CSC231 Homework 3 Fall 2017

--D. Thiebaut (talk) 17:26, 1 October 2017 (EDT)

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This assignment is due on Monday 10/11/17 at 11:55 p.m. You can work on this assignment in pairs, in which case you must include both your names in the header of the assembly language program you submit. Both members of a pair must submit a program and answer the quiz.

Problem 1

Assignment

• Write an assembly language program that you will link with the 231Lib library, and that will prompt the user for an integer (positive) number of seconds, which it will then translate in a number of days, hours, minutes and seconds.
• Call your program hw3.asm.
• The format of your output should be similar to the format illustrated in the examples shown below.
• The capture below shows how your program should be behaving.

cs231a@aurora ~/ $ ./hw3
> 1
0 days 0 hours 0 minutes 1 seconds 
cs231a@aurora ~/ $ ./hw3
> 0
0 days 0 hours 0 minutes 0 seconds 
cs231a@aurora ~/ $ ./hw3  
> 3601
0 days 1 hours 0 minutes 1 seconds 
cs231a@aurora ~/ $ ./hw3 
> 8641
0 days 2 hours 24 minutes 1 seconds 
cs231a@aurora ~/ $ ./hw3  
> 86401
1 days 0 hours 0 minutes 1 seconds 
cs231a@aurora ~/ $ 864001
864001: command not found
cs231a@aurora ~/ $ ./hw3  
> 864001
10 days 0 hours 0 minutes 1 seconds 
cs231a@aurora ~/ $ 

Additional Information

• Use the DIV instruction
• Use ints (declared with dd) to store the different quantities your program will compute, including the original number of seconds provided by the user.
• Do not worry about whether words should be singular or plural. We do not know how to test quantities yet. Make your program output all the words in their plural form.
• Make your program output all the quantities on one line.
• You can use WolfranAlpha to convert seconds to day/hours/minutes/seconds, to test your program. WolframAlpha will correctly understand what to do if you enter something like "864001 seconds" in the search bar.

Submission

• Document your program well, and submit it on Moodle, in the Homework 3, Problem 1 section. Be careful as Moodle gives only 5-minute increments for the closing time, which means you have until 11:55 p.m. on Monday to submit the program.

Problem 2

• Answer the quiz on Moodle, in the Homework 3 Problem 2 section. This quiz refers to the program you wrote in Problem 1.

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Solution Program

;;; ; program_name.asm
;;; ; your name
;;; ;
;;; ; a description of the program
;;; ;
;;; ; to assemble and run:
;;; ;
;;; ;     nasm -f elf -F  stabs program.asm
;;; ;     ld -melf_i386 -o program program.o
;;; ;     ./program
;;; ; -------------------------------------------------------------------

	;; %include files here...
	extern	_printInt
	extern	_getInput
	extern	_printString
	extern	_println
	
;;;  ------------------------------------------------------------
;;;  data areas
;;;  ------------------------------------------------------------

	        section .data
seconds		dd	0
days		dd	0
hours		dd	0
min		dd	0
sec		dd	0
	
prompt		db	"> "
secStrings	db	" secs "	
daysString	db	" days "
hoursString	db	" hours "
minutesString	db	" minutes "
secondsString	db	" seconds "
	
;;;  ------------------------------------------------------------
;;;  code area
;;;  ------------------------------------------------------------

	        section .text
	        global  _start
_start:
;;; get number of seconds
		mov	ecx, prompt
		mov	edx, 2
		call	_printString
		call	_getInput
		mov	dword[seconds], eax

;;; compute # of minutes and left-over seconds
		mov	edx, 0
		mov	ebx, 60
		div	ebx
		mov	dword[sec],edx
		mov	edx, 0	; edx:eax contains # of minutes
	
;;; compute # of hours and left-over minutes
		div	ebx
		mov	dword[min], edx
		mov	edx, 0	; edx:eax contains # of hours

;;; compute # of days and left-over hours
		mov	ebx, 24
		div	ebx
		mov	dword[hours], edx
		mov	dword[days], eax
	
;;; print the whole day, hours, minutes, seconds string
		mov	eax, dword[days]
		call	_printInt
		mov	ecx, daysString
		mov	edx, 6
		call	_printString

		mov	eax, dword[hours]
		call	_printInt
		mov	ecx, hoursString
		mov	edx, 7
		call	_printString

		mov	eax,dword[min]
		call	_printInt
		mov	ecx, minutesString
		mov	edx, 9
		call	_printString

		mov	eax, dword[sec]
		call	_printInt
		mov	ecx, secondsString
		mov	edx, 9
		call	_printString
		call	_println
;;;  exit()

	        mov     eax,1
	        mov     ebx,0
	        int     0x80	; final system call

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