Mastering Reverse Engineering

MOV and LEA

MOV is used to read the value at a given address, while LEA (Load Effective Address) is used to get the address instead:

mov eax, dword ptr [00000060]           ; stores 63626160h to eaxmov eax, dword ptr [00000060]           ; stores 00000060h to eax

So, how is the LEA instruction helpful if you can calculate the address by yourself? Let's take the following C code as an example:

struct Test {    int x;    int y;} test[10];int value;int *p;// some code here that fills up the test[] arrayfor (int i=0; i<10, i++) {    value = test[i].y;    p = &test[i].y;}

The C code starts with defining test[10], an array of struct Test, which contains two integers, x and y. The for-loop statement takes the value of y and the pointer address of y in a struct test element.  ...