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.

 
AAPL
$104.85
Apple Inc.
+1.86
MSFT
$44.99
Microsoft Corpora
+0.61
GOOG
$545.04
Google Inc.
+12.33

MacTech Search:
Community Search:

Software Updates via MacUpdate

Art Text 2.4.8 - Create high quality hea...
Art Text is an OS X application for creating high quality textual graphics, headings, logos, icons, Web site elements, and buttons. Thanks to multi-layer support, creating complex graphics is no... Read more
Live Interior 3D Pro 2.9.6 - Powerful an...
Live Interior 3D Pro is a powerful yet very intuitive interior designing application. View Video Tutorials It has every feature of Live Interior 3D Standard, plus some exclusive ones: Create multi... Read more
The Hit List 1.1.7 - Advanced reminder a...
The Hit List manages the daily chaos of your modern life. It's easy to learn - it's as easy as making lists. And it's powerful enough to let you plan, then forget, then act when the time is right.... Read more
jAlbum Pro 12.2.4 - Organize your digita...
jAlbum Pro has all the features you love in jAlbum, but comes with a commercial license. With jAlbum, you can create gorgeous custom photo galleries for the Web without writing a line of code!... Read more
jAlbum 12.2.4 - Create custom photo gall...
With jAlbum, you can create gorgeous custom photo galleries for the Web without writing a line of code! Beginner-friendly, with pro results Simply drag and drop photos into groups, choose a design... Read more
ExpanDrive 4.1.7 - Access remote files o...
ExpanDrive builds cloud storage in every application, acts just like a USB drive plugged into your Mac. With ExpanDrive, you can securely access any remote file server directly from the Finder or... Read more
OmniOutliner Pro 4.1.3 - Pro version of...
OmniOutliner Pro is a flexible program for creating, collecting, and organizing information. Give your creativity a kick start by using an application that's actually designed to help you think. It'... Read more
Evernote 5.6.2 - Create searchable notes...
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
OmniOutliner 4.1.3 - Organize your ideas...
OmniOutliner is a flexible program for creating, collecting, and organizing information. Give your creativity a kick start by using an application that's actually designed to help you think. It's... Read more
BBEdit 11.0 - Powerful text and HTML edi...
BBEdit is the leading professional HTML and text editor for the Mac. Specifically crafted in response to the needs of Web authors and software developers, this award-winning product provides a... Read more

Latest Forum Discussions

See All

Sleep Attack TD Review
Sleep Attack TD Review By Jennifer Allen on October 23rd, 2014 Our Rating: :: A TRUE TWISTUniversal App - Designed for iPhone and iPad Sleep Attack TD is a tower defense game with a difference – you can rotate the layout – and it’s... | Read more »
Earn Your Master Camper Badge in Camp Po...
Earn Your Master Camper Badge in Camp Pokemon Posted by Jessica Fisher on October 23rd, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
Garruk Gets His Revenge in a New Magic 2...
Garruk Gets His Revenge in a New Magic 2015 Expansion, Coming This November Posted by Jessica Fisher on October 23rd, 2014 [ permalink ] | Read more »
Sentinels of the Multiverse Review
Sentinels of the Multiverse Review By Rob Thomas on October 23rd, 2014 Our Rating: :: SENTINELS ASSEMBLEiPad Only App - Designed for the iPad Greater Than Games’ tabletop classic, Sentinels of the Multiverse swoops in to save the... | Read more »
Build Your Own Fantasy Football Dynasty...
Build Your Own Fantasy Football Dynasty with Draft Day Posted by Jessica Fisher on October 23rd, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
Cars: Fast as Lightning – Tips, Tricks,...
Hey there, Stickers: Want to know all about how impressed we were with Radiator Springs? Check out our Cars: Fast as Lightning review! Cars: Fast as Lightning is a cute and fun app that combines racing and town-building with the charisma and... | Read more »
Jam Messenger Review
Jam Messenger Review By Jennifer Allen on October 23rd, 2014 Our Rating: :: SIMPLE MESSAGINGiPhone App - Designed for the iPhone, compatible with the iPad Want a very quick way to send push-based messages? Jam Messenger is basic... | Read more »
Felllice (Games)
Felllice 1.0 Device: iOS Universal Category: Games Price: $.99, Version: 1.0 (iTunes) Description: EXCLUSIVE PRICE DROP! 50% OFF FOR A LIMITED TIME! EAT EAT EAT AND GROW ! | Read more »
The Arrow Game: by Grazie Media (Games)
The Arrow Game: by Grazie Media 1.0 Device: iOS Universal Category: Games Price: $.99, Version: 1.0 (iTunes) Description: Guide a flying arrow through skyscrapers and city streets to hit a distant target. Experience an endless... | Read more »
Worldly (Games)
Worldly 1.2 Device: iOS Universal Category: Games Price: $2.99, Version: 1.2 (iTunes) Description: | Read more »

Price Scanner via MacPrices.net

Save up to $125 on Retina MacBook Pros
B&H Photo has the new 2014 13″ and 15″ Retina MacBook Pros on sale for up to $125 off MSRP. Shipping is free, and B&H charges NY sales tax only. They’ll also include free copies of Parallels... Read more
Apple refurbished Time Capsules available sta...
The Apple Store has certified refurbished Time Capsules available for up to $60 off MSRP. Apple’s one-year warranty is included with each Time Capsule, and shipping is free: - 2TB Time Capsule: $255... Read more
Textilus New Word, Notes and PDF Processor fo...
Textilus is new word-crunching, notes, and PDF processor designed exclusively for the iPad. I haven’t had time to thoroughly check it out yet, but it looks great and early reviews are positive.... Read more
WD My Passport Pro Bus-Powered Thunderbolt RA...
WD’s My Passport Pro RAID solution is powered by an integrated Thunderbolt cable for true portability and speeds as high as 233 MB/s. HighlightsOverviewSpecifications Transfer, Back Up And Edit In... Read more
Save with Best Buy’s College Student Deals
Take an additional $50 off all MacBooks and iMacs at Best Buy Online with their College Students Deals Savings, valid through November 1st. Anyone with a valid .EDU email address can take advantage... Read more
iPad Air 2 & iPad mini 3 Best Tablets Yet...
The new iPads turned out to be pretty much everything I’d been hoping for and more than I’d expected.”More” particularly in terms of a drinking-from-a-firehose choice of models and configurations,... Read more
Drafts 4 Reinvents iOS Productivity App
N Richland Hills, Texas based Agile Tortoise has announced the release of Drafts 4 for iPhone and iPad. Drafts is a quick capture note taking app with flexible output actions. Drafts 4 scales from... Read more
AT&T accepting preorders for new iPads fo...
AT&T Wireless is accepting preorders for the new iPad Air 2 and iPad mini 3, cellular models, for $100 off MSRP with a 2-year service agreement: - 16GB iPad Air 2 WiFi + Cellular: $529.99 - 64GB... Read more
Apple offering refurbished Mac Pros for up to...
The Apple Store is offering Apple Certified Refurbished 2013 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
Select MacBook Airs $100 off MSRP, free shipp...
B&H Photo has 2014 a couple of MacBook Airs on sale for $100 off MSRP. Shipping is free, and B&H charges NY sales tax only. They also include free copies of Parallels Desktop and LoJack for... Read more

Jobs Board

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
*Apple* Solutions Consultant (ASC) - Apple (...
**Job Summary** The ASC is an Apple employee who serves as an Apple brand ambassador and influencer in a Reseller's store. The ASC's role is to grow Apple Read more
Project Manager / Business Analyst, WW *Appl...
…a senior project manager / business analyst to work within our Worldwide Apple Fulfillment Operations and the Business Process Re-engineering team. This role will work Read more
*Apple* Retail - Multiple Positions (US) - A...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
Position Opening at *Apple* - Apple (United...
…customers purchase our products, you're the one who helps them get more out of their new Apple technology. Your day in the Apple Store is filled with a range of Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.