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| struct GlobalAllocator
{
void* Allocate(size_t sizeBytes)
{
return ::operator new(sizeBytes);
}
void DeAllocate(void* ptr, size_t /*osize*/)
{
assert(ptr != nullptr); //can't decallocate null!!!
::operator delete(ptr);
}
void* ReAllocate(void* ptr, size_t osize, size_t nsize)
{
size_t bytesToCopy = osize;
if (nsize < bytesToCopy)
{
bytesToCopy = nsize;
}
void* newPtr = Allocate(nsize);
memcpy(newPtr, ptr, bytesToCopy);
DeAllocate(ptr, osize);
return newPtr;
}
static void *l_alloc(void *ud, void *ptr, size_t osize, size_t nsize) {
GlobalAllocator * pool = static_cast<GlobalAllocator *>(ud);
if (nsize == 0)
{
if (ptr != nullptr)
{
pool->DeAllocate(ptr, osize);
}
return NULL;
}
else
{
if (ptr == nullptr)
{
return pool->Allocate(nsize);
}
else
{
return pool->ReAllocate(ptr, osize, nsize);
}
}
}
};
/*! \brief Allocates from a fixed pool.
* Aligns all memory to 8 bytes
* Has a min allocation of 64 bytes
* Puts all free'd blocks on a free list.
* Falls back to GlobalAllocator when out of memory. */
struct ArenaAllocator
{
void* m_begin;
void* m_end;
char* m_curr;
static constexpr int ALIGNMENT = 8;
static constexpr int MIN_BLOCK_SIZE = ALIGNMENT * 8;
struct FreeList
{
FreeList* m_next;
};
FreeList* m_freeListHead;
GlobalAllocator m_globalAllocator;
ArenaAllocator(void* begin, void* end) :
m_begin(begin),
m_end(end)
{
Reset();
}
void Reset()
{
m_freeListHead = nullptr;
m_curr = static_cast<char*>(m_begin);
}
size_t SizeToAllocate(size_t size)
{
size_t allocatedSize = size;
if (allocatedSize < MIN_BLOCK_SIZE)
{
allocatedSize = MIN_BLOCK_SIZE;
}
return allocatedSize;
}
void* Allocate(size_t sizeBytes)
{
size_t allocatedBytes = SizeToAllocate(sizeBytes);
if (allocatedBytes <= MIN_BLOCK_SIZE && m_freeListHead)
{
//printf("-- allocated from the freelist --\n");
void* ptr = m_freeListHead;
m_freeListHead = m_freeListHead->m_next;
return ptr;
}
else
{
m_curr = (char*)((uintptr_t)m_curr + (ALIGNMENT - 1) & ~(ALIGNMENT - 1));
if (m_curr + allocatedBytes <= m_end)
{
printf("Allocated %d bytes\n", (int)allocatedBytes);
void* ptr = m_curr;
m_curr += allocatedBytes;
return ptr;
}
else
{
return m_globalAllocator.Allocate(sizeBytes);
}
}
}
void DeAllocate(void* ptr, size_t osize)
{
assert(ptr != nullptr); //can't decallocate null!!!
if (ptr >= m_begin && ptr <= m_end)
{
size_t allocatedBytes = SizeToAllocate(osize);
printf("DeAllocated %d bytes\n", (int)allocatedBytes);
if (allocatedBytes >= MIN_BLOCK_SIZE)
{
printf("-- deallocated to the freelist --\n");
FreeList* newHead = static_cast<FreeList*>(ptr);
newHead->m_next = m_freeListHead;
m_freeListHead = newHead;
}
}
else
{
m_globalAllocator.DeAllocate(ptr, osize);
}
}
void* ReAllocate(void* ptr, size_t osize, size_t nsize)
{
printf("ReAllocated %d bytes\n", (int)nsize);
size_t bytesToCopy = osize;
if (nsize < bytesToCopy)
{
bytesToCopy = nsize;
}
void* newPtr = Allocate(nsize);
memcpy(newPtr, ptr, bytesToCopy);
DeAllocate(ptr, osize);
return newPtr;
}
static void *l_alloc(void *ud, void *ptr, size_t osize, size_t nsize) {
ArenaAllocator * pool = static_cast<ArenaAllocator *>(ud);
if (nsize == 0)
{
if (ptr != nullptr)
{
pool->DeAllocate(ptr, osize);
}
return NULL;
}
else
{
if (ptr == nullptr)
{
return pool->Allocate(nsize);
}
else
{
return pool->ReAllocate(ptr, osize, nsize);
}
}
}
};
int main() {
constexpr int pool_size = 1024 * 10;
char memory[pool_size];
ArenaAllocator pool(memory, &memory[pool_size-1]);
lua_State *L = lua_newstate(ArenaAllocator::l_alloc, &memory);
//luaL_openlibs(L);
lua_assert(L != nullptr);
lua_close(L);
//cin.get();//ожидает ввода символа программа завершается.
return 0;
} |
(
