HATPC/engine/mempool.c

#include "mempool.h"
#include <stdlib.h>
#include <stdio.h>
#include <assert.h>
#include <string.h>

// Static allocate buffers
static Entity_t entity_buffer[MAX_COMP_POOL_SIZE];
static MemPool_t ent_mempool = {
    .buffer = entity_buffer,
    .max_size = MAX_COMP_POOL_SIZE,
    .elem_size = sizeof(Entity_t),
    .use_list = NULL,
    .free_list = {0}
};

static bool pool_inited = false;
void init_memory_pools(void)
{
    if (!pool_inited)
    {
        for (size_t i = 0; i < N_COMPONENTS; ++i)
        {
            memset(comp_mempools[i].buffer, 0, comp_mempools[i].elem_size * comp_mempools[i].max_size);
            comp_mempools[i].use_list = (bool*)calloc(comp_mempools[i].max_size, sizeof(bool));
            assert(comp_mempools[i].use_list != NULL);
            sc_queue_init(&comp_mempools[i].free_list);
            for (size_t j = 0; j < comp_mempools[i].max_size; ++j)
            {
                sc_queue_add_last(&comp_mempools[i].free_list, j);
            }
        }

        memset(ent_mempool.buffer, 0, ent_mempool.elem_size*ent_mempool.max_size);
        sc_queue_init(&ent_mempool.free_list);
        ent_mempool.use_list = (bool *)calloc(ent_mempool.max_size, sizeof(bool));
        for (size_t i = 0; i < ent_mempool.max_size; ++i)
        {
            entity_buffer[i].m_id = i;
            sc_queue_add_last(&ent_mempool.free_list, i);
        }
        pool_inited = true;
    }
}

void free_memory_pools(void)
{
    if (pool_inited)
    {
        for (size_t i = 0; i < N_COMPONENTS; ++i)
        {
            free(comp_mempools[i].use_list);
            sc_queue_term(&comp_mempools[i].free_list);
        }
        free(ent_mempool.use_list);
        sc_queue_term(&ent_mempool.free_list);

        pool_inited = false;
    }
}

Entity_t* new_entity_from_mempool(unsigned long* e_idx_ptr)
{
    if (sc_queue_empty(&ent_mempool.free_list)) return NULL;

    unsigned long e_idx = sc_queue_del_first(&ent_mempool.free_list);

    *e_idx_ptr = e_idx;
    ent_mempool.use_list[e_idx] = true;
    Entity_t* ent = entity_buffer + e_idx;
    for (size_t j = 0; j< N_COMPONENTS; j++)
    {
        ent->components[j] = MAX_COMP_POOL_SIZE;
    }
    ent->m_alive = true;
    ent->m_tag = 0;
    return ent;
}

Entity_t* get_entity_wtih_id(unsigned long idx)
{
    if (!ent_mempool.use_list[idx]) return NULL;
    return entity_buffer + idx;
}

void free_entity_to_mempool(unsigned long idx)
{
    if (ent_mempool.use_list[idx])
    {
        ent_mempool.use_list[idx] = false;
        sc_queue_add_first(&ent_mempool.free_list, idx);
    }
}

void* new_component_from_mempool(unsigned int comp_type, unsigned long* idx)
{
    assert(comp_type < N_COMPONENTS);

    if (sc_queue_empty(&comp_mempools[comp_type].free_list)) return NULL;

    *idx = sc_queue_del_first(&comp_mempools[comp_type].free_list);
    comp_mempools[comp_type].use_list[*idx] = true;

    void* comp = comp_mempools[comp_type].buffer + (*idx * comp_mempools[comp_type].elem_size);
    memset(comp, 0, comp_mempools[comp_type].elem_size);
    return comp;
}

void* get_component_wtih_id(unsigned int comp_type, unsigned long idx)
{
    void * comp = NULL;
    assert(comp_type < N_COMPONENTS);
    if (comp_mempools[comp_type].use_list[idx])
    {
        comp = comp_mempools[comp_type].buffer + (idx * comp_mempools[comp_type].elem_size);
    }
    return comp;
}

void free_component_to_mempool(unsigned int comp_type, unsigned long idx)
{
    assert(comp_type < N_COMPONENTS);
    // This just free the component from the memory pool
    if (comp_mempools[comp_type].use_list[idx])
    {
        comp_mempools[comp_type].use_list[idx] = false;
        sc_queue_add_first(&comp_mempools[comp_type].free_list, idx);
    }
}

void print_mempool_stats(char* buffer)
{
    buffer += sprintf(buffer, "Entity free: %lu\n", sc_queue_size(&ent_mempool.free_list));
    for (size_t i = 0; i < N_COMPONENTS; ++i)
    {
        buffer += sprintf(
            buffer, "%lu: %lu/%lu\n",
            i, sc_queue_size(&comp_mempools[i].free_list), comp_mempools[i].free_list.cap
        );
    }
}

uint32_t get_num_of_free_entities(void)
{
    return sc_queue_size(&ent_mempool.free_list);
}