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

 
AAPL
$103.30
Apple Inc.
+0.80
MSFT
$45.09
Microsoft Corpora
-0.34
GOOG
$577.33
Google Inc.
+5.73

MacTech Search:
Community Search:

Software Updates via MacUpdate

TextSoap 7.4.0 - Flexible text editing u...
TextSoap is for people who work with text. TextSoap effortlessly cleans up text from endlessly different formats. Wash away unwanted characters, spaces, tabs. Fix paragraphs with hard returns at the... Read more
NetShade 6.0.2 - Browse privately using...
NetShade is an Internet security tool that conceals your IP address on the web. NetShade routes your Web connection through either a public anonymous proxy server, or one of NetShade's own dedicated... Read more
Mac DVDRipper Pro 5.0 - Copy, backup, an...
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
pwSafe 3.1 - Secure password management...
pwSafe provides simple and secure password management across devices and computers. pwSafe uses iCloud to keep your password databases backed-up and synced between Macs and iOS devices. It is... Read more
StatsBar 1.8 - Monitor system processes...
StatsBar gives you a comprehensive and detailed analysis of the following areas of your Mac: CPU usage Memory usage Disk usage Network and bandwidth usage Battery power and health (MacBooks only)... Read more
Path Finder 6.5.5 - Powerful, award-winn...
Path Finder is a file browser that combines the familiar Finder interface with the powerful utilities and innovative features. Just a small selection of the Path Finder 6 feature set: Dual pane... Read more
QuarkXPress 10.2.1 - Desktop publishing...
With QuarkXPress, you can communicate in all the ways you need to -- and always look professional -- in print and digital media, all in a single tool. Features include: Easy to Use -- QuarkXPress is... Read more
Skype 6.19.0.450 - Voice-over-internet p...
Skype allows you to talk to friends, family and co-workers across the Internet without the inconvenience of long distance telephone charges. Using peer-to-peer data transmission technology, Skype... Read more
VueScan 9.4.41 - Scanner software with a...
VueScan is a scanning program that works with most high-quality flatbed and film scanners to produce scans that have excellent color fidelity and color balance. VueScan is easy to use, and has... Read more
Cloud 3.0.0 - File sharing from your men...
Cloud is simple file sharing for the Mac. Drag a file from your Mac to the CloudApp icon in the menubar and we take care of the rest. A link to the file will automatically be copied to your clipboard... Read more

Latest Forum Discussions

See All

Modern Combat 5 Gets a Major Multiplayer...
Modern Combat 5 Gets a Major Multiplayer Update Posted by Jessica Fisher on September 2nd, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
Alien Creeps TD Review
Alien Creeps TD Review By Jennifer Allen on September 2nd, 2014 Our Rating: :: EXPENSIVE DEFENSESUniversal App - Designed for iPhone and iPad Alien Creeps TD would be a fun if unremarkable Tower Defense game, but its heavy focus on... | Read more »
The Journey Down: Chapter Two Review
The Journey Down: Chapter Two Review By Jennifer Allen on September 2nd, 2014 Our Rating: :: DARK YET ENTICINGUniversal App - Designed for iPhone and iPad It’s a little dark, in every sense of the word, but The Journey Down:... | Read more »
Function Space, a Social Network App for...
Function Space, a Social Network App for Science, Launches on iOS Posted by Ellis Spice on September 2nd, 2014 [ permalink ] | Read more »
Stupidfast – How Taylor Martinez Switche...
How do you make an Endless Running game more than just another Endless Running game? By adding real life prizes to it, of course! That’s the thinking behind StupidFast: a game designed for football enthusiasts, and the brainchild of former college... | Read more »
Little Raiders: Robin’s Revenge Review
Little Raiders: Robin’s Revenge Review By Jennifer Allen on September 2nd, 2014 Our Rating: :: CASUAL RAIDINGUniversal App - Designed for iPhone and iPad Combining simple combat with village building is a potent combination for... | Read more »
Treasure Tombs: Ra Deal Coming from Bulk...
Treasure Tombs: Ra Deal Coming from Bulkypix and Dark Tonic This Fall Posted by Jessica Fisher on September 2nd, 2014 [ permalink ] Dark Tonic and | Read more »
Pirate Bash Review
Pirate Bash Review By Nadia Oxford on September 2nd, 2014 Our Rating: :: BAD PIRATES, GOOD TIMESUniversal App - Designed for iPhone and iPad Pirate Bash’s turn-based battles add an intriguing twist to a typical physics game.   | Read more »
Tiny Tower Vegas Review
Tiny Tower Vegas Review By Jennifer Allen on September 2nd, 2014 Our Rating: :: STEADY DEVELOPMENTUniversal App - Designed for iPhone and iPad Build a huge tower again but Vegas-style in Tiny Tower Vegas.   | Read more »
The Manhattan Project Review
The Manhattan Project Review By Andrew Fisher on September 2nd, 2014 Our Rating: :: ROCKET SCIENCEUniversal App - Designed for iPhone and iPad The Manhattan Project offers a great Euro-style gameplay experience, but it is totally... | Read more »

Price Scanner via MacPrices.net

Apple refurbished iPads available for up to $...
Apple is offering Certified Refurbished iPad Airs for up to $140 off MSRP. Apple’s one-year warranty is included with each model, and shipping is free. Stock tends to come and go with some of these... Read more
Are We Now In The Post-Post-PC Era?
A longtime and thoroughgoing laptop aficionado, I was more than a little dismayed by Steve Jobs’s declaration back in 2010 when he sprang the iPad on an unsuspecting world. that we’d entered a “post-... Read more
PC Outlook Improves, But 2014 Shipments Still...
According to the International Data Corporation (IDC) Worldwide Quarterly PC Tracker, worldwide PC shipments are expected to fall by -3.7 percent in 2014. To hat’s actually an improvement from the... Read more
IDC Lowers Tablet Sales Projections for 2014...
Following a second consecutive quarter of softer than expected demand, International Data Corporation (IDC) has lowered its worldwide tablet plus 2-in-1 forecast for 2014 to 233.1 million units. The... Read more
Apple now offering refurbished 21-inch 1.4GHz...
The Apple Store is now offering Apple Certified Refurbished 21″ 1.4GHz iMacs for $929 including free shipping plus Apple’s standard one-year warranty. Their price is $170 off the cost of new models,... Read more
Save $50 on the 2.5GHz Mac mini, on sale for...
B&H Photo has the 2.5GHz Mac mini on sale for $549.99 including free shipping. That’s $50 off MSRP, and B&H will also include a free copy of Parallels Desktop software. NY sales tax only. Read more
Save up to $300 on an iMac with Apple refurbi...
The Apple Store has Apple Certified Refurbished iMacs available for up to $300 off the cost of new models. Apple’s one-year warranty is standard, and shipping is free. These are the best prices on... Read more
The Rise of Phablets
Carlisle & Gallagher Consulting Group, a businesses and technology consulting firm focused solely on the financial services industry, has released an infographic depicting the convergence of... Read more
Bad Driver Database App Allows Good Drivers t...
Bad Driver Database 1.4 by Facile Group is a new iOS and Android app that lets users instantly input and see how many times a careless, reckless or just plain stupid driver has been added to the... Read more
Eddy – Cloud Music Player for iPhone/iPad Fre...
Ukraine based CapableBits announces the release of Eddy, its tiny, but smart and powerful cloud music player for iPhone and iPad that allows users to stream or download music directly from cloud... Read more

Jobs Board

*Apple* Retail - Multiple Positions (US) - A...
Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
*Apple* Retail - Multiple Positions (US) - A...
Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
*Apple* Retail - Multiple Positions (US) - A...
Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
*Apple* Retail - Multiple Positions (US) - A...
Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
Senior Event Manager, *Apple* Retail Market...
…This senior level position is responsible for leading and imagining the Apple Retail Team's global event strategy. Delivering an overarching brand story; in-store, Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.