Difference between revisions of "CSC231 Homework 3 2015"
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=Problem #3= | =Problem #3= | ||
Revision as of 15:01, 30 September 2015
--D. Thiebaut (talk) 15:56, 30 September 2015 (EDT)
--D. Thiebaut 13:51, 19 September 2012 (EDT)
This assignment is due on 10/07/15 at 11:55 p.m.
Problem #1
What is left in eax, ebx, ecx, and edx after the following instructions have executed?
mov eax, 0x0
mov ebx, 0x12345678
mov ecx, 0x87654321
mov edx, 0xffffffff
mov al, bl
mov ah, ch
mov dl, dh
mov dh, bl
mov bx, cx
mov ch, 'a'
mov cl, 'a'+32
Store your answers in a text file called hw3_1.txt, which contains just 4 lines, with the following format:
eax: 0xXXXXXXXX ebx: 0xXXXXXXXX ecx: 0xXXXXXXXX edx: 0xXXXXXXXX
where XXXXXXXX are 8 hexadecimal digits, ALL IN UPPERCASE. So, for example, if you think eax will contain the value 1234aaff after the instructions have executed, you would write:
eax: 0x1234AAFF
If, on the other hand, you figure that eax contains 1, then you would write:
eax: 0x00000001
Submit your file in Section HW 3 PB 1 on Moodle.
Problem #2
What is left in eax, ebx, ecx, and edx after the following instructions have executed?
mov eax, 0x0
mov ebx, 0x1
mov ecx, 0x2
mov edx, 32
mov al, bl
mov ah, ch
mov dl, dh
mov dh, bl
mov bx, cx
mov ch, 0x0a
mov cl, 0x0a+32
Store your answers in a text file called hw3_2.txt, which contains just 4 lines, with the following format:
eax: 0xXXXXXXXX ebx: 0xXXXXXXXX ecx: 0xXXXXXXXX edx: 0xXXXXXXXX
Submit your file in Section HW 3 PB 2 on Moodle.
Problem #3
section .data
msg1 db "I love chocolate", 10
msg1Len equ $-msg1
section .text
global _start
_start:
;;; print original string
mov eax, 4
mov ebx, 1
mov ecx, msg1
mov edx, msg1Len
int 0x80
;;; put your code here
;;; print modified string
mov eax, 4
mov ebx, 1
mov ecx, msg1
mov edx, msg1Len
int 0x80
;;; exit
mov ebx, 0
mov eax, 1
int 0x80
This program prints out:
I love chocolate
I love chocolate
Your assignment is to add a section of code between the two print sections that will modify msg1, so that when it is printed a second time, it will have changed. The output of your program should look exactly like this:
I love chocolate
J'aime chocolat!
Store your program in a file called hw3c.asm and submit it as follows:
rsubmit hw3 hw3c.asm
