assembly programming

1
assembly programming

• A little background on using the software

2
Irvine text examples etc

• The newer text (edition 5) contains chapter
  examples along with VC and uses this MS
  interface for editing and assembling assembly
  code.
• The Irvine assembly text editon 4 contains a CD
  with a version of the assembler, various batch
  files, as well as examples in chapter
  directories. I have this CD and it is on the
  Math Lab machines for you to copy.
• The assembler itself may be available in F200 and
  even in other campus labs.

3
Machine configuration

• You will typically create assembly program files
  using a text editor, so you may want to install
  Textpad on your own machine. This is shareware
  and is available from Helios.com. Notepad can
  also be used. As can VC.
• The only other sw needed is on the text CD. (The
  assembler is part of MS Windows, but is likely
  buried somewhere so you cant find it and may not
  have all versions we will use.)
• The text assembles and runs programs in the VC
  environment but I will use DOS.

4
Assembly is in the labs

• In the labs, assembler and linker are tools off
  Textpad. (Currently just 32 bit but I will ask
  them to add 16 bit).
• There is a shortcut to your p drive. From here,
  you can run your program

5
Entering a program into textpad (in lab)
6
Selecting tools option build 32-bit MASM from
textpad in labs

• Assembling addsub.asm
• LINK32 LNK6004 addsub.exe not found or not
  built by the last incremental link performing
  full link
• Volume in drive P is Faculty P Drives
• Volume Serial Number is 6255-760D
• Directory of P\assembly
• 08/28/2008 0658 AM 306 addsub.asm
• 08/28/2008 0659 AM 28,711 addsub.exe
• 08/28/2008 0659 AM 33,324 addsub.ilk
• 08/28/2008 0659 AM 15,246 addsub.lst
• 08/28/2008 0659 AM 6,938 addsub.map
• 08/28/2008 0659 AM 3,714 addsub.obj
• 08/28/2008 0658 AM 91,136 addsub.pdb
• 7 File(s) 179,375 bytes
• 0 Dir(s) 9,986,265,088 bytes
  free
• Tool completed successfully

7
Looks like this on p drive
8
Submissions

• Typically, youll submit screenshots of your
  program assembly/run along with an electronic
  copy of your code. (see previous slides)
• Both can be put (pasted) in an html file to which
  you send me the link.

9
On your own machineRun setup on the 4th edition
CD to copy the assembler and text examples to
your C drive
10
Path settings

• Youll have to put the assembler in your path
  settings to assemble and run asm programs, or
  move the asm files to the directory where masm is
  located.
• There are batch files provided which will run
  masm and then run the linker. These are named
  make16.bat, make32.bat.
• Make sure all included files are in the directory
  from which you are assembling or fix paths
  appropriately. Make sure all file modules are in
  the directory from which you link or fix paths
  appropriately.

11
extensions

• .asm marks an asm file. You may use textpad or
  notepad to create and edit these. Note You can
  also configure textpad to assemble and run the
  code.
• When writing your own assembly code, at least in
  the beginning, you may want to cut/paste to start
  with using one of my or one of the texts
  examples, then edit it.
• .obj marks an object file. It must be linked
  before it can be run. The assembler creates an
  obj file from an .asm file. The linker resolves
  symbol references and can create a single exe
  from several obj files. The first obj in the
  linker commandline list is the default main.
• .exe marks an executable. It can be run by
  clicking it with the mouse or typing its name on
  the commandline (assuming it is in the path).
• .lst marks a listing file of the assembly we
  wont use this.

12
More on how it works

• Masm.exe creates an .obj file from an .asm file.
• Link.exe creates an .exe file from a .obj file.
• The batch files provided assume the proper
  file-designation extensions. But you will get an
  error if you type the .asm extension when running
  the batch files.
• Use make16.bat to assemble and link a 16-bit
  format assembly program.
• Use make32.bat to assemble and link a 32-bit
  format assembly program.
• Or run the assembler and linker (exe files)
  directly, yourself, on the commandline.

13
Here is a text example (I renamed it
example16.asm)

• TITLE Add and Subtract (16-bit.asm)
• This program adds and subtracts 32-bit
  integers.
• Last update 2/1/02
• INCLUDE Irvine16.inc
• .code
• main PROC
• mov ax,_at_data
• mov ds,ax
• mov eax,10000h EAX 10000h
• add eax,40000h EAX 50000h
• sub eax,20000h EAX 30000h
• call DumpRegs
• exit
• main ENDP
• END main

14
Below I copied the previous16-bit example to my
masm directory to run it

• C\MASM615gtmake16 example16
• Assembling example16.asm
• Volume in drive C has no label.
• Volume Serial Number is 84F7-99D3
• Directory of C\Masm615
• 08/18/2006 1114 AM 343
  example16.asm
• 08/18/2006 1115 AM 6,824
  example16.exe
• 08/18/2006 1115 AM 7,961
  example16.lst
• 08/18/2006 1115 AM 2,424
  example16.obj
• 4 File(s) 17,552 bytes
• 0 Dir(s) 144,214,294,528 bytes
  free
• Press any key to continue . . .
• C\MASM615gtexample16
• EAX00030000 EBX00000000 ECX000000FF
  EDX00001050
• ESI00000000 EDI00000400 EBP0000091E
  ESP00000400
• EIP0000001A EFL00003206 CF0 SF0 ZF0
  OF0

15
Format and examples

• Here is another example, a 32 bit assembly
  program which assigns values to 3 registers and
  does some simple arithmetic. A procedure (not
  shown) is used to dump register contents to the
  DOS window.
• The example shown is from chapter 3.

16
program from the text shown earlier in textpad
youll need to run make32.bat to assemble it.

• TITLE Add and Subtract (AddSub.asm)
• This program adds and subtracts 32-bit
  integers.
• Last update 2/1/02
• INCLUDE Irvine32.inc
• .code
• main PROC
• mov eax,10000h EAX 10000h
• add eax,40000h EAX 50000h
• sub eax,20000h EAX 30000h
• call DumpRegs
• exit
• main ENDP
• END main

17
the blackscreen DOS window assemble run the
file

• Assembling addsub.asm
• Volume in drive C has no label.
• Volume Serial Number is 84F7-99D3
• Directory of C\Masm615
• 8/18/2006 1123 AM 316 AddSub.asm
• 8/18/2006 1124 AM 28,710 addsub.exe
• 8/18/2006 1124 AM 33,300 addsub.ilk
• 8/18/2006 1124 AM 15,256 addsub.lst
• 8/18/2006 1124 AM 6,938 addsub.map
• 8/18/2006 1124 AM 3,684 addsub.obj
• 8/18/2006 1124 AM 91,136 addsub.pdb
• 7 File(s) 179,340 bytes
• 0 Dir(s) 144,214,036,480 bytes
  free
• ress any key to continue . . .
• \MASM615gtaddsub
• EAX00030000 EBX7FFDD000 ECX0012FFB0
  EDX7C90EB94
• ESI00000000 EDI00000014 EBP0012FFF0
  ESP0012FFC4
• EIP00401024 EFL00000206 CF0 SF0 ZF0
  OF0

18
More remarks

• The 16-bit programs use an include file
  irvine16.inc and the 32-bit programs use
  irvine32.inc.
• These are just text files containing assembly
  code, but they must be in the current directory
  for the assembler to find and include them in the
  listing.
• Well write much of the code they contain as the
  semester progresses.

19
A fancier example Using procedures from Chapt 5

• This example uses procedures which the author
  provides and which are not shown here to
  read/write ints and write strings. We will use
  these utilities for quite a while, until we learn
  to replace them with our own later in the course.
• They are
• writestring
• readint
• writeint

20
Fancier example page 1

• TITLE IOExamples (IOEx.asm)
• INCLUDE Irvine32.inc
• CR 0Dh carriage return
• LF 0Ah line feed
• .data this is the data for the program
• prompt2 BYTE "Enter a 32-bit signed int",0
• prompt4 BYTE "enter another",0
• result byte "answer is",0
• val1 DWORD ?
• val2 dword ?

21
page 2, code section

• .code
• main PROCstart a proc called main
• Set text color to black text on white
  background
• mov eax,black (white 16)
• call SetTextColor
• call Clrscr clear the screen
• mov edx,OFFSET prompt2 "Enter a 32-bit..."
• call WriteString
• call ReadInt input the integer
• mov val1,eax save in a variable
• call Crlf new line
• call WriteInt display in signed decimal
• mov edx,OFFSET prompt4 "another..."
• call WriteString
• call ReadInt input the integer

22
page 3, more code

• mov val2,eax save in a variable...maybe use
  it later
• call Crlf new line
• call WriteInt display in signed decimal
• call Crlf
• mov ebx,val1
• add eax,ebx
• mov edx, offset result
• call WriteString
• call Crlf new line
• call WriteInt display in signed decimal
• call Crlf
• exit
• main ENDPend a proc named main
• END mainname of proc to run when this file is
  loaded

23
Output to a white popup DOS window

• Enter a 32-bit signed int123456
• 123456enter another900000
• 900000
• answer is
• 1023456
• C\Masm615\Examples\ch05gt

24
An assembly tutorial

• I provided a tutorial (link on classpage)
  detailing how to install the 4th edition software
  and examples we will use to your computer, and
  showing how to run them.
• If this ppt is not clear, go run the tutorial.