Linear Feedback Shift Registers for the Uninitiated, Part II: libgf2 and Primitive Polynomials
Summary
This blog post explains how the libgf2 library represents and manipulates polynomials over GF(2) and how to pick and verify primitive polynomials for LFSRs. The reader will learn practical techniques for implementing, testing, and reasoning about LFSRs and related firmware uses such as CRCs and PRNGs.
Key Takeaways
- Use libgf2 to represent, multiply, divide, and factor polynomials over GF(2) in C.
- Select and verify primitive polynomials to guarantee maximal-length LFSR sequences.
- Implement efficient bitwise LFSR update routines suitable for constrained microcontrollers.
- Test LFSR properties (period, linear complexity) and integrate them into firmware test harnesses.
- Apply LFSR and GF(2) techniques to practical tasks such as CRC calculation and simple PRNGs.
Who Should Read This
Embedded firmware engineers or advanced students with some C experience who implement or analyze LFSRs, CRCs, or lightweight PRNGs on microcontrollers and want practical guidance on GF(2) polynomials and testing.
TimelessIntermediate
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