# Protocol Generator

Generate consistent, idiomatic communication protocol code from a JSON specification.  
Supports communication between embedded systems and host machines (e.g. ESP ↔ PC), with code generation for multiple languages like C and Go.

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## Overview

Define your messages once in a simple JSON format, and generate code to handle:
- Typed payload structs
- Message ID enums
- Dispatcher logic
- Send & receive helpers

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## Message Package Format

Currently, the protocol structure is statically defined as:
- `start_byte`
- `message_length`
- `payload`
- `checksum`

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## Message Definition Format (JSON)

Each message is described as:

```json
{
  "name": "Status",
  "id": "0xE2",
  "payload": [
    { "name": "clientid", "type": "uint8_t" },
    { "name": "mac", "type": "uint8_t[6]" }
  ]
}
```

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## Code Generation

### Current: C (ESP → PC)
- Header file with `MessageID` enums (`ESP_TO_PC`, `PC_TO_ESP`)
- Typed payload structs
- Union of all payloads
- Hook declarations for incoming messages
- Message dispatcher (switch on `MessageID`)
- Send functions per message

> Uses casting for payloads — fast but not fault-tolerant.

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### Planned: Go (PC → ESP)
- Generate constants for `MessageID`
- Define structs for payloads (consider endianess!)
- Dispatcher switch logic
- Hook functions
- Send functions
- Explore alternatives to unions (e.g., interfaces)

> Go is less constrained, so performance isn't the top priority.

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### Planned: ESP ↔ ESP (C, ESP-NOW)
- Separate enums for `MasterToSlave`, `SlaveToMaster`
- Shared payload format
- Union for all message types
- Dispatcher on `MessageID`
- Role-specific send functions

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## Implemented

- [x] Code-Generierung für C (ESP → PC)
  - [x] Header-Dateien mit Enums
  - [x] Payload-Structs
  - [x] Union-Typen
  - [x] Hook-Funktionen
  - [x] Message-Dispatcher (Switch-Case)
  - [x] Send-Funktionen
  - [x] Generate Header and Source File
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## To-Do

### Language Support: Go
- [ ] MessageID generation (`iota`)
- [ ] Payload structs
- [ ] Endianess handling
- [ ] Dispatcher
- [ ] Hooks & senders
- [ ] Union alternative

### ESP-to-ESP
- [ ] Master/Slave Message IDs
- [ ] Shared payload definitions
- [ ] Dispatcher & send logic

### Generator Features
- [ ] Direction config (`esp→pc`, etc.)
- [ ] Configurable package structure (e.g. `start_byte`, `checksum`)
- [ ] Field type aliases (`u8`, `uint8_t`, etc.)
- [ ] Support for optional fields / versioning

### JSON Format
- [ ] JSON schema for validation
- [ ] Field descriptions
- [ ] Global protocol settings (endianness, direction)
- [ ] Multi-message support

### Tooling
- [ ] CLI interface (`--input`, `--output`, `--language`, ...)
- [ ] Logging / verbose mode
- [x] Build script / Makefile

### Testing
- [ ] Unit tests for generator
- [ ] JSON test inputs (esp→pc, pc→esp, etc.)
- [ ] Golden files for regression testing
- [ ] Use Generated Code in actual Project

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## Roadmap Ideas
- Add checksum algorithm config
- Integration with code linters or CI