df[1] = np.where(df[0].diff() > 0, df[0].diff(), df[0].shift() + 2**32 - df[0])

df = pd.DataFrame({'A': [20, 22, 25, 43, 23, 45, 67, 50, 70]})
df['result'] = df['A'].diff()
df['result'][ df['result'] < 0 ] += 2**32  # you can disregard the pandas warning

s1=np.array(df[0])
s=s1[1:]-s1[0:-1]
s[s<0]=s[s<0]+(2**32)