LINEAR FEED BACK SHIFT REGISTERS

LINEAR FEED BACK SHIFT REGISTERS

Aim: The main aim of this project is to design a Barrel Shifter.

Block Diagram:

 

DESCRIPTION: 

A barrel shifter is a digital circuit that can shift a data word by a specified number of bits in one clock cycle. It can be implemented as a sequence of multiplexers (mux.), and in such an implementation the output of one mux. is connected to the input of the next mux. in a way that depends on the shift distance.

A common usage of a barrel shifter is in the hardware implementation of floating-point arithmetic. For a floating-point add or subtract operation, the significand of the two numbers must be aligned, which requires shifting the smaller number to the right, increasing its exponent, until it matches the exponent of the larger number. This is done by subtracting the exponents, and using the barrel shifter to shift the smaller number to the right by the difference, in one cycle. If a simple shifter were used, shifting by n bit positions would require n clock cycles.

A N-bit barrel shifter can shift left or right by N-1 bits. In general, barrel shifter can implement arithematic shifting, logical shifting and rotation functions. The input signals for a N-bit barrel shifter. 

REQUIRED COMPONENTS:

• FPGA
• XILINX ISE