Difference between revisions of "CSC231 Mini Lab 1 Solution and Discussion"

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(Created page with "--~~~~ ---- =Solution 1= <br /> <source lang="asm"> ;;; minilab1.asm ;;; D. Thiebaut ;;; prints this string on the screen: ;;; ;;; ********************************* ;;; * ...")
 
(→‎Understanding what's inside the executable)
 
(12 intermediate revisions by the same user not shown)
Line 1: Line 1:
 
--[[User:Thiebaut|D. Thiebaut]] 09:38, 12 September 2012 (EDT)
 
--[[User:Thiebaut|D. Thiebaut]] 09:38, 12 September 2012 (EDT)
 
----
 
----
 +
__TOC__
 +
<br />
 +
<tanbox>
 +
This is a presentation of two solutions to the [[CSC231 Lab 1 | Mini Lab #1]] and a discussion of the two different approaches.
 +
</tanbox>
 +
<br />
 
=Solution 1=
 
=Solution 1=
  
Line 6: Line 12:
 
<source lang="asm">
 
<source lang="asm">
  
−
;;; minilab1.asm
+
;;; minilab1_v1.asm
 
;;; D. Thiebaut
 
;;; D. Thiebaut
 
;;; prints this string on the screen:
 
;;; prints this string on the screen:
Line 45: Line 51:
 
<source lang="asm">
 
<source lang="asm">
  
−
;;; minilab1.asm
+
;;; minilab1_v2.asm
 
;;; D. Thiebaut
 
;;; D. Thiebaut
 
;;; prints this string on the screen:
 
;;; prints this string on the screen:
Line 89: Line 95:
  
 
<br />
 
<br />
 +
=Understanding what's inside the executable=
  
 +
* Generate the '''listing''' of the assembly program:
 +
 +
      nasm -f elf -F stabs '''-l minilab1_v1.lst'''  minilab1_v1.asm            ''(that's a minus ell option in the command)''
 +
   
 +
 +
* Look at the new files in your account:
 +
 +
      ls -l minilab1_v1.*
 +
 
 +
      -rwx------. 1 231a 231a 1079 Sep 12 09:18 minilab1_v1*
 +
      -rw-------. 1 231a 231a  606 Sep 12 09:18 minilab1_v1.asm
 +
      -rw-------. 1 231a 231a 2398 Sep 12 09:47 '''minilab1_v1.lst'''
 +
      -rw-------. 1 231a 231a 1168 Sep 12 09:47 minilab1_v1.o
 +
 +
* Look at the listing file generated by the '''-l''' switch
 
<br />
 
<br />
 +
 +
<source lang="asm">
 +
    1                                  ;;; minilab1.asm
 +
    2                                  ;;; D. Thiebaut
 +
    3                                  ;;; prints this string on the screen:
 +
    4                                  ;;;
 +
    5                                  ;;; *********************************
 +
    6                                  ;;;    * Welcome to CSC231            *
 +
    7                                  ;;;    * Home of the Assembly Language *
 +
    8                                  ;;;    *********************************
 +
    9                                 
 +
    10                                 
 +
    11                                  section .data
 +
    12                                 
 +
    13 00000000 2A2A2A2A2A2A2A2A2A-    msg db "*********************************", 10
 +
    14 00000009 2A2A2A2A2A2A2A2A2A-
 +
    15 00000012 2A2A2A2A2A2A2A2A2A-
 +
    16 0000001B 2A2A2A2A2A2A0A   
 +
    17 00000022 2A2057656C636F6D65-    db "* Welcome to CSC231            *", 10
 +
    18 0000002B 20746F204353433233-
 +
    19 00000034 312020202020202020-
 +
    20 0000003D 20202020202A0A   
 +
    21 00000044 2A20486F6D65206F66-    db "* Home of the Assembly Language *", 10
 +
    22 0000004D 207468652041737365-
 +
    23 00000056 6D626C79204C616E67-
 +
    24 0000005F 75616765202A0A   
 +
    25 00000066 2A2A2A2A2A2A2A2A2A-    db "*********************************", 10, 10
 +
    26 0000006F 2A2A2A2A2A2A2A2A2A-
 +
    27 00000078 2A2A2A2A2A2A2A2A2A-
 +
    28 00000081 2A2A2A2A2A2A0A0A 
 +
    29                                 
 +
    30                                  msgLen equ $-msg
 +
    31                                 
 +
    32                                  section .text
 +
    33                                  global _start
 +
    34                                  _start:
 +
    35 00000000 B804000000              mov eax,4
 +
    36 00000005 BB01000000              mov ebx,1
 +
    37 0000000A B9[00000000]            mov ecx,msg
 +
    38 0000000F BA89000000              mov edx,msgLen
 +
    39 00000014 CD80                    int 0x80
 +
    40                                 
 +
    41                                  ;;; exit
 +
    42 00000016 B801000000              mov eax,1
 +
    43 0000001B BB00000000              mov ebx,0
 +
    44 00000020 CD80                    int 0x80
 +
    45                                 
 +
    46                                 
 +
 +
 +
</source>
 +
<br />
 +
* Try to recognize all the features.  What is code, what is data, what strings like "CD80" mean... (we'll do that in class!)
 +
* A quick review of hexadecimal: [http://www.electronics-tutorials.ws/binary/bin_3.html tutorial from electronics-tutorials.ws]
 +
<br />
 +
 +
=How does this relate to the size of the executable?=
 +
 +
    -rw-r--r--. 1 231a 231a  324 Sep 12 10:04 skel.asm
 +
    -rw-r--r--. 1 231a 231a  780 Sep 12 10:04 skel2.asm
 +
    -rw-------. 1 231a 231a  707 Sep 12 10:04 minilab1_v2.asm
 +
    -rw-------. 1 231a 231a  606 Sep 12 10:04 minilab1_v1.asm
 +
    -rw-------. 1 231a 231a  606 Sep 12 10:04 minilab1.asm
 +
    -rw-r--r--. 1 231a 231a  996 Sep 12 10:04 lab1.asm
 +
    -rw-r--r--. 1 231a 231a  556 Sep 12 10:04 hello.asm
 +
    -rw-r--r--. 1 231a 231a  208 Sep 12 10:04 hello3.asm
 +
    -rw-r--r--. 1 231a 231a  501 Sep 12 10:04 hello2.asm
 +
    -rw-------. 1 231a 231a  752 Sep 12 10:05 skel.o
 +
    -rw-------. 1 231a 231a 1248 Sep 12 10:05 minilab1_v2.o
 +
    -rw-------. 1 231a 231a 1168 Sep 12 10:05 minilab1_v1.o
 +
    -rw-------. 1 231a 231a 1136 Sep 12 10:05 minilab1.o
 +
    -rw-r--r--. 1 231a 231a 1024 Sep 12 10:05 lab1.o
 +
    -rw-r--r--. 1 231a 231a 1024 Sep 12 10:05 hello.o
 +
    -rwx------. 1 231a 231a  705 Sep 12 10:05 skel*
 +
    -rwx------. 1 231a 231a '''1148''' Sep 12 10:05 minilab1_v2*
 +
    -rwx------. 1 231a 231a '''1079''' Sep 12 10:05 minilab1_v1*
 +
 +
 +
=The Hexdump utility=
 +
 +
* Hexdump is a Linux utility that will take any file on your disk and '''dump''' its byte contents to the screen in hexadecimal and Ascii format (it supports many options to display the bytes in various formats; hexadecimal and Ascii is fine for us).
 +
 +
:Here is the output of the command <font size="+1"><tt>hexdump -C minilab1_v1</tt></font>:
 +
 +
hexdump -C minilab1_v1
 +
00000000  7f 45 4c 46 01 01 01 00  00 00 00 00 00 00 00 00  |.ELF............|
 +
00000010  02 00 03 00 01 00 00 00  80 80 04 08 34 00 00 00  |............4...|
 +
00000020  fc 01 00 00 00 00 00 00  34 00 20 00 02 00 28 00  |........4. ...(.|
 +
00000030  08 00 05 00 01 00 00 00  00 00 00 00 00 80 04 08  |................|
 +
00000040  00 80 04 08 a2 00 00 00  a2 00 00 00 05 00 00 00  |................|
 +
00000050  00 10 00 00 01 00 00 00  a4 00 00 00 a4 90 04 08  |................|
 +
00000060  a4 90 04 08 89 00 00 00  89 00 00 00 06 00 00 00  |................|
 +
00000070  00 10 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
 +
00000080  b8 04 00 00 00 bb 01 00  00 00 b9 a4 90 04 08 ba  |................|
 +
00000090  89 00 00 00 cd 80 b8 01  00 00 00 bb 00 00 00 00  |................|
 +
000000a0  cd 80 00 00 2a 2a 2a 2a  2a 2a 2a 2a 2a 2a 2a 2a  |....************|
 +
000000b0  2a 2a 2a 2a 2a 2a 2a 2a  2a 2a 2a 2a 2a 2a 2a 2a  |****************|
 +
000000c0  2a 2a 2a 2a 2a 0a 2a 20  57 65 6c 63 6f 6d 65 20  |*****.* Welcome |
 +
000000d0  74 6f 20 43 53 43 32 33  31 20 20 20 20 20 20 20  |to CSC231      |
 +
000000e0  20 20 20 20 20 20 2a 0a  2a 20 48 6f 6d 65 20 6f  |      *.* Home o|
 +
000000f0  66 20 74 68 65 20 41 73  73 65 6d 62 6c 79 20 4c  |f the Assembly L|
 +
00000100  61 6e 67 75 61 67 65 20  2a 0a 2a 2a 2a 2a 2a 2a  |anguage *.******|
 +
00000110  2a 2a 2a 2a 2a 2a 2a 2a  2a 2a 2a 2a 2a 2a 2a 2a  |****************|
 +
00000120  2a 2a 2a 2a 2a 2a 2a 2a  2a 2a 2a 0a 0a 00 00 00  |***********.....|
 +
00000130  01 00 00 00 00 00 0a 00  11 00 00 00 01 00 00 00  |................|
 +
00000140  64 00 00 00 80 80 04 08  00 00 00 00 44 00 17 00  |d...........D...|
 +
00000150  80 80 04 08 00 00 00 00  44 00 18 00 85 80 04 08  |........D.......|
 +
00000160  00 00 00 00 44 00 19 00  8a 80 04 08 00 00 00 00  |....D...........|
 +
00000170  44 00 1a 00 8f 80 04 08  00 00 00 00 44 00 1b 00  |D...........D...|
 +
00000180  94 80 04 08 00 00 00 00  44 00 1e 00 96 80 04 08  |........D.......|
 +
00000190  00 00 00 00 44 00 1f 00  9b 80 04 08 00 00 00 00  |....D...........|
 +
000001a0  44 00 20 00 a0 80 04 08  00 00 00 00 64 00 00 00  |D. .........d...|
 +
000001b0  00 00 00 00 00 6d 69 6e  69 6c 61 62 31 5f 76 31  |.....minilab1_v1|
 +
000001c0  2e 61 73 6d 00 00 2e 73  79 6d 74 61 62 00 2e 73  |.asm...symtab..s|
 +
000001d0  74 72 74 61 62 00 2e 73  68 73 74 72 74 61 62 00  |trtab..shstrtab.|
 +
000001e0  2e 74 65 78 74 00 2e 64  61 74 61 00 2e 73 74 61  |.text..data..sta|
 +
000001f0  62 00 2e 73 74 61 62 73  74 72 00 00 00 00 00 00  |b..stabstr......|
 +
00000200  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
 +
*
 +
00000220  00 00 00 00 1b 00 00 00  01 00 00 00 06 00 00 00  |................|
 +
00000230  80 80 04 08 80 00 00 00  22 00 00 00 00 00 00 00  |........".......|
 +
00000240  00 00 00 00 10 00 00 00  00 00 00 00 21 00 00 00  |............!...|
 +
00000250  01 00 00 00 03 00 00 00  a4 90 04 08 a4 00 00 00  |................|
 +
00000260  89 00 00 00 00 00 00 00  00 00 00 00 04 00 00 00  |................|
 +
00000270  00 00 00 00 27 00 00 00  01 00 00 00 00 00 00 00  |....'...........|
 +
00000280  00 00 00 00 30 01 00 00  84 00 00 00 04 00 00 00  |....0...........|
 +
00000290  00 00 00 00 04 00 00 00  0c 00 00 00 2d 00 00 00  |............-...|
 +
000002a0  03 00 00 00 00 00 00 00  00 00 00 00 b4 01 00 00  |................|
 +
000002b0  11 00 00 00 00 00 00 00  00 00 00 00 01 00 00 00  |................|
 +
000002c0  00 00 00 00 11 00 00 00  03 00 00 00 00 00 00 00  |................|
 +
000002d0  00 00 00 00 c5 01 00 00  36 00 00 00 00 00 00 00  |........6.......|
 +
000002e0  00 00 00 00 01 00 00 00  00 00 00 00 01 00 00 00  |................|
 +
000002f0  02 00 00 00 00 00 00 00  00 00 00 00 3c 03 00 00  |............<...|
 +
00000300  c0 00 00 00 07 00 00 00  08 00 00 00 04 00 00 00  |................|
 +
00000310  10 00 00 00 09 00 00 00  03 00 00 00 00 00 00 00  |................|
 +
00000320  00 00 00 00 fc 03 00 00  3b 00 00 00 00 00 00 00  |........;.......|
 +
00000330  00 00 00 00 01 00 00 00  00 00 00 00 00 00 00 00  |................|
 +
00000340  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
 +
00000350  80 80 04 08 00 00 00 00  03 00 01 00 00 00 00 00  |................|
 +
00000360  a4 90 04 08 00 00 00 00  03 00 02 00 00 00 00 00  |................|
 +
00000370  00 00 00 00 00 00 00 00  03 00 03 00 00 00 00 00  |................|
 +
00000380  00 00 00 00 00 00 00 00  03 00 04 00 01 00 00 00  |................|
 +
00000390  00 00 00 00 00 00 00 00  04 00 f1 ff 11 00 00 00  |................|
 +
000003a0  a4 90 04 08 01 00 00 00  01 00 02 00 15 00 00 00  |................|
 +
000003b0  89 00 00 00 00 00 00 00  00 00 f1 ff 1c 00 00 00  |................|
 +
000003c0  80 80 04 08 00 00 00 00  10 00 01 00 23 00 00 00  |............#...|
 +
000003d0  2d 91 04 08 00 00 00 00  10 00 f1 ff 2f 00 00 00  |-.........../...|
 +
000003e0  2d 91 04 08 00 00 00 00  10 00 f1 ff 36 00 00 00  |-...........6...|
 +
000003f0  30 91 04 08 00 00 00 00  10 00 f1 ff 00 6d 69 6e  |0............min|
 +
00000400  69 6c 61 62 31 5f 76 31  2e 61 73 6d 00 6d 73 67  |ilab1_v1.asm.msg|
 +
00000410  00 6d 73 67 4c 65 6e 00  5f 73 74 61 72 74 00 5f  |.msgLen._start._|
 +
00000420  5f 62 73 73 5f 73 74 61  72 74 00 5f 65 64 61 74  |_bss_start._edat|
 +
00000430  61 00 5f 65 6e 64 00                              |a._end.|
 +
00000437
 +
 +
=Could skel.asm be useful?=
 +
 +
* More precisely, could skel.asm be useful to compare different assembly-language programs in terms of their length?
  
 
<br />
 
<br />
 +
<source lang="asm">
 +
;;; skel.asm
 +
;;; D. Thiebaut
 +
;;;
 +
;;;
 +
;;;
 +
;;; To assemble, link, and run:
 +
;;; nasm -f elf -F stabs skel.asm
 +
;;; ld -melf_i386 -o skel skel.o
 +
;;; ./skel
 +
;;;
  
 +
section .data
 +
;;; put your variables here...
 +
 +
 +
section .text
 +
global _start
 +
_start:
 +
 +
;;; put your code here
 +
 +
;;; exit
 +
mov ebx, 0
 +
mov eax, 1
 +
int 0x80
 +
 +
 +
</source>
 
<br />
 
<br />
  

Latest revision as of 09:31, 12 September 2012

--D. Thiebaut 09:38, 12 September 2012 (EDT)


This is a presentation of two solutions to the Mini Lab #1 and a discussion of the two different approaches.


Solution 1


;;; minilab1_v1.asm
;;; D. Thiebaut
;;; prints this string on the screen:
;;;
;;; 	*********************************
;;;     * Welcome to CSC231             *
;;;     * Home of the Assembly Language *
;;;     *********************************


	section	.data

msg	db	"*********************************", 10
	db	"* Welcome to CSC231             *", 10
	db	"* Home of the Assembly Language *", 10	
	db	"*********************************", 10, 10
	
msgLen	equ	$-msg

	section	.text
	global	_start
_start:
	mov	eax,4
	mov	ebx,1
	mov	ecx,msg
	mov	edx,msgLen
	int	0x80

;;; exit
	mov	eax,1
	mov	ebx,0
	int	0x80


Solution 2


;;; minilab1_v2.asm
;;; D. Thiebaut
;;; prints this string on the screen:
;;;
;;; 	*********************************
;;;     * Welcome to CSC231             *
;;;     * Home of the Assembly Language *
;;;     *********************************


	section	.data

msg	db	"*********************************", 10
msgLen1	equ	$-msg	
	db	"* Welcome to CSC231             *", 10
	db	"* Home of the Assembly Language *", 10	
msgLen2	equ	$-msg
	
	section	.text
	global	_start
_start:
	
;;; print first 3 lines
	mov	eax,4
	mov	ebx,1
	mov	ecx,msg
	mov	edx,msgLen2
	int	0x80

;;; print first line back, to close box
	mov	eax,4
	mov	ebx,1
	mov	ecx,msg
	mov	edx,msgLen1
	int	0x80

;;; exit
	mov	eax,1
	mov	ebx,0
	int	0x80



Understanding what's inside the executable

  • Generate the listing of the assembly program:
      nasm -f elf -F stabs -l minilab1_v1.lst  minilab1_v1.asm            (that's a minus ell option in the command)
  • Look at the new files in your account: 
      ls -l minilab1_v1.*
 
      -rwx------. 1 231a 231a 1079 Sep 12 09:18 minilab1_v1*
      -rw-------. 1 231a 231a  606 Sep 12 09:18 minilab1_v1.asm
      -rw-------. 1 231a 231a 2398 Sep 12 09:47 minilab1_v1.lst
      -rw-------. 1 231a 231a 1168 Sep 12 09:47 minilab1_v1.o
  • Look at the listing file generated by the -l switch


     1                                  ;;; minilab1.asm
     2                                  ;;; D. Thiebaut
     3                                  ;;; prints this string on the screen:
     4                                  ;;;
     5                                  ;;; 	*********************************
     6                                  ;;;     * Welcome to CSC231             *
     7                                  ;;;     * Home of the Assembly Language *
     8                                  ;;;     *********************************
     9                                  
    10                                  
    11                                  	section	.data
    12                                  
    13 00000000 2A2A2A2A2A2A2A2A2A-     msg	db	"*********************************", 10
    14 00000009 2A2A2A2A2A2A2A2A2A-
    15 00000012 2A2A2A2A2A2A2A2A2A-
    16 0000001B 2A2A2A2A2A2A0A     
    17 00000022 2A2057656C636F6D65-     	db	"* Welcome to CSC231             *", 10
    18 0000002B 20746F204353433233-
    19 00000034 312020202020202020-
    20 0000003D 20202020202A0A     
    21 00000044 2A20486F6D65206F66-     	db	"* Home of the Assembly Language *", 10	
    22 0000004D 207468652041737365-
    23 00000056 6D626C79204C616E67-
    24 0000005F 75616765202A0A     
    25 00000066 2A2A2A2A2A2A2A2A2A-     	db	"*********************************", 10, 10
    26 0000006F 2A2A2A2A2A2A2A2A2A-
    27 00000078 2A2A2A2A2A2A2A2A2A-
    28 00000081 2A2A2A2A2A2A0A0A   
    29                                  	
    30                                  msgLen	equ	$-msg
    31                                  
    32                                  	section	.text
    33                                  	global	_start
    34                                  _start:
    35 00000000 B804000000              	mov	eax,4
    36 00000005 BB01000000              	mov	ebx,1
    37 0000000A B9[00000000]            	mov	ecx,msg
    38 0000000F BA89000000              	mov	edx,msgLen
    39 00000014 CD80                    	int	0x80
    40                                  
    41                                  ;;; exit
    42 00000016 B801000000              	mov	eax,1
    43 0000001B BB00000000              	mov	ebx,0
    44 00000020 CD80                    	int	0x80
    45                                  
    46


  • Try to recognize all the features. What is code, what is data, what strings like "CD80" mean... (we'll do that in class!)
  • A quick review of hexadecimal: tutorial from electronics-tutorials.ws


How does this relate to the size of the executable?

    -rw-r--r--. 1 231a 231a  324 Sep 12 10:04 skel.asm
    -rw-r--r--. 1 231a 231a  780 Sep 12 10:04 skel2.asm
    -rw-------. 1 231a 231a  707 Sep 12 10:04 minilab1_v2.asm
    -rw-------. 1 231a 231a  606 Sep 12 10:04 minilab1_v1.asm
    -rw-------. 1 231a 231a  606 Sep 12 10:04 minilab1.asm
    -rw-r--r--. 1 231a 231a  996 Sep 12 10:04 lab1.asm
    -rw-r--r--. 1 231a 231a  556 Sep 12 10:04 hello.asm
    -rw-r--r--. 1 231a 231a  208 Sep 12 10:04 hello3.asm
    -rw-r--r--. 1 231a 231a  501 Sep 12 10:04 hello2.asm
    -rw-------. 1 231a 231a  752 Sep 12 10:05 skel.o
    -rw-------. 1 231a 231a 1248 Sep 12 10:05 minilab1_v2.o
    -rw-------. 1 231a 231a 1168 Sep 12 10:05 minilab1_v1.o
    -rw-------. 1 231a 231a 1136 Sep 12 10:05 minilab1.o
    -rw-r--r--. 1 231a 231a 1024 Sep 12 10:05 lab1.o
    -rw-r--r--. 1 231a 231a 1024 Sep 12 10:05 hello.o
    -rwx------. 1 231a 231a  705 Sep 12 10:05 skel*
    -rwx------. 1 231a 231a 1148 Sep 12 10:05 minilab1_v2*
    -rwx------. 1 231a 231a 1079 Sep 12 10:05 minilab1_v1*


The Hexdump utility

  • Hexdump is a Linux utility that will take any file on your disk and dump its byte contents to the screen in hexadecimal and Ascii format (it supports many options to display the bytes in various formats; hexadecimal and Ascii is fine for us).
Here is the output of the command hexdump -C minilab1_v1:
hexdump -C minilab1_v1 
00000000  7f 45 4c 46 01 01 01 00  00 00 00 00 00 00 00 00  |.ELF............|
00000010  02 00 03 00 01 00 00 00  80 80 04 08 34 00 00 00  |............4...|
00000020  fc 01 00 00 00 00 00 00  34 00 20 00 02 00 28 00  |........4. ...(.|
00000030  08 00 05 00 01 00 00 00  00 00 00 00 00 80 04 08  |................|
00000040  00 80 04 08 a2 00 00 00  a2 00 00 00 05 00 00 00  |................|
00000050  00 10 00 00 01 00 00 00  a4 00 00 00 a4 90 04 08  |................| 
00000060  a4 90 04 08 89 00 00 00  89 00 00 00 06 00 00 00  |................|
00000070  00 10 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000080  b8 04 00 00 00 bb 01 00  00 00 b9 a4 90 04 08 ba  |................|
00000090  89 00 00 00 cd 80 b8 01  00 00 00 bb 00 00 00 00  |................|
000000a0  cd 80 00 00 2a 2a 2a 2a  2a 2a 2a 2a 2a 2a 2a 2a  |....************|
000000b0  2a 2a 2a 2a 2a 2a 2a 2a  2a 2a 2a 2a 2a 2a 2a 2a  |****************|
000000c0  2a 2a 2a 2a 2a 0a 2a 20  57 65 6c 63 6f 6d 65 20  |*****.* Welcome |
000000d0  74 6f 20 43 53 43 32 33  31 20 20 20 20 20 20 20  |to CSC231       |
000000e0  20 20 20 20 20 20 2a 0a  2a 20 48 6f 6d 65 20 6f  |      *.* Home o|
000000f0  66 20 74 68 65 20 41 73  73 65 6d 62 6c 79 20 4c  |f the Assembly L|
00000100  61 6e 67 75 61 67 65 20  2a 0a 2a 2a 2a 2a 2a 2a  |anguage *.******|
00000110  2a 2a 2a 2a 2a 2a 2a 2a  2a 2a 2a 2a 2a 2a 2a 2a  |****************|
00000120  2a 2a 2a 2a 2a 2a 2a 2a  2a 2a 2a 0a 0a 00 00 00  |***********.....|
00000130  01 00 00 00 00 00 0a 00  11 00 00 00 01 00 00 00  |................|
00000140  64 00 00 00 80 80 04 08  00 00 00 00 44 00 17 00  |d...........D...|
00000150  80 80 04 08 00 00 00 00  44 00 18 00 85 80 04 08  |........D.......|
00000160  00 00 00 00 44 00 19 00  8a 80 04 08 00 00 00 00  |....D...........|
00000170  44 00 1a 00 8f 80 04 08  00 00 00 00 44 00 1b 00  |D...........D...|
00000180  94 80 04 08 00 00 00 00  44 00 1e 00 96 80 04 08  |........D.......|
00000190  00 00 00 00 44 00 1f 00  9b 80 04 08 00 00 00 00  |....D...........|
000001a0  44 00 20 00 a0 80 04 08  00 00 00 00 64 00 00 00  |D. .........d...|
000001b0  00 00 00 00 00 6d 69 6e  69 6c 61 62 31 5f 76 31  |.....minilab1_v1|
000001c0  2e 61 73 6d 00 00 2e 73  79 6d 74 61 62 00 2e 73  |.asm...symtab..s|
000001d0  74 72 74 61 62 00 2e 73  68 73 74 72 74 61 62 00  |trtab..shstrtab.|
000001e0  2e 74 65 78 74 00 2e 64  61 74 61 00 2e 73 74 61  |.text..data..sta|
000001f0  62 00 2e 73 74 61 62 73  74 72 00 00 00 00 00 00  |b..stabstr......|
00000200  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
00000220  00 00 00 00 1b 00 00 00  01 00 00 00 06 00 00 00  |................|
00000230  80 80 04 08 80 00 00 00  22 00 00 00 00 00 00 00  |........".......|
00000240  00 00 00 00 10 00 00 00  00 00 00 00 21 00 00 00  |............!...|
00000250  01 00 00 00 03 00 00 00  a4 90 04 08 a4 00 00 00  |................|
00000260  89 00 00 00 00 00 00 00  00 00 00 00 04 00 00 00  |................|
00000270  00 00 00 00 27 00 00 00  01 00 00 00 00 00 00 00  |....'...........|
00000280  00 00 00 00 30 01 00 00  84 00 00 00 04 00 00 00  |....0...........|
00000290  00 00 00 00 04 00 00 00  0c 00 00 00 2d 00 00 00  |............-...|
000002a0  03 00 00 00 00 00 00 00  00 00 00 00 b4 01 00 00  |................|
000002b0  11 00 00 00 00 00 00 00  00 00 00 00 01 00 00 00  |................|
000002c0  00 00 00 00 11 00 00 00  03 00 00 00 00 00 00 00  |................|
000002d0  00 00 00 00 c5 01 00 00  36 00 00 00 00 00 00 00  |........6.......|
000002e0  00 00 00 00 01 00 00 00  00 00 00 00 01 00 00 00  |................|
000002f0  02 00 00 00 00 00 00 00  00 00 00 00 3c 03 00 00  |............<...|
00000300  c0 00 00 00 07 00 00 00  08 00 00 00 04 00 00 00  |................|
00000310  10 00 00 00 09 00 00 00  03 00 00 00 00 00 00 00  |................|
00000320  00 00 00 00 fc 03 00 00  3b 00 00 00 00 00 00 00  |........;.......|
00000330  00 00 00 00 01 00 00 00  00 00 00 00 00 00 00 00  |................|
00000340  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000350  80 80 04 08 00 00 00 00  03 00 01 00 00 00 00 00  |................|
00000360  a4 90 04 08 00 00 00 00  03 00 02 00 00 00 00 00  |................|
00000370  00 00 00 00 00 00 00 00  03 00 03 00 00 00 00 00  |................|
00000380  00 00 00 00 00 00 00 00  03 00 04 00 01 00 00 00  |................|
00000390  00 00 00 00 00 00 00 00  04 00 f1 ff 11 00 00 00  |................|
000003a0  a4 90 04 08 01 00 00 00  01 00 02 00 15 00 00 00  |................|
000003b0  89 00 00 00 00 00 00 00  00 00 f1 ff 1c 00 00 00  |................|
000003c0  80 80 04 08 00 00 00 00  10 00 01 00 23 00 00 00  |............#...|
000003d0  2d 91 04 08 00 00 00 00  10 00 f1 ff 2f 00 00 00  |-.........../...|
000003e0  2d 91 04 08 00 00 00 00  10 00 f1 ff 36 00 00 00  |-...........6...|
000003f0  30 91 04 08 00 00 00 00  10 00 f1 ff 00 6d 69 6e  |0............min|
00000400  69 6c 61 62 31 5f 76 31  2e 61 73 6d 00 6d 73 67  |ilab1_v1.asm.msg|
00000410  00 6d 73 67 4c 65 6e 00  5f 73 74 61 72 74 00 5f  |.msgLen._start._|
00000420  5f 62 73 73 5f 73 74 61  72 74 00 5f 65 64 61 74  |_bss_start._edat|
00000430  61 00 5f 65 6e 64 00                              |a._end.|
00000437

Could skel.asm be useful?

  • More precisely, could skel.asm be useful to compare different assembly-language programs in terms of their length?


;;; skel.asm
;;; D. Thiebaut
;;;
;;; 
;;;
;;; To assemble, link, and run:
;;; 	nasm -f elf -F stabs skel.asm
;;; 	ld -melf_i386 -o skel skel.o
;;; 	./skel
;;;

		section	.data
;;; put your variables here...

	
		section	.text
		global	_start
_start:	

;;; put your code here

;;; exit
		mov	ebx, 0
		mov	eax, 1
		int	0x80







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