Iris is a high-performance C inference engine for diffusion image generation models, specifically designed for FLUX.2 Klein (4B/9B) and Z-Image-Turbo (6B) architectures. It provides a complete pipeline from text encoding (Qwen3-4B/8B) through transformer denoising to VAE decoding, outputting PNG or PPM images. The system operates as both a standalone CLI tool with an interactive REPL and a C library (libiris.a), featuring memory-mapped weight loading for efficiency (~4-5GB peak for 4B model) and optional Metal GPU acceleration on Apple Silicon for significant speedups. The architecture is modular: separate components handle safetensors weight loading, BPE tokenization, transformer blocks (double/single stream for Flux, main/refiner for Z-Image), VAE decoding, and image I/O (PNG/JPEG/PPM). The CLI supports text-to-image, image-to-image, multi-reference generation, and various scheduling strategies (shifted sigmoid, linear, power). Memory optimization techniques include releasing the text encoder after embedding extraction, embedding caching with 4-bit quantization, and dynamic attention memory budgeting for reference images. The codebase demonstrates deep systems engineering and ML inference expertise, with hand-optimized kernels, custom Metal shaders, and detailed performance instrumentation. It is self-contained with no external dependencies beyond standard C libraries and optional BLAS/Metal, making it portable across Linux and macOS. The project includes regression test vectors and a JPEG decoder fuzzer, indicating a focus on correctness and reliability.
PMetal is a comprehensive machine learning framework specifically optimized for Apple Silicon hardware. It provides a complete suite for LLM training, fine-tuning, inference, and deployment through multiple interfaces (CLI, TUI, GUI, Python SDK, and REST API). The framework leverages Apple-specific technologies like Metal GPU, ANE, and UltraFusion for performance optimization while supporting standard ML workflows including LoRA/QLoRA fine-tuning, knowledge distillation, model merging, and quantization to formats like GGUF. The architecture follows a modular workspace design with over 20 specialized crates handling different aspects of the ML lifecycle, unified through a job specification system and configuration framework.