Difference between revisions of "CSC231 Homework Solutions 2017"

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(hw1.asm)
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</source>
 
</source>
 +
<br />
 +
=hw2.asm=
 +
<br />
 +
::<source lang="asm">
 +
;;; ; ; hw2sol.asm
 +
;;; ; ; D. Thiebaut
 +
;;; ; ;
 +
;;; ; ;
 +
 +
 +
        extern  _printDec
 +
        extern  _printString
 +
        extern  _println
 +
        extern  _getInput
 +
 +
section .data
 +
prompt db "> "
 +
promptLen equ $-prompt
 +
ansStr          db      "ans = "
 +
ansStrLen equ $-ansStr
 +
 +
a dd 0
 +
b dd 0
 +
c dd 0
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ans dd 0
 +
 +
section .text
 +
global _start
 +
_start:
 +
;; display prompt
 +
mov ecx, prompt
 +
mov edx, promptLen
 +
call _printString
 +
;; get a
 +
call _getInput
 +
mov dword[a], eax
 +
 +
;; display prompt
 +
mov ecx, prompt
 +
mov edx, promptLen
 +
call _printString
 +
;; get b
 +
call _getInput
 +
mov dword[b], eax
 +
 +
;; display prompt
 +
mov ecx, prompt
 +
mov edx, promptLen
 +
call _printString
 +
;; get c
 +
call _getInput
 +
mov dword[c], eax
 +
 +
;; -----------------------------------
 +
;; computation: ans = 2*(a-b) + 3*c
 +
;; -----------------------------------
 +
 +
; your code will go here...
 +
 +
 +
;; -----------------------------------
 +
;; display "ans ="
 +
;; -----------------------------------
 +
mov ecx, ansStr
 +
mov edx, ansStrLen
 +
call _printString
 +
 +
;; -----------------------------------
 +
;; display ans variable
 +
;; -----------------------------------
 +
mov eax, dword[ans]
 +
call _printDec
 +
call _println
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call _println
 +
 +
;;; exit
 +
mov ebx, 0
 +
mov eax, 1
 +
int    0x80
 +
 +
</source>
 +
<br />

Revision as of 16:59, 22 April 2017

--D. Thiebaut (talk) 17:57, 22 April 2017 (EDT)


Problem 1

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

                section .data
Hello           db      "Hello there!", 10, 10
HelloLen        equ     $-Hello
	
                section .text
                global  _start
_start:

;;; print Hello and a space after it
	
                mov     eax, 4          ; write    
                mov     ebx, 1          ; stdout  
                mov     ecx, Hello      ; address of message to print    
                mov     edx, 6          ; print only 6 chars
                int     0x80

;;; print ! and two line feed chars

                mov     eax, 4          ; write    
                mov     ebx, 1          ; stdout  
                mov     ecx, Hello+11   ; address of ! char
                mov     edx, 3          ; print only 3 chars
                int     0x80

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


hw1.asm


;;; hw1.asm
;;; D. Thiebaut  
;;;                
;;; To assemble, link, and run:  
;;;     nasm -f elf  hw1.asm  
;;;     ld -melf_i386 -o hw1 hw1.o 
;;;     ./hw1        
;;;      

                section .data
msg             db      "  CSC231 Assembly "
linefeed	db	10
dashline        db	"------------------"
lineLen		equ	$-dashline
	
                section .text
                global  _start
_start:

;;; print message                                                                                                                           
                mov     eax, 4          ; write    
                mov     ebx, 1          ; stdout  
                mov     ecx, dashline   ; address of message to print    
                mov     edx, lineLen   	; # of chars to print  
                int     0x80

                mov     eax, 4          ; write    
                mov     ebx, 1          ; stdout  
                mov     ecx, dashline   ; address of message to print    
                mov     edx, lineLen   	; # of chars to print  
                int     0x80

		mov	eax, 4		;print line-feed
		mov	ebx, 1
		mov	ecx, linefeed
		mov	edx, 1
		int	0x80

                mov     eax, 4		; write ----
		mov     ebx, 1 		; stdout
		mov     ecx, dashline 	; address of message to print
		mov     edx, 9  	; # of chars to print
		int     0x80

                mov     eax, 4          ; write message
                mov     ebx, 1          ; stdout  
                mov     ecx, msg 	; address of message to print    
                mov     edx, lineLen    ; # of chars to print  
                int     0x80
	
                mov     eax, 4		; write ----
		mov     ebx, 1 		; stdout
		mov     ecx, dashline 	; address of message to print
		mov     edx, 9  	; # of chars to print
		int     0x80

		mov	eax, 4		;print line-feed
		mov	ebx, 1
		mov	ecx, linefeed
		mov	edx, 1
		int	0x80

                mov     eax, 4          ; write    
                mov     ebx, 1          ; stdout  
                mov     ecx, dashline   ; address of message to print    
                mov     edx, lineLen   	; # of chars to print  
                int     0x80

                mov     eax, 4          ; write    
                mov     ebx, 1          ; stdout  
                mov     ecx, dashline   ; address of message to print    
                mov     edx, lineLen   	; # of chars to print  
                int     0x80

		mov	eax, 4		;print line-feed
		mov	ebx, 1
		mov	ecx, linefeed
		mov	edx, 1
		int	0x80

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


hw2.asm


;;; ; ; hw2sol.asm
;;; ; ; D. Thiebaut
;;; ; ;
;;; ; ;


	        extern  _printDec
	        extern  _printString
	        extern  _println
	        extern  _getInput
	
	section	.data
prompt		db	"> "
promptLen	equ	$-prompt	
ansStr          db      "ans = "
ansStrLen	equ	$-ansStr	

a		dd	0
b		dd	0
c		dd	0
ans		dd	0
	
		section	.text
		global	_start
_start:
	;; display prompt
		mov	ecx, prompt
		mov	edx, promptLen
		call	_printString
	;; get a
		call	_getInput
		mov	dword[a], eax

	;; display prompt
		mov	ecx, prompt
		mov	edx, promptLen
		call	_printString
	;; get b
		call	_getInput
		mov	dword[b], eax
	
	;; display prompt
		mov	ecx, prompt
		mov	edx, promptLen
		call	_printString
	;; get c
		call	_getInput
		mov	dword[c], eax
	
	;; -----------------------------------
	;; computation: ans = 2*(a-b) + 3*c
	;; -----------------------------------
	
	; your code will go here...
	

	;; -----------------------------------
	;; display "ans ="
	;; -----------------------------------
		mov	ecx, ansStr
		mov	edx, ansStrLen
		call	_printString

	;; -----------------------------------
	;; display ans variable
	;; -----------------------------------
		mov	eax, dword[ans]
		call	_printDec
		call	_println
		call	_println
	
;;; exit
		mov	ebx, 0
		mov	eax, 1
		int     0x80