Reversible Barrel Shifter and Shift Register
Hafiz Md. Hasan Babu · 2020
This chapter describes the design of an n-bit reversible bidirectional barrel shifter. In the reversible bidirectional barrel shifter the 2's complement of a binary number can be calculated in two steps: finding 1's complement by complementing each bit, and adding 1 to the least-significant-bit position. The chapter presents an algorithm to generate 2's complement of log n-bit select input of an n-bit barrel shifter. To synthesize reversible memory circuits, reversible sequential circuits such as shift registers are very essential. A shift register consists of a group of flip-flops connected together so that information bits can be shifted from one position to either right or left depending on the design of the device. The chapter introduces several types of shift registers including serial-in serial-out (SISO), serial-in parallel-out (SIPO), parallel-in serial-out (PISO), parallel-in parallel-out (PIPO) and universal shift registers.