assembly programming
A little background on using the
software
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.
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 can’t 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.
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
Entering a program into textpad
(in lab)
Selecting tools option “build 32bit MASM” from textpad in labs
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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
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Directory of P:\assembly
08/28/2008 06:58 AM
306 addsub.asm
08/28/2008 06:59 AM
28,711 addsub.exe
08/28/2008 06:59 AM
33,324 addsub.ilk
08/28/2008 06:59 AM
15,246 addsub.lst
08/28/2008 06:59 AM
6,938 addsub.map
08/28/2008 06:59 AM
3,714 addsub.obj
08/28/2008 06:58 AM
91,136 addsub.pdb
7 File(s)
179,375 bytes
0 Dir(s) 9,986,265,088 bytes free
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Tool completed successfully
Looks like this on p drive
Submissions
• Typically, you’ll 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.
On your own machine…Run setup on the 4th
edition CD to copy the assembler and text
examples to your C drive
Path settings
• You’ll 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.
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 text’s
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 it’s name on the commandline (assuming it is in the path).
• .lst marks a listing file of the assembly – we won’t use this.
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.
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,@data
mov ds,ax
mov eax,10000h
add eax,40000h
sub eax,20000h
call DumpRegs
exit
main ENDP
END main
; EAX = 10000h
; EAX = 50000h
; EAX = 30000h
Below I copied the previous16-bit example to
my masm directory to run it
C:\MASM615>make16 example16
Assembling: example16.asm
Volume in drive C has no label.
Volume Serial Number is 84F7-99D3
Directory of C:\Masm615
08/18/2006 11:14 AM
343 example16.asm
08/18/2006 11:15 AM
6,824 example16.exe
08/18/2006 11:15 AM
7,961 example16.lst
08/18/2006 11:15 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:\MASM615>example16
EAX=00030000 EBX=00000000 ECX=000000FF EDX=00001050
ESI=00000000 EDI=00000400 EBP=0000091E ESP=00000400
EIP=0000001A EFL=00003206 CF=0 SF=0 ZF=0 OF=0
C:\MASM615>
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.
program from the text shown earlier in
textpad : you’ll 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
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 11:23 AM
316 AddSub.asm
8/18/2006 11:24 AM
28,710 addsub.exe
8/18/2006 11:24 AM
33,300 addsub.ilk
8/18/2006 11:24 AM
15,256 addsub.lst
8/18/2006 11:24 AM
6,938 addsub.map
8/18/2006 11:24 AM
3,684 addsub.obj
8/18/2006 11:24 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 . . .
:\MASM615>addsub
EAX=00030000 EBX=7FFDD000 ECX=0012FFB0 EDX=7C90EB94
ESI=00000000 EDI=00000014 EBP=0012FFF0 ESP=0012FFC4
EIP=00401024 EFL=00000206 CF=0 SF=0 ZF=0 OF=0
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.
• We’ll write much of the code they contain as the
semester progresses.
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
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 ?
page 2, code section
.code
main PROC;;start 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
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 ENDP;;;end a proc named main
END main;;name of proc to run when this file is loaded
Output to a white “popup” DOS
window
Enter a 32-bit signed int123456
+123456enter another:900000
+900000
answer is:
+1023456
C:\Masm615\Examples\ch05>
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.