#ifndef INCLUDED_POOL_H
#define INCLUDED_POOL_H

#ifndef INCLUDED_OS_TYPES_H
#include <os_types.h>
#endif /*INCLUDED_OS_TYPES_H*/

#ifndef INCLUDED_OS_COMPILER_H
#include <os_compiler.h>
#endif /*INCLUDED_OS_COMPILER_H*/



/* ------------------------------------------------------------------------------------------------------------------ */
/* https://www.gingerbill.org/article/2019/02/16/memory-allocation-strategies-004/ */

typedef struct pool_link_s {
    struct pool_link_s* next;
}pool_link_t;

typedef struct {
    pool_link_t* free_list_p;       /* 对象内存链表，每个节点指向一个对象内存地址 */
    os_size_t obj_size;             /* 每个对象的大小 */
    os_size_t capacity;             /* 池中最大能分配的对象数量 */
    os_size_t count;                /* 已分配的对象数量 */
}pool_t;



/* ------------------------------------------------------------------------------------------------------------------ */
/*  */

void pool_add_block(pool_t* self, void* block, os_size_t block_size);

/*
 * pool_t pool;
 * uint8_t block1[512];
 * uint8_t block2[1024];
 * uint8_t block3[256];
 *
 * pool_init(&pool, 16);
 * pool_add_block(&pool, block1, 512);
 * pool_add_block(&pool, block2, 1024);
 * pool_add_block(&pool, block3, 256);
 *
 * void* obj1 = pool_alloc(&pool);
 * ...
 * pool_free(&pool, obj1);
 *
 */

OS_STATIC_FORCE_INLINE
void pool_init(pool_t* self, os_size_t obj_size){
    self->free_list_p = 0;
    self->obj_size = obj_size;
    self->count = 0;
    self->capacity = 0;
}

OS_STATIC_FORCE_INLINE
void* pool_alloc(pool_t* self){
    if(!self->free_list_p){
        return NULL;
    }
    pool_link_t* p = self->free_list_p;
    self->free_list_p = p->next;
    self->count++;
    return p;
}

OS_STATIC_FORCE_INLINE
void pool_free(pool_t* self, void* obj){
    pool_link_t* p_link = (pool_link_t*) obj;
    p_link->next = self->free_list_p;
    self->free_list_p = p_link;
    self->count--;
}


#endif /*INCLUDED_POOL_H*/