First attempt at removing StackUtil.

common/buildcraft/core/inventory/Transactor.java

@@ -0,0 +1,32 @@
+package buildcraft.core.inventory;
+
+import buildcraft.api.core.Orientations;
+import buildcraft.api.inventory.ISpecialInventory;
+import net.minecraft.src.IInventory;
+import net.minecraft.src.ItemStack;
+import net.minecraftforge.common.ISidedInventory;
+
+public abstract class Transactor {
+
+	public ItemStack add(ItemStack stack, Orientations orientation, boolean doAdd) {
+		ItemStack added = stack.copy();
+		added.stackSize = inject(stack, orientation, doAdd);	
+		return added;
+	}
+	
+	public abstract int inject(ItemStack stack, Orientations orientation, boolean doAdd);
+	
+	public static Transactor getTransactorFor(Object object) {
+		
+		if(object instanceof ISpecialInventory)
+			return new TransactorSpecial((ISpecialInventory)object);
+		
+		else if(object instanceof ISidedInventory)
+			return new TransactorSided((ISidedInventory)object);
+		
+		else if(object instanceof IInventory)
+			return new TransactorSimple((IInventory)object);
+		
+		return null;
+	}
+}

common/buildcraft/core/inventory/TransactorSided.java

@@ -0,0 +1,33 @@
+package buildcraft.core.inventory;
+
+import buildcraft.api.core.Orientations;
+import net.minecraft.src.ItemStack;
+import net.minecraftforge.common.ISidedInventory;
+
+public class TransactorSided extends TransactorSimple {
+
+	ISidedInventory sided;
+	
+	public TransactorSided(ISidedInventory inventory) {
+		super(inventory);
+		this.sided = inventory;
+	}
+
+	@Override
+	protected int getPartialSlot(ItemStack stack, Orientations orientation, int skipAhead) {
+		
+		if(skipAhead < sided.getStartInventorySide(orientation.toDirection())
+				|| skipAhead > sided.getStartInventorySide(orientation.toDirection()) + sided.getSizeInventorySide(orientation.toDirection()))
+			return -1;
+		
+		return getPartialSlot(stack, skipAhead, sided.getStartInventorySide(orientation.toDirection()) + sided.getSizeInventorySide(orientation.toDirection()));
+	}
+	
+	@Override
+	protected int getEmptySlot(Orientations orientation) {
+		return getEmptySlot(sided.getStartInventorySide(orientation.toDirection()),
+				sided.getStartInventorySide(orientation.toDirection()) + sided.getSizeInventorySide(orientation.toDirection()));
+	}
+	
+
+}

common/buildcraft/core/inventory/TransactorSimple.java

@@ -0,0 +1,95 @@
+package buildcraft.core.inventory;
+
+import net.minecraft.src.IInventory;
+import net.minecraft.src.ItemStack;
+import buildcraft.api.core.Orientations;
+
+public class TransactorSimple extends Transactor {
+
+	private IInventory inventory;
+	
+	public TransactorSimple(IInventory inventory) {
+		this.inventory = inventory;
+	}
+	
+	@Override
+	public int inject(ItemStack stack, Orientations orientation, boolean doAdd) {
+		
+		int injected = 0;
+		
+		int slot = 0;
+		while((slot = getPartialSlot(stack, orientation, slot)) >= 0
+				&& injected < stack.stackSize)
+			injected += addToSlot(slot, stack, injected, doAdd);
+
+		slot = 0;
+		while((slot = getEmptySlot(orientation)) >= 0
+				&& injected < stack.stackSize)
+			injected += addToSlot(slot, stack, injected, doAdd);
+		
+		return injected;
+	}
+	
+	protected int getPartialSlot(ItemStack stack, Orientations orientation, int skipAhead) {
+		return getPartialSlot(stack, skipAhead, inventory.getSizeInventory());
+	}
+	
+	protected int getPartialSlot(ItemStack stack, int startSlot, int endSlot) {
+
+		for(int i = startSlot; i < endSlot; i++) {
+			if(inventory.getStackInSlot(i) == null)
+				continue;
+			
+			if(!inventory.getStackInSlot(i).isItemEqual(stack))
+				continue;
+			
+			if(inventory.getStackInSlot(i).stackSize >= inventory.getStackInSlot(i).getMaxStackSize())
+				continue;
+			
+			return i;
+		}
+	
+		return -1;
+	}
+
+	protected int getEmptySlot(Orientations orientation) {
+		return getEmptySlot(0, inventory.getSizeInventory());
+	}
+	
+	protected int getEmptySlot(int startSlot, int endSlot) {
+		for(int i = startSlot; i < endSlot; i++)
+			if(inventory.getStackInSlot(i) == null)
+				return i;
+		
+		return -1;
+	}
+	
+	protected int addToSlot(int slot, ItemStack stack, int injected, boolean doAdd) {
+		int remaining = stack.stackSize - injected;
+		
+		if(inventory.getStackInSlot(slot) == null) {
+			if(doAdd) {
+				inventory.setInventorySlotContents(slot, stack.copy());
+				inventory.getStackInSlot(slot).stackSize = remaining;
+			}
+			return remaining;
+		}
+		
+		if(!inventory.getStackInSlot(slot).isItemEqual(stack))
+			return 0;
+		
+		int space = inventory.getStackInSlot(slot).getMaxStackSize() - inventory.getStackInSlot(slot).stackSize;
+		if(space <= 0)
+			return 0;
+		
+		if(space >= remaining) {
+			if(doAdd)
+				inventory.getStackInSlot(slot).stackSize += remaining;
+			return remaining;
+		} else {
+			if(doAdd)
+				inventory.getStackInSlot(slot).stackSize = inventory.getStackInSlot(slot).getMaxStackSize();
+			return space;
+		}
+	}
+}

common/buildcraft/core/inventory/TransactorSpecial.java

@@ -0,0 +1,20 @@
+package buildcraft.core.inventory;
+
+import net.minecraft.src.ItemStack;
+import buildcraft.api.core.Orientations;
+import buildcraft.api.inventory.ISpecialInventory;
+
+public class TransactorSpecial extends Transactor {
+
+	protected ISpecialInventory inventory;
+	
+	public TransactorSpecial(ISpecialInventory inventory) {
+		this.inventory = inventory;
+	}
+	
+	@Override
+	public int inject(ItemStack stack, Orientations orientation, boolean doAdd) {
+		return inventory.addItem(stack, doAdd, orientation);
+	}
+
+}

common/buildcraft/factory/TileAssemblyTable.java

@@ -148,7 +148,6 @@ public class TileAssemblyTable extends TileEntity implements IMachine, IInventor
 				}
 
 				StackUtil stackUtils = new StackUtil(currentRecipe.output.copy());
-
 				boolean added = stackUtils.addToRandomInventory(this, Orientations.Unknown);
 
 				if (!added || stackUtils.items.stackSize > 0) {

common/buildcraft/transport/PipeTransportItems.java

@@ -28,10 +28,10 @@ import buildcraft.api.transport.IPipedItem;
 import buildcraft.core.DefaultProps;
 import buildcraft.core.EntityPassiveItem;
 import buildcraft.core.IMachine;
+import buildcraft.core.inventory.Transactor;
 import buildcraft.core.network.PacketIds;
 import buildcraft.core.network.PacketPipeTransportContent;
 import buildcraft.core.proxy.CoreProxy;
-import buildcraft.core.utils.StackUtil;
 import buildcraft.core.utils.Utils;
 
 import net.minecraft.src.EntityItem;
@@ -152,7 +152,7 @@ public class PipeTransportItems extends PipeTransport {
 
 			return pipe.pipe.transport instanceof PipeTransportItems;
 		} else if (entity instanceof IInventory)
-			if (new StackUtil(item.getItemStack()).checkAvailableSlot((IInventory) entity, false, o.reverse()))
+			if(Transactor.getTransactorFor(entity).add(item.getItemStack(), o.reverse(), false).stackSize > 0)
 				return true;
 
 		return false;
@@ -255,13 +255,13 @@ public class PipeTransportItems extends PipeTransport {
 
 			((PipeTransportItems) pipe.pipe.transport).entityEntering(data.item, data.orientation);
 		} else if (tile instanceof IInventory) {
-			StackUtil utils = new StackUtil(data.item.getItemStack());
+			ItemStack added = Transactor.getTransactorFor(tile).add(data.item.getItemStack(), data.orientation.reverse(), true);
 
 			if (!CoreProxy.proxy.isRemote(worldObj))
-				if (utils.checkAvailableSlot((IInventory) tile, true, data.orientation.reverse()) && utils.items.stackSize == 0)
+				if(added.stackSize >= data.item.getItemStack().stackSize)
 					data.item.remove();
 				else {
-					data.item.setItemStack(utils.items);
+					data.item.getItemStack().stackSize -= added.stackSize;
 					EntityItem dropped = data.item.toEntityItem(data.orientation);
 
 					if (dropped != null)