inav/docs/javascript_programming/GENERATE_CONSTANTS_README.md

INAV Constants Generator

Purpose

Generates inav_constants.js from the INAV firmware header file (logic_condition.h) to ensure the transpiler/decompiler constants exactly match the actual firmware.

Single Source of Truth Architecture

Firmware Header (logic_condition.h) ↓ (parse) Constants File (inav_constants.js) - AUTO-GENERATED ↓ (import) API Definitions (flight.js, etc.) - Reference constants ↓ (use) Transpiler & Decompiler - Use constants

Usage

Generate Constants

node scripts/generate-constants.js <path-to-logic_condition.h> [output-path]

Example

# From INAV configurator root
node scripts/generate-constants.js \
  ../inav/src/main/programming/logic_condition.h \
  js/transpiler/transpiler/inav_constants.js

Default Output

If output path is not specified, defaults to:

js/transpiler/transpiler/inav_constants.js

What It Parses

The parser extracts these enums from logic_condition.h:

1. logicOperation_e → OPERATION

   • TRUE, EQUAL, GREATER_THAN, etc.

2. logicOperandType_s → OPERAND_TYPE

   • VALUE, RC_CHANNEL, FLIGHT, etc.

3. logicFlightOperands_e → FLIGHT_PARAM

   • ARM_TIMER, HOME_DISTANCE, RSSI, YAW, etc.

4. logicFlightModeOperands_e → FLIGHT_MODE

   • FAILSAFE, MANUAL, RTH, etc.

5. logicWaypointOperands_e → WAYPOINT_PARAM

   • IS_WP, WAYPOINT_INDEX, etc.

Generated File Format

/**
 * AUTO-GENERATED from firmware header files
 * DO NOT EDIT MANUALLY
 */

const OPERAND_TYPE = {
  VALUE: 0,
  RC_CHANNEL: 1,
  FLIGHT: 2,
  // ...
};

const OPERATION = {
  TRUE: 0,
  EQUAL: 1,
  // ...
};

const FLIGHT_PARAM = {
  ARM_TIMER: 0,
  HOME_DISTANCE: 1,
  // ...
  YAW: 40,  // ← Correct value from firmware!
  // ...
};

// ... exports

Build Integration

Add to package.json scripts:

{
  "scripts": {
    "generate-constants": "node scripts/generate-constants.js ../inav/src/main/programming/logic_condition.h",
    "prebuild": "npm run generate-constants"
  }
}

This ensures constants are regenerated before each build.

Next Steps: Update API Definitions

Currently, API definitions have hardcoded values:

// inav.flight.js - WRONG (hardcoded)
yaw: {
  inavOperand: { type: 2, value: 17 }  // Wrong value!
}

Change to reference constants:

// inav.flight.js - CORRECT (references constants)
const { OPERAND_TYPE, FLIGHT_PARAM } = require('../../transpiler/inav_constants.js');

yaw: {
  inavOperand: { type: OPERAND_TYPE.FLIGHT, value: FLIGHT_PARAM.ATTITUDE_YAW }
}

Benefits:

• ✅ Single source of truth (firmware)
• ✅ Type-safe references
• ✅ Compile-time errors if constants missing
• ✅ Auto-update when firmware changes

Verification

After generating, verify key values:

grep "ATTITUDE_YAW" js/transpiler/transpiler/inav_constants.js
# Should show: ATTITUDE_YAW: 40,

grep "IS_ARMED" js/transpiler/transpiler/inav_constants.js  
# Should show: IS_ARMED: 17,

Error Handling

The parser handles:

• ✅ Both typedef enum { } name_e; and typedef enum name { } formats
• ✅ Explicit values (= 40)
• ✅ Auto-incrementing values
• ✅ Hex values (= 0x10)
• ✅ C-style comments (// and /* */)
• ✅ Missing enums (warns but continues)

Maintenance

When INAV firmware updates:

1. Get new logic_condition.h from firmware repo
2. Run npm run generate-constants
3. Review diff in inav_constants.js
4. Test transpiler/decompiler
5. Commit updated constants file

DO NOT manually edit inav_constants.js - all changes will be overwritten!