FSR-Tools: Feedback/Feedforward Shift Registers in Python

Designed to test FSR Mathematically for verification of Verilog Design. This package provides an abstract base class for Feedback/Feedforward Shift Registers (FSRs) and two concrete implementations:

• Fibonacci LFSR (linear feedback)
• Galois LFSR (linear feedforward)

Supports:

• Custom characteristic polynomials
• Arbitrary initial states
• State table generation
• Algebraic polynomial form
• Bitwise access to register positions

Installation

Clone the repo and place the module in your project:

git clone https://github.com/anubhav-narayan/fsr-tools.git

Use poetry

poetry install

Usage

General Usage

from fsr_tools import Galois_LFSR as LFSR

lfsr = LFSR(poly=0b10011, state=0b1010)

# Get full cycle of states
print(lfsr.state_table)
# Access bits
print(lfsr[0]) # Read a bit
lfsr[4] = lfsr[3] & 0b1 # Write a bit

Usage with CoCoTB

from fsr_tools import Galois_LFSR as LFSR
from cocotb import BinaryValue

lfsr = LFSR(poly=0b10011, state=0b1010)

# Assign state
dut.lfsr.value = BinaryValue(lfsr.state, n_bits=lfsr.field_order)

Extend the FSR Abstract Class to create custom Feedback/Feedforward Shift Registers. Just override the round function.