module ecs.entity_allocator;

import ecs.manager;

import std.experimental.allocator;
import std.experimental.allocator.mallocator : AlignedMallocator, Mallocator;

struct EntityAllocator
{
    void* next_block;

    void* getBlock()
    {
        if(next_block is null)allocBlock();
        void* ret = next_block;
        next_block = *cast(void**)next_block;
        return ret;
    }

    private void allocBlock()
    {
        next_block = cast(void*)AlignedMallocator.instance.alignedAllocate(EntityManager.page_size * EntityManager.pages_in_block, EntityManager.page_size);
        foreach(i;0..EntityManager.pages_in_block-1)
        {
            void** pointer = cast(void**)(next_block + i * EntityManager.page_size);
            *pointer = next_block + (i+1) * EntityManager.page_size;
        }
    }
}