void*
rtm_alloc(rtm_pool* pool, size_t size)
{
if (pool == NULL)
return malloc(size);
if (pool->heap_base == NULL || size == 0)
return NULL;
MutexLocker _(&pool->lock);
// align the size requirement to a kAlignment bytes boundary
size = (size - 1 + kAlignment) & ~(size_t)(kAlignment - 1);
if (size > pool->available) {
TRACE("malloc(): Out of memory!\n");
return NULL;
}
FreeChunk* chunk = pool->free_anchor.Next();
FreeChunk* last = &pool->free_anchor;
while (chunk && chunk->Size() < size) {
last = chunk;
chunk = chunk->Next();
}
if (chunk == NULL) {
// could not find a free chunk as large as needed
TRACE("malloc(): Out of memory!\n");
return NULL;
}
if (chunk->Size() > size + sizeof(FreeChunk) + kAlignment) {
// if this chunk is bigger than the requested size,
// we split it to form two chunks (with a minimal
// size of kAlignment allocatable bytes).
FreeChunk* freeChunk = chunk->Split(size);
last->SetNext(freeChunk);
// re-enqueue the free chunk at the correct position
freeChunk->Remove(pool, last);
freeChunk->Enqueue(pool);
} else {
// remove the chunk from the free list
last->SetNext(chunk->Next());
}
pool->available -= size + sizeof(uint32);
TRACE("malloc(%lu) -> %p\n", size, chunk->AllocatedAddress());
return chunk->AllocatedAddress();
}
void
rtm_pool::Free(void* allocated)
{
FreeChunk* freedChunk = FreeChunk::SetToAllocated(allocated);
available += freedChunk->CompleteSize();
// try to join the new free chunk with an existing one
// it may be joined with up to two chunks
FreeChunk* chunk = free_anchor.Next();
FreeChunk* last = &free_anchor;
int32 joinCount = 0;
while (chunk) {
if (chunk->IsTouching(freedChunk)) {
// almost "insert" it into the list before joining
// because the next pointer is inherited by the chunk
freedChunk->SetNext(chunk->Next());
freedChunk = chunk->Join(freedChunk);
// remove the joined chunk from the list
last->SetNext(freedChunk->Next());
chunk = last;
if (++joinCount == 2)
break;
}
last = chunk;
chunk = chunk->Next();
}
// enqueue the link at the right position; the
// free link queue is ordered by size
freedChunk->Enqueue(this);
}
