TweetFollow Us on Twitter

Assembler Intro
Volume Number:1
Issue Number:1
Column Tag:Mac Assembler

“Introducing the Mac Assembler”

By David E. Smith

“Introducing the Mac Assembler”

Welcome to the Assembly Language Lab. In this column, we will be discussing programming techniques and applications using the Macintosh Assembler, due to be released. With the assembler, Apple has at last provided a complete stand-alone development system for the Macintosh computer.

The Mac assembler was written by Bill Duvall under contract from Apple and is an excellent product. It includes an editor, assembler, linker and debugger in addition to a number of useful utilities for manipulating icons, fonts and resources. All of the Macintosh toolbox and operating system trap calls are fully supported with macros and equate files. This month’s column is based on the August 29, 1984 pre-release version of the assembler/editor system.

EDITOR

The editor is nicely integrated with the whole system and provides a very flexible tool for examining and modifying any text file, including BASIC, MacWrite and C as well as assembly source files. The editor is fully disk-based, fast, and outputs text files that can be read directly by MacWrite. Of course, it does not provide formatting capability for word processing as MacWrite does, but it is very efficient for source code editing, or for examining any text file; in this regard, it is the closest thing we have to a universal editor on the Macintosh.

EDITOR FILES

A number of text files are created by the editor, as shown in Fig. 1. These are:

.asm Assembler source file input

.files List of source file names

.link Linker input instructions

.job Exec type input file

.R Resource maker input file

Each of these file extensions indicates a different type of text file created by the editor for use with the other development system tools. The ‘.files’ type is simply a file containing a list of assembly source code file names. This allows a batch of files to be assembled at one time. The ‘.job’ type is similar to the old EXEC file on the Apple II in that it is a list of assembly and link commands that are executed one after another as if they were selected with the mouse. The ‘.R’ type file is unique to the Macintosh. This is a text file of resource descriptions that are compiled into a binary format that can be inserted into the system resource file or an application resource. The ‘.link’ type provides a list of linker instructions to tell the linker how to create a stand-alone application from the relocatable output of the assembler.

ASSEMBLER

The assembler takes text files with the ‘.asm’ extension and produces relocatable code files with the ‘.rel’ extension. These files are not runable however. To be runable, they must first be linked together with the linker. Other files created by the assembler include the listing file and an error file. One non-standard feature is the directive ‘.dump’ that creates a symbol table file from equate files. The purpose of this is to allow a method of compacting the huge library of system equates that Apple has created as part of the Macintosh development effort on the Lisa. These files take up a considerable amount of room. But with the ‘.dump’ directive, and a utility to pack the symbols file called PackSym, this overhead is greatly reduced.

LINKER

The linker is the heart of the development system. It is what actually puts together an application program for you. Macintosh files are composed of two sections called a “Resource Fork” and a “Data Fork”. The resource part of an application file includes icon and font definitions, window making instructions and the actual binary code of the program itself. The data part of the file is defined by the application program and normally is empty when the program starts up. The linker knows about resource files and how to pack the code into the application resource fork.

A number of important memory considerations involve the linker. Macintosh has a memory manager and segment loader that control where in memory different parts of an application program should be placed. Data structures defined in the source code by use of the “DC” directive are stored on the application heap along with the program code in segments. Variable storage defined by the “DS” directive are relocated by the linker and stored in an applcations globals area which is referenced to register A5, as shown in Fig. 2. The start of this applications globals area is set in the linker input instructions with the GLOBALS command.

The linker input file defines the segments in which the program code will be loaded by the linker. After the program is running, the segment manager can then dispose of unused segments. The manner in which the linker input file is put together determines which code files are associated with which segment. The linker also allows precompiled resource files and predefined data files to be linked to the application code as well. This allows all the files, both resource and data, that are required by a program to be linked together into the resource fork and data fork of the application. In this manner, the user sees only a single file on the disk; a file that in actuality is composed of several files. The system file is an example of a single file composed of many parts.

GETTING STARTED

In this month’s column, we get our feet wet with a program to create a window on the Macintosh. Since our program will call a number of toolbox routines, a few words about macros are in order. The Macintosh assembler uses both a Lisa type of macro and a style unique to the Mac. The Mac style is delimitated by the word MACRO followed by the macro name, and a vertical bar, ‘|’, that signifies the end of the macro. Be careful not to confuse this with a number one.

Our first step is to define the trap macros for the toolbox and operating system routines. This is done by setting the toolbox routine name equal to a trap word constant using the “DC.W” directive. All intructions found in memory that begin with $A are unimplemented instructions that cause the 68000 to “trap” to a special routine to handle the exception. Apple has taken advantage of this arrangement to extend the 68000 instruction set by a whole series of toolbox routines that are called as a result of this “1010” trap.

THE MAC DOES WINDOWS!

; EXAMPLE ASSEMBLY PROGRAM 
; WINDOWS2.5 (MacTech 1-1)
; VERSION 13 OCT 84
; (C) 1984 MacTec by David E. Smith

;    Macro subset for Toolbox stuff

MACRO _InitGraf =  DC.W $A86E|
MACRO _InitWind =DC.W $A912| 
MACRO _NewWindow = DC.W $A913|
MACRO _setport = DC.W $A873|
MACRO _InitFont =DC.W $A8FE|
MACRO _InitMenu =DC.W $A930|
MACRO _InitDialog =DC.W $A97B|
MACRO _TEInit   =DC.W $A9CC|
MACRO _Initpack =         DC.W $A9E5|
MACRO _FlushEvents = DC.W $A032|
MACRO _InitCursor =DC.W $A850|
MACRO _GetNextEvent =DC.W $A970|
MACRO _FrameRect = DC.W $A8A1|

;      DECLARE LABELS EXTERNAL

XDEF  START              ; required for linker 
 
;     LOCAL EQUATES
 
MouseDown equ  1
AllEvents equ  $0000FFFF
 
;     MAIN PROGRAM SEGMENT

 DC.B ‘MINE’;find start of program
 
; -- SAVE THE WORLD ------------
 
START:   MOVEM.L      D0-D7/A0-A6, -(SP)
  LEA SAVEREGS,A0
  MOVE.LA6,(A0)    ; local var
  MOVE.LA7,4(A0) ; stack ptr

Since a window is a grafport, our first task is to initialize quickdraw. To do this, we must supply a memory location where the quickdraw globals can be stored. In Fig. 3 we see how the quickdraw globals are stored relative to A5, between the application parameters, and the application globals.

; --INITIALIZE ALL MANAGERS--------

; SET UP QUICKDRAW GLOBALS
 
PEA -4(A5);push qd global ptr
_InitGraf ;init quickdraw global 

The quickdraw globals point to the current drawing port, as shown in Fig. 4. From A5, the application globals area is found. Then the pointer to the quickdraw globals, followed by the quickdraw globals themselves. Finally, the first entry in the quickdraw globals is a pointer to the current port defined by the current grafport data structure. The quickdraw globals are defined in Fig. 5. The grafport is described in “Inside Macintosh” and is too long to be included here.

Our next task is to define the remaining toolbox managers:

   
;---- SET UP REMAINING MANAGERS  --

_InitFont        ; init font manager
_InitWind   ; init window manager
_InitMenu   ; init menu manager
 
CLR.L -(SP) ; kill the restart 
_InitDialog ; init dialog manager
 
_TEInit ; init text edit (ROM) 
 
MOVE.W  #2,-(SP)   ;  set-up
_Initpack          ; init package mgr

There are two types of windows; those defined on the heap, as we are doing here, and those defined as resources, which we will cover next month. The window definition is defined on the heap by the _NewWindow routine, and is not relocatable. Hence, the heap can not be managed as effectively, but our program is small enough for this not to be a problem. Like all toolbox routines, we must imitate the Lisa Pascal calling sequence by pushing the necessary variables on the stack before actually calling the tooblox routine. The first item pushed is always space for any returned value, in this case, the pointer to the new window.

 
;-- SET UP NEW WINDOW ON HEAP ----
 
CLR.L -(SP)          ;return window ptr
CLR.L -(SP)          ;window record ptr.
PEA WBOUNDS              ;window rectangle 
PEA WINDTITLE            ; window title
MOVE.W #$100,-(SP)    ; true = visible 
MOVE.W #0,-(SP)           ; doc type window
MOVE.L #-1,-(SP)           ; window in front
MOVE.W #$100,-(SP)    ; true=closebox
MOVE.L #0, -(SP)         ; reference value 
_NewWindow                ; make new window
 
; --  ACTIVATE THIS NEW WINDOW ------

LEA WPOINTER,A0         ; copy window ptr 
MOVE.L (SP),(A0)        ; to stacksave
_setport                  ;current window

Now that we have a window on the desktop, we can draw into it. The remaining code sets up the event manager to detect a press of the mouse button. If the button has not been pressed, then we draw something (a box) in our window with a call to the subroutine QDSTUFF. Otherwise, when the button is pushed, we exit back to the finder. Note that the defined box we are drawing is set up as variables with the ‘DS’ assembly command. These values will be stored in the application globals area where they can be modified dynamically by our program if we wanted to animate the box.

; --EVENT LOOP ------------

MOVE.L  #AllEvents,D0     ;all events
_FlushEvents      ;flushed
 
_InitCursor   ; make cursor the arrow
 
GetEvent:

CLR-(SP);returned event 
MOVE  #AllEvents,-(SP)  ;mask all events
PEAEventRecord   ; event record block
_GetNextEvent    ;go check the mouse 
MOVE  (SP)+,D0 ;get event result 
CMP#0,D0;if 0 then no event 
BEQGetEvent ;loop until it happens

 ; JUMP TABLE OF EVENT PROCESSING
 
MOVE  What,D0    ;what to do!
CMP#MouseDown,D0      ; button down?
BEQEXIT ;yes so exit...
BSRQDSTUFF;no so draw box 
JMP    GetEvent  ;get next event

; ---------- END OF MAIN --------------

; ---------- QDSTUFF SUBROUTINE ----------
QDSTUFF:

LEAtop,A0
MOVE.W #10,   (A0) ;set up top
MOVE.W #30,  2(A0) ;left
MOVE.W #100, 4(A0) ;bottom
MOVE.W #200, 6(A0) ;right 

PEA top               ;window rectangle
_FrameRect;draw rectangle
RTS

; -- RESTORE THE WORLD --------

EXIT: LEA SAVEREGS,A0   ; get ‘em back
    MOVE.L   (A0),A6 ; local var
    MOVE.L 4(A0),A7;restore stack 
    MOVEM.L (SP)+,D0-D7/A0-A6 
 
; ---- RETURN TO FINDER --------

        RTS      ; return to finder

; ----LOCAL DATA AREA ----------

SAVEREGS: DCB.L   2,0     ;set  save area
WPOINTER: DC.L     0       ;store window pt
WBOUNDS:DC.W   40   ;rectangle 
 DC.W    2
 DC.W    335
 DC.W    508
WINDTITLE:       DC.B    12        ; title length
               DC.B    ‘DAVES WINDOW’,0      

EventRecord:
 
 What:  DC.W    0; what event
 Message: DC.L    0; ptr. to msg
 When:  DC.L    0
 Point:   DC.L    0
 Modify:  DC.W    0
 
EventTable:

 DC.L GetEvent ;null event
 DC.L Exit     ;mouse down event
 DC.L GetEvent ;mouse up
 DC.L GetEvent ;key down event
 DC.L GetEvent ;key up event
 DC.L GetEvent ;auto key
 DC.L GetEvent   ;update event
 DC.L GetEvent ;Disk Event
 DC.L GetEvent ;activate event
 
; --------------   APPLICATION GLOBALS  ----------
 
top:    DS.W1
left:   DS.W1
bottom: DS.W1
right:  DS.W1

; ------------   END OF PROGRAM ----------------

This completes our program. A typical Macintosh application follows this style of sitting in an event loop and waiting for something to happen. Join us next month for more from the Assembly Lab.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

TinkerTool 5.4 - Expanded preference set...
TinkerTool is an application that gives you access to additional preference settings Apple has built into Mac OS X. This allows to activate hidden features in the operating system and in some of the... Read more
Tinderbox 6.3.1 - Store and organize you...
Tinderbox is a personal content management assistant. It stores your notes, ideas, and plans. It can help you organize and understand them. And Tinderbox helps you share ideas through Web journals... Read more
Parallels Desktop 10.2.2 - Run Windows a...
Parallels Desktop is simply the world's bestselling, top-rated, and most trusted solution for running Windows applications on your Mac. With Parallels Desktop for Mac, you can seamlessly run both... Read more
Adobe Premiere Pro CC 2015 9.0.1 - Digit...
Premiere Pro CC 2015 is available as part of Adobe Creative Cloud for as little as $19.99/month (or $9.99/month if you're a previous Premiere Pro customer). Premiere Pro CS6 is still available for... Read more
Adobe After Effects CC 2015 13.5.1 - Cre...
After Effects CC 2015 is available as part of Adobe Creative Cloud for as little as $19.99/month (or $9.99/month if you're a previous After Effects customer). After Effects CS6 is still available... Read more
Adobe Creative Cloud 2.2.0.129 - Access...
Adobe Creative Cloud costs $49.99/month (or less if you're a previous Creative Suite customer). Creative Suite 6 is still available for purchase (without a monthly plan) if you prefer. Introducing... Read more
Tower 2.2.3 - Version control with Git m...
Tower is a powerful Git client for OS X that makes using Git easy and more efficient. Users benefit from its elegant and comprehensive interface and a feature set that lets them enjoy the full power... Read more
Apple Java 2015-001 - For OS X 10.7, 10....
Apple Java for OS X 2015-001 installs the legacy Java 6 runtime for OS X 10.11 El Capitan, OS X 10.10 Yosemite, OS X 10.9 Mavericks, OS X 10.8 Mountain Lion, and OS X 10.7 Lion. This package is... Read more
Adobe Muse CC 2015 2015.0.1 - Design and...
Muse CC 2015 is available as part of Adobe Creative Cloud for as little as $14.99/month (or $9.99/month if you're a previous Muse customer). Muse CS6 is still available for purchase (without a... Read more
Adobe Illustrator CC 2015 19.1.0 - Profe...
Illustrator CC 2015 is available as part of Adobe Creative Cloud for as little as $19.99/month (or $9.99/month if you're a previous Illustrator customer). Illustrator CS6 is still available for... Read more

This Week at 148Apps: July 20-24, 2015
July is Heating Up With 148Apps How do you know what apps are worth your time and money? Just look to the review team at 148Apps. We sort through the chaos and find the apps you're looking for. The ones we love become Editor’s Choice, standing out... | Read more »
Red Game Without A Great Name (Games)
Red Game Without A Great Name 1.0.3 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0.3 (iTunes) Description: The mechanical bird is flying through an unfriendly, Steampunk world. Help it avoid obstacles and deadly... | Read more »
Warhammer: Arcane Magic (Games)
Warhammer: Arcane Magic 1.0.2 Device: iOS Universal Category: Games Price: $9.99, Version: 1.0.2 (iTunes) Description: Engage in epic battles and tactical gameplay that challenge both novice and veteran in Warhammer: Arcane Magic, a... | Read more »
Mazes of Karradash (Games)
Mazes of Karradash 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: The city of Karradash is under attack: the monsters of the Shadow Realms are emerging from the depths.No adventurer is... | Read more »
Battle Golf is the Newest Game from the...
Wrassling was a pretty weird - and equally great - little wressling game. Now the developers, Folmer Kelly and Colin Lane, have turned their attention to a different sport: golfing. This is gonna be weird. [Read more] | Read more »
Qbert Rebooted has the App Store Going...
The weird little orange... whatever... is back, mostly thanks to that movie which shall remain nameless (you know the one). But anyway it's been "rebooted" and now you can play the fancy-looking Qbert Rebooted on iOS devices. [Read more] | Read more »
Giant Monsters Run Amok in The Sandbox...
So The Sandbox has just hit version number 1.99987 (seriously), and it's added a lot more stuff. Just like every other update, really. [Read more] | Read more »
Fish Pond Park (Games)
Fish Pond Park 1.0.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0.0 (iTunes) Description: Nurture an idyllic slice of tourist's heaven into the top nature spot of the nation, furnishing it with a variety of... | Read more »
Look after Baby Buddy on your Apple Watc...
Parigami Gold is the new premium version of the match three puzzler that includes Apple Watch support and all new content. You won't simply be sliding tiles around on your wrist, the Apple Watch companion app is an all new mini-game in itself. You'... | Read more »
Swallow all of your opponents as the big...
Eat all of the opposition and become the largest ball in Battle of Balls now available in the App Store and Google Play. Battle of Balls pits you against other opponents in real time and challenges you to eat more balls and grow larger than all of... | Read more »

Price Scanner via MacPrices.net

Sale! 13″ 1.6GHz/256GB MacBook Air for $1099,...
B&H Photo has the 13″ 1.6GHz/256GB MacBook Air on sale for $1099 including free shipping plus NY tax only. Their price is $100 off MSRP, and it’s the lowest price available for this model. Read more
iPad mini 4 To Be Upgraded To iPad Air 2 Spec...
There’s a certain inevitability about making Apple product predictions this time of year. Come September, we can pretty reliably count on the release of refreshed iPhones, along with the iOS 9... Read more
Apple restocks refurbished Mac minis for up t...
The Apple Store has restocked Apple 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... Read more
13-inch 2.5GHz MacBook Pro on sale for $899,...
Best Buy has the 13″ 2.5GHz MacBook Pro available for $899.99 on their online store. Choose free shipping or free instant local store pickup (if available). Their price is $200 off MSRP. Price is... Read more
21-inch 2.9GHz iMac on sale for $1299, save $...
Best Buy has the 21″ 2.9GHz iMac on sale today for $1299.99 on their online store. Choose free shipping or free local store pickup (if available). Their price is $200 off MSRP, and it’s the lowest... Read more
Free Image Sizer 1.3 for iOS Offers Photo Edi...
Xi’An, China based G-Power has announced the release of Image Sizer 1.3 for the iPhone, iPad, and iPod touch, an important update to their free photo editing app. Image Sizer’s collection of easy to... Read more
Sale! 13″ 1.6GHz/128GB MacBook Air for $899,...
B&H Photo has the 13″ 1.6GHz/128GB MacBook Air on sale for $899 including free shipping plus NY tax only. Their price is $100 off MSRP, and it’s the lowest price available for this model. Read more
13-inch Retina MacBook Pros on sale for $100...
Best Buy has 13-inch Retina MacBook Pros on sale for $100 off MSRP on their online store. Choose free shipping or free local store pickup (if available). Prices are for online orders only, in-store... Read more
Will BMW’s i3 Electric Vehicle Be The Automo...
The German-language business journal Manager Magazin’s Michael Freitag reports that Apple and the German performance/luxury automaker Bayerishe Motoren Werke (BMW) are back at far-reaching... Read more
Sale! $250 off 15-inch Retina MacBook Pro, $2...
B&H Photo has lowered their price for the 15″ 2.2GHz Retina MacBook Pro to $1749, or $250 off MSRP. Shipping is free, and B&H charges NY sales tax only. They have the 27″ 3.3GHz 5K iMac on... Read more

Jobs Board

*Apple* Customer Experience (ACE) Leader - A...
…management to deliver on business objectives Training partner store staff on Apple products, services, and merchandising guidelines Coaching partner store staff on Read more
Project Manager - *Apple* Pay Security - Ap...
**Job Summary** The Apple Pay Security team is seeking a highly organized, results-driven Project Manager to drive the development of Apple Pay Security. If you are Read more
*Apple* TV Product Design Internship (Spring...
…the mechanical design effort associated with creating world-class products with the Apple TV PD Group. Responsibilities will include working closely with manufacturing, Read more
*Apple* Watch SW Application Project Manager...
**Job Summary** The Apple Watch software team is looking for an Application Engineering Project Manager to work on new projects for Apple . The successful candidate 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
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.