Barrel shifter

This section shows several simple HDL coding examples of commonly used building blocks such as RAMs, ROMs, barrel shifters and incrementors. Examples are provided in both VHDL and Verilog. 

Example 2.15 describes a barrel shifter which is capable of shift left or shift right based upon an input control signal. The width of the data bus is 3 bits and the shift coimt bus is S bits wide. Zeros are shifted in when shifting either right or left. 

Next, we will show that a practical circuit can be synthesized by describing hardware organization in SFL and using the basic synthesis mechanisms mentioned above. As there are no operators for add, multiply or shift in SFL syntax, an adder, multiplier and barrel shifter must be described in SFL at least once. Of course, the user can easily refer to these descriptions by name. Therefore, SFL can be used as if it had many built-in operators. 

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