Arena/include/arena.h

#ifndef ARENA_H
#define ARENA_H

#include <stdint.h>
#include <stdlib.h>
#include <inttypes.h>
#include <stdbool.h>

typedef struct {
    uint8_t *buffer;
    size_t capacity;
    size_t offset;
} Arena;

typedef enum {
    ARENA_OK = 0,
    ARENA_BAD_ALLOC,
    ARENA_OUT_OF_SPACE,
    ARENA_NULL_ARG,
    ARENA_INVALID_SIZE,
    ARENA_INVALID_ALIGN,
    ARENA_CAPACITY_OVERFLOW,
} ArenaErr;

typedef struct {
    bool is_valid;
    union {
        ArenaErr err;
        struct {
            Arena *arena;
            size_t offset;
        };
    };
} ArenaPointer;

typedef struct {
    bool is_valid;
    union {
        ArenaErr err;
        Arena arena;
    };
} ArenaResult;

typedef struct {
    bool is_valid;
    union {
        ArenaErr err;
        size_t val;
    };
} SizeResult;

ArenaResult arena_init(size_t capacity);
void arena_destroy(Arena *arena);

ArenaPointer arena_alloc(Arena *arena, size_t size, size_t alignment);
ArenaPointer arena_push(Arena *arena, void *data, size_t size, size_t alignment);
ArenaErr arena_realloc(Arena *arena, size_t new_capacity);
void *arena_unwrap_pointer(ArenaPointer p);

SizeResult arena_get_align_padding(Arena *arena, size_t alignment);
// can take big sizes but of sourse there is a limit,
// its protected against SIZE_MAX but anything that
// is big may break it, still, is an edge case that
// I shouldn't cover.
ArenaErr arena_ensure_capacity(Arena *arena, size_t size, size_t alignment);

// Should be moved to something like general utilities,
// i should make one for all my c projects
static inline bool mul_size_t_safe(size_t a, size_t b, size_t *out);
static inline bool add_size_t_safe(size_t a, size_t b, size_t *out);
static inline bool is_power_of_two(size_t x);

#endif // !ARENA_H