pm_arena.h

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#ifndef PRISM_ARENA_H
#define PRISM_ARENA_H
 
#include "prism/defines.h"
 
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
 
typedef struct pm_arena_block {
    struct pm_arena_block *prev;
 
    size_t capacity;
 
    size_t used;
 
    char data[PM_FLEX_ARY_LEN];
} pm_arena_block_t;
 
typedef struct {
    pm_arena_block_t *current;
 
    size_t block_count;
} pm_arena_t;
 
void pm_arena_reserve(pm_arena_t *arena, size_t capacity);
 
void * pm_arena_alloc_slow(pm_arena_t *arena, size_t size);
 
static PRISM_FORCE_INLINE void *
pm_arena_alloc(pm_arena_t *arena, size_t size, size_t alignment) {
    if (arena->current != NULL) {
        size_t used_aligned = (arena->current->used + alignment - 1) & ~(alignment - 1);
        size_t needed = used_aligned + size;
 
        if (used_aligned >= arena->current->used && needed >= used_aligned && needed <= arena->current->capacity) {
            arena->current->used = needed;
            return arena->current->data + used_aligned;
        }
    }
 
    return pm_arena_alloc_slow(arena, size);
}
 
static inline void *
pm_arena_zalloc(pm_arena_t *arena, size_t size, size_t alignment) {
    void *ptr = pm_arena_alloc(arena, size, alignment);
    memset(ptr, 0, size);
    return ptr;
}
 
static inline void *
pm_arena_memdup(pm_arena_t *arena, const void *src, size_t size, size_t alignment) {
    void *dst = pm_arena_alloc(arena, size, alignment);
    memcpy(dst, src, size);
    return dst;
}
 
PRISM_EXPORTED_FUNCTION void pm_arena_free(pm_arena_t *arena);
 
#endif