Arena Allocator (C)

A small stack-style arena allocator written in C for learning and portfolio use. It supports fast linear allocation with LIFO pop semantics by storing a tiny header before each payload.

Project Goals

• Implement a minimal custom allocator in plain C
• Practice low-level memory layout and pointer arithmetic
• Provide a clean, readable codebase suitable for a portfolio

Structure

• include/arena.h: public API and types
• src/arena.c: allocator implementation
• src/main.c: small demo program
• Makefile: build and run helpers

Build

make

Run

make run

Clean

make clean

API Overview

• Arena *ArenaAlloc(U64 capacity): create arena with capacity in U64 elements
• void ArenaRelease(Arena *arena): free arena memory
• U64 ArenaPos(const Arena *arena): current write position
• void ArenaClear(Arena *arena): reset arena to empty state
• void *ArenaPushNoZero(Arena *arena, U64 size): allocate payload without zeroing
• void *ArenaPush(Arena *arena, U64 size): allocate payload and zero memory
• void *ArenaPop(Arena *arena): pop most recent allocation (LIFO)
• bool IsFull(const Arena *arena): true when arena is full

Notes

• Capacity and allocation sizes are measured in U64 elements (not bytes).
• ArenaPop returns NULL when there is nothing left to pop.

Next Improvements

• Add unit tests for edge cases and overflow behavior
• Add CI workflow for build checks