libgnss-codes

libgnss-codes-swift

A modern, type-safe Swift 6.0 library for generating GNSS ranging codes across multiple constellations.

This project is a high-performance port of the Oriental AI C library.

Features

• Swift-Native Architecture: Built from the ground up for Swift 6.0, leveraging enums for type safety and Swift Package Manager (SPM) for seamless integration.
• Multi-Constellation Support:
  • GPS: L1 C/A, L1C (Pilot/Data/Overlay), L2C (CM/CL), L5 (I/Q)
  • Galileo: E1B/C, E5a (I/Q), E5b (I/Q)
  • GLONASS: G1 (C/A)
  • BeiDou: B1I
• Memory Safe: Replaces manual C memory management with Swift’s automatic memory management and safe array buffers.
• Bit-Perfect Parity: Verified against the original C library and reference Matlab data.
• Rich Documentation: Integrated DocC support for browsable API documentation.

Quick Start

Installation

Add the package to your Package.swift dependencies:

dependencies: [
    .package(url: "https://github.com/shuwang1/libgnss-codes-swift.git", from: "1.0.0")
]

Basic Usage

import GNSSCodes

// Generate GPS L1 C/A chips for PRN 1
if let code = GNSSCodes.generate(prn: 1, type: .L1CA) {
    print("Signal: GPS L1 C/A")
    print("Length: \(code.length) chips")
    print("Rate: \(code.chipRate / 1e6) MHz")
    print("First 5 chips: \(code.chips.prefix(5))")
}

// Generate Galileo E1B chips for PRN 10
if let galileo = GNSSCodes.generate(prn: 10, type: .E1B) {
    // Process Galileo chips...
}

Documentation & Testing

• Installation & Setup: See INSTALL.md for detailed setup and build instructions.
• Verification: Run swift test to execute the comprehensive test suite.
• API Reference: Generate documentation with swift package generate-documentation.
• CI/CD: Automated builds and tests are performed via GitHub Actions on every push to main. Documentation is automatically deployed to GitHub Pages.

Known Issues & Future Work

• SIMD Optimization: Currently, chips are represented as [Int16]. Transitioning to bit-packed [UInt64] with SIMD-accelerated correlation is planned for a future release.
• Extended Constellation Support: Porting of additional signals (e.g., L1 SBAS, NH10/20 integration) is ongoing.
• Resource Management: Galileo binary resources are currently bundled. Exploring dynamic downloading or more compact packing formats to reduce initial clone size.

License

2016 All Rights Reserved by Shu Wang shuwang1@outlook.com This project is licensed under the same terms as the original libgnss-codes library. See the LICENSE file (if available) or contact Shu Wang shuwang1@outlook.com.

Credits

Original C implementation by Shu Wang. Swift port and optimization developed as part of Orientable AI internel C project.

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