first word in the DA header. When an application terminates, the system software looks at each open desk accessory and sends a goodbye kiss if the appropriate bit is set in the DA header.

The goodbye kiss is a good idea. It prevents your desk accessory from being blown away without warning. The problem is that Inside Macintosh doesn't document how the goodbye kiss is implemented. In my book, I said that the goodbye kiss invoked the desk accessory's close routine. Now, after investigating a little further as a result of Kirk's letter, I find that the goodbye kiss doesn't invoke the close routine. Instead, the goodbye kiss is a control call with CSCode = -1. This causes big problems for my DA code because I use a jump table based on the belief that CSCode will ALWAYS be between 64 and 73. When the -1 CSCode hits the jump table it heads for ozone city; reach for the reset button.

The solution is to put a special case at the beginning of the control routine to watch for the goodbye control call and route it around the jump table (or just disable the goodbye call in the header, as Kirk did).

The modified code section follows:

;--------------------------------- 
; Control handles the control messages, which are the heart
; of the driver. Code values range from 64-73 (*** and -1
; for goodbye kiss ***) enter with pointer to DCE in A1 
; and pointer to Paramblock in A0 

Control 
 
 MOVEM.LA3-A4,-(SP); preserve A3 - A4  
 MOVE.L A1,A4    ; keep DCE ptr in A4 
 MOVE.L A0,A3    ; keep Pblock ptr in A3
 MOVE.W CSCode(A3),D0; get control opCode Pblock 
 ;******* 
 CMP.W  #-1,D0   ; is this the goodbye kiss? 
 BEQ    DoGoodbye; goodbye routine 
 ;******* 
 SUB.W  #64,D0   ; adjust range to 0-9 
 ADD.W  D0,D0    ; multiply by 2 for table 
 MOVE.W ControlTable(D0),D0 ; offset to routine 
 JMP    ControlTable(D0)  ; jump to it  

;---------- Offset table for Control routines --------- 
; **almost** all possible control messages that can be sent to
; a DA are here. All the routines mentioned here should 
; return by branching to CtlDone. 

ControlTable:
   
DC.W  DoEvent-ControlTable; an event (64) 
DC.W  DoPeriodic-ControlTable ; a periodic interupt (65) 
DC.W  DoCursor-ControlTable ; adjust cursor on DA wind (66) DC.W
 DoMenu-ControlTable ; menu selection (67) 
DC.W  DoUndo-ControlTable ; undo (68)  
DC.W  CtlDone-ControlTable; *** code 69 is not used *** DC.W   DoCut-ControlTable
 ; cut (70)
DC.W  DoCopy-ControlTable ; copy (71) 
DC.W  DoPaste-ControlTable; paste (72) 
DC.W  DoClear-ControlTable; clear (73)  

;--------------------------------------------   
CtlDone:  
 MOVE.L A4,A1    ; return DCE ptr to A1
 MOVE.L A3,A0    ; return PBlock ptr to A0
 MOVEM.L(SP)+,A3-A4; A3 - A4 restored 

 MOVE.W #0,D0    ; no error 
 RTS    ; go back to calling program 

;----------------------------------------------------   
DoGoodBye:
 MOVE.L A4,A1    ; return DCE ptr to A1
 MOVE.L A3,A0    ; return PBlock ptr to A0
 MOVEM.L(SP)+,A3-A4; A3 - A4 restored  
 MOVE.W #0,D0    ; no error
 MOVE.L JIODone,-(SP); return vector for asynch calls 
 RTS    ; go back to calling program 
 
 BRA.S  CtlDone  
;-------------------------------------------------------- 

One other detail that is important to note is that the goodbye kiss is an asynchronous control call. All other calls to desk accessories are synchronous, which means that they can return with a simple RTS. Asynchronous calls, on the other hand, must return via the JIODone routine. The low memery global JIODone, holds a pointer to this system routine, which clears the request from the I/O queue. We move this pointer onto the stack and then RTS. This routes our return through the JIODone routine.

Thanks to Kirk for bringing this to my attention. If anyone else has bugs to report from the book I'd love to hear about them. As best I can, I'll fix the bugs and post the information here in Mactutor.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

PopChar 7.1 - Floating window shows avai...
We're also selling a 5-license family pack for only $25.99! PopChar helps you get the most out of your font collection. With its crystal-clear interface, PopChar X provides a frustration-free way to... Read more
BBEdit 11.1.1 - Powerful text and HTML e...
BBEdit is the leading professional HTML and text editor for the Mac. Specifically crafted in response to the needs of Web authors and software developers, this award-winning product provides a... Read more
Picasa 3.9.139 - Organize, edit, and sha...
Picasa and Picasa Web Albums allows you to organize, edit, and upload your photos to the Web from your computer in quick, simple steps. Arrange your photos into folders and albums and erase their... Read more
Mac DVDRipper Pro 5.0.5 - Copy, backup,...
Mac DVDRipper Pro is the DVD backup solution that lets you protect your DVDs from scratches, save your batteries by reading your movies from your hard disk, manage your collection with just a few... Read more
NetShade 6.2 - Browse privately using an...
This promotion is for NetShade and 1 year of Proxy and VPN services NetShade is an anonymous proxy and VPN app+service for Mac. Unblock your Internet through NetShade's high-speed proxy and VPN... Read more
CrossOver 14.1.3 - Run Windows apps on y...
CrossOver can get your Windows productivity applications and PC games up and running on your Mac quickly and easily. CrossOver runs the Windows software that you need on Mac at home, in the office,... Read more
Little Snitch 3.5.3 - Alerts you about o...
Little Snitch gives you control over your private outgoing data. Track background activity As soon as your computer connects to the Internet, applications often have permission to send any... Read more
OmniGraffle Pro 6.2.3 - Create diagrams,...
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
OmniFocus 2.2 - GTD task manager with iO...
OmniFocus helps you manage your tasks the way that you want, freeing you to focus your attention on the things that matter to you most. Capturing tasks and ideas is always a keyboard shortcut away in... Read more
1Password 5.3.2 - 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

Block Fortress has a Big New Update for...
Block Fortress is a survival-style game that's as fun as it is blocky. It's also just gotten a rather sizeable update that adds a lot more cool stuff. [Read more] | Read more »
Simple and Surreal Star Base Sim rymdkap...
I really like rymdkapsel. Not just because I'm a sucker for games that are cleverly simple or highly stylisitc, but because it's fun and challenging. Actually it's extremely challenging, which is why I was excited to learn that it's getting a couple... | Read more »
Check out the anticipated Angel Stone in...
Fincon has finally revealed Angel Stone in action in the first ever official gameplay trailer for the anticipated hack and slasher. Angel Stone is set in a post-apocalyptic world in which humanity is in danger of being wiped out by the demonic... | Read more »
Moleskine Timepage is an All-New Calenda...
Moleskine Timepage is a bit of a departure for the notebook manufacturer (since it has little to do with notebooks), but it certainly carries their simple and elegant style quite well. [Read more] | Read more »
Jog on Over and Check Out the New Runtas...
Runtastic has put out a fair number of apps to help you sleep, track excercise, and train various parts of your body. Now it's time for your legs to have their own time in the spotlight with Runtastic Leg Trainer. [Read more] | Read more »
It's Lights Out in the Upcoming Pla...
Ember’s Journey is a stark puzzle platformer with a twist: the entire game is played in darkness. The only light you can see by is the one emanating from your own character. [Read more] | Read more »
MooVee - Your Movies Guru (Entertainmen...
MooVee - Your Movies Guru 1.0 Device: iOS iPhone Category: Entertainment Price: $1.99, Version: 1.0 (iTunes) Description: MooVee helps you effortlessly manage your movies, on your iPhone. | Read more »
Geometry Wars 3: Dimensions (Games)
Geometry Wars 3: Dimensions 1.0.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0.0 (iTunes) Description: Enjoy the next chapter in the award-winning Geometry Wars franchise and enjoy stunning, console-quality... | Read more »
CHAOS RINGS Ⅲ (Games)
CHAOS RINGS Ⅲ 1.0.0 Device: iOS Universal Category: Games Price: $19.99, Version: 1.0.0 (iTunes) Description: The newest addition to the popular smartphone RPG series is finally here! ・CHAOS RINGS Overview | Read more »
The Popular Insight Series of Travel Gui...
Getting around in a country when you can't understand the primary language can be tough. Fortunately there are several options available to help wold travellers with the important stuff like giving directions to a cab driver or asking where the... | Read more »

Price Scanner via MacPrices.net

Apple refurbished 2014 13-inch Retina MacBook...
The Apple Store has Apple Certified Refurbished 2014 13″ Retina MacBook Pros available for up to $400 off original MSRP, starting at $979. An Apple one-year warranty is included with each model, and... Read more
What Would the ideal Apple Productivity Platf...
For the past four years I’ve kept a foot in both the Mac and iPad camps respectively. my daily computing hours divided about 50/50 between the two devices with remarkable consistency. However, there’... Read more
PageMeUp 1.2.1 Ten Dollar Page Layout Applica...
Paris, France-based Softobe, an OS X software development company, has announced that their PageMeUp v. 1.2.1, is available on the Mac App Store for $9.99. The license can be installed on up to 5... Read more
Eight New Products For USB Type-C Application...
Fresco Logic, specialists in advanced connectivity technologies and ICs, has introduced two new product families targeting the Type-C connector recently introduced across a number of consumer... Read more
Scripps National Spelling Bee Launches Buzzwo...
Scripps National Spelling Bee fans can monitor the action at the 2015 Spelling Bee with the new Buzzworthy app for iOS, Android and Windows mobile devices. The free Buzzworthy app provides friendly... Read more
13-inch 2.5GHz MacBook Pro on sale for $120 o...
B&H Photo has the 13″ 2.5GHz MacBook Pro on sale for $979 including free shipping plus NY sales tax only. Their price is $120 off MSRP, and it’s the lowest price for this model (except for Apple’... Read more
27-inch 3.3GHz 5K iMac on sale for $1899, $10...
B&H Photo has the new 27″ 3.3GHz 5K iMac on sale for $1899.99 including free shipping plus NY tax only. Their price is $100 off MSRP. Read more
Save up to $50 on iPad Air 2, NY tax only, fr...
B&H Photo has iPad Air 2s on sale for up to $50 off MSRP including free shipping plus NY sales tax only: - 16GB iPad Air 2 WiFi: $469 $30 off - 64GB iPad Air 2 WiFi: $549.99 $50 off - 128GB iPad... Read more
Updated Mac Price Trackers
We’ve updated our Mac Price Trackers with the latest information on prices, bundles, and availability on systems from Apple’s authorized internet/catalog resellers: - 15″ MacBook Pros - 13″ MacBook... Read more
New 13-inch 2.9GHz Retina MacBook Pro on sale...
B&H Photo has the 13″ 2.9GHz/512GB Retina MacBook Pro on sale for $1699.99 including free shipping plus NY tax only. Their price is $100 off MSRP, and it’s the lowest price for this model from... Read more

Jobs Board

Program Manager, *Apple* Community Support...
**Job Summary** Apple Support Communities ( discussions. apple .com) helps customers get the most from their Apple products and services by providing access to Read more
Senior Data Scientist, *Apple* Retail - Onl...
**Job Summary** Apple Retail - Online sells Apple products to customers around the world. In addition to selling Apple products with unique services such as iPad Read more
*Apple* Solutions Consultant - Retail Sales...
**Job Summary** As an Apple Solutions Consultant (ASC) you are the link between our customers and our products. Your role is to drive the Apple business in a retail Read more
*Apple* Watch SW Application Project Manager...
**Job Summary** The Apple Watch software team is looking for an Application Engineering Project Manager to work on new projects for Apple . The successful candidate Read more
Engineering Manager for *Apple* Maps on the...
…the Maps App Team get to take part in just about any new feature in Apple Maps, often contributing a majority of the feature work. In our day-to-day engineering work, we Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.