C-From-Scratch

Learn to build safety-critical systems in C.

Not "Hello World". Real kernels. Mathematical rigour. Zero dependencies.

"Don't learn to code. Learn to prove, then transcribe."

Philosophy

Most tutorials teach you to write code that seems to work.
This course teaches you to write code that provably works.

The method:

1. Define the problem precisely
2. Prove correctness mathematically
3. Design structs that embody the proof
4. Code (it writes itself)
5. Test against the contracts

┌─────────────────────────────────────────────────────────────┐
│                    THE APPROACH                             │
├─────────────────────────────────────────────────────────────┤
│                                                             │
│   Problem  ──►  Math Model  ──►  Proof  ──►  Structs        │
│                                                │            │
│                                                ▼            │
│                           Verification  ◄──  Code           │
│                                                             │
└─────────────────────────────────────────────────────────────┘

Projects

Module 1: Pulse — Heartbeat Liveness Monitor

"Does something exist in time?"

A tiny, provably-correct state machine that answers: "Is this process alive?"

• 5 lessons from problem definition to hardened code
• ~200 lines of C with mathematical proofs
• Handles clock wrap, faults, and edge cases
• Zero dependencies beyond libc

Contracts proven: Soundness, Liveness, Stability

---

Module 2: Baseline — Statistical Normality Monitor

"Is what's happening normal?"

A closed, total, deterministic FSM for detecting statistical anomalies in scalar streams.

• 6 lessons from problem statement to composition
• EMA-based anomaly detection with O(1) memory
• 18 contract and invariant tests
• Composes with Pulse for timing anomaly detection

Contracts proven: Convergence, Sensitivity, Stability, Spike Resistance

---

Coming Next: Module 3 — Composition

Pulse + Baseline = Timing Anomaly Detector

event_t → Pulse → Δt → Baseline → deviation?

The Big Picture

Module	Question	Output
Pulse	Does something happen?	Yes / No
Baseline	Is what's happening normal?	Degree of deviation
Composition	Is the system healthy?	Proof-carrying signal

Each module is:

• Closed — State depends only on previous state + input
• Total — Always returns a valid result
• Bounded — O(1) memory, O(1) compute
• Deterministic — Same inputs → same outputs
• Contract-defined — Behaviour is specified, not implied

Who This Is For

• Developers who want to understand why code works, not just that it works
• Systems programmers building safety-critical software
• Anyone tired of "it works on my machine" engineering
• Students who want to learn C the right way

Prerequisites

• Basic C syntax (variables, functions, structs)
• Comfort with command line
• Willingness to think before coding

Getting Started

# Module 1: Pulse
cd projects/pulse
make
make demo
make test

# Module 2: Baseline
cd projects/baseline
make
make demo
make test

Then start with Pulse Lesson 1: The Problem.

Author

William Murray — 30 years UNIX systems engineering

• GitHub: @williamofai
• LinkedIn: William Murray
• Website: speytech.com

License

MIT — See LICENSE