Techneck/code/source-c/entity/entity_pool.c

#include "entity.h"
#include "state.h"

#include <stdlib.h>

// TODO: Write a *real* pool allocator

tc_entity_pool_s * tc_create_entity_pool(u32_t capacity)
{
    tc_entity_pool_s           *pool                = malloc(sizeof(tc_entity_pool_s));
    pool->entities_capacity         = capacity;
    pool->entities                  = calloc(sizeof(tc_entity_pool_entry_s), capacity);
    pool->first_free                = &pool->entities[0];
    pool->continuation              = NULL;
    
    u32_t                    entity_index        = 0;
    while(entity_index < capacity)
    {
        pool->entities[entity_index].next           = &pool->entities[entity_index+1];
        pool->entities[entity_index].previous       = &pool->entities[entity_index-1];
        ++entity_index;
    }
    pool->entities[0].previous      = NULL; 
    pool->entities[capacity-1].next = NULL;
    
    return pool;
}

void tc_reset_entity(tc_entity_s *entity)
{
    if(entity->attributes != NULL) free(entity->attributes);
    entity->attributes_capacity     = 8;
    entity->attributes              =
        calloc(sizeof(tc_entity_attribute_s), entity->attributes_capacity);
    
}

tc_entity_s * tc_allocate_entity_from_pool(tc_entity_pool_s *pool)
{
    if(pool->first_free == NULL)
    {
        if(pool->continuation == NULL)
            pool->continuation = tc_create_entity_pool(pool->entities_capacity * 2);
        
        return tc_allocate_entity_from_pool(pool->continuation);
    }
    
    tc_entity_s                *entity              = &pool->first_free->entity;
    entity->pool_entry              = pool->first_free;
    pool->first_free                = pool->first_free->next;
    
    return entity;
}

tc_entity_s * tc_allocate_entity()
{
    return tc_allocate_entity_from_pool(tc_game_state_g.entity_registry.pool);
}

void tc_deallocate_entity(tc_entity_s *entity)
{
    tc_entity_pool_s           *pool                = tc_game_state_g.entity_registry.pool;
    entity->pool_entry->next        = pool->first_free;
    pool->first_free                = entity->pool_entry;
}