TweetFollow Us on Twitter

Sep 93 Think 10
Volume Number:9
Issue Number:9
Column Tag:Think Top 10

Think Top 10

By Thomas Emerson, THINK Technical Support, Symantec Corp.

This a monthly column written by Symantec's Technical Support Engineers intended to provide you with information on Symantec products. This month we cover some more commonly asked questions of Symantec’s developer technical support group.

Q. I want to write some assembly language for my C++ project, but I can't! The C++ compiler doesn't have an inline assembler and I can't figure out how to call my C++ functions from THINK C. Is there no hope?

A. You can call a C++ function from within an inline assembler block in the same way you would a C function: just JSR to the function. There is a slight complication though: the C++ language implements its type-safe linkage by “mangling” the name of functions and methods to contain the type information. So to call a C++ function from C, you need to use its mangled name. You can get the mangled name by turning on the “Generate MacsBug names” option in the Symantec C++ options dialog and disassembling the file containing the function whose mangled name you want. The mangled name will appear in a string at the end of the function. For example, assume that foo.cp contains the function:

void foo()
{
 for(int i=0;i<10;i++)
 ;
}

Disassembling foo.cp yields in part the following:

00000012: 261F              MOVE.L    (A7)+,D3
00000014: 4E75              RTS
00000016: 8766 6F6F 5F5F    DC.B      $80+$07, 'foo__Fv'
          4676           
0000001E: 0000              DC.W      0  ; size of literals
00000020

The mangled name for foo() is foo__Fv. So to call it from within the inline assembler we would write:

 asm {
 jsr    foo__Fv
 addq.l #4,sp
 };

remembering to prototype the function correctly, i.e.

 extern void foo__Fv(void);

and remember to use C++ calling conventions when passing arguments to the function. See pp. 73-75 of the C++ Compiler Guide for more details.

Q. On a related note, whenever I try to use the asm() statement in C++, I'm told that the function asm has no prototype. What's going on?

A. You will get this error if you have “ANSI conformance” option turned on in the Language Settings page of the Symantec C++ for Macintosh options dialog. As it says on page 40 of the C++ Compiler Guide , the keyword asm is not recognized. Turn this off and you will be all set.

Q. Can I build a code resource using Symantec C++ that uses C++ objects?

A. Sure, you can use C++ objects in code resources, though they cannot contain virtual methods. This is because the resource loader code does not support the 32-bit offsets used to build the vtables that are used for virtual method dispatch. We would recommend deriving all of your classes from PascalObject, which will support virtual methods and is an all around better way of doing it.

Q. It appears that your IOStreams library doesn't work when I turn on 68881 code generation. I built a version of IOStreams with the C++ compiler set to generate 881 instructions, but the simplest programs still don't work. What's wrong?

A. There are two things you need to do when using IOStreams with 68881 code generation. The library itself contains both C and C++ code, so you need to turn on 881 code generation for both the THINK C and Symantec C++ compilers. You also need to build a version of ANSI++ that uses 68881 code generation, since IOStreams makes calls to ANSI++ to do the dirty work.

Q. I’m a little confused on the difference between Stream.h and iostream.h. When should I use one and not the other?

A. The short and sweet answer is that you should ignore Stream.h completely and always use iostream.h. Stream.h contains the classes for the old Streams library described in the first edition of The C++ Programming Language. The header file is part of the Symantec C++ for Macintosh distribution, but the library itself was left out (though it is part of the MPW version, called SCOldstreamsIO.o and SCOldstreamsIO881.o). Unless you are porting old C++ source code that uses Stream.h you should use iostream.h instead.

Q. Since we're talking about streams here, I've found that when I create an fstream it shows up on my disk as a blank icon, and I can't open it. Is there any way to tell the compiler that I want a THINK C text file?

A. You can use a “feature” of the standard library to set the type and creator used when creating files. This works because the IOStreams library calls upon ANSI++ to do its dirty work, like creating and opening files. The file <stdio.h> declared two external globals, _ftype and _fcreator. These are used to set the initial type and creator for a file, so settings these to 'TEXT' and 'KAHL' respectively will solve your problem. The following code snippet should give you an idea of what to do:

#include <fstream.h>
#include <stdio.h>

void main()
{
 fstream fs;

 // set the type and creator for any streams we open
 _ftype = 'TEXT';
 _fcreator = 'KAHL';

 fs.open("foo.bar");
  
}

Q. I've heard about something called ToolServer. What is it and how do I use it?

A. ToolServer is a product developed by Apple that allows you to execute most MPW tools and scripts (the major exceptions being the editor and Projector commands.) Applications communicate with ToolServer by exchanging Apple events: in effect an MPW command line is sent to ToolServer, and the results of the command sent back to the calling application. The THINK Project Manager provides ToolServer support with this mechanism: if you press Command-Enter within any THINK editing window then the current selection (or the line the cursor is on if there isn't a selection) is sent to ToolServer. The TPM looks for an alias called “ToolServer” in the Tools folder, and launches this application if ToolServer isn't running.

ToolServer is distributed by Apple on the E.T.O. series (it first appeared in released form on E.T.O. #11) and in the MPW 3.3 distribution, both of which are available through APDA.

Q. Supposedly this is the THINK Top 10, yet there are only 8 questions, counting this one. What's the deal?

A. Well, perhaps we should have called this month's column the “THINK Top 010.” [read it in octal for those of you scratching your heads. - Ed.]

Thanks to Chris Prinos, Kevin Irlen, and Phil Shapiro for their contributions to the answers this month.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Shadow Blade: Reload guide - How to hack...
Shadow Blade: Reload is the kind of action-platformer that would have happily sucked up hours of your time on a console a few years back.Now, you can take it with you wherever you go, and its mobile conversion is not too shabby at all. To help you... | Read more »
Tomb of the Mask guide - How to increase...
Tomb of the Mask is a great endless arcade game from Happymagenta in which quick reflexes and a persistent attitude can go a long way toward earning a top score. Check out these tips to see if you can give yourself an edge on the leaderboards. [... | Read more »
Smooth Operator! (Games)
Smooth Operator! 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: Smooth Operator is a weird, weird two-player kissing game. Squeeze in for 2 player fun on a single iPad, creating awkward... | Read more »
Sinless: Remastered (Games)
Sinless: Remastered 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: | Read more »
_PRISM Guide - How to solve those puzzle...
_PRISM is a rather delightful puzzle game that’s been tailor made for touch screens. While part of the fun is figuring things out as you go along, we thought we’d offer you a helping hand at getting in the right mindset. Don’t worry about messing... | Read more »
Fractal Space (Games)
Fractal Space 1.3.1 Device: iOS Universal Category: Games Price: $.99, Version: 1.3.1 (iTunes) Description: Live the memorable experience of Fractal Space, a unique first person adventure & puzzle game by Haze Games! Will you... | Read more »
Set off on an adventure through the Cand...
Like match three puzzlers? If so, Jelly Blast, the innovative iOS and Android game which launched last year, is worth a look. Jelly Blast sees you head off on an epic adventure through the Candy Kingdom with your friends Lily, Mr. Hare, and Mr.... | Read more »
Ellipsis - Touch. Explore. Survive. (...
Ellipsis - Touch. Explore. Survive. 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: | Read more »
Abzorb (Games)
Abzorb 1 Device: iOS Universal Category: Games Price: $2.99, Version: 1 (iTunes) Description: Abzorb is a tilt game about consuming orbs by getting as close as you can to them without touching. By tilting your mobile device, collect... | Read more »
A Short Tale (Games)
A Short Tale 1.0 Device: iOS Universal Category: Games Price: $3.99, Version: 1.0 (iTunes) Description: It’s been years since I lost Ben, so long yet it doesn’t seem long enough. I never thought I’d return here, to where everything... | Read more »

Price Scanner via MacPrices.net

cb Hardcase – Handmade and Premium Protective...
Baden-Baden, Germany based company cb innovations has introduced the new cb Hardcase for iPhone. Featuring fine Italian Premium leather that makes for a unique look and feel, the cb Hardcase... Read more
Sale! B&H Photo offers 12-inch Retina Mac...
B&H Photo has 12″ Retina MacBooks on sale for $300 off MSRP for a limited time. Shipping is free, and B&H charges NY tax only: - 12″ 1.1GHz Gray Retina MacBook: $999 $300 off MSRP - 12″ 1.... Read more
App Annie Reveals Future of the App Economy:...
App Annie, a San Francisco based mobile app data and insights platform, has launched its first comprehensive app economy forecast. This new offering will provide brands, agencies, investors and app... Read more
Apple restocks Certified Refurbished Mac mini...
Apple has restocked 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 Mac mini: $419 $... Read more
What iPad Pro Still Needs To Make It Truly Pr...
I love my iPad Air 2. So much that I’m grudgingly willing to put up with its compromises and limitations as a production tool in order to take advantage of its virtues. However, since a computer for... Read more
21-inch 3.1GHz 4K on sale for $1399, $100 off...
B&H Photo has the 21″ 3.1GHz 4K iMac on sale $1399 for a limited time. Shipping is free, and B&H charges NY sales tax only. Their price is $100 off MSRP: - 21″ 3.1GHz 4K iMac (MK452LL/A): $... Read more
Apple price trackers, updated continuously
Scan our Apple Price Trackers for the latest information on sales, bundles, and availability on systems from Apple’s authorized internet/catalog resellers. We update the trackers continuously: - 15″... Read more
Save up to $240 with Apple Certified Refurbis...
Apple is now offering Certified Refurbished 12″ Retina MacBooks for up to $240 off the cost of new models. Apple will include a standard one-year warranty with each MacBook, and shipping is free. The... Read more
Apple refurbished 13-inch Retina MacBook Pros...
Apple has Certified Refurbished 13″ Retina MacBook Pros available for up to $270 off the cost of new models. An Apple one-year warranty is included with each model, and shipping is free: - 13″ 2.7GHz... Read more
Apple refurbished Time Capsules available for...
Apple has certified refurbished Time Capsules available for $120 off MSRP. Apple’s one-year warranty is included with each Time Capsule, and shipping is free: - 2TB Time Capsule: $179, $120 off - 3TB... Read more

Jobs Board

Lead Engineer *Apple* OSX & Hardware -...
Lead Engineer Apple OSX & Hardware **Job ID:** 3125919 **Full/Part\-Time:** Full\-time **Regular/Temporary:** Regular **Listed:** 2016\-02\-10 **Location:** Cary, Read more
*Apple* Mobile Master - Best Buy (United Sta...
Job Title Apple Mobile Master **Brand** Best Buy **Job Description** **What does a Best Buy Apple Mobile Master do?** At Best Buy, our mission is to leverage the Read more
Infrastructure Engineer - *Apple* /Mac - Rem...
…part of a team Requires proven problem solving skills Preferred Additional: Apple Certified System Administrator (ACSA) Apple Certified Technical Coordinator (ACTC) Read more
Lead Engineer - *Apple* OSX & Hardware...
Lead Engineer - Apple OSX & Hardware **Job ID:** 3125919 **Full/Part\-Time:** Full\-time **Regular/Temporary:** Regular **Listed:** 2016\-02\-10 **Location:** Cary, Read more
Simply Mac *Apple* Specialist- Service Repa...
Simply Mac is the largest premier retailer of Apple products in the nation. In order to support our growing customer base, we are currently looking for a driven Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.