How to create nested loops in x86 assembly language

Question

Is it possible to create nested loops in x86 assembly language?

I'd like to translate this psedocode into correct x86 assembly code (using MASM syntax), but I'm not sure how to initialize each loop counter here. Is it even possible to declare local variables in x86 assembly (as in most other programming languages)?

for (var i = 0; i < 10; i++){
    for(var j = 0; j < 10; j++){
        for(var k = 0; k < 10; k++){
            mov eax, i + j + k;
        }
    }
}

Answer 1

Sure, it's possible. Since every computer program eventually boils down to assembly - it is naturally the most powerful language possible (excluding direct bit manipulation).

The actual code depends on your system, compiler and applied optimizations, but basically it should be something like this (example for 2 nested loops, not 3):

           mov ecx, 0

outerLoop:

           cmp ecx, 10
           je done
           mov ebx, 0

innerLoop:
           mov eax, ecx        ; do your thing here
           add eax, ebx

           cmp ebx, 10
           je innerLoopDone
           inc ebx
           jmp innerLoop

innerLoopDone:

           inc ecx
           jmp outerLoop
done:

Note, you don't need local variables, you've got general-purpose registers for the usage that you need. If you insist on having variables, you can use memory addresses for that and read/write using register pointers.