izanagi-2022/src/packages/game/memory/IZ_pool.c

#include "IZ_pool.h"

void IZ_PoolInitialize(IZ_Pool* pool, size_t size) {
	IZ_ListInitialize(&pool->items);
	pool->memory = SDL_malloc(size);
	SDL_memset(pool->memory, 0, size);
	pool->allocated_memory = 0;
	pool->next_address = 0;
	pool->max_size = size;
}

bool IZ_PoolFindItemsWithLowerPrecedence(IZ_ListNode** node, u64 index, IZ_List* list) {
	IZ_PoolItem* item = (IZ_PoolItem*)(*node)->value;
	IZ_PoolAllocationArgs* args = (IZ_PoolAllocationArgs*) list->find_predicate_userdata;
	return item->args.priority < args->priority;
}

IZ_PoolItem* IZ_PoolAllocate(IZ_Pool* pool, IZ_PoolAllocationArgs args) {
	// 1. check next free allocation for size
	// 2. if 1. returns non-null,

//	u64 alloc_end = pool->next_address + size;
//
//	for (u64 i = 0; i < POOL_MAX_ALLOCATIONS; i += 1) {
//		if (pool->allocation[i].length == 0) {
//			continue;
//		}
//	}

	if (pool->max_size < args.size) {
		// couldn't allocate anything bigger than the pool
		return NULL;
	}

	if (pool->max_size - pool->allocated_memory < args.size) {
		pool->items.find_predicate_userdata = &args;
		IZ_ListDeleteFirstNode(&pool->items, IZ_PoolFindItemsWithLowerPrecedence);
		// TODO deallocate memory based from priority
	}

	void* pointer = &pool->memory[pool->next_address];
	IZ_ListNode** new_item = IZ_ListAppendNode(&pool->items, &(IZ_PoolItem) {
		.pointer = pointer,
		.args = args,
		.pool = pool,
	});

	pool->next_address = (pool->next_address + args.size) % POOL_MAX_SIZE;
	pool->allocated_memory += args.size;
	return (*new_item)->value;
}

bool IZ_PoolGetSameItem(IZ_ListNode** node, u64 _index, IZ_List* list) {
	return (*node)->value == (*list->iterator)->value;
}

void IZ_PoolDeallocate(IZ_PoolItem* item) {
	IZ_ListDeleteFirstNode(&item->pool->items, IZ_PoolGetSameItem);
}

void IZ_PoolTeardown(IZ_Pool* pool) {
	SDL_free(pool->memory);
	pool->memory = NULL;
}