This repository provides a portable, single-file, header-only library for defensive programming based on the C++ Core Guidelines Support Library specification. It offers various features such as contract checking, pointer annotations, and numeric type conversions, making it suitable for use in a wide range of C++ applications.
lockfree is a header-only C++11 library providing lock-free data structures for concurrent programming. It offers both single-producer single-consumer (SPSC) and multi-producer multi-consumer (MPMC) variants of queues, ring buffers, bipartite buffers, and priority queues. The library is designed for use across a wide spectrum of systems from deeply embedded to HPC, featuring no dynamic allocation and optimized for high performance. Architecture-wise, it's organized into spsc/ and mpmc/ namespaces with each data structure having separate header and implementation files, aggregated through lockfree.hpp. The implementation uses atomic operations and clever algorithms to achieve lock-free behavior without mutexes.
ExprTk is a header-only C++ library for runtime mathematical expression parsing and evaluation. It provides a complete system for defining mathematical expressions as strings, compiling them into an internal AST representation, and evaluating them with variable values. The library supports scalar, vector, and string types, arithmetic operations, trigonometric functions, logarithms, control structures (if, for, while, switch), user-defined functions, and assignment operations within expressions. It employs sophisticated parsing techniques including constant folding, strength reduction optimizations, and runtime safety checks for vector bounds and loop execution time. The architecture consists of three main components: symbol table (for variables/constants/functions), expression (holding the parsed AST), and parser (compiling expression strings).
EFANNA is a header-only C++ library for approximate nearest neighbor (ANN) search. It builds an index combining a k-nearest neighbors graph and tree structures (KD-trees or hash tables) to enable efficient search on high-dimensional data. The library provides optimized distance computations with SSE/AVX intrinsics and a matrix class for SIMD-friendly data access. Key functionalities include index building, saving/loading indices, and performing ANN search via command-line examples or a MATLAB interface. The architecture is modular, with core algorithms in base_index.hpp and specialized index implementations in kdtreeub_index.hpp and hashing_index.hpp.
This repository provides a header-only library, NEON_2_SSE.h, that enables porting of ARM NEON intrinsics code to x86 platforms by mapping ARM NEON intrinsics to equivalent x86 SIMD intrinsics (SSE, AVX2, etc.). The library is designed to be used as a drop-in replacement for arm_neon.h when compiling for x86, allowing developers to write SIMD code using NEON intrinsics that can be compiled on both ARM and x86 without modification. The project includes a CMake-based build system for installation and packaging, and the header is self-contained, requiring only the target platform's compiler intrinsics headers. The codebase appears to be stale, with the latest copyright dates in the provided files (LICENSE, CMakeLists.txt) indicating updates up to 2020. The provided last commit date (2026-04-28) is invalid (future date), suggesting a data error, but the file copyrights imply no recent activity. The library focuses on compatibility up to AVX2 and does not show signs of technical drift, as it relies on stable compiler intrinsics interfaces. The primary value lies in the NEON_2_SSE.h header, which implements a non-trivial mapping between SIMD architectures.