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.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

How to become the ultimate robot warrior...
Chrono Strike is a delightfully immersive beat ‘em up with a sense of humor (any game with a good Sims reference gets points in my book). [Read more] | Read more »
Tips and tricks to get a higher score in...
Snow Roll is a devilish endless runner very much in the vein of Flappy Bird. It revels in its dastardly level of difficulty, and doesn’t really care how angry you get at it as it knows you’ll keep coming back for more. [Read more] | Read more »
How to win big in Slots Deluxe
Cheating while gambling is illegal and morally wrong, and in some parts of the world it leads to men with names like Vinnie "Six Knuckles" Manchenzo beating you to a pulp in a dark alley. [Read more] | Read more »
How to take over the world in Dictator 2
Running a country isn't easy - especially when you're a dictator who wants to take over the world and crush everyone in your path while you do it. [Read more] | Read more »
Tips and tricks to get a higher score in...
Tank.iois - you guessed it! - another multiplayer arena battler likeAgar.io and Slither.io. It does differentiate itself by putting you in a tiny tank though, so it's not exactly the same. To help you get that all-important high score, we've got a... | Read more »
How to unlock characters in One Tap Tenn...
As the title suggests, One Tap Tennis requires only a single tap to play its particular brand of tennis, and rewards you with a ton of unlockable characters if you perform well. Fortunately for you, we at 148Apps have got a few tips and tricks to... | Read more »
Grab it now: Game Craft’s Legend of War...
The real time strategy game is now available for you to sink your teeth into, through the App Store and Google Play. Combining elements of skill, strategy and empire building, Legend of War is a real gamers’ game. [Read more] | Read more »
Skateboard Party 3 ft. Greg Lutzka (Gam...
Skateboard Party 3 ft. Greg Lutzka 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: Skateboard Party is back! This third edition of the popular sports franchise features professional skater... | Read more »
Cubious (Games)
Cubious 1.0 Device: iOS Universal Category: Games Price: $.99, Version: 1.0 (iTunes) Description: Cubious – How smart are you? How high is your IQube? Solve the impossible puzzles to find out, and help a lost little cube find his... | Read more »
Goat Simulator Waste of Space (Games)
Goat Simulator Waste of Space 1.1 Device: iOS Universal Category: Games Price: $4.99, Version: 1.1 (iTunes) Description: ** IMPORTANT - SUPPORTED DEVICESiPhone 4S, iPad 2, iPod Touch 5 or better.** | Read more »

Price Scanner via MacPrices.net

Enterprise Workers Pick Technology Over Perks...
New Adobe study shows surprising attitudes about office jobs and where the future of work is heading. Adobe has released survey findings revealing that a surprising 70 percent of U.S. office workers... Read more
Memorial Day Weekend Sale: $50-$100 off 11-in...
B&H Photo has 13″ and 11″ MacBook Airs with 256GB SSDs on sale for $50-$100 off MSRP. Shipping is free, and B&H charges NY sales tax only: - 11″ 1.6GHz/256GB MacBook Air: $999 $100 off MSRP... Read more
Memorial Day Weekend Sales: Apple MacBook Pro...
B&H Photo has 13″ and 15″ Retina MacBook Pros on sale for up to $210 off MSRP. Shipping is free, and B&H charges NY tax only: - 15″ 2.2GHz Retina MacBook Pro: $1799 $200 off MSRP - 15″ 2.5GHz... Read more
Memorial Day Weekend Sales: Apple iMacs and M...
Take up to $150 off the price of a new iMac or Mac mini at the following Apple resellers this Memorial Day weekend: iMacs: B&H Photo has 21″ and 27″ iMacs on sale for up to $150 off MSRP... Read more
Apple refurbished Retina MacBook Pros availab...
Apple has Certified Refurbished 2015 13″ and 15″ Retina MacBook Pros available for up to $380 off the cost of new models. An Apple one-year warranty is included with each model, and shipping is free... Read more
Apple refurbished 11-inch MacBook Airs availa...
Apple has Certified Refurbished 11″ MacBook Airs (the latest models), available for up to $170 off the cost of new models. An Apple one-year warranty is included with each MacBook, and shipping is... Read more
Goal Zero and OtterBox Partner to Expand iPh...
Goal Zero, specialists in portable power, have announced a partnership with OtterBox, brand smartphone case protection, to offer the Slide and Slide Plus Batteries as modules compatible with the new... Read more
15-inch Retina MacBook Pros on sale for up to...
B&H Photo has 15″ Retina MacBook Pros on sale for up to $210 off MSRP. Shipping is free, and B&H charges NY tax only: - 15″ 2.2GHz Retina MacBook Pro: $1799 $200 off MSRP - 15″ 2.5GHz Retina... Read more
Clearance 2015 13-inch MacBook Airs available...
B&H Photo has clearance 2015 13″ MacBook Airs available for $250 off original MSRP. Shipping is free, and B&H charges NY sales tax only: - 13″ 1.6GHz/4GB/128GB MacBook Air (MJVE2LL/A): $799... Read more
Apple refurbished Apple TVs available for up...
Apple has Certified Refurbished 32GB and 64GB Apple TVs available for up to $30 off the cost of new models. Apple’s standard one-year warranty is included with each model, and shipping is free: -... Read more

Jobs Board

Senior *Apple* Engineer - Signature Technol...
One-year contract for an Apple consultant. The resource should be an Apple Certified Technical Coordinator or get the certification within 60 days of starting Read more
*Apple* Architect - AECOM (United States)
**Requisition/Vacancy No.** 132759BR **Position Title** Apple Architect **Job Category** Information Technology **Business Line** Government **Country** United Read more
*Apple* Solutions Consultant - APPLE (United...
Job Summary As an Apple Solutions Consultant, you'll be the link between our future customers and our products. You'll showcase your entrepreneurial spirit as you Read more
*Apple* Project Engineer - Smart Source Inc...
SmartSource is in need of an Apple Project Engineer for a 12 month contract opportunity in Pittsburg, PA. Role: Apple Project Engineer Location: Pittsburg, PA Read more
Automotive Sales Consultant - Apple Ford Linc...
…you. The best candidates are smart, technologically savvy and are customer focused. Apple Ford Lincoln Apple Valley is different, because: $30,000 annual salary Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.