README.md

bumpalloc

A simple bump allocator written in C for linux with x86_64 CPU. Bump allocators are extremely fast because they have near-0 overhead, however they are also very niche, since they cannot free a single allocation. This implementation is designed to be modular, reusable and not dependant on printf, malloc or any other function that should allocate.

Limmitations

Obviously, the biggest limmitation is that single allocations cannot be freed. In this implementation, alignment is not tested or accounted for and this implementation only considers x86_64 CPUs. It's also a considerable flaw that only one bump allocator can be present at any time and it is dependant on linux system calls. Aditionally, this cannot be used alongside the whole standard library because it often relies on a different builtin allocator. You can bring some functions into scope with a custom header file, similarly to ateexit.h, however you must ensure none of them make calls to sbrk or malloc or similar, else heap corruption may ensue.

How to use

Requires the make build system and a PC with 4GB of ram. Run the following command. It will take a while, because several tests will run, if any fail every time, your platform may not be supported.

make

The generated .a library files and .h headers will be generated and put into a lib folder. To use the bump allocator, there is 2 distinct approaches to using this library.

1. With the malloc wrapper. Put the files into your project folder and link them. Then malloc() and free() can be used like normal, except that free does nothing.

   # linking example
   gcc main.c -Lbumpalloc_wrapper.h bumpalloc_wrapper.a -Lbumpalloc.h bumpalloc.a -Latexit.h 
   

2. Raw - Put the files into your project folder and link them. You are then required to initalize bumpalloc_create and take a pointer to it for all other functions. bumpalloc_alloc is used to allocate, bumpalloc_free does nothing and bumpalloc_destroy deallocates everything. Consult bumpalloc.h for the function documentation.

   #linking example
   gcc main.c -Lbumpalloc.h bumpalloc.a