TweetFollow Us on Twitter

Nov 93 Tips, Tidbits
Volume Number:9
Issue Number:11
Column Tag:Tips & Tidbits

Tips & Tidbits

By Neil Ticktin, Editor-in-Chief

Tip of the Month

In the September, 1993 issue of MacTech Magazine, one reader wrote in asking about finding out if QuickTime is installed via the Gestalt call. We asked you, the readers, to respond and you a number of you did. Thanks to all of you who responded including: Gary Woodcock, Gary McGath and Mats Hummel who were among the first to respond.

The first answer came from Robert Howe with a nice “clean” answer. The most interesting answer came from Alain Danteny who not only answered this question, but more about Gestalt. Robert and Alain are splitting this month’s prize.

First, the direct answer from Robert Howe: There is a new gestalt selector. You can modify your GestaltEqu.h file (with Think C) to include the following:

/* 1 */

#define gestaltQuickTime 'qtim'

(Realize that this may be included in the new header files that come with the THINK C 6.0.1 update). You may then call it as you would any other gestalt call. If QuickTime is not installed, gestalt returns an error.

A quick boolean check could be written as

/* 2 */

#include <GestaltEqu.h>
 
if (QuickTimeInstalled());
     // play a movie
 

Boolean QuickTimeInstalled ( void ) {
     return (noErr == gestalt('qtim', &result)); 
}

- Robert Howe,

via America Online

More Gestalt information

Next, comes the additional information from Alain Danteny. If you want to have a full view of all currently installed and registered gestaltSelectors, follow these steps: First, call Gestalt with selector "tabl". The response (a pointer) is the starting address of an array containing all the gestaltSelector and procAddress. The format of each entry is:

{ 3 }

gestaltTableEntry = RECORD
      gestaltSelector : OSType;
      gestaltAddr : LongInt;
    END; {Pascal-like}

/* 4 */

struct{
    OSType gestaltSelector;
    long gestaltAddr;
}gestaltTableEntry;//C-like

The very first 2 entries are:

0000 000C xxxx xxxx ; (selector = $0000 000C in hexa)
0000 0007 yyyy yyyy ;

Those are undoubtly the selectors of Gestalt's developers at Apple: Carl C. Hewitt and <unknown?>. Moreover, under macsbug, if you type:

ip xxxx xxxx (see above)

you will decompile the gestaltProc and see that those selectors are probably used internaly by the traps Gestalt, NewGestalt, ReplaceGestalt... the gestaltProc uses two signatures: "carl" and "bbmc" (who's bbmc?)

Following entries are non-Apple gestaltSelectors: mainly INITS and cdev signatures (ADex, ADrk, MClk, NowT aso). Last are well-known Apple's system Selectors. This array ends up with longint $7FFF FFFF.

- Alain Danteny,

Nancy, France

MOVEM.L Warning!

The MOVEM is a 680x0 assembler instruction. It is used a lot for saving and restoring the values of multiple data and address registers. I tried to save off two address register values with the lower register first and then restoring it later using two MOVE.L instructions. I ran into an unexpected surprise. The instruction:

MOVEM.L A2/A4,-(A7)

is not equivalent as you would expect to the 2 instructions:

MOVE.L  A2,-(A7)
MOVE.L  A4,-(A7)

but instead to:

MOVE.L  A4,-(A7)
MOVE.L  A2,-(A7)

The instruction MOVEM.L stores the registers from high to low, ignoring the order you specify. In other words,

MOVEM.L A2/A4,-(A7)

does the same thing as:

MOVEM.L A4/A2,-(A7)

Using MOVEM pre-decriment, -(A7), in conjunction with MOVEM postincrement, (A7)+, addressing, saving off and restoring the same registers is what the instruction was apparently designed for and works just fine for that purpose.

- Marek Hajek

Hajek’s Solutions

Reno, Nevada

Toggle invisibles in MPW

I often need to see “invisible” characters in text files, because many of mine come from BBS captures and may have glitches in them. MPW’s sequence for turning the display of invisible characters on and off is cumbersome, so I added a menu and keyboard shortcut; a single command to toggle the display. The following command adds a “Toggle Invisibles” to the Edit menu, so Command-Option-Y (displayed as ¥, option-Y) does the trick.

/* 5 */

AddMenu Edit "Toggle Invisibles/¥" 
 'If `Format -x a "{Active}"` == "Ail" ; 
   Format -a AIl "{Active}" ; 
  Else ; 
   Format -a Ail "{Active}" ; 
  End'

What this does: The first Format command, `Format -x a "{Active}"`, emits a string describing the active window’s format attributes. The If statement compares this to a default string of “Ail”: “A” for Auto-indent on, “i” for invisibles off, and “l” for lock-scroll off. Based on the result of that comparison, another Format command is issued to turn the display of invisible characters on or off (Format -a AIl or Format -ia Ail, respectively).

The format attribute strings “Ail” and “AIl” assume the other defaults for the file format attributes are Auto-indent ON and lock-scroll OFF. These are the common defaults, but you can change them by switching the case of the A and L in the format command. For example, if you prefer to not auto-indent, the format attribute strings would be “ail” and “aIl” instead.

- Lee David Rimar

Absoft Corporation

Need information on your Macintosh?

Need some extensive information about your Mac? In AppleLink, press Option - Command - D.

- William Modesitt

Maui Software

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Latest Forum Discussions

See All

Combo Quest (Games)
Combo Quest 1.0 Device: iOS Universal Category: Games Price: $.99, Version: 1.0 (iTunes) Description: Combo Quest is an epic, time tap role-playing adventure. In this unique masterpiece, you are a knight on a heroic quest to retrieve... | Read more »
Hero Emblems (Games)
Hero Emblems 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: ** 25% OFF for a limited time to celebrate the release ** ** Note for iPhone 6 user: If it doesn't run fullscreen on your device... | Read more »
Puzzle Blitz (Games)
Puzzle Blitz 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: Puzzle Blitz is a frantic puzzle solving race against the clock! Solve as many puzzles as you can, before time runs out! You have... | Read more »
Sky Patrol (Games)
Sky Patrol 1.0.1 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0.1 (iTunes) Description: 'Strategic Twist On The Classic Shooter Genre' - Indie Game Mag... | Read more »
The Princess Bride - The Official Game...
The Princess Bride - The Official Game 1.1 Device: iOS Universal Category: Games Price: $3.99, Version: 1.1 (iTunes) Description: An epic game based on the beloved classic movie? Inconceivable! Play the world of The Princess Bride... | Read more »
Frozen Synapse (Games)
Frozen Synapse 1.0 Device: iOS iPhone Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: Frozen Synapse is a multi-award-winning tactical game. (Full cross-play with desktop and tablet versions) 9/10 Edge 9/10 Eurogamer... | Read more »
Space Marshals (Games)
Space Marshals 1.0.1 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0.1 (iTunes) Description: ### IMPORTANT ### Please note that iPhone 4 is not supported. Space Marshals is a Sci-fi Wild West adventure taking place... | Read more »
Battle Slimes (Games)
Battle Slimes 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: BATTLE SLIMES is a fun local multiplayer game. Control speedy & bouncy slime blobs as you compete with friends and family.... | Read more »
Spectrum - 3D Avenue (Games)
Spectrum - 3D Avenue 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: "Spectrum is a pretty cool take on twitchy/reaction-based gameplay with enough complexity and style to stand out from the... | Read more »
Drop Wizard (Games)
Drop Wizard 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: Bring back the joy of arcade games! Drop Wizard is an action arcade game where you play as Teo, a wizard on a quest to save his... | Read more »

Price Scanner via MacPrices.net

14-inch M4 Pro/M4 Max MacBook Pros on sale th...
Don’t pay full price! Get a new 14″ MacBook Pro with an M4 Pro or M4 Max CPU for up to $320 off Apple’s MSRP this weekend at these retailers…they are the lowest prices available for these MacBook... Read more
Get a 15-inch M4 MacBook Air for $150 off App...
A couple of Apple retailers are offering $150 discounts on new 15″ M4 MacBook Airs this weekend. Prices at these retailers start at $1049: (1): Amazon has new 15″ M4 MacBook Airs on sale for $150 off... Read more
Unreal Mobile is offering a $100 discount on...
Unreal Mobile, an MVNO using AT&T and T-Mobile’s networks, is offering a $100 discount on any new iPhone with service. This includes new iPhone 16 models as well as iPhone 15, 13, and SE phones... Read more
16-inch M4 Pro MacBook Pros on sale for $250-...
Don’t pay full price! Amazon has 16-inch M4 Pro MacBook Pros (Silver or Black colors) on sale right now for up to $300 off Apple’s MSRP. Shipping is free. These are the lowest prices currently... Read more
Get a 14-inch M4 MacBook Pro for up to $240 o...
Amazon is offering a $150-$250 discount on Apple’s 14-inch M4 MacBook Pros right now. Shipping is free. Be sure to select Amazon as the seller, rather than a third-party seller: – 14″ M4 MacBook Pro... Read more
Clearance 14-inch M3 Pro MacBook Pros availab...
B&H Photo has clearance 14″ M3 Pro MacBook Pros (in Black or Silver) on sale for $500 off original MSRP, only $1499. B&H offers free 1-2 day delivery to most US addresses: – 14″ 11-Core M3... Read more
Sams Club is offering a $50 discount on Titan...
Sams Club has Titanium Apple Watch Series 10 models on sale for $50 off Apple’s MSRP. Sams Club Membership required. Note that sale prices are for online orders only, in-store prices may vary. Choose... Read more
Sunday Sale: Apple’s latest 13-inch M4 MacBoo...
Amazon has new 13″ M4 MacBook Airs on sale for $150 off MSRP right now, starting at $849. Sale prices apply to most colors and configurations. Be sure to select Amazon as the seller, rather than a... Read more
Apple’s M4 Mac minis on sale for record-low p...
B&H Photo has M4 and M4 Pro Mac minis in stock and on sale right now for up to $150 off Apple’s MSRP, each including free 1-2 day shipping to most US addresses. Prices start at only $469: – M4... Read more
Week’s Best Deals: 14-inch M4 MacBook Pros fo...
Don’t pay full price! These retailers are offering $200-$250 discounts on new 14-inch M4 MacBook Pros this week…they are the lowest sale prices available for new MacBook Pros: (1): Amazon is offering... Read more

Jobs Board

All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.