Difference between revisions of "CSC231 Addressing Mode Exercises"
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=Exercises on Addressing Modes= | =Exercises on Addressing Modes= | ||
| + | <br /> | ||
| + | <!--(Highlight the boxes to see one possible solution...)--> | ||
| + | ==Exercise 0== | ||
| + | <br /> | ||
| + | Indicate the addressing used by each of the instructions below. | ||
| + | <br /> | ||
| + | <source lang="asm"> | ||
| − | + | ;;; ------------------------------------------------------------ | |
| + | ;;; Identify possible errors in the instructions below, and | ||
| + | ;;; indicate the addressing mode for each one. | ||
| + | ;;; ------------------------------------------------------------ | ||
| + | |||
| + | section .data | ||
| + | a db 3 | ||
| + | b db 0x12345678 | ||
| + | c dw 0 | ||
| + | x dd 30 | ||
| + | array dd 1,2,3,4,5,6,7,8,9,10 | ||
| + | |||
| + | section .text | ||
| + | global _start | ||
| + | |||
| + | _start: mov eax, a | ||
| + | mov eax, dword[a] ; is it an error? | ||
| + | mov ebx, array | ||
| + | mov eax, dword[ebx] | ||
| + | mov esi, 0 | ||
| + | mov dword[ebx+esi], 0 | ||
| + | mov dword[ebx+esi+4], eax | ||
| + | mov edi, b | ||
| + | mov byte[edi], 'Z' | ||
| + | add al, 'z'-'Z' | ||
| + | ;;; exit() | ||
| + | |||
| + | mov eax,1 | ||
| + | mov ebx,0 | ||
| + | int 0x80 ; final system call | ||
| + | </source> | ||
| + | <br /> | ||
==Exercise 1== | ==Exercise 1== | ||
Write a program that changes all the characters of an all-uppercase string to all-lowercase. We assume the string does not contain blank spaces. You can find an ASCII table [http://www.asciitable.com/ here]. | Write a program that changes all the characters of an all-uppercase string to all-lowercase. We assume the string does not contain blank spaces. You can find an ASCII table [http://www.asciitable.com/ here]. | ||
Revision as of 06:17, 2 October 2014
Contents
Exercises on Addressing Modes
Exercise 0
Indicate the addressing used by each of the instructions below.
;;; ------------------------------------------------------------
;;; Identify possible errors in the instructions below, and
;;; indicate the addressing mode for each one.
;;; ------------------------------------------------------------
section .data
a db 3
b db 0x12345678
c dw 0
x dd 30
array dd 1,2,3,4,5,6,7,8,9,10
section .text
global _start
_start: mov eax, a
mov eax, dword[a] ; is it an error?
mov ebx, array
mov eax, dword[ebx]
mov esi, 0
mov dword[ebx+esi], 0
mov dword[ebx+esi+4], eax
mov edi, b
mov byte[edi], 'Z'
add al, 'z'-'Z'
;;; exit()
mov eax,1
mov ebx,0
int 0x80 ; final system call
Exercise 1
Write a program that changes all the characters of an all-uppercase string to all-lowercase. We assume the string does not contain blank spaces. You can find an ASCII table here.
Exercise 2
Write a program that fills an array of 8 bytes with the first 8 powers of 2: 1, 2, 4, 8, 16, etc.
Exercise 3
Write a program that fills an array of 16 words with the first 16 fibonacci terms
Exercise 4
Write a program that fills an array of 10 double-words with the first 10 powers of 2.
Exercise 5
Assume Powers is an array of 11 words, and the first word contains a constant. Write the program that stores 1/2 the value of the constant in the 2nd word, 1/4 the value in the 3rd word, 1/8 4th word, 1/16 5th word, etc.
Exercise 6
The example below copies a string into another string, reversing the order of the string to see if they are palindromes. Rewrite it using a based indexed addressing mode.
