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

Yasu 4.0.0 β - System maintenance app; p...
Yasu was created with System Administrators who service large groups of workstations in mind, Yasu (Yet Another System Utility) was made to do a specific group of maintenance tasks quickly within a... Read more
Skype 7.37.0.178 - Voice-over-internet p...
Skype allows you to talk to friends, family and co-workers across the Internet without the inconvenience of long distance telephone charges. Using peer-to-peer data transmission technology, Skype... Read more
EtreCheck 3.0.5 - For troubleshooting yo...
EtreCheck is an app that displays the important details of your system configuration and allow you to copy that information to the Clipboard. It is meant to be used with Apple Support Communities to... Read more
Amadeus Pro 2.3.1 - Multitrack sound rec...
Amadeus Pro lets you use your Mac computer for any audio-related task, such as live audio recording, digitizing tapes and records, converting between a variety of sound formats, etc. Thanks to its... Read more
NeoFinder 6.9.3 - Catalog your external...
NeoFinder (formerly CDFinder) rapidly organizes your data, either on external or internal disks, or any other volumes. It catalogs all your data, so you stay in control of your data archive or disk... Read more
WhatsApp 0.2.1880 - Desktop client for W...
WhatsApp is the desktop client for WhatsApp Messenger, a cross-platform mobile messaging app which allows you to exchange messages without having to pay for SMS. WhatsApp Messenger is available for... Read more
Hazel 4.0.6 - Create rules for organizin...
Hazel is your personal housekeeper, organizing and cleaning folders based on rules you define. Hazel can also manage your trash and uninstall your applications. Organize your files using a familiar... Read more
Apple iBooks Author 2.5 - Create and pub...
Apple iBooks Author helps you create and publish amazing Multi-Touch books for iPad. Now anyone can create stunning iBooks textbooks, cookbooks, history books, picture books, and more for iPad. All... Read more
MYStuff Pro 2.0.26 - $39.99
MYStuff Pro is the most flexible way to create detail-rich inventories for your home or small business. Add items to MYStuff by dragging and dropping existing information, uploading new images, or... Read more
MarsEdit 3.7.8 - Quick and convenient bl...
MarsEdit is a blog editor for OS X that makes editing your blog like writing email, with spell-checking, drafts, multiple windows, and even AppleScript support. It works with with most blog services... Read more

The new Clash of Kings is just for Weste...
If you’ve played the original Clash of Kings, you’ll probably recognise the city building, alliance forging and strategic battles in Clash of Kings: The West. What sets this version apart is that it’s tailor made for a Western audience and the... | Read more »
Frost - Survival card game (Games)
Frost - Survival card game 1.12.1 Device: iOS Universal Category: Games Price: $3.99, Version: 1.12.1 (iTunes) Description: *Warning: the game will work on iPhone 5C and above and iPad Pro / 4. Other devices are not supported* | Read more »
How to build and care for your team in D...
Before you hit the trail and become a dog sledding legend, there’s actually a fair bit of prep work to be done. In Dog Sled Saga, you’re not only racing, you’re also building and caring for a team of furry friends. There’s a lot to consider—... | Read more »
How to win every race in Dog Sled Saga
If I had to guess, I’d say Dog Sled Saga is the most adorable racing game on the App Store right now. It’s a dog sled racing sim full of adorable, loyal puppies. Just look at those fluffy little tails wagging. Behind that cute, pixelated facade is... | Read more »
Let the war games commence in Gunship Ba...
Buzz Lightyear famously said, “This isn’t flying, this is falling – with style!” In the case of Gunship Battle: Second War, though, this really is flying - with style! The flight simulator app from Joycity puts you in control of 20 faithfully... | Read more »
How to get a high score in Fired Up
Fired Up is Noodlecake Games’ high score chasing, firefighting adventure. You take control of a wayward firefighter who propels himself up the side of a highrise with blasts of water. Sound silly? It is. It’s also pretty difficult. You can’t... | Read more »
NBA 2K17 (Games)
NBA 2K17 1.0 Device: iOS iPhone Category: Games Price: $7.99, Version: 1.0 (iTunes) Description: Following the record-breaking launch of NBA 2K16, the NBA 2K franchise continues to stake its claim as the most authentic sports video... | Read more »
Dog Sled Saga (Games)
Dog Sled Saga 1.0.1 Device: iOS Universal Category: Games Price: $3.99, Version: 1.0.1 (iTunes) Description: A game by Dan + Lisa As a rookie musher, foster a dogsledding team whose skills will grow if they're treated right. Week by... | Read more »
60 Seconds! Atomic Adventure (Games)
60 Seconds! Atomic Adventure 1.2 Device: iOS Universal Category: Games Price: $2.99, Version: 1.2 (iTunes) Description: 60 Seconds! is a dark comedy atomic adventure of scavenge and survival. Collect supplies and rescue your family... | Read more »
Tons of Bullets! (Games)
Tons of Bullets! 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: Tons of BulletsA retro 2D pixel platformer infused with tons of bullets and tons of features!Fight as Kenji the Ninja and... | Read more »

Price Scanner via MacPrices.net

21-inch iMacs on sale for up to $120 off MSRP
B&H Photo has 21″ iMacs on sale for up to $120 off MSRP including free shipping plus NY sales tax only: - 21″ 3.1GHz iMac 4K: $1379 $120 off MSRP - 21″ 2.8GHz iMac: $1199.99 $100 off MSRP - 21″ 1... Read more
13-inch 2.7GHz/256GB Retina MacBook Pro on sa...
Amazon.com has the 13″ 2.7GHz/256GB Retina Apple MacBook Pro on sale for $151 off MSRP including free shipping: - 13″ 2.7GHz/256GB Retina MacBook Pro (sku MF840LL/A): $1348 $151 off MSRP Read more
Apple TVs on sale for up to $50 off MSRP
Best Buy has 32GB and 64GB Apple TVs on sale for $40-$50 off MSRP on their online store. Choose free shipping or free local store pickup (if available). Sale prices for online orders only, in-store... 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
Duplicate Sweeper Free On Mac App Store For O...
To celebrate the launch of Apple’s latest macOS Sierra, Stafford, United Kingdom based Wide Angle Software has announced that its duplicate file finder software, Duplicate Sweeper, is now available... Read more
13-inch Retina MacBook Pros on sale for up to...
B&H Photo has 13″ Retina Apple MacBook Pros on sale for up to $150 off MSRP. Shipping is free, and B&H charges NY tax only: - 13″ 2.7GHz/128GB Retina MacBook Pro: $1174.99 $125 off MSRP - 13... Read more
Evidence Surfaces Pointing To New A10X Chip F...
Citing a job description for a Project Lead position at Apple’s Austin, Texas engineering labs, Motley Fool’s Ashraf Eassa deduces that development is progressing well on Apple’s next-generation in-... Read more
Check Print’R for macOS Allows Anyone to Easi...
Delaware-based Match Software has announced the release and immediate availability of Check Print’R 3.21, an important update to their easy-to-use check printing application for macOS. Check Print’R... 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
Apple refurbished 15-inch Retina MacBook Pros...
Apple has Certified Refurbished 2015 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: - 15″ 2... Read more

Jobs Board

Lead *Apple* Solutions Consultant - Apple (...
# Lead Apple Solutions Consultant Job Number: 51829230 Detroit, Michigan, United States Posted: Sep. 19, 2016 Weekly Hours: 40.00 **Job Summary** The Lead ASC is an Read more
US- *Apple* Store Leader Program - Apple (Un...
…Summary Learn and grow as you explore the art of leadership at the Apple Store. You'll master our retail business inside and out through training, hands-on Read more
Integration Technician, *Apple* - Zones (Un...
…at Zones and for our customers each day. Position Overview The Apple Integration Technician will be responsible for performing customer specific configuration Read more
*Apple* Retail - Multiple Positions- Manhatt...
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. *Apple* Mac Engineer - Net2Source Inc....
…staffing, training and technology. We have following position open with our client. Sr. Apple Mac Engineer6+ Months CTH Start date : 19th Sept Travelling Job If Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.