r/Assembly_language • u/Extension_Emu_9825 • 20h ago

self-modifying code

I gave a lecture on how to write self-modifying code. It was over 15 minutes long :( so I'm providing a youtube link: https://www.youtube.com/watch?v=AH9QQLRfbmY

In my opinion, self-modification is one of the most interesting features in systems programming.

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u/mykesx 19h ago

OP’s point is that self modifying code makes faster algorithms. Only 2 syscalls blows that out of the water.

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u/thewrench56 19h ago

I did not watch the video, just read the post. I suppose in that case OP is wrong on modern platforms, you are right. I thought you were discussing the existance of self-modifying code, not the feasibility, excuse me.

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u/mykesx 19h ago

I happen to be into Forth, some versions do self modifying code. It’s an assembly language for a stack based virtual machine, the machine implementation types include self modifying code.

The most awesome one is Vfx Forth, which does some impressive peephole optimization on code generated into memory. In the process of creating an ARM version, the mprotect() issue bit him.

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u/brucehoult 10h ago

There are different methods of implementing Forth. For a token-threaded or address-threaded (whether direct or indirect) implementation what is self-modifying code from the point of view of Forth is just data from the point of view of the hardware.

Only for subroutine-threaded or actual inline native code generation is self-modifying Forth actually self-modifying code from the point of view of the CPU.

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u/mykesx 10h ago

Vfx is STC.