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adder.py
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adder.py
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'''
!!!!!!!!!!! Don't us i for iterator !!!!!!!!!!!!!
#Basic halfAdder function
def hA(a,b):
s=a^b
c=a&b
return s,c
i=0 #input can also be 1 if i=o (see below); used in fA below
o=0 #the assignment is not important, will be overwritten by the fullAdder function
#Basic fullAdder function
def fA(a,b):
global i_, i_b, o_
i_b=i_
s1,c1=hA(a,b)
s2,c2=hA(i_,s1) #i is carry input
s=s2
o_=c2|c1 #o is carry output
i_=o_ #the output of a fullAdder can be used by the next fullAdder
return s #the o is not returned, it's already in global variable o
'''
#HalfAdder class
class HalfAdder(object):
def __init__(self,a,b):
self.a=a
self.b=b
#hA (halfAdder) function using input from __init__
def hA(self,a,b):
s=a^b
c=a&b
return s,c
#an instance of HalfAdder (scaffold)
'''HA11=HalfAdder(1,1)
print HA11.hA()
'''
class FullAdder(HalfAdder):
i_ = o_= i_b = 0 #initialize I/O of carry
def __init__(self,a,b):
self.a=a
self.b=b
def fA(self):
FullAdder.i_b = FullAdder.i_ #used as scaffold
s1,c1=self.hA(self.a, self.b)
s2,c2=self.hA(FullAdder.i_,s1)
s=s2 #optional (see line 50)
FullAdder.o_=c2|c1
FullAdder.i_=FullAdder.o_
return s
#an instance of FullAdder chain (scaffold)
'''
FA1=FullAdder(1,1)
FA2=FullAdder(1,1)
FA1.fA()
print FullAdder.i_b,FullAdder.o_
FA2.fA()
print FullAdder.i_b,FullAdder.o_
FA1.fA()
print FullAdder.i_b,FullAdder.o_
'''