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AztecLib Project Status

Version: 1.0.1

This document describes the current implementation status, ISO compliance, and known limitations.

Overview

AztecLib is a pure Swift implementation of Aztec 2D barcode encoding per ISO/IEC 24778. The library generates Aztec symbols that are fully compatible with standard barcode decoders including ZXing and Apple's Vision framework.

Implementation Status

Completed Features

Feature Status Notes
Compact symbols (1-4 layers) ✅ Complete 15x15 to 27x27 modules
Full symbols (4-32 layers) ✅ Complete 31x31 to 151x151 modules
Text encoding modes ✅ Complete Upper, Lower, Mixed, Punct, Digit
Binary/Byte mode ✅ Complete Short (1-31 bytes) and long (32+ bytes) forms
Mode transitions ✅ Complete Latch and shift with cost-based optimization
Reed-Solomon encoding ✅ Complete GF(2^6), GF(2^8), GF(2^10), GF(2^12)
Mode message encoding ✅ Complete RS-protected nibble encoding
Finder pattern ✅ Complete 9x9 (compact) and 13x13 (full)
Reference grid ✅ Complete For full symbols with large layer counts
Data placement ✅ Complete Clockwise spiral with layer mapping
Codeword stuffing ✅ Complete Bit stuffing to avoid all-0/all-1 patterns
Configurable error correction ✅ Complete 5-95% error correction percentage
SwiftUI views ✅ Complete AztecSymbolView and AztecCodeView

Encoding Pipeline

The library implements the full 6-step Aztec encoding pipeline:

  1. Data Encoding - Converts input to bits using optimal mode selection
  2. Configuration Selection - Picks smallest symbol fitting payload + EC
  3. Codeword Packing - Packs bits with stuff bits per ISO spec
  4. Reed-Solomon Encoding - Adds parity codewords for error correction
  5. Matrix Building - Assembles finder, mode message, grid, and data
  6. Export - Outputs packed bitmap with configurable bit ordering

ISO/IEC 24778 Compliance

Compliant Areas

Specification Compliance Reference
Symbol structure ✅ Compliant ISO 24778 §7.1
Finder pattern ✅ Compliant ISO 24778 §7.2
Orientation pattern ✅ Compliant ISO 24778 §7.3
Mode message ✅ Compliant ISO 24778 §7.4
Reference grid ✅ Compliant ISO 24778 §7.5
Data region ✅ Compliant ISO 24778 §7.6
Character encoding ✅ Compliant ISO 24778 §8 (Tables 2-6)
Codeword stuffing ✅ Compliant ISO 24778 §9
Reed-Solomon codes ✅ Compliant ISO 24778 §10
Primitive polynomials ✅ Compliant ISO 24778 Annex A

Character Encoding Tables

The library implements all five text modes per ISO 24778:

  • Upper mode (5 bits): Space + A-Z (codes 1-27)
  • Lower mode (5 bits): Space + a-z (codes 1-27)
  • Mixed mode (5 bits): Control characters + special symbols (@, , ^, _, `, |, ~)
  • Punct mode (5 bits): Punctuation (!, ", #, $, %, etc.) + two-char sequences
  • Digit mode (4 bits): Space + 0-9 + comma + period

Primitive Polynomials (per ISO 24778 Annex A)

Field Polynomial Usage
GF(2^6) 0x43 (x^6 + x + 1) Compact symbols
GF(2^8) 0x12D (x^8 + x^5 + x^3 + x^2 + 1) Full L1-L8
GF(2^10) 0x409 (x^10 + x^3 + 1) Full L9-L22
GF(2^12) 0x1069 (x^12 + x^6 + x^5 + x^3 + 1) Full L23-L32

Validation

ZXing Compatibility

The library has been validated against ZXing (the reference Aztec implementation):

Test Case Result
"Hello" encoding ✅ Identical output
"123" encoding ✅ Identical output
"Mixed123Content!@#" ✅ Identical output
Binary data (5 bytes) ✅ ZXing decodes correctly
Binary data (128 bytes) ✅ ZXing decodes correctly
Large payloads (366 bytes) ✅ ZXing decodes correctly

Test Suite Results

The library passes comprehensive validation testing against multiple decoders:

  • Apple Vision framework
  • zxing-cpp

Future Enhancements

The following features are planned for future releases:

  1. Decoder implementation: Add Aztec decoding support (currently encode-only)

  2. Structured Append: Support for multi-symbol encoding of large payloads

  3. FNC1 support: Add support for GS1 Aztec Code format

  4. Reader Initialization: Add support for reader programming symbols

  5. Performance optimization: Profile and optimize for large symbols

Last updated: January 2026 (v1.0.1)