TweetFollow Us on Twitter

Apr 95 Tips
Volume Number:11
Issue Number:4
Column Tag:Tips & Tidbits

Tips & Tidbits

By Scott T Boyd, Editor

Note: Source code files accompanying article are located on MacTech CD-ROM or source code disks.

TIP OF THE MONTH

Doing Passwords the Simple Way

A common problem for people writing multi-user software for the Mac is the need to have a username/password dialog which allows the user to type the password without actually printing the real characters. Apple’s inimitable Tim Dierks released a snippet appropriately entitled “Password” which shows how to accomplish this in a variety of ways, most of which involve keeping one buffer which holds what the user actually types and another which contains the ‘display’ text (usually a line of bullets).

The following snippet shows how to accomplish this by replacing the QuickDraw bottlenecks. The beauty of this approach is that there is no messy buffer-update code needed for handling Cut/Copy/Paste, and text selection with the mouse is handled correctly. You may, however, want to prevent people from cutting or copying text to the clipboard, since if that text is pasted into any other TextEdit area it will display the password in normal text.

#ifdef __cplusplus
extern "C" { 
#endif

PasswordDrawProc
        void    PasswordDrawProc (void)
        {
                Ptr textBuff;
                short byteOff;
                short byteCnt, i;

                // load the correct parameters
                asm     {       move.l  A0, textBuff
                                move.w  D0, byteOff
                                move.w  D1, byteCnt
                        }
                for (i = 1; i <= byteCnt; i++)
                  DrawChar ('•');
        }
PasswordMeasureProc 
        void    PasswordMeasureProc (void)
        {
                short   textLen, offset;
                Ptr     textBuffer;
                short   width;
                
                // load the correct parameters
                asm     {       move.w  D0, textLen
                                move.w  D1, offset
                                move.l  A0, textBuffer
                        }
                width = CharWidth('•') * textLen;
                
                // return the width of the text
                asm     {       move.w  width, D1       }
        }

        TEHandle MakePasswordTextBox (void)
        {
                Rect     viewRect, destRect;
                TEHandle textBlock = NULL;
                
                SetRect (&viewRect, 15, 15, 165, 31);
                SetRect (&destRect, 15, 15, 165, 31);
                textBlock = TENew (&destRect, &viewRect);
                
                if (textBlock)
                  {
                   TECustomHook (intDrawHook,
                     (ProcPtr)PasswordDrawProc, textBlock);
                   TECustomHook (intWidthHook, 
                     (ProcPtr)PasswordMeasureProc, textBlock);
                  }
                return textBlock;
        }
#ifdef __cplusplus 
} 
#endif

- Eric Rosé, rose@nomos.com

SyncWait No More!

Sometimes when you’re AppleTalking or modeming and something goes wrong (like you switch the modem off while data is being sent to it), the computer will hang. The mouse will still move, but clicking will have no effect. Here’s the solution: Drop into MacsBug. You should see the routine name “_vSyncWait” plus something as the current location. If you don’t, you probably hit the system while it was doing something else. Hit Command-G to get back out of MacsBug, and try again. After a few tries you should find _vSyncWait.

_vSyncWait is the routine that the system uses to wait for some input from a serial port. If you can read assembly code, you’ll see that it’s pretty simple. Here’s the dump of the significant part:

+0000  4080BB8C   MOVE.W $0010(A0),D0              | 3028 0010      +0004 
 4080BB90   BGT.S  _vSyncWait   ; 4080BB8C   | 6EFA

Register A0 is pointing to a system data structure, in which a word will be cleared when the awaited input arrives. The MOVE.W instruction grabs this word and puts it into register D0. The BGT.S instruction then Branches back to the MOVE.W if the byte it just fetched is Greater Than zero (hence BGT). So it happens that this byte is never going to arrive for whatever reason, but the computer is going to wait for eternity. The secret to fixing this is to use Command-T to go step along until the MOVE.W instruction is displayed as the current instruction. Now use the “sw” command to set “@(a0+10)” to zero: sw @(a0+10) 0

Then hit Command-T twice more. The MOVE.W instruction will take the zero you just set into memory and put it in D0, so the D0 display on the right of the screen should have its right four digits all zeros. Then when you execute the BGT.S instruction, it should not go back to the MOVE.W since zero is not greater than zero.

Hit Command-G to go. If this was the only byte the software was waiting for, then it should continue running, although it may go a little crazy because it’s been suddenly disconnected from whatever peripheral it was talking to. Quit the program, fix your hardware, and try again.

- Macneil Shonle and Dustin Mitchell
MacneilS@aol.com and DustyM2@aol.com

So Easy To Forget These Things

I asked the question recently, “When debugging using Think C, after hitting the programmer’s switch and landing in MacsBug, how do I get back up to Think C’s source level debugger?”

The answer, while less than what I was looking for, was nonetheless useful. Think C’s debugger polls for Option-Command-Shift-Period. Use that instead of the programmer’s switch and you will be able to break into the debugger as long as the program is stuck in your own code, and not in the operating system somewhere.

- Jeffrey A. Lomicka, Marlboro MA, lomickaj@prnsys.enet.dec.com

What’ll They Call The Next One? Post-Modern Memory Manager?

So you’re trying to figure out whether a zone is a Modern Memory Manager zone? Why? Oh, never mind, you’ve certainly got a good reason (you do, don’t you?), so here’s how:

#define IsNewStyleZone(z)        \
              ((z)->heapType & 0x02)

if (IsNewStyleZone(LMGetSysZone()) {
   ...whatever...

- Dave Falkenburg, Apple

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

MacCleanse 9.0 - $29.95
MacCleanse is the product of thousands of hours of intense research and development. It meticulously scans all of the nooks and crannies of a computer for unnecessary junk that can take up huge... Read more
MacPilot 12.0 - $15.96
MacPilot gives you the power of UNIX and the simplicity of Macintosh, which means a phenomenal amount of untapped power in your hands! Use MacPilot to unlock over 1,200 features, and access them all... Read more
NetNewsWire 5.1 - RSS and Atom news read...
NetNewsWire is the best way to keep up with the sites and authors you read most regularly. Let NetNewsWire pull down the latest articles, and read them in a distraction-free and Mac-like way. Native... Read more
FontExplorer X Pro 7.1.3 - Font manageme...
FontExplorer X Pro is optimized for professional use; it's the solution that gives you the power you need to manage all your fonts. Now you can more easily manage, activate and organize your... Read more
DiskCatalogMaker 8.2.5 - 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
Skim 1.5.12 - PDF reader and note-taker...
Skim is a PDF reader and note-taker for OS X. It is designed to help you read and annotate scientific papers in PDF, but is also great for viewing any PDF file. Skim includes many features and has a... Read more
rekordbox 6.1.0.0030 - Professional DJ m...
rekordbox is the best way of preparing and managing your tracks, be it at home, in the studio, or even on the plane! It allows you to import music from other music-management software using the... Read more
iExplorer 4.4.0 - View and transfer file...
iExplorer is an iPhone browser for Mac lets you view the files on your iOS device. By using a drag and drop interface, you can quickly copy files and folders between your Mac and your iPhone or... Read more
OmniGraffle 7.17.5 - Create diagrams, fl...
OmniGraffle 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 Graffle to... Read more
Apple Configurator 2.13.1 - Configure an...
Apple Configurator makes it easy to deploy iPad, iPhone, iPod touch, and Apple TV devices in your school or business. Use Apple Configurator to quickly configure large numbers of devices connected to... Read more

Latest Forum Discussions

See All

Raziel: Dungeon Arena is a hack 'n...
Raziel: Dungeon Arena is available now on mobile and will appeal to fans of both comic books and old school dungeon crawlers. Not only will you hack 'n' slash your way through mobs of enemies but there's also fully-narrated animated comic to enjoy... | Read more »
Steam Link Spotlight - Hades
Steam Link Spotlight is a feature where we look at PC games that play exceptionally well using the Steam Link app. Our last entry was on Disco Elysium. Read about how it plays using Steam Link over here. | Read more »
Microsoft has acquired ZeniMax Media and...
In the latest of a series of blockbuster moves, Microsoft has now acquired Zenimax Media and its subsidiary, Bethesda Softworks, for $7.5 billion. [Read more] | Read more »
Infinity Mechs is an upcoming idle game...
Indie developer SkullStar studio has announced an upcoming idle mech game called Infinity Mechs. It draws inspiration from the mobile game Iron Saga and has been officially licensed by Game Duchy. It's set to launch for both iOS and Android on... | Read more »
PUBG Mobile Lite's latest update se...
PUBG Mobile Lite, the streamlined version of the popular battle royale that's designed to work on less powerful devices, sees the return of a popular game variant today, Survive Till Dawn mode. It arrives as part of the 0.19.0 content update. [... | Read more »
Matchy Catch, Jyamma Games’ new hyper-ca...
Matchy Catch is a new hyper-casual puzzler from Jyamma Games, the Italian studio behind the Pong-inspired puzzle-adventure Hi-Ball Rush. It’s only the developer’s second game for iOS and Android devices, but it promises to be every bit as fun and... | Read more »
Among Us! Imposter Guide - How to be a s...
Among Us! continues to be getting a lot of play in these parts, and since our first guide we've learned a thing or two about the game. This is especially true regarding the imposter role, as its a relatively rare opportunity that we've now put... | Read more »
Paladin's Story is an upcoming fant...
Paladin's Story is an upcoming fantasy RPG with an off-kilter sense of humour that's heading for iOS and Android. It will officially launch for both on September 16th though the game is already available on Google Play in Early Access. [Read more... | Read more »
Among Us! Guide - Tips for the uninitiat...
| Read more »
A Pretty Odd Bunny is a stealth-platform...
A Pretty Odd Bunny is a stealth-platformer from two-man team AJ Ordaz and René Rivera. It follows the story of a red-eyed rabbit who is allergic to carrots and instead has a penchant for devouring pigs. It's available now for Android devices. [... | Read more »

Price Scanner via MacPrices.net

The cheapest Macs are back in stock today at...
Apple has restocked clearance, previous-generation, Certified Refurbished Mac minis starting at only $599. Each mini comes with free shipping plus Apple’s standard one-year warranty. These are the... Read more
Sale! Amazon has 2020 13″ 2.0GHz MacBook Pros...
Amazon has 2020 13″ MacBook Pros with 10th generation Intel CPUs back in stock on sale again today for $150-$200 off Apple’s MSRP. Shipping is free. Be sure to purchase the MacBook Pro from Amazon,... Read more
Base 13″ 1.4GHz Apple MacBook Pros on sale fo...
Apple reseller Expercom is offering a $65-$75 discount on new 2020 13″ 1.4GHz MacBook Pros, depending on configuration. Shipping is free. Expercom estimates shipping in 3-5 days, as stock of Apple’s... Read more
Price drop! Get a 44mm Apple Watch Series 5 G...
Amazon has dropped their price on the 44mm Apple Watch Series 5 GPS + Cellular by $100 to $429 shipped. That’s $100 off Apple’s original MSRP for this model. For the latest prices and sales, see our... Read more
Verizon offers $200 discount on new Apple Wat...
Verizon will take up to $200 off the purchase of a new GPS + Cellular Apple Watch Series 6 or Apple Watch SE with select trade-in and the purchase of a new iPhone with service. The fine print: “Get... Read more
Verizon offers $250 discount on new 8th gener...
Verizon will take up to $250 off the price of an 8th generation 2020 Apple Cellular iPad with select trade-ins and a new iPhone purchase. Plus get Apple News+ free for 6 months. The fine print: “Save... Read more
Apple’s Implementation Of COVID-19 Exposure...
NEWS: 09.18.20 – The latest effort by Apple to embed exposure notifications for COVID-19 contact tracing right into its mobile operating system has some iPhone users weary of being exposed to... Read more
Here’s how to get a 16″ MacBook Pro for $300...
B&H Photo has new 16″ MacBook Pros on sale today for $250-$300 off Apple’s MSRP, starting at $2099. Expedited shipping is free to many addresses in the US: – 2019 16″ 2.6GHz 6-Core MacBook Pro... Read more
Apple has Certified Refurbished 16″ MacBook P...
Apple has Certified Refurbished 2019 16″ MacBook Pros available for up to $420 off the cost of new models, starting at $2039. Each model features a new outer case, shipping is free, and an Apple 1-... Read more
Price drops! Apple reseller B&H drops App...
B&H Photo has dropped prices on Apple Watch Series 5 models by $50-$70 off Apple’s original MSRP. Shipping is free. These are the same Apple Watch models sold by Apple in their retail and online... Read more

Jobs Board

Security Officer ($23.00/Hourly) - *Apple*...
**Security Officer \($23\.00/Hourly\) \- Apple Store** **Description** About NMS Built on a culture of safety and integrity, NMSdelivers award\-winning, integrated Read more
Security Officer ($23.00/Hourly) - *Apple*...
**Security Officer \($23\.00/Hourly\) \- Apple Store** **Description** About NMS Built on a culture of safety and integrity, NMSdelivers award\-winning, integrated Read more
Platform - Workplace Eng - *Apple* Enterpri...
MORE ABOUT THIS JOB We are looking for an Apple Platform Engineer who will bring a unique engineering skill set, support, clarity, organization and above all else, Read more
*Apple* Certified Repair Technician - Utah S...
…selected candidate will work in the USU Campus Store Tech Department as an Apple Certified Repair Technician and floor associate. This position is for both summer Read more
Senior Data Engineer - *Apple* - Theorem, L...
Job Summary Apple is seeking an experienced, detail-minded data engineeringconsultant to join our worldwide business development and strategy team. If you are Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.