DOOM
llvm-project
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DOOM | llvm-project | |
---|---|---|
91 | 348 | |
12,640 | 25,314 | |
2.4% | 3.1% | |
2.5 | 10.0 | |
22 days ago | 6 days ago | |
C++ | C++ | |
GNU General Public License v3.0 only | GNU General Public License v3.0 or later |
Stars - the number of stars that a project has on GitHub. Growth - month over month growth in stars.
Activity is a relative number indicating how actively a project is being developed. Recent commits have higher weight than older ones.
For example, an activity of 9.0 indicates that a project is amongst the top 10% of the most actively developed projects that we are tracking.
DOOM
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Doom Released Under GPLv2
commercially exploit or use for any commercial purpose."
[1] https://github.com/id-Software/DOOM/commit/4eb368a960647c8cc...
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GTA 5 source code leaks online
The original Doom had third-party audio playback routines, so the source came with a rewritten sound server: https://github.com/id-Software/DOOM/tree/master/sndserv
The bad news: this code only compiles and runs on linux. We couldn't
- What you can do with C ?
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Software Disenchantment
Here's a repo for you with no test coverage and no auto-generated DI. They using unsafe pointers all over the place, too!
https://github.com/id-Software/DOOM
Shall I prepare the postage for the letter in which you'll call John Carmack an MBA? Should we send another to Chris Sawyer? I heard he didn't even write a formal design doc for Roller Coaster Tycoon!
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Ask HN: Good practices for my first C project
cURL is one of the most used C libs and is an example of good quality C code. If you follow the style used there, see e.g. https://github.com/curl/curl/blob/master/lib/dynhds.h (and associated dynhds.c) you will be good.
Looking at the source of some of the old game-engines from the era that have since been released as open-source can also be helpful, like https://github.com/id-Software/DOOM.
In both cases notice how simple and elegant a lot of the code is. There is already enough complexity inherent in the problem they are solving, and that is where the focus should be.
Any IDE with a working language server to make it easy to jump around and refactor should work fine. Limitations might be due to the C language itself?
Error handling on such a fixed platform does not need to be super-advanced. You should always be within the confines of the system so there shouldn't be much that can go wrong. If stuff goes wrong anyway just being able call a function Fatal("FooBar failed with code 34") when unexpected stuff happens and have it log somewhere to be able to dig around should be enough. You never need to be able to recover and retry.
Make sure to use https://clang.llvm.org/docs/AddressSanitizer.html or a similar tool when developing outside of the PSOne.
That said, consider statically allocating global buffers for most stuff and avoid using the heap for most stuff.
Good luck working within the confines of the PSOne! Many hackers have pulled the hair from their head on that platform ;)
- Ask HN: Where do I find good code to read?
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Running Stable Diffusion in 260MB of RAM
Probably more easily than you'd think. DOOM is open source[1], and as GP alludes, is probably the most frequently ported game in existence, so its source code almost certainly appears multiple times in GPT-4's training set, likely alongside multiple annotated explanations.
- Where can I get game files to study?
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Some were meant for C [pdf]
I'd define an arena as the pattern where the arena itself owns N objects. So you free the arena to free all objects.
My first job was at EA working on console games (PS2, GameCube, XBox, no OS or virtual memory on any of them), and while at the time I was too junior to touch the memory allocators themselves, we were definitely not malloc-ing and freeing all the time.
It was more like you load data for the level in one stage, which creates a ton of data structures, and then you enter a loop to draw every frame quickly. There were many global variables.
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Wikipedia calls it a region, zone, arena, area, or memory context, and that seems about right:
https://en.wikipedia.org/wiki/Region-based_memory_management
It describes history from 1967 (before C was invented!) and has some good examples from Apache ("pools") and Postgres ("memory contexts").
I also just looked at these codebases:
https://github.com/mit-pdos/xv6-public (based on code from the 70's)
https://github.com/id-Software/DOOM (1997)
I looked at allocproc() in xv6, and gives you an object from a fixed global array. A lot of C code in the 80's and 90's was essentially "kernel code" in that it didn't have an OS underneath it. Embedded systems didn't run on full-fledges OSes.
DOOM tends to use a lot of what I would call "pools" -- arrays of objects of a fixed size, and that's basically what I remember from EA.
Though in g_game.c, there is definitely an arena of size 0x20000 called "demobuffer". It's used with a bump allocator.
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So I'd say
- malloc / free of individual objects was NEVER what C code looked like (aside from toy code in college)
- arena allocators were used, but global vars and pools are also very common.
- arenas are more or less wash for memory safety. they help you in some ways, but hurt you in others.
The reason C programmers don't malloc/free all the time is for speed, not memory safety. Arenas are still unsafe.
When you free an arena, you have no guarantee there's nothing that points to it anymore.
Also, something that shouldn't be underestimated is that arena allocators break tools like ASAN, which use the malloc() free() interface. This was underscored to me by writing a garbage collector -- the custom allocator "broke" ASAN, and that was actually a problem:
https://www.oilshell.org/blog/2023/01/garbage-collector.html
If you want memory safety in your C code, you should be using ASAN (dynamically instrumented allocators) and good test coverage. Arenas don't help -- they can actually hurt. An arena is a trivial idea -- the problem is more if that usage pattern actually matches your application, and apps evolve over time.
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What is your gender?
Doom
llvm-project
- Flang-new: How to force arrays to be allocated on the heap?
- The LLVM Compiler Infrastructure
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Programming from Top to Bottom - Parsing
You can never mistake type_declaration with an identifier, otherwise the program will not work. Aside from that constraint, you are free to name them whatever you like, there is no one standard, and each parser has it own naming conventions, unless you are planning to use something like LLVM. If you are interested, you can see examples of naming in different language parsers in the AST Explorer.
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Look ma, I wrote a new JIT compiler for PostgreSQL
> There is one way to make the LLVM JIT compiler more usable, but I fear it’s going to take years to be implemented: being able to cache and reuse compiled queries.
Actually, it's implemented in LLVM for years :) https://github.com/llvm/llvm-project/commit/a98546ebcd2a692e...
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C++ Safety, in Context
> It's true, this was a CVE in Rust and not a CVE in C++, but only because C++ doesn't regard the issue as a problem at all. The problem definitely exists in C++, but it's not acknowledged as a problem, let alone fixed.
Can you find a link that substantiates your claim? You're throwing out some heavy accusations here that don't seem to match reality at all.
Case in point, this was fixed in both major C++ libraries:
https://github.com/gcc-mirror/gcc/commit/ebf6175464768983a2d...
https://github.com/llvm/llvm-project/commit/4f67a909902d8ab9...
So what C++ community refused to regard this as an issue and refused to fix it? Where is your supporting evidence for your claims?
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Clang accepts MSVC arguments and targets Windows if its binary is named clang-cl
For everyone else looking for the magic in this almost 7k lines monster, look at line 6610 [1].
[1] https://github.com/llvm/llvm-project/blob/8ec28af8eaff5acd0d...
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Rewrite the VP9 codec library in Rust
Through value tracking. It's actually LLVM that does this, GCC probably does it as well, so in theory explicit bounds checks in regular C code would also be removed by the compiler.
How it works exactly I don't know, and apparently it's so complex that it requires over 9000 lines of C++ to express:
https://github.com/llvm/llvm-project/blob/main/llvm/lib/Anal...
- Fortran 2023
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MiniScript Ports
• Go • Rust • Lua • pure C (sans C++) • 6502 assembly • WebAssembly • compiler backends, like LLVM or Cranelift
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On Avoiding Register Spills in Vectorized Code with Many Constants
Compilers also may even spill data to stack from memory, even when the original location is still available, as can be seen in this issue: https://github.com/llvm/llvm-project/issues/53348
I vaguely remember that spilling like this could allow high-end CPUs to use something similar to register renaming, i.e. stack locations like [rsp + 96] could be stay in a physical registers during function execution (high-end CPUs often have more physical registers, than logical ones), but could find good references whether such optimization exists in practice or not.
Unfortunately, I think more often than note it causes performance regressions and in some cases it may even cause unnecessary stack spilling of sensitive data: https://github.com/rust-lang/rust/issues/88930#issuecomment-...
What are some alternatives?
open-watcom-v2 - Open Watcom V2.0 - Source code repository, Wiki, Latest Binary build, Archived builds including all installers for download.
zig - General-purpose programming language and toolchain for maintaining robust, optimal, and reusable software.
project-based-tutorials-in-c - A curated list of project-based tutorials in C
Lark - Lark is a parsing toolkit for Python, built with a focus on ergonomics, performance and modularity.
Apollo-11 - Original Apollo 11 Guidance Computer (AGC) source code for the command and lunar modules.
gcc
doomgeneric - Easily portable doom
SDL - Simple Directmedia Layer
luxtorpeda - Steam Play compatibility tool to run games using native Linux engines
cosmopolitan - build-once run-anywhere c library
angband - A free, single-player roguelike dungeon exploration game
STL - MSVC's implementation of the C++ Standard Library.