This repository provides a high-performance, header-only C++11 library implementing a lock-free, wait-free single-producer single-consumer (SPSC) queue (ReaderWriterQueue) and a blocking variant (BlockingReaderWriterQueue). The core design uses a queue-of-blocks architecture with circular buffers to minimize memory allocation and contention. It also includes a fixed-size blocking circular buffer (BlockingReaderWriterCircularBuffer) with support for timed waits. The library is built on top of a portable atomic operations layer (atomicops.h) that abstracts memory barriers, compiler fences, and a lightweight semaphore across Windows, macOS, Linux, and FreeRTOS. The code demonstrates exceptional attention to cache-line padding, memory ordering, and elimination of false sharing, making it suitable for ultra-low-latency inter-thread communication. It is extensively tested with unit tests and stability tests, and includes benchmarks comparing performance against other SPSC queues such as Dmitry Vyukov's and Facebook's folly. The library is single-purpose, self-contained, and easily integrable into any C++ project via drop-in headers or CMake FetchContent.