16 BIT BARREL SHIFTER A Mini Project Report

16 -BIT BARREL SHIFTER A Mini Project Report Submitted in the partial fulfillment of the requirements for the award of the Degree of Bachelor of Technology ELECTRONICS AND COMMUNICATION ENGINEERING Under the guidance of ( MR S. V. S. PRASAD ) Submitted by G. SHYAMKUMAR (08 E 31 A 0458) G. RAMESH (08 R 21 A 0499) P. PARDTHASARADHI (08 R 21 A 0487)

Abstract � A barrel shifter is a digital circuit that can shift a data word by a specified number of bits in one clock cycle. � The number of multiplexers required for an n-bit word is n X log 2(n) � The shifter works by shifting the bits left. � Inputs: Data bits D 0 -D 7 & encoded Select lines S 2, S 1, S 0. � Outputs: Shifted Data bits Q 0 – Q 7. � Implementation Technology : 0. 6 micron process. � A barrel shifter, comprising: an n-bit by n-bit transistor array arranged into n rows and n columns

8 Bit Barrel Shifter Block Diagram data(16 - bits) clk rst dataout(16 bits load_shift no. of bits to be shifted(16 bit BARREL SHIFTER 3

FUNCTION OF BARREL SHIFTER Each shifter will be designed as a 16 -bit shifter that receives a 16 -bit input data value along with a two’s compliment encoded shift value, and will produce a 16 - bit shifted result. This section will describe the internal design characteristics for each shifter. 4

Introduction to barrel shifter A hardware device that can shift or rotate a data word by any number of bits in a single operation. It is implemented like a {multiplexer}, each output can be connected to any input depending on the shift distance Four common word sizes and the number of multiplexers needed are listed below: 64 -bit — 64 * log 2(64) = 64 * 6 = 384 32 -bit — 32 * log 2(32) = 32 * 5 = 160 16 -bit — 16 * log 2(16) = 16 * 4 = 64 8 -bit — 8 * log 2(8) = 8 * 3 = 24 5

Simulations 6

Project Summary �We designed a 16 bit Barrel Shifter that shifts data from an input to an output depending on the combination of three select lines. �Our design of the Barrel shifter allows for an increase in the number of input bits without having to modify the existing design. �Our design met the specifications for the project. 7

Applications of barrel shifter Digital Signal Processing Array Processing Graphics Database Addressing High Speed Arithmetic Processors 8

Summary �Our project was a worthwhile endeavor as not many people know what a barrel shifter is and what it is used for. As such, doing it and presenting it to the class has helped to enlighten our classmates. �Most importantly we got our circuit design to work and meet specification as we have ably shown in our presentation. �We believe that our circuit can become a stepping stone to improving computer organization and memory. 9

CONCLUSION Hence we have designed the IP Core for Barrel Shifter using VHDL. The simulation has been done using ISE Simulator. The synthesis has been done using XILINX ISE 9. 1 i. The bit file has been generated and the output is dumped on the FPGA Device (Spartan 3 E). 10

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