TweetFollow Us on Twitter

Powering Up
Volume Number:10
Issue Number:1
Column Tag:Powering Up

Moving to PowerPC

What do you need to get ready for Macintosh with PowerPC

By Richard Clark and Jordan Mattson, Apple Computer, Inc.

About your tour guides

For the next six months we will be serving as your tour guides, showing off the work of some of the best talent at Apple Computer. Therefore, we thought that it was appropriate to introduce ourselves to you:

Richard Clark - is a senior instructor and course designer in Apple’s Developer University group. No stranger to new technologies, Richard spearheaded the System 7, AppleScript, and PowerPC developer training projects, and is presently offering PowerPC classes to Apple’s engineers and third-party developers.

Jordan Mattson - is a product marketing manager in Apple’s Developer Product’s group. Jordan has been at Apple for seven years and in that time has been a product manager for MacsBug, ResEdit, MPW, and now our PowerPC developer tools.

What is Powering up?

Welcome to Powering Up our new monthly column about preparing yourself and your code for Apple’s next generation Macintosh® platform - Macintosh with PowerPC™. In this column we will give you the straight scoop on Macintosh with PowerPC, give you the information that you need to move your current applications to the PowerPC processor-based systems, and give you the background to create new applications that exploit the new features of the Macintosh with PowerPC.

Sometime in the first half of 1994, Apple Computer, Inc. will introduce Macintosh with PowerPC: the next generation of Macintosh computers, based on RISC technology, that will boost the base-level performance of Macintosh systems to two to four times that of today’s high-end Quadras. And, while other computer companies are relegating their RISC offerings to the high-end or to specific market niches, Apple will drive PowerPC processor-based systems throughout the Macintosh product line. Our intention is to, over time, convert from Macintosh with 68K to Macintosh with PowerPC at every price point.

What is Macintosh with PowerPC?

Since the announcement of our intention to deliver Macintosh systems based on PowerPC, there has been lots of misinformation and supposition circulating. If you want to make yourself an instant expert on Macintosh with PowerPC, remember the following:

• It’s a Macintosh - Because Macintosh with PowerPC is first and foremost a Macintosh, almost everything that you know about programming Macintosh is still true. This also means that it is extremely easy for you to move your application over to Macintosh with PowerPC. A number of developers have been able to port their major applications over to PowerPC in as little as two weeks and have seen substantial performance improvements.

• Your software runs - Due to the high fidelity, high performance emulator included in the system software of all Macintosh with PowerPC systems, today’s 68K applications run just fine, and run fast.

• New software flies - those developers that choose to make the move to PowerPC will find that they are richly rewarded. The average application, without much work on your part, can expect to enjoy a performance boost of 2 to 4 times what you see on today’s high-end Quadras.

Making the move

In preparing yourself and your application for Macintosh with PowerPC, much of this work can be done before you get your hands on development tools or a Macintosh with PowerPC system. In the rest of this month’s column, we will give you an overview of what is involved in preparing your source code to make the move to Macintosh with PowerPC and tell you what you can do today to get ready.

Basic Macintosh Compatibility

While Macintosh with PowerPC is a Macintosh, the first step in making the move to PowerPC is making sure that your application is faithfully following the Macintosh compatibility guidelines that Apple has been preaching for years. While programs could get away with a lot in the past, porting certain managers over to the PowerPC architecture gave Apple's engineers a chance for a “clean start". Therefore, many of the suggested compatibility rules are actually going to be enforced on Macintosh with PowerPC.

The rules for ensuring your code will run on Macintosh with PowerPC are essentially the same as those you’ve heard all along from Macintosh Developer Technical Support. (The following discussion highlights some key points from Technical Note M.OV 13 “10+ Commandments" by Rich Collyer and Dave Radcliffe, and incorporates some additional PowerPC-specific information. In addition, more information on programming for the PowerPC can be found in the self-paced “Introduction to RISC and PowerPC” course available from APDA.)

• Minimize use of low memory

• Avoid writing to or reading from hardware directly

• Write 32-bit clean code

• Don't intermix data and code

• Avoid patching traps

There are a few new rules that apply to the new machines:

• Eliminate dependencies on 80- and 96-bit floating point

• Isolate dependencies on the runtime model

• Don't assume you know what's going to be fast

Low memory globals: Applications that use low-memory globals may no longer be compatible when Apple revises the system software. This hinders Apple from adding commonly requested features to the system and enhancing system performance.

Since some applications depend critically on the documented low-memory globals, Apple is supplying a set of accessor calls for all documented low-memory globals. (These calls are in a new set of C/C++ header files located on E.T.O. 12 and coming soon to better development systems near you.) For compatibility reasons, the accessors are implemented as macros on the 68K, but are implemented as actual routines on Macintosh with PowerPC.

These accessor routines should be used now to replace explicit pointers to low memory. However, this is not a license to use undocumented low-memory globals. Apple makes no guarantee that these globals will continue to be available in future system software releases.

Avoid writing to hardware: In addition to the low-memory locations used by the operating system and Toolbox, the Macintosh often uses special addresses for Memory-Mapped I/O. These addresses vary from Macintosh to Macintosh, and limit your code to working with particular versions of the hardware.

Write 32-bit clean code: 68K Macintosh computers can be set to use only the lower 24 bits of an address, for compatibility with the original 68000 addressing model. In contrast, the PowerPC processor-based Macintosh computers will use all 32 bits of a memory address. Most developers have removed dependencies on 24-bit addresses, but some are using the upper bit of an address for other purposes. If you are doing this, be aware that your code is only 31-bit clean. It will not work on Macintosh with PowerPC.

Don’t intermix data and code: The PowerPC runtime system may load native code into a special read-only area. You should not include data either in your code or at the end of your code, nor should you have self-modifying code. A future column will discuss how the new runtime system supports static data (i.e. global variables) for all code.

Avoid patching traps: Trap patches can impact the performance of a PowerPC processor based Macintosh system due to some additional dispatching work that the system has to perform. In addition, the new machines include special “split traps” which incorporate separate versions tuned for the best performance when called from emulation or when called from “native” code. These are traps that had no cause to be patched in the past (such as AddPt), and will not be patchable in the future.

Eliminate dependencies on 80- and 96-bit floating point: The PowerPC processor follows the IEEE 754 standard for floating-point arithmetic. In this standard, float is 32 bits, and double is 64 bits. (Apple has implemented a 128 bit “long double” type in software for those applications which need the extra precision.) However, the PowerPC Floating-Point Unit does not support Motorola’s 80/96-bit extended type. Therefore, any code which depends on “extended” should be converted to one of the hardware-supported types (for speed) or long double (for precision.)

Emulated code can use the 80 and 96-bit extended types via SANE, but the emulator does not support direct calls to the 6888x FPU. Therefore, if you are porting code which contains direct 6888x FPU calls, you should re-code using portable ANSI C. Don’t be tempted to require that the user install a “software FPU” which will run slower than SANE - do the right thing!

Isolate dependencies on runtime model: The existing runtime model contains many features that are processor dependent or optimized for systems with extremely limited memory. If your code depends on parts of the 68000 runtime architecture (such as setting and restoring A5, examining the stack, or looking at the jump table entries), you should try to eliminate this code, or at a minimum, wrap conditional compilation directives around it.

Don’t assume you know what’s going to be fast: The new Macintosh with PowerPC computers are being tuned for both compatibility and performance. Programs which assume that 6888x-direct calls are faster than “standard” floating-point calls will be in for a surprise, as will programs that assume that one particular toolbox call is faster than another. Write your code to be as generic and compatible as possible, then test it once you get your hands on the new systems.

Compiler Compatibility

With a new processor comes new compilers. And the new compiler from Apple, as well as the compilers coming from third-parties, is a lot stricter than the 68K compilers you are used to using. Therefore, you may need to spend some time preparing your code for compilers which adhere more closely to the ANSI standards.

While the ultimate test will be re-compiling on the new PowerPC compilers, you can learn much from your current compiler. THINK C users can use the “ANSI Settings” button in the compiler options dialog to get a feel for what the new compilers will be like. (When using the “ANSI compatibility” settings, turn “THINK C extensions” back on so that the compiler will recognize the “pascal” keyword in the Macintosh headers. Selecting “4 byte ints” is also a good idea, as this is the size used by both the MPW and PowerPC compilers.) MPW users already have a fairly ANSI-compliant compiler, though they should use the “-r” flag to detect calls to undefined routines.)

In any case, running the MPW C and C++ compilers is a good benchmark to illustrate what will and will not work on the PowerPC compilers. The MPW compiler doesn’t implement THINK C’s “asm {}” directive, and neither does the PowerPC compiler. (Such in-line assembly should be re-written as portable ANSI C, not just moved into PowerPC assembler. You should only consider going to assembler after testing the compiled code for performance.) MPW doesn’t use precompiled headers by default, and the PowerPC compilers may not support them at all. MPW watches for pointer assignment incompatibilities that THINK C passes by. In general, your code will be more portable after running through two compilers than after running through only one.

ANSI Compatibility

Just being able to survive the MPW compiler isn’t enough - your code has to survive an ANSI-compliant compiler and a new runtime environment. Fortunately, you can take three simple steps to improve your code’s portability and robustness:

• Don’t make assumptions about the size of an int

• Add function prototypes and self-prototyping functions

• Remove language extensions where you can

Don’t make assumptions about the size of an int: Portable C code should not make assumptions about the size of an integer. For example, THINK C assumes int is 16 bits unless you set the “4 byte ints” option. MPW and the current PowerPC compilers all assume that int is 32 bits. Therefore, you should perform a global search for int in your code and replace these references with something less compiler-specific. The safest solution is to declare some “virtual types” such as a 16-bit int16 and a 32-bit int32 in a special header. You can modify for each compiler and still retain portability.

In general, you should use int only if you need the “natural” word size of the machine, as you do for loop counters, array indices, and other values that are likely to be manipulated in registers and that require efficient handling by the processor.

Add function prototypes and self-prototyping functions: Function prototypes are an ANSI addition to the C language which allows the compiler to check (and potentially coerce) the values being passed to and from a function. The PowerPC compilers, which are true ANSI compilers, do a better job of type checking (and may be able to generate better code) if you use declarations in this style. Adding function prototypes also allows the compiler to catch potential parameter-passing errors at compile time instead of allowing the debugger to catch them at runtime.

Remove language extensions where you can: The first step is to make your C code as ANSI-compliant as possible, except for the “pascal” keyword, which is Apple-specific, and "//" comments which are part of C++ but not ANSI C. All current Macintosh C compilers (including PowerPC compilers) implement these language extensions.

One major challenge that faces C++ programmers is the use of handle-based objects. Handle-based objects are a non-ANSI extension to C++ that is not supported by the PowerPC compilers. Therefore, you must change your code to use pointer-based objects and update to a version of your class library that supports pointer-based objects. (One advantage of this change is that it gives you access to C++'s full range of features.)

Coming next month

We hope that this brief introduction to PowerPC development will help you begin preparing your code for the next generation of Macintosh computers. In next month’s column, we will give you are tour of the PowerPC processor architecture, give you a taste of PowerPC assembly language, and show you why you won’t be writing much assembly language in the future.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

MacFamilyTree 7.3.4 - Create and explore...
MacFamilyTree gives genealogy a facelift: it's modern, interactive, incredibly fast, and easy to use. We're convinced that generations of chroniclers would have loved to trade in their genealogy... Read more
Yummy FTP 1.10.2 - FTP/SFTP/FTPS client...
Yummy FTP is an FTP + SFTP + FTPS file transfer client which focuses on speed, reliability and productivity. Whether you need to transfer a few files or a few thousand, schedule automatic backups, or... Read more
VueScan 9.5.08 - 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
Iridient Developer 3.0.1 - Powerful imag...
Iridient Developer (was RAW Developer) is a powerful image conversion application designed specifically for OS X. Iridient Developer gives advanced photographers total control over every aspect of... Read more
Air Video Server HD 2.1.0 - Stream video...
Air Video Server HD streams videos instantly from your computer on your iPhone, iPad, iPod touch or Apple TV. No need to worry about converting or transferring files. We took everything that was... Read more
Duplicate Annihilator 5.7.5 - Find and d...
Duplicate Annihilator takes on the time-consuming task of comparing the images in your iPhoto library using effective algorithms to make sure that no duplicate escapes. Duplicate Annihilator... Read more
BusyContacts 1.0.2 - Fast, efficient con...
BusyContacts is a contact manager for OS X that makes creating, finding, and managing contacts faster and more efficient. It brings to contact management the same power, flexibility, and sharing... Read more
Capture One Pro 8.2.0.82 - RAW workflow...
Capture One Pro 8 is a professional RAW converter offering you ultimate image quality with accurate colors and incredible detail from more than 300 high-end cameras -- straight out of the box. It... Read more
Backblaze 4.0.0.872 - Online backup serv...
Backblaze is an online backup service designed from the ground-up for the Mac.With unlimited storage available for $5 per month, as well as a free 15-day trial, peace of mind is within reach with... Read more
Little Snitch 3.5.2 - Alerts you about o...
Little Snitch gives you control over your private outgoing data. Track background activity As soon as your computer connects to the Internet, applications often have permission to send any... Read more

2K Announces WWE 2K, Mobile's First...
It seems like this month has been pretty big for wrestling. First Wrestlemania, then 2K has announces that they're releasing  WWE 2K for iOS. It's a simulation-based WWE game where you'll get to play with several WWE superstars such as John Cena, ... | Read more »
How the Apple Watch Could Change the Fac...
The Apple Watch is still a ways out, but my previous musings on the wearable’s various features got me thinking: what might it be like a year after launch? Two years? Five years? What if it becomes a symbiotic part of the iOS framework to the point... | Read more »
Pie In The Sky: A Pizza Odyssey (Games)
Pie In The Sky: A Pizza Odyssey 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: A game about delivering pizza. In space. | Read more »
Chosen Gives Hopeful Singers, Songwriter...
If YouTube videos and reality TV shows like The Voice have taught us one thing, it’s that there are a lot of people out there who are anxious to show the world their talents. And if they’ve taught us a second thing, it’s that there’s an almost... | Read more »
Android's Popular OfficeSuite Now A...
Once only available for Android devices, OfficeSuite has finally landed on the app store. The Mobile Systems app lets you view, edit, create, and share Word, Excel, and PowerPoint documents as well as convert them to/from PDFs. It's touted as being... | Read more »
Warhammer: Arcane Magic is Coming Soon,...
Turbo Tape Games has announced that they're joining forces with Games Workshop to bring the turn-based strategy board game, Warhammer: Arcane Magic, to life on the iOS. | Read more »
Fast & Furious: Legacy's Creati...
| Read more »
N-Fusion and 505's Ember is Totally...
| Read more »
These are All the Apple Watch Apps and G...
The Apple Watch is less than a month from hitting store shelves, and once you get your hands on it you're probably going to want some apps and games to install. Fear not! We've compiled a list of all the Apple Watch apps and games we've been able to... | Read more »
Appy to Have Known You - Lee Hamlet Look...
Being at 148Apps these past 2 years has been an awesome experience that has taught me a great deal, and working with such a great team has been a privilege. Thank you to Rob Rich, and to both Rob LeFebvre and Jeff Scott before him, for helping me... | Read more »

Price Scanner via MacPrices.net

Adobe Brings Powerful Layout-Design Capabilit...
Adobe today announced the availability of Adobe Comp CC, a free iPad app that enables rapid creation of layout concepts for mobile, Web and print projects. With Comp CC, designers can rough out and... Read more
Apple offering refurbished 27-inch 5K iMacs f...
The Apple Store is offering Apple Certified Refurbished 27″ 3.5GHz 5K iMacs for $2119 including free shipping. Their price is $380 off the price of new models, and it’s the lowest price available for... Read more
16GB iPad mini on sale for $199, save $50
Walmart has 16GB iPad minis (1st generation) available for $199.99 on their online store, including free shipping. Their price is $50 off MSRP. Online orders only. Read more
New 128GB MacBook Airs on sale for $50 off MS...
 B&H Photo has 128GB 11″ and 13″ 2015 MacBook Airs on sale today for $50 off MSRP including free shipping plus NY sales tax only: - 11″ 1.6GHz/128GB MacBook Air (Model #MJVM2LL/A): $849 $50 off... Read more
13-inch 2.6GHz Retina MacBook Pro (refurbishe...
The Apple Store has Apple Certified Refurbished 13″ 2.6GHz/128GB Retina MacBook Pros available for $979 including free shipping. Original MSRP for this model was $1299. 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
Samsung Galaxy S 6 and Galaxy S 6 edge U.S. P...
Samsung Electronics America, Inc. has announced the Galaxy S 6 and Galaxy S 6 edge will be available in the U.S. beginning April 10, with pre-orders being accepted now. “We have completely reimagined... Read more
13-inch 2.5GHz MacBook Pro (refurbished) avai...
The Apple Store has Apple Certified Refurbished 13″ 2.5GHz MacBook Pros available for $829, or $270 off the cost of new models. Apple’s one-year warranty is standard, and shipping is free: - 13″ 2.... Read more
Save up to $80 on iPad Air 2s, NY tax only, f...
 B&H Photo has iPad Air 2s on sale for $80 off MSRP including free shipping plus NY sales tax only: - 16GB iPad Air 2 WiFi: $469.99 $30 off - 64GB iPad Air 2 WiFi: $549.99 $50 off - 128GB iPad... Read more
iMacs on sale for up to $205 off MSRP
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: $1019 $80 off - 21″ 2.7GHz iMac: $1189 $110 off - 21″ 2.9GHz... Read more

Jobs Board

DevOps Software Engineer - *Apple* Pay, iOS...
**Job Summary** Imagine what you could do here. At Apple , great ideas have a way of becoming great products, services, and customer experiences very quickly. Bring 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
Sr. Technical Services Consultant, *Apple*...
**Job Summary** Apple Professional Services (APS) has an opening for a senior technical position that contributes to Apple 's efforts for strategic and transactional Read more
Lead *Apple* Solutions Consultant - Retail...
**Job Summary** Job Summary The Lead ASC is an Apple employee who serves as the Apple business manager and influencer in a hyper-business critical Reseller's store Read more
*Apple* Pay - Site Reliability Engineer - Ap...
**Job Summary** Imagine what you could do here. At Apple , great ideas have a way of becoming great products, services, and customer experiences very quickly. Bring Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.