#!/usr/bin/python

class Caretaker:
	
	def __init__(self):
		self.objects=dict() # Create empty objects pool
		# Add registers to pool
		for reg in ["MAR","MDR", "PC", "MBR", "SP","LV","CPP","TOS","OPC","H"]:
			self.objects[reg]=0
		self.objects["RAM"]=None
	
	def __getitem__(self,key):
		if key=="MBRU": # If we ask for unsigned
			return(abs(self.objects["MBR"]))
		elif key== "MBR":
			if (self.objects[key]>>7)==1: # If it a negative number (2 complement)
				return(-((self.objects[key]-1)^0xFF)) # transforme bin negative number to python negative number
			else:
				return(self.objects[key])
		return(self.objects[key])

	def __setitem__(self,key,value):
		if key!="RAM":
			if value > (2**32) and key!="MBR" and key!="MBRU": # Check value fit in word
				print("Warning word overflow: value {} on register {}".format(value,key))
				value=value%(2**32) # Force to fit in word
			elif value > (2**8) and key=="MBR" and key=="MBRU": # Check value fit in byte
				print("Warning byte overflow: value {} on register {}".format(value,key))
				value=value%256 # Force to fit in byte
		self.objects[key]=value
		
	def items(self):
		return(self.objects.items())