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Rewriting "sleep" from scratch - no libraries, not even libc - only syscalls and some assembly magic

Valigo

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Advanced. Deep dive for people who know the field.

166K views10 months ago2 recommendations

Systems programmingProgramming languagesCOperating systemsConcurrency and parallelism

How to implement the sleep utility in C from scratch using raw Linux system calls and inline assembly.

Let's rewrite "sleep" program absolutely from scrath - not even with libc. Only the compiler, the kernel, and a magic of inline assembly! Let me know if this kind of long-form video is something you like. Sources: the code: github.com/valignatev/sleep-from-scratch That tweet: x.com/valigo_gg/status/1994169596929024103 GCC inline assembly howto: ibiblio.org/gferg/ldp/GCC-Inline-Assembly-HOWTO.html#toc6 System V Application Binary Interface: raw.githubusercontent.com/wiki/hjl-tools/x86-psABI/x86-64-ps… GCC Manual: gcc.gnu.org/onlinedocs/gcc/Machine-Constraints.html

Why it's here

2 people recommend this

What people say. Recommended for learning how to write C code without standard libraries by interacting directly with the kernel.

u/Ancient_Telephone_50in r/C_Programming • Recommends

On “What functionality is available in C without including any headers?”

link to this video There is this video where he writes the function sleep() without any libraries, its a bit long but you learn interesting things
1View on Reddit

u/gogok10in r/C_Programming • Recommends

On “correct me if im wrong but C is "memory safe" if you ensure to handle...stuff that takes up memeory...in a safe manner, right?”

You can write C code without libc, it's just a big headache managing the stack. Here's a cool link to this video of a guy writing sleep() from scratch
-1View on Reddit