Shift & Bit Manipulation

Byte Rotate 32-bit

Combinational module that rotates a 32-bit word by 0 to 3 bytes.

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Byte Rotate 32-bit is a Verilog reference block in the Shift & Bit Manipulation catalog. Shifters, rotators, bit masks, and bitwise manipulation blocks. Marked Easy: a small block you can read, simulate, and synthesize in one sitting.

This IP rotates the four bytes of a 32-bit word by a specified count. It supports rotation amounts from 0 to 3 bytes. The implementation uses combinational logic for high throughput. The shift amount is controlled by a 2-bit input signal.

This module provides a simple and efficient byte rotation for 32-bit data. It is suitable for data packing and unpacking applications. The design is fully combinational and easy to integrate.

Choose Open in IDE. RTL Studio loads the packaged workspace for Byte Rotate 32-bit.
Read the Verilog module in the editor. The catalog line for this block: Combinational module that rotates a 32-bit word by 0 to 3 bytes.
Run the packaged testbench with the in-browser Verilator simulator, then open the VCD in the waveform viewer.
Run Yosys in the same IDE for a generic netlist. Sky130 liberty mapping is a separate Pro library option.

RTL Studio is the Verilog simulator and IDE around this block: Slang lint, Verilator, VCD waveforms, and Yosys, in the browser. Simulation guide · Yosys guide.

Features

Rotates 32-bit data by 0, 1, 2, or 3 bytes.
Pure combinational logic with no clock dependency.
Supports arbitrary 32-bit input values.
Verified with comprehensive testbench cases.

Ports

Port Name	Direction	Width	Description
data_in	Input	32	Input data word to be rotated
shift_bytes	Input	2	Number of bytes to rotate right (0-3)
data_out	Output	32	Rotated output data word

Verification

The testbench covers all rotation counts and edge cases. All seven test cases passed successfully.

Test Case	Input Data	Shift Bytes	Expected Output	Result
TC1	0xFDEADBEEF	0	0xFDEADBEEF	PASS
TC2	0xFDEADBEEF	1	0xEEFDEADB	PASS
TC3	0xFDEADBEEF	2	0xDBEEFDEA	PASS
TC4	0xFDEADBEEF	3	0xEADBEEFD	PASS
TC5	0x12345678	1	0x78123456	PASS
TC6	0x00000000	1	0x00000000	PASS
TC7	0xFFFFFFFF	3	0xFFFFFFFF	PASS

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