39 lines
1.2 KiB
Plaintext
39 lines
1.2 KiB
Plaintext
sub half_add( byval a as ubyte, byval b as ubyte,_
|
|
byref s as ubyte, byref c as ubyte)
|
|
s = a xor b
|
|
c = a and b
|
|
end sub
|
|
|
|
sub full_add( byval a as ubyte, byval b as ubyte, byval c as ubyte,_
|
|
byref s as ubyte, byref g as ubyte )
|
|
dim as ubyte x, y, z
|
|
half_add( a, c, x, y )
|
|
half_add( x, b, s, z )
|
|
g = y or z
|
|
end sub
|
|
|
|
sub fourbit_add( byval a3 as ubyte, byval a2 as ubyte, byval a1 as ubyte, byval a0 as ubyte,_
|
|
byval b3 as ubyte, byval b2 as ubyte, byval b1 as ubyte, byval b0 as ubyte,_
|
|
byref s3 as ubyte, byref s2 as ubyte, byref s1 as ubyte, byref s0 as ubyte,_
|
|
byref carry as ubyte )
|
|
dim as ubyte c2, c1, c0
|
|
full_add(a0, b0, 0, s0, c0)
|
|
full_add(a1, b1, c0, s1, c1)
|
|
full_add(a2, b2, c1, s2, c2)
|
|
full_add(a3, b3, c2, s3, carry )
|
|
end sub
|
|
|
|
dim as ubyte s3, s2, s1, s0, carry
|
|
|
|
print "1100 + 0011 = ";
|
|
fourbit_add( 1, 1, 0, 0, 0, 0, 1, 1, s3, s2, s1, s0, carry )
|
|
print carry;s3;s2;s1;s0
|
|
|
|
print "1111 + 0001 = ";
|
|
fourbit_add( 1, 1, 1, 1, 0, 0, 0, 1, s3, s2, s1, s0, carry )
|
|
print carry;s3;s2;s1;s0
|
|
|
|
print "1111 + 1111 = ";
|
|
fourbit_add( 1, 1, 1, 1, 1, 1, 1, 1, s3, s2, s1, s0, carry )
|
|
print carry;s3;s2;s1;s0
|