/cscript

A C runtime for funsies

Primary LanguageC

cscript

This repository contains useful C-runtime stuff for implementing interpreters, compilers, and whatever other cool stuff.

Structure

core contains only the things that are absolutely necessary to get a working runtime, like the initialization steps before calling main(), definitions for primitive types, and wrappers for system calls.

lib contains useful abstractions built atop the core for things like file i/o and basic scripting.

types contains implementations of more high-level structures and functionality for things like string manipulation, lists, et cetera.

Purpose

Mainly, this exists to help show what the guts of a C program actually looks like under it all. Given I'm writing my own runtimes and compilers and stuff, I felt like I was gonna be doing this kinda stuff anywho and I should throw this at GitHub or whatever.

This is not intended for actual, real-world use, but rather as just a cool look into how a functional C-like runtime works

Usage

After building the runtime with the build script, you should be able to link against the core.o, lib.o, or any other parts you need alongside their header files.

The main differences between this core and something like glibc are the size and complexity of them. In our tests folder, we have some comparisons of simple scripts using our standard library versus glibc and difference is massive.

clib_core    14 kilobytes 
clib_lib     19 kilobytes 
glibc_core   744 kilobytes
glibc_lib    749 kilobytes

Note

This runtime also isn't done yet, so the size will go up a little. That noted, I do not expect that I will even approach closing the gab between the two.

Limitations

This is specifically a runtime for x86-64 Linux, and will not be rewritten for any other systems. Additionally, this is not a replacement for the standard C library -- it does things a little differently, and also just leaves out a lot of standard lib stuff.

Functions Lists

✓ core.h Function Args Notes
x __init program entry point, initializes heap and stack
x brk void *addr core-implemented bump allocator
x read u32 fd, u8 *buf, i32 count
x write u32 fd, u8 *buf, i32 count
x open const char *pathname, i32 flags, i32 mode
x close u32 fd
x mmap void *addr, u32 length, i32 prot, i32 flags, i32 fd, u32 offset
x munmap void *addr, u32 length
x execve char *pathname, char *argv[], char *envp[]
x exit i32 status
x fstat u32 fd, stat *
_ fork
_ socket i32 domain, i32 type, i32 protocol
_ connect i32 sockfd, const void *addr, u32 addrlen
_ bind i32 sockfd, const void *addr, u32 addrlen
_ listen i32 sockfd, i32 backlog
_ accept i32 sockfd, void *addr, u32 *addrlen
_ send i32 sockfd, const void *buf, u32 len, i32 flags
_ recv i32 sockfd, void *buf, u32 len, i32 flags
_ poll void *fds, u32 nfds, i32 timeout
_ ioctl i32 fd, u32 request, void *argp
✓ lib.h Function Args Notes
x print char *
x printf char *fmt void *[] ... ... is a list of pointers, not values
x strfmt char *fmt, void *[]...
x strlen char *, int max
x strcpy char *dest, char *src, int max
x strcat char *base, char *adder, int max
x strcmp char *base, char *adder, int max
x memcpy void *dest, void *src, int size
x memcmp void *base, void *adder, int size
x string_hex32 u32
x string_u32 u32
x string_i32 i32
_ string_f32 f32/f64 rename function
x string_e32 f32/f64 rename function
_ string_b32 u32
x file_read char *filename checks size, allocates memory, and returns filled buffer
x file_write char *filename, char *buffer, int size
_ file_append char *filename, char *buffer, int size
x file_size char *filename
✓ types.h Function Args Notes
_ list_new int size
_ list_push list_t *, void *
_ list_pop list_t *
_ list_insert list_t *, int index, void *
_ list_remove list_t *, int index
_ list_merge list_t *base, list_t *adder
_ list_memsize list_t * used to determine size for list_flatten(*dest)
_ list_flatten void *dest, list_t *src, int newsize
_ table_new int size, int spill spill handles collisions & requests a resize if filled
_ table_get table_t *, int index interally handles wrapping
_ table_set table_t *, int index, void *
_ table_hashid char * returns an index
_ table_merge table_t *dest, table_t *src
_ table_memsize table_t *
_ table_flatten void *dest, table_t *src, int newsize
✓ rand.h Function Args Notes
x rand always returns 0 if not initialized
x rands u32 _sets seed for randfn
x randfn function *(void) sets the PRNG function
x glibc_rand void a reimplementation of glibc's rand function