Difference between revisions of "CSC231 Addressing Mode Exercises"
| Line 42: | Line 42: | ||
Write a program that fills an array of 16 words with the first 16 fibonacci terms | Write a program that fills an array of 16 words with the first 16 fibonacci terms | ||
| + | <onlydft> | ||
<code><pre> | <code><pre> | ||
fib dw 1, 1, 0, 0, 0, 0, 0, 0 | fib dw 1, 1, 0, 0, 0, 0, 0, 0 | ||
| Line 56: | Line 57: | ||
loop for ; go back | loop for ; go back | ||
</pre></code> | </pre></code> | ||
| + | </onlydft> | ||
| + | ==Exercise 4== | ||
| − | |||
Write a program that fills an array of 10 double-words with the first 10 powers of 2. | Write a program that fills an array of 10 double-words with the first 10 powers of 2. | ||
| − | + | <onlydft> | |
<code><pre> | <code><pre> | ||
Powers dd 0,0,0,0,0,0,0,0,0,0 | Powers dd 0,0,0,0,0,0,0,0,0,0 | ||
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loop for ; go 9 times | loop for ; go 9 times | ||
</pre></code> | </pre></code> | ||
| − | + | </onlydft> | |
==Exercise 5== | ==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. | 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. | ||
| − | + | <onlydft> | |
<code><pre> | <code><pre> | ||
Powers dd 57,0,0,0,0,0,0,0,0,0 | Powers dd 57,0,0,0,0,0,0,0,0,0 | ||
| Line 95: | Line 97: | ||
loop for ; go 9 times | loop for ; go 9 times | ||
</pre></code> | </pre></code> | ||
| − | + | </onlydft> | |
==Exercise 6== | ==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. | |
| − | |||
<code><pre> | <code><pre> | ||
Revision as of 08:44, 22 October 2010
Contents
Exercises on Addressing Modes
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
msg db "hellotherehowareyou"
MSGLEN equ $-msg
mov ebx, msg ; ebx points to 1st char of msg
mov ecx, MSGLEN ; # of chars in string
for: sub byte[ebx],32 ; lower to upper case, in memory
inc ebx ; ebx points to next char
loop for
Exercise 2
Write a program that fills an array of 8 bytes with the first 8 fibonacci terms
fib db 1, 1, 0, 0, 0, 0, 0, 0
NOFIB equ $-fib
mov ebx, fib
mov esi, 2 ; point to Fib[3]
mov ecx, NOFIB-2 ; skip first 2 Fibs
mov al, byte[ebx+esi-1] ;
for: add al, byte[ebx+esi-2]
mov byte[ebx+esi], al ; fib_i = fib_i-1 + fib_i-2
inc esi ; point to next uncomputed fib
loop for ; go back
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.
msg1 db "Esope reste ici et se repose"
msg2 db " "
MSGLEN equ $-msg2
mov esi, msg1
mov edi, msg2
mov ecx, MSGLEN
for mov al, byte[esi]
mov byte[edi], al
inc esi
inc edi
loop for
