D2/   D2*   S>D

D2/ ( d1 --- d2)

d2 is the result of shifting d1 one bit toward the least-significant bit, leaving the most-significant bit unchanged.

D2* ( d1 --- d2)

d2 is the result of shifting d1 one bit toward the most-significant bit, leaving the least-significant bit unchanged.

S>D ( n --- d)

Convert the number n to the double-cell number d with the same numerical value.