TweetFollow Us on Twitter

Disassembler
Volume Number:1
Issue Number:6
Column Tag:MacNosy

A New Disassembler

By Steve Jasik

A New Disassembler

As a compiler writer specializing in code generation, I decided to build a Disassembler to better understand the Motorola 68000 and the Macintosh operating system. Given the poor quality of the documentation and the general lack of source listings, a powerful disassembler is a useful tool for debugging and getting information about the system.

MacNosy and its helper programs consist of over 7000 lines of Pascal and about 300 lines of assembly lanaguage code. Internally, MacNosy contains many features usually associated with a compiler such as a table manager, symbol table enter/lookup routines, a reference map, global flow analysis, etc.

Features

MacNosy has many features that place it an order of magnitude above other disassemblers. They include:

• Symbol dictionaries of the Rom names and global symbols (0 - $B00) along with value to symbol substitution in appropriate places.

• Selective list of procedures in a file by procedure name or substring.

• Ability to place the disassembled output on a file in assembler listing output or assembler input format (MDS “.list” or “.asm” format).

• References to the symbols are collected and may be selectively viewed.

• Ability to search the program file for references to selected address’s, trap (rom) calls, resource type references, constant or string references.

• Ability to translate the segment relative address of an instruction to the disk file relative address for code patching purposes.

• MacNosy records its input on a “.jrnl” file (in text format) for later playback. This feature is used as an educational tool and as a medium of communication between developers, hackers, etc.

• Ability to reformat data in its “natural format” via directives. This is in addition to the automatic recognition of various character string formats.

• A full or selective listing of the resources in a file. Format is similar to that of the Resource Mover, but you get more information with less work.

• A built-in mini editor to view files without leaving Nosy.

Facts and Specifications

MacNosy runs on a 512K Mac or a 1 Meg Lisa under the Workshop O.S. or the Macworks environment.

It is capable of disassembling the resource fork of any application file, ROM, Macsbug, and various resource types in the System file (DRVR, PACK, INIT, CDEF, WDEF, etc). Note that source listing of the WDEF, CDEF procedures come with the MacSupplement.

The released disk contains both the Mac and Lisa versions of MacNosy, some sample “.jrnl’ files to acquaint you with it, source code for the table manager (this may be useful to other developers) and the SfGetFile routines so you can see how it selects files to disassemble.

How does MacNosy work?

When disassembling a file, one must know the structure (code or data) of a given piece of the file. To do this, Nosy uses the fact that every program has a “call graph”. The nodes of the graph are the procedures and the edges are the calls (A calls B, etc). As Nosy is primarily interested in the size of the nodes, it ignores some aspects of the graph (such as recursion) which leads to cycles in the graph. Because of this, the graph reduces to a Directed Acyclic (without cycles) Graph. We can get sloppy in our terminology and refer to the DAG as a “tree of procedures”.

Discovering the size and extent of a procedure is a messy problem that entails disassembling instructions, and looking for the procedure exits. The potential presence of spaghetti code makes the algorithm more complicated.

At this point a reasonable strategy is to treat the file as a collection of code and data blocks (contigious set of bytes). We start at the entry points and walk the tree until all possible procedures have been discovered. The remaining areas are caterogized as “data” blocks. During the tree walk Nosy builds symbol tables for the various categories of labels which are:

Procedure (JSR X) X = proc’nnn’ or the 8 character name following the proc if compiled by Lisa Pascal with the D+ option on.

Global labels ( X(A5) )

X = glob’nnn’

Data labels (LEA X or PEA X)

X = data’nnn’

Common labels (JMP X, Bcc X from another proc) - com_’nnn’

Local labels within a procedure - loc_’nnn’

You can change the names of all but the local labels in Nosy.

Example 1 - A fragment of the resource list of a System file.

Note that for the DITL’s the accompanying text/controls are listed.

      26 resource types, data index =   100
Type FRSV    att   indx  length   name
  ID     1     00   CF12        A        0      0
Type ALRT    att   indx  length   name
  ID  -3997   20   CDBC       C        0        0
  ID  -3996   20   CDCC       C        0        0
  ID  -3995   20   CDDC       C        0        0
  ID  -3994   20   CDEC       C        0        0
Type DITL    att   indx  length   name
  ID  -15936  20   BA6C      1E    
  ID   -6047  20   CA18     1A6    <Initialize> <Eject> <OK> 
                               Do you want to initialize it? 
                               This disk is unreadable: 
                                This disk is damaged: 
                               This is not a Macintosh disk: 
                               Please name this disk: 
                               Initializing disk . . .  
                               Initialization failed! 
                               Initialize this disk? 
  ID   -4000  20   CC7C      A8    <Open> <O> <Cancel> <Eject> <Drive> 
h 
  ID   -3999  20   CD28      90    <Save> <Cancel> Save as: <Eject> <Drive> 

Example 2 - code fragment from a little test program I wrote.

The output listing format is:

aaa: hhhh hhhh ‘cccc’ label opcode address $ssaaaaaa

aaa = segment relative address , hhhh and ccccc are the value of the instruction in hex and ascii. The field ssaaaaaa is the address of any label or symbol reference in the

address field. ss is the segment number of the reference.

I have suppressed leading zeros in most cases and many of the numeric formats use decimal conversion. The macros POP and PUSH have the obvious meaning. The QUAL pseudo implies that all the labels of the form loc_nnn are local to the procedure. The line right after it tells us who calls it. The line with “_Button” is a trap macro. The DNAME macro expands to the 8 character name which is used by Lisabug and Nosy.

    440:                                 QUAL    CHK_USER
                                ; refs - TEST  
    440:                                  
    440: 4E56 0000      ‘NV..’  CHK_USER LINK    A6,#0
    444: 4267           ‘Bg’             CLR     -(A7)
    446: A974           ‘.t’             _Button 
    448: 101F           ‘..’             POP.B   D0
    44A: 6714           ‘g.’             BEQ     loc_2               
      $1000460
    44C: 2F0E           ‘/.’             PUSH.L  A6
    44E: 4EBA FFC0      ‘N...’           JSR     WAITBUTT            
      $1000410
    452: 4267           ‘Bg’    loc_1    CLR     -(A7)
    454: A974           ‘.t’             _Button 
    456: 101F           ‘..’             POP.B   D0
    458: 67F8           ‘g.’             BEQ     loc_1               
      $1000452
    45A: 2F0E           ‘/.’             PUSH.L  A6
    45C: 4EBA FFB2      ‘N...’           JSR     WAITBUTT            
      $1000410
    460: 4E5E           ‘N^’    loc_2    UNLK    A6
    462: 4E75           ‘Nu’             RTS     
    464:                                  
    464: C348                   data21   DNAME   CHK_USER,0,2

Example 3 - This next routine was dumped to the hardcopy file in “.asm” format.

It is suitable for input to the MDS assembler ASM.

         QUAL    WCR
; refs - TEST 
          
WCR      LINK    A6,#0
         PUSH.L  glob13(A5)
         PEA     data19
         CLR     -(A7)
         JSR     %W_STR
         PUSH.L  glob13(A5)
         JSR     %W_LN
         PUSH.L  glob12(A5)
         PEA     glob8(A5)
         PUSH    #255
         JSR     %R_STR
         PUSH.L  glob12(A5)
         JSR     %R_LN
         UNLK    A6
         RTS     
          
data18   DNAME   WCR     ,0,2
          
; refs - WCR+8  
data19   STR     ‘wait for cr’

Example 4 - Note the Value to Symbol substitution in this ROM fragment listing

 404C12: 50F8 0902      ‘P...’  Launch   S_T     LaunchFlag          
      $902
 404C16: 31E8 0004 0936 ‘1....6 loc_2    MOVE    4(A0),CurPageOption 
      $936
 404C1C: 2058           ‘ X’             MOVE.L  (A0)+,A0
 404C1E: 43F8 0910      ‘C...’           LEA     CurApName,A1        
      $910
 404C22: 7020           ‘p ‘             MOVEQ   #32,D0
 404C24: A02E           ‘..’             _BlockMove  

Example 5 - Sample Reference Map listing fragment of the “System Globals” from ROM

      114 HeapEnd      proc203  MaxMem  proc253  
      118 TheZone      proc201  proc203  GetZone  MaxMem  proc212  proc232 
 
                       InitResources  proc852  MoreMasters  InitZone 
 proc204  
                       SetGrowZone  
      11C uTableBase   proc36  proc89  proc96  RDrvrInstall  SystemTask 
 proc942  
                       SystemMenu  OpenDeskacc  BlockMove  com_28

Example 6 - Sample Segment Reference Map listing fragment of Nosy.

Inter seg refs are prefixed with “n/”. This map may be used for procedure balancing.

seg# procedure   fba  blen  refs (seg#/proc) called by
  1] HEAP_OVF    1D6    50   ADD_USED    4/NEW_TBL    
  1] SET_MAX     208   120   CLR_TBL     4/REL_TBLS    3/RTN_PTR    
  1] CLR_TBL     280    46   DI_PROC     3/SEARCH_C    4/DI_FILE     
3/SEARCH_C   
  1] MOVEUP      2AE    80   ADD_USED   
  1] ADD_ENTR    2FE    42   DI_PROC       ENTER_LA      PUT_REF     
  NEW_CASE   
                             ADD_ISPR    3/CHK_PROC    4/NI_FILE     
4/DI_FILE    
                             PROCESS_   
  1] SET_USED    328    44 4/NI_FILE    

Disassemblling the ROM

I Would like to show a sample listing of a piece or two of ROM but I don’t want to start any fights with Apple’s Lawyers. So like sex, I leave it for you to do it in the privacy of your own home.

I found a few interesting things looking around the ROM. One is an interesting piece of unreachable code at 40AD30 which blasts 32 long words into RAM and then hangs. Another is the “come from” code in the rom patch area in the system heap. In many cases bugs were patched by placing a CMPI.L $40xxxx,28(A7) followed by a suitable jump in unrelated routines. A rather obnoxious example is BlockMove which contains 3 such checks. I will be forming a MacNosy Users Group (Special Interest Group) on the Delphi Information Service (800-544-4005) starting in April to study the ROM and swap “jrnl” files. Admission will be limited to registered owners of MacNosy.

Ordering Information

If ordered from the author before May 1, 1985 cost is $55, including sales tax for CA. residents. After that it will be sold in selected stores or direct for $70. Orders should be addressed to:

Steve Jasik

343 Trenton Way

Menlo Park, Ca. 94025

(415-322-1386)

 
AAPL
$111.78
Apple Inc.
-0.87
MSFT
$47.66
Microsoft Corpora
+0.14
GOOG
$516.35
Google Inc.
+5.25

MacTech Search:
Community Search:

Software Updates via MacUpdate

LibreOffice 4.3.5.2 - Free Open Source o...
LibreOffice is an office suite (word processor, spreadsheet, presentations, drawing tool) compatible with other major office suites. The Document Foundation is coordinating development and... Read more
CleanApp 5.0.0 Beta 5 - Application dein...
CleanApp is an application deinstaller and archiver.... Your hard drive gets fuller day by day, but do you know why? CleanApp 5 provides you with insights how to reclaim disk space. There are... Read more
Monolingual 1.6.2 - Remove unwanted OS X...
Monolingual is a program for removing unnecesary language resources from OS X, in order to reclaim several hundred megabytes of disk space. It requires a 64-bit capable Intel-based Mac and at least... Read more
NetShade 6.1 - Browse privately using an...
NetShade is an Internet security tool that conceals your IP address on the web. NetShade routes your Web connection through either a public anonymous proxy server, or one of NetShade's own dedicated... Read more
calibre 2.13 - Complete e-library manage...
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 librarian... Read more
Mellel 3.3.7 - Powerful word processor w...
Mellel is the leading word processor for OS X and has been widely considered the industry standard since its inception. Mellel focuses on writers and scholars for technical writing and multilingual... Read more
ScreenFlow 5.0.1 - Create screen recordi...
Save 10% with the exclusive MacUpdate coupon code: AFMacUpdate10 Buy now! ScreenFlow is powerful, easy-to-use screencasting software for the Mac. With ScreenFlow you can record the contents of your... Read more
Simon 4.0 - Monitor changes and crashes...
Simon monitors websites and alerts you of crashes and changes. Select pages to monitor, choose your alert options, and customize your settings. Simon does the rest. Keep a watchful eye on your... Read more
BBEdit 11.0.2 - Powerful text and HTML e...
BBEdit is the leading professional HTML and text editor for the Mac. Specifically crafted in response to the needs of Web authors and software developers, this award-winning product provides a... Read more
ExpanDrive 4.2.1 - Access cloud storage...
ExpanDrive builds cloud storage in every application, acts just like a USB drive plugged into your Mac. With ExpanDrive, you can securely access any remote file server directly from the Finder or... Read more

Latest Forum Discussions

See All

Make your own Tribez Figures (and More)...
Make your own Tribez Figures (and More) with Toyze Posted by Jessica Fisher on December 19th, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
So Many Holiday iOS Sales Oh My Goodness...
The holiday season is in full-swing, which means a whole lot of iOS apps and games are going on sale. A bunch already have, in fact. Naturally this means we’re putting together a hand-picked list of the best discounts and sales we can find in order... | Read more »
It’s Bird vs. Bird in the New PvP Mode f...
It’s Bird vs. Bird in the New PvP Mode for Angry Birds Epic Posted by Jessica Fisher on December 19th, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
Telltale Games and Mojang Announce Minec...
Telltale Games and Mojang Announce Minecraft: Story Mode – A Telltale Games Series Posted by Jessica Fisher on December 19th, 2014 [ permalink ] | Read more »
WarChest and Splash Damage Annouce Their...
WarChest and Splash Damage Annouce Their New Game: Tempo Posted by Jessica Fisher on December 19th, 2014 [ permalink ] WarChest Ltd and Splash Damage Ltd are teaming up again to work | Read more »
BulkyPix Celebrates its 6th Anniversary...
BulkyPix Celebrates its 6th Anniversary with a Bunch of Free Games Posted by Jessica Fisher on December 19th, 2014 [ permalink ] BulkyPix has | Read more »
Indulge in Japanese cuisine in Cooking F...
Indulge in Japanese cuisine in Cooking Fever’s new sushi-themed update Posted by Simon Reed on December 19th, 2014 [ permalink ] Lithuanian developer Nordcurrent has yet again updated its restaurant simulat | Read more »
Badland Daydream Level Pack Arrives to C...
Badland Daydream Level Pack Arrives to Celebrate 20 Million Downloads Posted by Ellis Spice on December 19th, 2014 [ permalink ] | Read more »
Far Cry 4, Assassin’s Creed Unity, Desti...
Far Cry 4, Assassin’s Creed Unity, Destiny, and Beyond – AppSpy Takes a Look at AAA Companion Apps Posted by Rob Rich on December 19th, 2014 [ permalink ] These day | Read more »
A Bunch of Halfbrick Games Are Going Fre...
A Bunch of Halfbrick Games Are Going Free for the Holidays Posted by Ellis Spice on December 19th, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »

Price Scanner via MacPrices.net

The Apple Store offering free next-day shippi...
The Apple Store is now offering free next-day shipping on all in stock items if ordered before 12/23/14 at 10:00am PT. Local store pickup is also available within an hour of ordering for any in stock... Read more
It’s 1992 Again At Sony Pictures, Except For...
Techcrunch’s John Biggs interviewed a Sony Pictures Entertainment (SPE) employee, who quite understandably wished to remain anonymous, regarding post-hack conditions in SPE’s L.A office, explaining “... Read more
Holiday sales this weekend: MacBook Pros for...
 B&H Photo has new MacBook Pros on sale for up to $300 off MSRP as part of their Holiday pricing. Shipping is free, and B&H charges NY sales tax only: - 15″ 2.2GHz Retina MacBook Pro: $1699... Read more
Holiday sales this weekend: MacBook Airs for...
B&H Photo has 2014 MacBook Airs on sale for up to $120 off MSRP, for a limited time, for the Thanksgiving/Christmas Holiday shopping season. Shipping is free, and B&H charges NY sales tax... Read more
Holiday sales this weekend: iMacs for up to $...
B&H Photo has 21″ and 27″ iMacs on sale for up to $200 off MSRP including free shipping plus NY sales tax only. B&H will also include a free copy of Parallels Desktop software: - 21″ 1.4GHz... Read more
Holiday sales this weekend: Mac minis availab...
B&H Photo has new 2014 Mac minis on sale for up to $80 off MSRP. Shipping is free, and B&H charges NY sales tax only: - 1.4GHz Mac mini: $459 $40 off MSRP - 2.6GHz Mac mini: $629 $70 off MSRP... Read more
Holiday sales this weekend: Mac Pros for up t...
B&H Photo has Mac Pros on sale for up to $500 off MSRP. Shipping is free, and B&H charges sales tax in NY only: - 3.7GHz 4-core Mac Pro: $2599, $400 off MSRP - 3.5GHz 6-core Mac Pro: $3499, $... Read more
Save up to $400 on MacBooks with Apple Certif...
The Apple Store has Apple Certified Refurbished 2014 MacBook Pros and MacBook Airs available for up to $400 off the cost of new models. An Apple one-year warranty is included with each model, and... Read more
Save up to $300 on Macs, $30 on iPads with Ap...
Purchase a new Mac or iPad at The Apple Store for Education and take up to $300 off MSRP. All teachers, students, and staff of any educational institution qualify for the discount. Shipping is free,... Read more
iOS and Android OS Targeted by Man-in-the-Mid...
Cloud services security provider Akamai Technologies, Inc. has released, through the company’s Prolexic Security Engineering & Research Team (PLXsert), a new cybersecurity threat advisory. The... Read more

Jobs Board

*Apple* Store Leader Program (US) - Apple, I...
…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 experience, Read more
Project Manager, *Apple* Financial Services...
**Job Summary** Apple Financial Services (AFS) offers consumers, businesses and educational institutions ways to finance Apple purchases. We work with national and 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
*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
*Apple* Retail - Multiple Positions (US) - A...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.