Question

Write down the value of each destination operand:

.data

var1 WORD 0A8B4h, 1234h, 0BA23h

var2 DWORD 0E2A478C1h

.code

mov ax, WORD PTR [var1+3]

mov eax, WORD PTR [var2+1]

mov ebx, DWORD PTR [var1+2]

Answer 1

.data

var1 WORD 0A8B4h, 1234h, 0BA23h // it stores data in memory for little endian B4 A8 34 12 23 BA and var1 points to memory of first byte B4

var2 DWORD 0E2A478C1h // it stores data in memory in little endian C1 78 47 2A and var2 poitns to C1 , skip E2 it is more than 4 byte (DWORD)

.code

mov ax, WORD PTR [var1+3]

// ax=2312 => var1 is point B4 after adding pointer 3 it points 12 so it read 2 bytes 12 an 23 and arrange in MSB to LSB 2312

mov eax, WORD PTR [var2+1]

// eax=4778=> var2 is point C1 after adding pointer 1 it points 78 so it read 78 an 47 and arrange in MSB to LSB 4778

mov ebx, DWORD PTR [var1+2]

// ebx=1234 => var1 is point B4 after adding pointer 2 it points 34 so it read 2 bytes 34 an 12 and arrange in MSB to LSB 1234