Example of Self modifying ASM code :P

[Demonic722]

From the looks of the source, I'm assuming 'adr' points to AddOrSubtract label.

[yoshisrock]

Neat. So it kind of cycles through to the amount you need?

[Demonic722]

I think his code adds 100 bells to your current amount until you reach 99,000. After that, the code subtracts 100 bells until you get to 100 bells then it adds back up to 99,000 bells and keeps repeating itself.

[dragonboy269]

In regular ARM mod, you could just the pc to overwrite any instruction. In THUMB it says it's not allowed (cause the pc is r15)
(the pc stands for program counter, it basically tells where the next instruction to be executed is)
In ARM everything is 32 bit though, including the instructions, so it'd take up more room, but it's definitely more powerful.
Like, let's say in ARM you wanted to overwrite the very next instruction. Let's say r5 has the instruction you wanna write. To overwrite the very next instruction you'd put....
str r5, [pc, #-0x4]

to overwrite the instruction after that instead
str r5, [pc]
etc.

[Vash]

I don't know about "self-modifying". Makes it sound like polymorphism. It's more like an ASM switch case.

[dragonboy269]

I don't know about "self-modifying". Makes it sound like polymorphism. It's more like an ASM switch case.

Well, it might not be exactly, but...
according to wikipedia
"In computer science, self-modifying code is code that alters its own instructions while it is executing."
and that alters a single instruction while executing XD (it directly overwrites an "add" instruction with a "subtract" instruction, or vice versa)
Although I'm probably wrong, you're the more advanced hacker.

[Area51_Hacker2]

Self modifying suggest to me that it actively changes it's own base level instructions, i.e. I could put it in - run it and then go and look at it later and it would have changed - this is obviously impossible as the instructions are stored on your ARDS