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

Vitamin-R 2.48 - Personal productivity t...
Vitamin-R creates the optimal conditions for your brain to work at its best by structuring your work into short bursts of distraction-free, highly focused activity alternating with opportunities for... Read more
Beamer 3.3 - Stream any movie file from...
Beamer streams to your Apple TV.... Plays any movie file - Just like the popular desktop movie players, Beamer accepts all common formats, codecs and resolutions. AVI, MKV, MOV, MP4, WMV, FLV. To... Read more
Shredo 1.2.2 - $9.99
Shredo is a beautiful, functional file-shredding and privacy scan utility. It permanently shreds files, folders, and external volumes' contents to keep information secure and impossible for anyone to... Read more
Final Draft 10.0.3 - Industry-leading sc...
Final Draft allows you to use your creative energy to focus on the content; let Final Draft take care of the style. Final Draft is the number-one selling application specifically designed for writing... Read more
Google Chrome 59.0.3071.109 - 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 59.0.3071.109 - 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 59.0.3071.109: This update has no Flash plug-... Read more
iShowU Instant 1.1.8 - Full-featured scr...
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
MacFamilyTree 8.2 - Create and explore y...
MacFamilyTree gives genealogy a facelift: modern, interactive, convenient and fast. Explore your family tree and your family history in a way generations of chroniclers before you would have loved.... Read more
DiskCatalogMaker 7.0.2 - Catalog your di...
DiskCatalogMaker is a simple disk management tool which catalogs disks. Simple, light-weight, and fast Finder-like intuitive look and feel Super-fast search algorithm Can compress catalog data for... Read more
ExpanDrive 5.5.4 - Access cloud storage...
ExpanDrive builds cloud storage in every application, acts just like a USB drive plugged into your Mac. With ExpanDrive, you can securely access any remote file server directly from the Finder or... Read more

Latest Forum Discussions

See All

Solve the disappearance of history’s gre...
Blue Brain Games invites you to indulge in an immersive hands-on 3D puzzle adventure in similar vein to The Room series, with its debut release The House of Da Vinci. Set during the historic period of the Italian Renaissance (when Leonardo himself... | Read more »
Age of Rivals (Games)
Age of Rivals 3.3 Device: iOS Universal Category: Games Price: $.99, Version: 3.3 (iTunes) Description: Deep civilization-building strategy in a fast-paced card game! | Read more »
Panthera Frontier (Games)
Panthera Frontier 1.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0 (iTunes) Description: | Read more »
Angry Birds Evolution beginner's gu...
Angry Birds changes things up a fair bit in its latest iteration, Angry Birds Evolution. The familiar sling-shot physics mechanics are still there, but the game now features team-based gameplay, RPG elements, and a new top-down view. With all of... | Read more »
Sega Forever is for the retro game fans
Sega is launching a new retro games service titled Sega Forever, in a move that's sure to delight games enthusiasts with a bit of nostalgia. Sega's releasing five classic games for free. The titles include Sonic the Hedgehog, Phantasy Star II,... | Read more »
The Little Acre (Games)
The Little Acre 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: | Read more »
Lovely adventure game 'The Little A...
The Little Acre makes its way from PC to iOS today and it's a real charmer. It's a lovely little adventure game set in 1950's Ireland, gorgeously animated in a style slightly reminiscent of old Disney films. The game won a lot of praise for its... | Read more »
Futurama: Worlds of Tomorrow officially...
Futurama: Worlds of Tomorrow arrives next Thursday, and it features . . . Stephen Hawking? Turns out a few of your favorite science super stars, including Bill Nye, Neil DeGrasse Tyson, and George Takei will be making an appearance alongside the... | Read more »
MU Origin’s new update offers exciting c...
MU Origin is kicking off the summer with style. Its latest update is a real doozy, offering up plenty of fresh content. New challenges, some extra help for newcomers, and new costumes are just a few of the things you will find in the new patch. | Read more »
Pokémon GO introduces Raid Battles and a...
If you were hoping to conquer any gyms today in Pokémon GO you're in for a bit of disappointment. Niantic has closed gyms in the game to prepare for a huge upcoming update that is going to complete change Pokémon GO's competitive elements. The... | Read more »

Price Scanner via MacPrices.net

10.5-inch iPad Pros available for up to $20 o...
B&H Photo has the new 2017 10.5″ iPad Pros available for up to $20 off MSRP including free shipping plus NY & NJ sales tax only: - 64GB iPad Pro WiFi: $649 - 256GB iPad Pro WiFi: $749 - 512GB... Read more
Three Off-The-Beaten-Track iOS Apps That Dese...
One of the great things about using iPads and iPhones is the vast selection of apps available for most anything you want or need to do. The three outlined in this article have been in my core app... Read more
Apple No. 1 Spot In Gartner Top 100 Vendors i...
Gartner, Inc. has unveiled the top global 100 vendors in IT in 2016 based on their revenue across IT (excluding communication services) and component market segments. In the Gartner Global Top 100:... Read more
Clearance iMacs available for up to $300 off...
B&H Photo has clearance 21″ and 27″ Apple iMacs available starting at $949, each including free shipping plus NY & NJ sales tax only: - 27″ 3.3GHz iMac 5K: $1999 $300 off original MSRP - 27″... Read more
1.4GHz Mac mini, refurbished, available for $...
The Apple Store has Apple Certified Refurbished 1.4GHz Mac minis available for $419. Apple’s one-year warranty is included, and shipping is free. Their price is $80 off MSRP, and it’s the lowest... Read more
Free Mixoo iOS Photo Editing App Gets Major U...
Button Software Technology has announced Mixoo 3.0, an important feature update to the company’s photo editor for iOS devices. Mixoo offers amazing ways to edit as well as decorate personal photo... Read more
FNable 2.0 Function Key Enabling Software Get...
Briksoftware has released FNable 2.0 With Touch Bar Support, a major new version of the function key enabling software now compatible with Touch Bar keyboards. FNable’s simplicity that allows users... Read more
Clearance 2016 12-inch Retina MacBooks, Apple...
Apple recently dropped prices on Certified Refurbished 2016 12″ Retina MacBooks, with models now available starting at $1019. Apple will include a standard one-year warranty with each MacBook, and... Read more
Clearance iPad Pros, Apple refurbished, avail...
Apple recently dropped prices on Certified Refurbished 2016 9″ and 12″ iPad Pros, with models now available starting at $469. An Apple one-year warranty is included with each model, and shipping is... Read more
13-inch 2.7GHz Retina MacBook Pro, Apple refu...
Apple has Certified Refurbished 13″ 2.7GHz/128GB Retina MacBook Pros available for $929–a recent $170 price drop. An Apple one-year warranty is included, and shipping is free: - 13″ 2.7GHz/128GB... Read more

Jobs Board

Product Manager, *Apple* News - Apple Inc....
…on new product areas, many of which have great potential impact to Apple .Drives the definition of broad, complex, and high impact products for worldwide markets, Read more
Sr. Software Engineer, *Apple* Online Store...
…building high throughput, high performance, reliable, checkout & payment platform that support Apple online stores. You will be working with the latest in services Read more
Product Owner, *Apple* Communities - Apple...
…for managing and delivering a world-class community experience to Apple 's customers. Your primary responsibilities include developing internal-facing tools, Read more
*Apple* Customer Experience (ACE) Leader - A...
…management to deliver on business objectivesTraining partner store staff on Apple products, services, and merchandising guidelinesCoaching partner store staff on Read more
Pan Europe Market Development Manager %u2014...
…local artists across the region.* Building strong relationships with local Apple teams & collaborating on mutually beneficial projects.* Building strong Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.