Need Help with Computer architecture Assembly practice midte

Need Help with Computer architecture Assembly practice midtem

1. Given the following partial data segment, which starts at address 0x021A :

.data

list DWORD 1, 3, 9, 27, 81, 243, 729, 2187, 6561, 19683

x DWORD LENGTHOF list

y DWORD SIZEOF list

Show addresses in 4-digit hexadecimal, and contents in decimal.

a) x contains

b) y contains

c) The address of x is____________ (hex)

d) Given this code fragment:

mov esi, OFFSET list

mov eax, [esi+3*TYPE list]

eax contains :__________

e) Given this code fragment:

mov esi, OFFSET list

mov ebx, y

sub ebx, TYPE y

add esi, ebx [esi] contains :_____________

f) Given this code fragment:

mov esi, OFFSET list

mov ebx, y

sub ebx, TYPE y

add esi, ebx

mov al, BYTE PTR [esi+2]

The AL register contains : ___________________________

Solution

1)
a) x contains 10 since total list elements are 10
b) y contains 10 since size and length gives same result.
c) The address of x is 0x031A (already given in question itself).
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d)
So esi is 0x031A
list start address 0x021A
TYPE list is integer, where 4 bytes.
So 3*4 = 12 and 31+12 ==> 43
eax has 0x0043A
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e)
offset of list -> esi -> 0x031A
y contains 10
Finally esi contains 0x031A[10] + 0x031A ==> 31+31 => 0x062A

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f)
mov esi, OFFSET list ---> 0x031A
mov ebx, y -----> 10
sub ebx, TYPE y ---> 4 (int)
add esi, ebx ----> 0x035A
mov al, BYTE PTR [esi+2] ----> 0x037A
The AL register contains : ----> 0x037A