libctru/libctru/source/allocator/linear.cpp

#include <3ds/types.h>
#include <3ds/util/rbtree.h>

#include "mem_pool.h"

extern u32 __linear_heap, __linear_heap_size;

static MemPool sLinearPool;
static rbtree_t sAddrMap;

struct addrMapNode
{
	rbtree_node node;
	MemChunk chunk;
};

#define getAddrMapNode(x) rbtree_item((x), addrMapNode, node)

static int addrMapNodeComparator(const rbtree_node_t* _lhs, const rbtree_node_t* _rhs)
{
	auto lhs = getAddrMapNode(_lhs)->chunk.addr;
	auto rhs = getAddrMapNode(_rhs)->chunk.addr;
	if (lhs < rhs)
		return -1;
	if (lhs > rhs)
		return 1;
	return 0;
}

static void addrMapNodeDestructor(rbtree_node_t* a)
{
	free(getAddrMapNode(a));
}

static addrMapNode* getNode(void* addr)
{
	addrMapNode n;
	n.chunk.addr = (u8*)addr;
	auto p = rbtree_find(&sAddrMap, &n.node);
	return p ? getAddrMapNode(p) : nullptr;
}

static addrMapNode* newNode(const MemChunk& chunk)
{
	auto p = (addrMapNode*)malloc(sizeof(addrMapNode));
	if (!p) return nullptr;
	p->chunk = chunk;
	return p;
}

static void delNode(addrMapNode* node)
{
	rbtree_remove(&sAddrMap, &node->node, addrMapNodeDestructor);
}

static bool linearInit()
{
	auto blk = MemBlock::Create((u8*)__linear_heap, __linear_heap_size);
	if (blk)
	{
		sLinearPool.AddBlock(blk);
		rbtree_init(&sAddrMap, addrMapNodeComparator);
		return true;
	}
	return false;
}

void* linearMemAlign(size_t size, size_t alignment)
{
	// Enforce minimum alignment
	if (alignment < 16)
		alignment = 16;

	// Convert alignment to shift amount
	int shift;
	for (shift = 4; shift < 32; shift ++)
	{
		if ((1U<<shift) == alignment)
			break;
	}
	if (shift == 32) // Invalid alignment
		return nullptr;

	// Initialize the pool if it is not ready
	if (!sLinearPool.Ready() && !linearInit())
		return nullptr;

	// Allocate the chunk
	MemChunk chunk;
	if (!sLinearPool.Allocate(chunk, size, shift))
		return nullptr;

	auto node = newNode(chunk);
	if (!node)
	{
		sLinearPool.Deallocate(chunk);
		return nullptr;
	}
	if (rbtree_insert(&sAddrMap, &node->node));
	return chunk.addr;
}

void* linearAlloc(size_t size)
{
	return linearMemAlign(size, 16);
}

void* linearRealloc(void* mem, size_t size)
{
	// TODO
	return NULL;
}

void linearFree(void* mem)
{
	auto node = getNode(mem);
	if (!node) return;

	// Free the chunk
	sLinearPool.Deallocate(node->chunk);

	// Free the node
	delNode(node);
}

u32 linearSpaceFree()
{
	return sLinearPool.GetFreeSpace();
}