private KMemoryBlock SplitBlock(KMemoryBlock block, uint address, uint size)
{
Debug.Assert(size > 0);
KMemoryBlock newBlock = new KMemoryBlock(this, address, size, false);
LinkedListEntry <KMemoryBlock> blockEntry = Blocks.Find(block);
Debug.Assert(blockEntry != null);
if (address == block.Address)
{
// Bottom up - put right before free and shift free up
block.Address += size;
block.Size -= size;
Blocks.InsertBefore(newBlock, blockEntry);
}
else if (address == block.UpperBound - size)
{
// Top down - put right after and free shift free down
block.Size -= size;
Blocks.InsertAfter(newBlock, blockEntry);
}
else
{
// Middle - need a real split
uint originalSize = block.Size;
block.Size = newBlock.Address - block.Address;
if (block.Size == 0)
{
// Special case of block replacing block
Blocks.InsertAfter(newBlock, blockEntry);
// block will be removed below
}
else
{
uint freeAddress = newBlock.Address + newBlock.Size;
uint freeSize = originalSize - block.Size - newBlock.Size;
KMemoryBlock freeBlock = new KMemoryBlock(this, freeAddress, freeSize, true);
// Add free space after start block if needed
if (freeSize > 0)
{
LinkedListEntry <KMemoryBlock> blockEntryFree = FreeList.Find(block);
Blocks.InsertAfter(freeBlock, blockEntry);
FreeList.InsertAfter(freeBlock, blockEntryFree);
}
// Add after the block (but before the freeBlock if there was one)
Blocks.InsertAfter(newBlock, blockEntry);
}
}
Debug.Assert(block.Size >= 0);
// Remove old block if dead
if (block.Size == 0)
{
Blocks.Remove(blockEntry);
FreeList.Remove(block);
}
return(newBlock);
}