TweetFollow Us on Twitter

Feb 98 Factory Floor

Volume Number: 14 (1998)
Issue Number: 2
Column Tag: From The Factory Floor

CodeWarrior Latitude: Porting Custom Definition Functions and More

by David Hempling, Bob McBeth, and Dave Mark, ©1998 by Metrowerks, Inc., all rights reserved.

This month, we'll continue our ongoing look at CodeWarrior Latitude. We'll start off with a look at the issues that crop up when porting custom definition functions from the Mac to Unix systems such as Rhapsody.

CodeWarrior Latitude is a porting library that greatly simplifies the process of porting Mac OS applications to Rhapsody. Latitude is an implementation of the Macintosh System 7 application programming interfaces (APIs) that allows source code for a Macintosh application to be compiled with little modification on a Rhapsody platform, resulting in a native Rhapsody application. Latitude maps the Mac API requests to native Unix system calls. An application built with Latitude attains the look and feel of the new native platform.

Custom Definition Functions

Customized definition functions provided to the Mac Toolbox API as function pointers require no changes for porting from the Mac OS platform using CodeWarrior Latitude. The function pointer you provide to ModalDialog(), for example, does not need to be changed. However, you may want to add functionality to your modal definition function to handle events that weren't expected on the Mac.

On platforms supported by Latitude, modal dialog windows are moveable at all times. If the user moves a modal dialog window, the mouseDown inDrag event will go undetected in your own modal definition function ported from the Mac since on the Mac your app didn't have to deal with this possibility. Therefore, you will need to add a case for the mouseDown inDrag event, which calls DragWindow() to handle that event's processing. You will know if you neglected to handle the mouseDown inDrag event if your dialog window contains a popup menu. If DragWindow() has not been called in a moved window and the user clicks on the popup menu button, the menu will appear on screen were the popup button was on the screen before the window was moved. The DragWindow() call updates the window's port bounds which are used by PopUpMenuSelect() to display the popup menu.

Because this new possibility of unforeseen events arises on non Mac OS platforms, your own application's windows may become obscured or uncovered at times when they couldn't have been on the Mac. For example, say the user causes a system dialog to appear, such as one of Latitude's "Apple" menu desktop services like Copy Files or other system level alerts which are movable, and then the user moves one of these alerts causing a portion of your own app's windows to require updating. You now have a blank area of your application windows that you want to refresh. But, you don't have control since Latitude is servicing some other request.

Latitude provides a means for applications to register a special modal filter function whose job is to receive update events for all application windows when Latitude is in control of a presently displayed modal dialog. The filter function prototype is simply:

void my_app_modal_update_hook(EventRecord *theEvent)

You provide this function at lg_latitude_init() time as one of the field settings in the LG_APP_INFO_BLOCK:

void  main( long argc, char **argv )
{
#ifdef _LATITUDE_
    LG_APP_INFO_BLOCK lblock;

    lblock.flags =   LG_APP_INFO_SIGNATURE |
                           LG_APP_INFO_CLASSNAME |
                           LG_APP_INFO_MODAL_EVENT_HOOK;
    lblock.signature = QUADCONST('C','T','T','R');
    lblock.classname = "Latitude";
    lblock.modal_event_hook = my_app_modal_update_hook;
    lg_latitude_init(argc,argv, &lblock);
#endif

Another type of custom definition function are those that define custom controls, menus, lists, and windows. Mac applications provide these functions to the Mac toolbox in one of two ways. They either compile these functions separately into special code resources -- CDEF for controls, MDEF for menus, LDEF for lists, and WDEF for windows -- or they compile these functions with their application and patch special CDEF, MDEF, LDEF, or WDEF resources that contain assembly instructions. These patch resources typically contain twelve byte structures defined like this:

typedef struct {
  short jmp_inst;
  ProcPtr long def_func;
} DEF_STRUCT;

And are set up at init time like this:

DEF_STRUCT **my_cdef;
extern long my_cdef(short varCode, ControlHandle theControl,
        short message, long param);

my_cdef = (DEF_STRUCT **) GetResoure('CDEF', 128);

(**my_cdef).jmp_inst = 0x4EF9; 
                /* 680x0 for JMP (i.e. Jump) */
(**my_cdef).def_func = (ProcPtr) my_cdef;

There are two problems with this practice that come up for porting. The first problem is the 680x0 assembly code in the handle. Since CodeWarrior Latitude contains no machine code interpreter, the 680x0 JMP instruction is meaningless. The second problem is a little less obvious and far more hazardous. Since we're probably porting to a RISC based platform where long words are aligned on long word boundaries, the size of the DEF_STRUCT structure above is not 12 bytes, it's 16! (The compiler will insert 4 bytes of padding after the jmp_inst member so that def_func falls on a long word boundary.) The size of the CDEF 128 handle is 12 bytes. The assignment of the structure's def_func member writes passed the end of the 12 byte handle, thus corrupting memory.

CodeWarrior Latitude provides a means to register your definition functions so as to avoid these types of problems:

Handle lg_latitude_code_resource(ResType type, short id, 
          StringPtr name, ProcPtr defproc);

Latitude creates a special handle and places it in the ROM Resource Map (ROMMapHndl). When CW Latitude's toolbox requires a CDEF, LDEF, MDEF, or WDEF, it searches the ROM Map for the registered code resource first.

If your app needs to get at the handle, you can use the one returned by lg_latitude_code_resource(), or if that one isn't readily available, you can use regular Resource Manager calls to retrieve it. The standard way to get a ROM map resource is:

  short cur_map;
  Handle h;

  cur_map = CurResFile();
  UseResFile(1);
  h = Get1Resource(QUADCONST('C','D','E','F'), 128);
  UseResFile(cur_map);

To get the function pointer out of a CW Latitude created code resource handle, use the call

ProcPtr lg_latitude_code_address(Handle h);

CDEFs, LDEFs and MDEFs for popup menus are completely handled by CW Latitude. MDEFs for menus off of the menubar need to be handled differently since CW Latitude is not drawing those menus itself but rather sending the appropriate instructions to the native system to display the menus.

If your app has a custom MDEF for menubar menus solely for the purpose of displaying multiple key combination menu item key equivalents (such as shift-control-option-F), then you can use a special MDEF provided by CW Latitude, called lg_latitude_custom_mdef, specifically designed for such menus.

WDEFs are also a little tricky. Again, CodeWarrior Latitude is not drawing the window itself, so you have no way of drawing a window's adornments under Latitude. However, by using some of Latitude's special window functions like lg_latitude_next_window (discussed in last month's article) and lg_latitude_register_window, you can provide Latitude with a description of the functionality of your WDEF, including floating attributes, and let Latitude handle communicating those details to the native system.

Games with A5

Macintosh applications have all kinds of games they play with the A5 register to save and restore contexts. Sometimes this is done when the application is in the background but wants to communicate something to the user. Since the native Unix systems supported by CodeWarrior Latitude do their own context switching, your application doesn't have to provide its own context management. If your application is awoken from suspension, you can be assured that the system will restore the proper stack and processor register context before executing more of your application's code.

Some applications use A5 as a sort of stack jump maneuver to recover from an error. The equivalent in Unix systems is the setjmp and longjmp pair of functions. You use setjmp to save the stack environment in a given buffer for later use by longjmp. A call to longjmp zaps execution and context back to the place were the setjmp call was made.

Games with the Memory Manager

Some Macintosh applications play interesting games with the Mac Memory Manager. They try to gobble up all of the memory available, tickling a grow zone proc in the process, to determine how much memory is really available. Others allocate a large block of memory and proceed to parse off parts of it themselves, acting as their own Memory Manager. CodeWarrior Latitude's Memory Manager provides handles and pointers the way Mac applications expect, even simulating a System Zone and an Application Zone. However there are no large, specially zoned pools of memory that Latitude allocates from. Each handle and pointer allocation done by CW Latitude's Memory Manager is mapped directly to Unix system malloc() and realloc() calls. Since we're operating in true virtual memory systems, these common games applications play with the Memory Manager are completely meaningless. If your app is using these tricks, you should disable them and just let Latitude's Memory Manager do its thing.

Precompiled Headers

On Latitude supported systems where the available compilers do not support precompiled headers, you will have to explicitly add inclusion of your desired include files to your source code. It will probably be helpful to create one include file that sites the set of files included in the precompiled header you used on the Mac. CodeWarrior Latitude includes an include file like this for the often used MacHeaders file. It is located in the $LATITUDE_ROOT/utilities directory. You can copy it to your application's development environment for your use.

At the time of this article's writing, Metrowerks has not yet released our own C/C++/ObjC compiler for Rhapsody. However, by the time this article hits the stands, this issue of precompiled headers will be moot for Rhapsody. However, until we bring the IDE to Rhapsody, you will still have to explicitly add any includes that were implicitly added by the IDE's prefix file feature.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

VueScan 9.5.09 - 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
Airmail 2.1 - Powerful, minimal email cl...
Airmail 2 is a new mail client designed for OS X 10.10 Yosemite with fast performance and intuitive interaction. Support for iCloud, MS Exchange, Gmail, Google Apps, IMAP, POP3, Yahoo!, AOL, Outlook.... Read more
Logitech Control Center 3.9.2 - Keyboard...
Logitech Control Center (LCC) is designed to support OS X and allows you to take full advantage of your Logitech keyboard, mouse, or trackball. With the LCC you can: Browse the Internet using... Read more
Adobe Acrobat Pro 15.007.20033 - Powerfu...
Acrobat Pro DC is available only as a part of Adobe Creative Cloud, and can only be installed and/or updated through Adobe's Creative Cloud app. Adobe Acrobat Pro DC with Adobe Document Cloud... Read more
CleanMyMac 3.0.1 - Delete files that was...
CleanMyMac makes space for the things you love. Sporting a range of ingenious new features, CleanMyMac lets you safely and intelligently scan and clean your entire system, delete large, unused files... Read more
Evernote 6.0.10 - Create searchable note...
Evernote allows you to easily capture information in any environment using whatever device or platform you find most convenient, and makes this information accessible and searchable at anytime, from... Read more
CleanApp 5.0.1 - Application deinstaller...
CleanApp is an application deinstaller and archiver.... Your hard drive gets fuller day by day, but do you know why? CleanApp 5 provides you with insights how to reclaim disk space. There are... Read more
Quicken 2015 2.5.0 - Complete personal f...
Quicken 2015 helps you manage all your personal finances in one place, so you can see where you're spending and where you can save. Quicken automatically categorizes your financial transactions,... Read more
Tonality Pro 1.1.4 - Professional-grade...
Tonality Pro gives you the power to create stunning and dramatic black & white images. This is a complete monochrome image editor with more than 150 one-click style presets, totally unique... Read more
Adobe Photoshop CC 2014 15.2.2 - Profess...
Photoshop CC 2015 is available as part of Adobe Creative Cloud for as little as $19.99/month (or $9.99/month if you're a previous Photoshop customer). Photoshop CS6 is still available for purchase (... Read more

WAVE Personal Calendar Now Connects You...
WAVE Calendar, by e-sites, has added an interesting new feature: real life personal assistants. The e-sites webpage has been redesigned so personal assistants can apply to work directly with WAVE. [Read more] | Read more »
Find Your Vacation Home With Dwellable
Dwellable is a new travel app that helps you to find rental homes for your vacation, allowing you to swipe your way through listings from over 15,000 destinations worldwide. [Read more] | Read more »
Play Endless Golf in Flick Golf Free...
Full Fat has released a new update for Flick Golf! Free. The ‘Eliminator’ update brings a whole new way to play with its endless round. [Read more] | Read more »
The Enchanted Cave 2 (Games)
The Enchanted Cave 2 2.1 Device: iOS Universal Category: Games Price: $2.99, Version: 2.1 (iTunes) Description: Delve into a strange cave with a seemingly endless supply of treasure, strategically choosing your battles to gather as... | Read more »
Crystal Siege is on Sale With a New Univ...
Crystal Siege,  FDG Entertainment's RPG  Tower Defense game, has gone universal in its latest update. [Read more] | Read more »
Platforming Action RPG Swordigo is Curre...
Touch Foo's 2D action-platformer, Swordigo, is free for a limited time on the App Store. Now you can run, jump, and slash your way through adventure for absolutely nothing. [Read more] | Read more »
Watch This Homerun Slides into Home on t...
Eyes Wide Games has launched their one-touch baseball game, Watch This Homerun, for the Apple Watch. [Read more] | Read more »
Disney Celebrates May 4th With Galaxy Si...
For Star Wars Day, May 4, join Disney Interactive and Lucasfilm as they celebrate with a whole lot of in=-app sales for their Star Wars apps. [Read more] | Read more »
Oh My Pixel! We Go Hands-on With The Kni...
I recently had a chance to play around with the upcoming Knights of Pen & Paper 2 from Paradox Interactive. I was a huge fan of the first game, so I had a lot of expectations going into it - and I wasn't disappointed. The game has gotten some... | Read more »
Throw Out Your Stylus and Sketch With Pe...
Penpoint Drawing, by Damin Liu,  is a new creative drawing app that uses your finger as your stylus. [Read more] | Read more »

Price Scanner via MacPrices.net

Mac Pros on sale for up to $260 off MSRP
B&H Photo has Mac Pros on sale for up to $260 off MSRP. Shipping is free, and B&H charges sales tax in NY only: - 3.7GHz 4-core Mac Pro: $2799, $200 off MSRP - 3.5GHz 6-core Mac Pro: $3719.99... Read more
Save up to $600 with Apple refurbished Mac Pr...
The Apple Store is offering Apple Certified Refurbished Mac Pros for up to $600 off the cost of new models. An Apple one-year warranty is included with each Mac Pro, and shipping is free. The... Read more
iMacs on sale for up to $205 off MSRP, NY tax...
B&H Photo has 21″ and 27″ iMacs on sale for up to $205 off MSRP including free shipping plus NY sales tax only: - 21″ 1.4GHz iMac: $999 $100 off - 21″ 2.7GHz iMac: $1189 $110 off - 21″ 2.9GHz... Read more
12-inch 1.1GHz Silver MacBook in stock today
B&H Photo has the new 12″ 1.1GHz Silver MacBook in stock today for $1299 including free shipping plus NY sales tax only. Act now if you’re interested, since we don’t expect B&H to have this... Read more
iPad Air 2s on sale for up to $50 off, NY tax...
B&H Photo has iPad Air 2s on sale for up to $64 off MSRP including free shipping plus NY sales tax only: - 16GB iPad Air 2 WiFi: $469 $30 off - 64GB iPad Air 2 WiFi: $549.99 $50 off - 128GB iPad... Read more
Check Apple prices on any device with the iTr...
MacPrices is proud to offer readers a free iOS app (iPhones, iPads, & iPod touch) and Android app (Google Play and Amazon App Store) called iTracx, which allows you to glance at today’s lowest... Read more
Sale! New 13-inch 256GB MacBook Air for $1099...
B&H Photo has the new 2015 13″ 1.6GHz/256GB MacBook Air on sale for $1099.99 including free shipping plus NY tax only. Their price is $100 off MSRP. Read more
Japan Post Group, IBM and Apple Deliver iPads...
Japan Post Group, IBM and Apple executives meeting in in New York City yesterday announced a first-of-its-kind initiative aimed at improving the quality of life for millions of Japanese senior... Read more
Worldwide Tablet Market Contracts For Second...
Worldwide tablet shipments recorded a second consecutive quarter of year-over-year decline in the first calendar quarter of 2015 (1Q15), according to preliminary data from the International Data... Read more
Apple restocks refurbished Mac minis for up t...
The Apple Store has restocked Apple Certified Refurbished 2014 Mac minis, with models available starting at $419. Apple’s one-year warranty is included with each mini, and shipping is free: - 1.4GHz... Read more

Jobs Board

Senior Identity Architect - *Apple* Pay - A...
Changing the world is all in a day039s work at Apple . If you love innovation, here039s your chance to make a career of it. You039ll work hard. But the job comes with Read more
Hardware Systems Integration Engineer - *App...
Changing the world is all in a day039s work at Apple . If you love innovation, here039s your chance to make a career of it. You039ll work hard. But the job comes with Read more
Senior Identity Architect - *Apple* Pay - A...
Changing the world is all in a day039s work at Apple . If you love innovation, here039s your chance to make a career of it. You039ll work hard. But the job comes with Read more
Hardware Systems Integration Engineer - *App...
Changing the world is all in a day039s work at Apple . If you love innovation, here039s your chance to make a career of it. You039ll work hard. But the job comes with Read more
Senior Identity Architect - *Apple* Pay - A...
Changing the world is all in a day039s work at Apple . If you love innovation, here039s your chance to make a career of it. You039ll work hard. But the job comes with Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.