Tips & Tidbits

By Scott T Boyd, Editor

TIP OF THE MONTH

Set Breakpoints In ROM

About a year ago I wrote a little control panel called AV Turbo ROM. What it does is set an undocumented bit in PRAM that the ROMs of Power Macs and AV class machines (840AV and 660AV) check upon restart. If the bit is set, the ROM is copied down into RAM.

While this may or may not speed up things a little (I’ve listened to several people debate this issue), that’s not why I wrote it. I wrote it because now that the ROM code is in RAM, I can set breakpoints in “ROM” code. This is very handy when debugging or for those times when you are wondering, “how does that work?”

There are a few gotchas to be aware of:

1) Now that the ROM is in RAM, RAM Doubler from Connectix and The Debugger from Jasik Designs won’t work because they expect the ROM code to be where it’s supposed to be. Sorry about that, but remember that AV Turbo ROM is simply a tool to be used in special circumstances, and it’s quite reasonable to expect system products of their nature to make certain assumptions about the ROM.

2) Restarting on a PowerMac sometimes doesn’t work. Here’s the workaround - just hit the reset button again; it usually works the second time.

3) Since the ROM can be written to now, errant code could trash things. It’s too bad that The Debugger can’t help out with it’s memory protection technology, but sometimes it’s worth making the tradeoff.

I’ve been running this for a year and haven’t had any problems, just lots of fun walking through the ROMs. AV Turbo ROM is available on most online services. Here’s one place to get it:

ftp://freebsd.cdrom.com:/.13/mac/umich/system.extensions/cdev/avturborom1.0.cpt.hqx

Another Quick Tip

Do you use TMON Pro? Do you know about trap record? If not, find out. It’s a very useful debugging tool if you are debugging code other than your own.

- Steve Kiene, mindvision@mindvision.com

Copy Bits Quicker

If you are using custom color palettes in combination with lots of calls to CopyBits, you can speed up your graphics routines by making sure that the ctSeed of both the source and destination PixMap’s color tables are the same.

If the ctSeed values are different, QuickDraw will map each color in the source color table to colors in the destination color table, slowing down the CopyBits operation. If the ctSeed values are the same, QuickDraw will assume that both PixMaps use the same color table, and it will simply copy the bits directly. This has the disadvantage that if the palettes are completely different, you will end up with the wrong colors in the destination.

- Jeremy Vineyard, jeremyv@farallon.com

Hey, Finder, Pay Attention!

I have run into several things which change a file’s creator, but the finder doesn’t update the file’s icon right away. The user often has to close and reopen the Finder window to get the proper icons to appear. If your application needs to fiddle with a file’s creator type or other attributes, you can solve the above problem by changing the ioDrMdDat field of your file’s parent directory. This “tricks” the Finder into updating the window.

void ForceFinderToUpdateFileIcon(
 FSSpecPtr theFile) 
{
CInfoPBRectempPB;

if(theFile != 0L)
 {
 tempPB.dirInfo.ioNamePtr = 0L;
 tempPB.dirInfo.ioVRefNum=theFile->vRefNum;
 tempPB.dirInfo.ioFDirIndex = -1;
 tempPB.dirInfo.ioDrDirID = theFile->parID;

 if(PBGetCatInfoSync(&tempPB) == noErr) 
 {
 tempPB.dirInfo.ioDrMdDat = LMGetTime();
 tempPB.dirInfo.ioDrDirID = theFile->parID;
 PBSetCatInfoSync(&tempPB);
 }
 } 
}

- Craig Marciniak
TemplarDev@aol.com

Hot Tip for Hot Keys

One of the things I appreciate in applications is the ability to select buttons with keystrokes (the keyboard shortcut is known as a hotkey). The following code example adds hotkey functionality to alert dialogs and can be easily added to modal dialogs. The next time you use an alert, add AlertKeyProc to the function and you will have instant hotkey functionality. Simply change

 CautionAlert(ALERT_ID, NIL) 

to

 CautionAlert(SAVE_ALERT_ID, AlertKeyProc)
 
#include <Dialogs.h>
#define kEnterKey               3
#define kReturnKey              13
#define kEscapeKey              27

pascal Boolean AlertKeyProc(DialogPtr theDialog, 
  EventRecord *e, short *itemHit)
{
   char         theChar;
   short        num, i, iType;
   Handle       iHandle;
   Rect         iRect;
   Str255       iText;
   long         finalTicks;
 
   switch( e->what )
   {
      case keyDown:
      case autoKey:
         theChar = (e->message & charCodeMask);
         if(theChar == kReturnKey || theChar == kEnterKey)
         {
            *itemHit = 1;
            return( TRUE );
         }
         else if(theChar == kEscapeKey)
         {
            *itemHit = 2;
            return( TRUE );
         }
         else
         {
            num = CountDITL( theDialog );
            for(i=0; i<num; i++)
            {
               GetDItem(theDialog, i, &iType, &iHandle, &iRect);
               if(iType == ctrlItem + btnCtrl)
               {// If the button is a push button
                  GetCTitle((ControlHandle )iHandle, iText);
                  if(theChar == iText[1] || 
                     theChar == tolower(iText[1]))
                  {
                     *itemHit = i;
                     HiliteControl((ControlHandle )iHandle, 1);
                     return( TRUE );
                  }
               }
            }
         }
         break;
   }
   return( FALSE );
}

- Jeff Beeghly, jbeeghly@u.washington.edu