Assembly isn’t that hard. It’s the same imperative programming, but more verbose, more work, and more random names and patterns to remember. If you can understand “x += 3 is the same as x = x + 3”, you can understand how the add instruction works.
I wouldn’t be able to write Rollercoaster Tycoon in assembly because keeping track of all that code in assembly files must be hell, but people pretending like you need to be some kind of wizard to write assembly code are exaggerating.
These days, you won’t be able to beat the compiler even if you wrote your code in assembly, maybe with the exception of bespoke SIMD algorithms. Writing assembly is something only kernel developers and microcontroller developers may need to do in their day to day life.
Reading assembly is still a valuable skill, though, especially if you come anywhere near native code. What you think you wrote and what the CPU is actually trying to do may not be the same, and a small bit of manual debugging work can help you get started resolving crashes that make no sense whatsoever. No need to remember thousands of instructions either, 99% of assembly code is just variations of copying memory, checking equality and jumping anyway. Look up the weird assembly instructions your disassembler spits out, they’re documented very well.
Assembly is hard, because you need to understand your problem on multiple levels and get absolute zero guidance by compilers.
Even C guides you a tiny bit and takes away some of the low level details, so you have more mental capacity to actually solve your problem.
Oh, and you have a standard library. Assembly seems to involve solving everything yourself. No simple function call to truncate a string or turn a char array to uppercase.
Unless you’re developing an OS or something, you’ll probably be using the C standard library and maybe a bunch of other libraries provided by most distros. Just because you’re doing assembly doesn’t mean you need to program syscalls manually.
Modern assemblers also come with plenty of macros to prevent common mistakes and provide common methods. For instance. NASM comes with things like %strcat to do string concatenation.
I suppose the lack of compiler warnings can be a challenge, but most low-level compilers don’t exactly provide guidance for when you design your program wrong.
No doubt Assembly is harder than Java or Python, but compared to languages like C, I don’t think it’s as hard as people pretend to it to be.
I wouldn’t be able to write Rollercoaster Tycoon in assembly because keeping track of all that code in assembly files must be hell, but people pretending like you need to be some kind of wizard to write assembly code are exaggerating.
Well, they’ve got a point for the bigger machine codes. Just the barebones specification for x86 is a doorstopper IIRC.
From what I’ve heard, writing big stuff in assembly comes down to play-acting the compiler yourself on paper, essentially.
From what I’ve heard, writing big stuff in assembly comes down to play-acting the compiler yourself on paper, essentially.
I think that’s true for just about any programming languages, though the program you’re “compiling” is a human understanding of what you’re trying to accomplish. Things like val bar = foo.let { it.widget?.frub() ?:FrubFactory::defaultFrub(it) } don’t come naturally to the human mind, you’re already working through the logic required before you start typing.
As for the x86 instruction count: you don’t need to know all of them. For instance, here’s a quick graph of all of the instructions in systemctl on my system:
With the top 15 or maybe to 25 of these instructions, you can probably write any program you can think of, and what’s missing will probably be easily found (just search for “multiply” or “divide”). You don’t need to know punpckldq to write a program.
What language is your pseudocode example modeled after? It vaguely reminds me of some iOs App code I helped debug (Swift?) but I never really learned the language so much as eyeballed it with educated guesses, and even with the few things I double checked it has been a few years, so I have no clue what is or isn’t legal syntax anymore.
That’s Kotlin. Mostly used for programming for the JVM, though it compiles to native code as well these days. Very interesting for cross platform app development, although I rarely do that these days.
I think Swift has a similar syntax, but it doesn’t do some of the less obvious Kotlin tricks as far as I’m aware.
I’ve heard of Kotlin in the context of Android apps, but never actually used or learned it. I did one mobile app dev project with Java in Android Studio, but never had any formal classes on it either and just learned as I went (the result was shit, but we got a decent grade for being able to evaluate the difficulties and shortcomings and point out learnings).
TIL. I had tried to understand it a bit, but felt lost pretty fast, and then eventually found out that’s because it’s huge. Is there a good intro to the basic instructions you’re aware of?
By “play act the compiler” I mean a fairly elaborate system of written notes that significantly exceeds the size of the actual program. Like, it’s no wonder they started thinking about building machine compilers at that stage.
I believe this guide can get you started pretty quickly to get the basics down. There are tons of guides online, but most of them will give you the basics (“this is how to find a prime number”) and then leave you on your own. Once you know how instructions, calling conventions, and system calls work, the rest of assembly programming is just reading documentation or Googling “how do I X in assembly”.
What can help is using websites like godbolt.org to write simple C programs and looking at the compiled output. Look up instructions you don’t recognize and make sure you don’t enable optimizations, unless you want to deal with atrocities like VGF2P8AFFINEINVQB.
If you don’t mind getting started with old assembly, there are also more comprehensive guides for MS-DOS and old Windows that mostly involve 16 bit and 32 bit programs programming. 64 bit programming is different (uses more registers to pass variables, floating point support is guaranteed, etc.) but there aren’t as many good books on the topic anymore now that it’s become a niche.
I think there are quite a few guides out there for ARM these days, if you have something like a Raspberry Pi or an emulator you can also learn ARM assembly (which has fewer supported weird instructions, but also a tonne of weird stuff).
If you want to go deep, you can also check Ben Eater’s youtube channel where he shows step by step how an 8 bit computer on a breadboard works, how instructions relate to memory, and all that. With some intuition from that, learning amd64 assembly may be a lot easier than going from normal programming languages to assembly.
Edit: to get into understanding assembly programming, [Human Resource Machine[(https://store.steampowered.com/app/375820/Human_Resource_Machine/) will explain the concepts of assembly programming without ever overtly explaining the concepts. Plus, it’s a fun puzzle game.
Having toyed with video game reverse engineering, I definitely feel like I ought to learn a bit more. I understand mov, pointers and registers, and I think there was some inc and add in the code I read to try to figure out base pointers and pointer paths (using Cheat Engine), but I think knowing some more would serve me well there.
Modern decompilers like the one packaged with Ghidra helps a lot for intuiting how instructions work. Unfortunately, a lot of video game code is obfuscated, so you’re probably more likely to run into weird instructions, but OK the other hand you’ll learn what they do faster than when you rarely encounter them.
Assembly isn’t that hard. It’s the same imperative programming, but more verbose, more work, and more random names and patterns to remember. If you can understand “
x += 3is the same asx = x + 3”, you can understand how theaddinstruction works.I wouldn’t be able to write Rollercoaster Tycoon in assembly because keeping track of all that code in assembly files must be hell, but people pretending like you need to be some kind of wizard to write assembly code are exaggerating.
These days, you won’t be able to beat the compiler even if you wrote your code in assembly, maybe with the exception of bespoke SIMD algorithms. Writing assembly is something only kernel developers and microcontroller developers may need to do in their day to day life.
Reading assembly is still a valuable skill, though, especially if you come anywhere near native code. What you think you wrote and what the CPU is actually trying to do may not be the same, and a small bit of manual debugging work can help you get started resolving crashes that make no sense whatsoever. No need to remember thousands of instructions either, 99% of assembly code is just variations of copying memory, checking equality and jumping anyway. Look up the weird assembly instructions your disassembler spits out, they’re documented very well.
Assembly is hard, because you need to understand your problem on multiple levels and get absolute zero guidance by compilers.
Even C guides you a tiny bit and takes away some of the low level details, so you have more mental capacity to actually solve your problem.
Oh, and you have a standard library. Assembly seems to involve solving everything yourself. No simple function call to truncate a string or turn a char array to uppercase.
Unless you’re developing an OS or something, you’ll probably be using the C standard library and maybe a bunch of other libraries provided by most distros. Just because you’re doing assembly doesn’t mean you need to program syscalls manually.
Modern assemblers also come with plenty of macros to prevent common mistakes and provide common methods. For instance. NASM comes with things like
%strcatto do string concatenation.I suppose the lack of compiler warnings can be a challenge, but most low-level compilers don’t exactly provide guidance for when you design your program wrong.
No doubt Assembly is harder than Java or Python, but compared to languages like C, I don’t think it’s as hard as people pretend to it to be.
Missing “;” on line 148.
Well, they’ve got a point for the bigger machine codes. Just the barebones specification for x86 is a doorstopper IIRC.
From what I’ve heard, writing big stuff in assembly comes down to play-acting the compiler yourself on paper, essentially.
I think that’s true for just about any programming languages, though the program you’re “compiling” is a human understanding of what you’re trying to accomplish. Things like
val bar = foo.let { it.widget?.frub() ?: FrubFactory::defaultFrub(it) }don’t come naturally to the human mind, you’re already working through the logic required before you start typing.As for the x86 instruction count: you don’t need to know all of them. For instance, here’s a quick graph of all of the instructions in
systemctlon my system:With the top 15 or maybe to 25 of these instructions, you can probably write any program you can think of, and what’s missing will probably be easily found (just search for “multiply” or “divide”). You don’t need to know
punpckldqto write a program.What language is your pseudocode example modeled after? It vaguely reminds me of some iOs App code I helped debug (Swift?) but I never really learned the language so much as eyeballed it with educated guesses, and even with the few things I double checked it has been a few years, so I have no clue what is or isn’t legal syntax anymore.
That’s Kotlin. Mostly used for programming for the JVM, though it compiles to native code as well these days. Very interesting for cross platform app development, although I rarely do that these days.
I think Swift has a similar syntax, but it doesn’t do some of the less obvious Kotlin tricks as far as I’m aware.
I’ve heard of Kotlin in the context of Android apps, but never actually used or learned it. I did one mobile app dev project with Java in Android Studio, but never had any formal classes on it either and just learned as I went (the result was shit, but we got a decent grade for being able to evaluate the difficulties and shortcomings and point out learnings).
TIL. I had tried to understand it a bit, but felt lost pretty fast, and then eventually found out that’s because it’s huge. Is there a good intro to the basic instructions you’re aware of?
By “play act the compiler” I mean a fairly elaborate system of written notes that significantly exceeds the size of the actual program. Like, it’s no wonder they started thinking about building machine compilers at that stage.
I believe this guide can get you started pretty quickly to get the basics down. There are tons of guides online, but most of them will give you the basics (“this is how to find a prime number”) and then leave you on your own. Once you know how instructions, calling conventions, and system calls work, the rest of assembly programming is just reading documentation or Googling “how do I X in assembly”.
What can help is using websites like godbolt.org to write simple C programs and looking at the compiled output. Look up instructions you don’t recognize and make sure you don’t enable optimizations, unless you want to deal with atrocities like
VGF2P8AFFINEINVQB.If you don’t mind getting started with old assembly, there are also more comprehensive guides for MS-DOS and old Windows that mostly involve 16 bit and 32 bit programs programming. 64 bit programming is different (uses more registers to pass variables, floating point support is guaranteed, etc.) but there aren’t as many good books on the topic anymore now that it’s become a niche.
I think there are quite a few guides out there for ARM these days, if you have something like a Raspberry Pi or an emulator you can also learn ARM assembly (which has fewer supported weird instructions, but also a tonne of weird stuff).
If you want to go deep, you can also check Ben Eater’s youtube channel where he shows step by step how an 8 bit computer on a breadboard works, how instructions relate to memory, and all that. With some intuition from that, learning amd64 assembly may be a lot easier than going from normal programming languages to assembly.
Edit: to get into understanding assembly programming, [Human Resource Machine[(https://store.steampowered.com/app/375820/Human_Resource_Machine/) will explain the concepts of assembly programming without ever overtly explaining the concepts. Plus, it’s a fun puzzle game.
Thank you!
Having toyed with video game reverse engineering, I definitely feel like I ought to learn a bit more. I understand
mov, pointers and registers, and I think there was someincandaddin the code I read to try to figure out base pointers and pointer paths (using Cheat Engine), but I think knowing some more would serve me well there.Modern decompilers like the one packaged with Ghidra helps a lot for intuiting how instructions work. Unfortunately, a lot of video game code is obfuscated, so you’re probably more likely to run into weird instructions, but OK the other hand you’ll learn what they do faster than when you rarely encounter them.
If you want to write amd64 code, you can get away with mastering just one instruction, and that’s the kind of tomfoolery that obfuscated programs will try to use to make your life harder.