TweetFollow Us on Twitter

Call Register Routines
Volume Number:1
Issue Number:5
Column Tag:Undocumented procedure

Call register-based Toolbox/OS routines

By Steve Brecher

Macintosh Pascal provides a built-in procedure named Generic that is not documented. Generic permits you to call register-based Toolbox/OS routines. It can also be used to execute any machine language code that you have stored in a Pascal data structure. This article describes the use of the Generic procedure.

In effect, the following procedure is pre-declared:

procedure Generic(InstructionWord :integer;
                  VAR Registers : RegRcd);

“RegRcd” denotes a data structure consisting of 13 32-bit values -- five address register values (A0..A4), followed by eight data register values (D0..D7). The exact type of Registers is immaterial, i.e., you could declare:

var
 Registers : record
   A : array[0..4] of longint;
   D : array[0..7] of longint
  end;

Or in some cases you might prefer something like:

var
 Registers : record
   A0, A1, A2, A3, A4 : ^char;
   D0, D1, D2, D3, D4, D5, D6, D7 : longint
  end;

The register values that you pass to Generic are written to the MC68000 registers. Then the one-word instruction denoted by the InstructionWord argument is executed. Finally, your Registers structure is updated with the (possibly) new values of the MC68000 registers before Generic returns to your program.

Any registers that are not used by the machine language routine you’re invoking do not have to have their corresponding elements in the Registers data structure initialized. The machine language routine will have garbage in those registers (but, since it’s not using them, it won’t care).

Usually, Generic will be used to execute a register-based Toolbox/OS trap. In such cases the value you pass to Generic via the InstructionWord argument is the trap value. Here’s an example routine that resets the modem output port to establish new communications parameters:

type
  DataBitsT = (Five, Seven, Six, Eight);  
                               { ^--sic--^ }
  ParityT = (OddParity, NoParity, EvenParity);
  StopBitsT = (One, OnePointFive, Two);

 function ResetSer (Baud : longint;
         DataBits : DataBitsT;
         Parity : ParityT;
         StopBits : StopBitsT) : boolean;
{returns true if no error, false if modem}
{port hasn’t been opened yet}
{}
 const
   PBControl = $A004; {trap value}
   noErr = 0;
   ModemOutRefNum = -7;
   SerReset = 8;      {CScode}
{}
  var
   ParamBlockRec : record
     Filler : array[0..11] of integer;
     ioRefNum : integer;
     csCode : integer;
     csParam : integer
    end;
   Registers : record
     A : array[0..4] of longint;
     D : array[0..7] of longint
    end;
   serConfig : longint;
 begin {ResetSer}
  with ParamBlockRec do
   begin
    ioRefNum := ModemOutRefNum;
    csCode := SerReset;
    serConfig := trunc(114571.7 / baud -
                                              1.338395)
                 + 1024 * ord(DataBits)
                 + 4096 * (ord(Parity) + 1)
                 + 16384 * (ord(StopBits) + 1);
    csParam := loword(serConfig);
   end;
  Registers.A[0] := ord(@ParamBlockRec);
  Generic(PBControl, Registers);
  ResetSer := (Registers.D[0] = noErr)
 end; {ResetSer}

The InstructionWord argument to Generic does not have to be a trap value, however. It can be any 16-bit MC68000 instruction, as shown in the following example:

 procedure CallCode(VAR Result :integer);
{}
{This example assumes a global integer }
{array named Code which contains a       }
{machine language subroutine that takes}
{one VAR (address) argument on the       }
{stack.  CallCode calls the routine,        }
{passing it the address of the Result     }
{parameter. }
{}
 const
  JsrIndirectA0 = $4E90; { Jsr (A0) }
 var
  Registers : record
    A : array[0..4] of ^integer;
    D : array[0..7] of longint
   end;
  Glue : array[1..4] of integer;
 begin
{ MoveA.L (SP),A0 ;return addr }
  Glue[1] := $2057;
{ Move.L A2,(SP) ;ptr to Result }
  Glue[2] := $2E8A;
{ Move.L A0,-(SP) ;return addr }
  Glue[3] := $2F08;
{ Jmp (A1)        ;to subr in Code array }
  Glue[4] := $4ED1;
  with Registers do
   begin
    A[0] := @Glue[1];
    A[1] := @Code[1];
    A[2] := @Result;
   end;
  {Call Glue routine, which invokes Code}
  {routine...}
  Generic(JsrIndirectA0, Registers);
 end; {CallCode}

Scroll Rectangle Notes

(NOTE: did not appear with above article in MacTutor)

ScrollRect is a QuickDraw routine which scrolls a rectangle. Bits (pixels) scrolled out of the rectangle are lost, and the area near the side of the rectangle opposite to the scroll direction is filled with the current Grafport’s background pattern. [The rectangle defining the area to be scrolled must be larger than the screen object you wish to be moved by this procedure to allow room to be lost at the top.]

A Performance Note

ScrollRect will slow down by a factor of 3 or 4 if the scrolled rectangle includes one or more borders of the current Grafport’s portrect. For fast scrolling, assure that each side of the rectangle passed to ScrollRect is at least two pixels away from a border of the portrect.

A Usage Note

The UpdateRgn parameter (a region handle) passed to ScrollRect enables it to return to you the specification of the region that was vacated by scrolled bits and which ScrollRect filled with the background pattern. (Usually the vacated area will be a sub-rectangle of the scrolled rectangle; but it may be other than rectangular if an odd-shapped visRgn or clipRgn affects the ScrollRect.) The previous contents of the region (i.e., the data structure) are destroyed. If you don’t need to know the specification of the area filled with the background pattern (or if you already know), just allocate a dummy region (using NewRgn) and pass ScrollRect a handle to the dummy region. You can allocate the dummy region once at the beginning of your program; or you can allocate it before each call to ScrollRect and then use DisposRgn after each call to free the memory used by the region data structure.

 
AAPL
$93.94
Apple Inc.
-0.49
MSFT
$44.84
Microsoft Corpora
+0.15
GOOG
$589.47
Google Inc.
-5.61

MacTech Search:
Community Search:

Software Updates via MacUpdate

OS X Yosemite 10.10 DP4 - Developer Prev...
Note: This is a Developer Preview. You must be a registered Apple Mac Developer to download this update. OS X Yosemite is Apple's newest operating system for Mac. An elegant design that feels... Read more
FinderPop 2.5.6 - Classic Mac utility, n...
FinderPop is a Universal preference pane that extends OS X's contextual menus using a FinderPop Items folder much as the Apple Menu Items folder used to do for the Apple menu. It has other features... Read more
SpiderOak 5.1.7 - Secure cloud backup, s...
SpiderOak is a multi-platform secure online backup, storage, access, and sharing solution engineered for the consumer and small businesses. You must first sign up to use SpiderOak. Running natively... Read more
Espionage 3.6 - Simple, state of the art...
Espionage offers state-of-the-art encryption and plausible deniability for your confidential data. Sometimes, encrypting your data isn't enough to protect it. That's why Espionage 3 goes beyond data... Read more
calibre 1.45.0 - Complete e-library mana...
Calibre is a complete e-book library manager. Organize your collection, convert your books to multiple formats, and sync with all of your devices. Let Calibre be your multi-tasking digital... Read more
iFFmpeg 4.3.1 - Convert multimedia files...
iFFmpeg is a graphical front-end for FFmpeg, a command-line tool used to convert multimedia files between formats. The command line instructions can be very hard to master/understand, so iFFmpeg does... Read more
Chromium 36.0.1985.125 - Fast and stable...
Chromium is an open-source browser project that aims to build a safer, faster, and more stable way for all Internet users to experience the web. FreeSMUG-Free OpenSource Mac User Group build is... Read more
pwSafe 3.0 - Secure password management...
pwSafe provides simple and secure password management across devices and computers. pwSafe uses iCloud to keep your password databases backed-up and synced between Macs and iOS devices. It is... Read more
Day One 1.9.6 - Maintain a daily journal...
Day One is the easiest and best-looking way to use a journal / diary / text-logging application for the Mac. Day One is well designed and extremely focused to encourage you to write more through... Read more
Google Chrome 36.0.1985.125 - Modern and...
Google Chrome is a Web browser by Google, created to be a modern platform for Web pages and applications. It utilizes very fast loading of Web pages and has a V8 engine, which is a custom built... Read more

Latest Forum Discussions

See All

HELMUT Review
HELMUT Review By Andrew Fisher on July 21st, 2014 Our Rating: :: TRUNDLE SIMULATOR 2014Universal App - Designed for iPhone and iPad HELMUT is a fun, fleeting time-sink that offers a momentary distraction and nothing else.   | Read more »
Walkr Review
Walkr Review By Jennifer Allen on July 21st, 2014 Our Rating: :: ORIGINAL WALKINGiPhone App - Designed for the iPhone, compatible with the iPad Walking is a bit more exciting thanks to this planet building/discovering sim reliant... | Read more »
Zombie Commando Review
Zombie Commando Review By Jennifer Allen on July 21st, 2014 Our Rating: :: MINDLESS SLAUGHTERUniversal App - Designed for iPhone and iPad Briefly fun but ultimately forgettable, Zombie Commando will scratch an itch then be... | Read more »
Swords & Poker Adventures Review
Swords & Poker Adventures Review By Jennifer Allen on July 21st, 2014 Our Rating: :: SOULLESS POKER PLAYUniversal App - Designed for iPhone and iPad Swords & Poker Adventures is a mishmash of Poker and RPGing, but it lacks... | Read more »
Warhammer 40,000: The Horus Heresy: Drop...
Warhammer 40,000: The Horus Heresy: Drop Assault Coming Soon to iOS Posted by Jennifer Allen on July 21st, 2014 [ permalink ] Coming soon to iOS will be an all-new Warhammer 40,000 tactical strategy game by the name of The Horus Heresy: Drop As | Read more »
A Life Worth Dying For Review
A Life Worth Dying For Review By Jordan Minor on July 21st, 2014 Our Rating: :: A BEAUTIFUL MINDUniversal App - Designed for iPhone and iPad A Life Worth Dying For is a fascinating portrait of a serious subject.   | Read more »
Zombie Puzzle Panic Review
Zombie Puzzle Panic Review By Jordan Minor on July 21st, 2014 Our Rating: :: THE MATCHING DEADUniversal App - Designed for iPhone and iPad Zombie Puzzle Panic puts some pretty neat undead twists on Match-3 puzzling.   | Read more »
This Week at 148Apps: July 14-18, 2014
Expert App Reviewers   So little time and so very many apps. What’s a poor iPhone/iPad lover to do? Fortunately, 148Apps is here to give you the rundown on the latest and greatest releases. And we even have a tremendous back catalog of reviews; just... | Read more »
Fallen Lords Review
Fallen Lords Review By Andrew Fisher on July 18th, 2014 Our Rating: :: FALLS SHORTiPad Only App - Designed for the iPad Fallen Lords is a decent game, but its similarity and inferiority compared to Ghost Stories makes it ultimately... | Read more »
Real Boxing’s New Combo Update is a Knoc...
Real Boxing’s New Combo Update is a Knockout Posted by Blake Grundman on July 18th, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »

Price Scanner via MacPrices.net

Twelve South HiRise For MacBook – Height-Adju...
If you use your MacBook as a workhorse desktop substitute, as many of us do, a laptop stand combined with an external keyboard and pointing device are pretty much obligatory if you want to avoid... Read more
Why The Mac Was Not Included In The Apple/IBM...
TUAW’s Yoni Heisler cites Fredrick Paul of Network World whoi blogged last week that the Mac’s conspicuous absence from Apple and IBM’s landmark partnership agreement represents a huge squandered... Read more
Save $100 on 13-inch Retina MacBook Pros, plu...
Adorama has 13″ Retina MacBook Pros on sale for $100 off MSRP. Shipping is free, and Adorama charges sales tax in NY & NJ only: - 13″ 2.4GHz/128GB MacBook Pro with Retina Display: $1199 - 13″ 2.... Read more
Blurr it 2.3 for iOS – Quickly Blurs Selected...
Hyderabad, India based TouchLabs has announced a new update of Blurr it 2.3, their photography app for iOS users. Blurr it allows you to blur part of the image to hide potentially sensitive or... Read more
MacBook Airs on sale for $100 off MSRP, start...
Best Buy has the new 2014 MacBook Airs on sale for up to $100 off MSRP on their online store. Choose free home shipping or free local store pickup (if available). Prices valid for online orders only... Read more
Amazon Announces Kindle Unlimited: Unlimited...
Amazon.com has introduced Kindle Unlimited — a new subscription service which allows customers to freely read as much as they want from over 600,000 Kindle books, and listen as much as they want to... Read more
New Linksys Wireless Range Extenders Boost Wi...
Linksys has announced its new lineup of Linksys Wi-Fi Range Extenders. Consumers often experience a weak wireless signal in some parts of their house or apartment caused by blocking elements such as... Read more
MacBook Airs available starting at $719
The Apple Store has Apple Certified Refurbished 2013 & 2012 MacBook Airs in stock today starting at $719. An Apple one-year warranty is included with each MacBook, and shipping is free: 2013... Read more
Get the best deals on iPad minis with Apple r...
The Apple Store has Certified Refurbished 2nd generation iPad minis with Retina Displays available for up to $130 off the cost of new models, starting at $339. Apple’s one-year warranty is included... Read more
Best Buy’s College Student Deals: $100 off Ma...
Take an additional $100 off all MacBooks and iMacs, $50 off iPad Airs and iPad minis, at Best Buy Online with their College Students Deals Savings, valid through July 25th. Anyone with a valid .EDU... Read more

Jobs Board

*Apple* Computer Technician - Fairfield Coun...
Company DescriptionWe are an Apple Authorized Sales and Service Provider. We have been selling and servicing Apple computers in the Fairfield County area for over 20 Read more
*Apple* Computer Technician - Fairfield Coun...
Company DescriptionWe are an Apple Authorized Sales and Service Provider. We have been selling and servicing Apple computers in the Fairfield County area for over 20 Read more
Mac Expert - *Apple* Online Store Mexico -...
…MUST be fluent in English and Spanish to be considered for this position At Apple , we believe that hard work, a fun environment, creativity and innovation fuel the Read more
*Apple* Computer Technician - Fairfield Coun...
Company DescriptionWe are an Apple Authorized Sales and Service Provider. We have been selling and servicing Apple computers in the Fairfield County area for over 20 Read more
Mac Expert - *Apple* Online Store - Apple (...
**Job Summary** At Apple , we believe that hard work, a fun environment, creativity and innovation fuel the ultimate customer experience. We believe each customer Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.