Introduction Writing fast, portable SIMD (Single Instruction, Multiple Data) code has always been painful - verbose intrinsics, platform differences, and a type system that fights you at every step. After three major iterations, the bx library now has a much more pleasant solution. The bx library has had SIMD support since its initial commit, originally in the form of float4_t. A later major update renamed float4_t to simd128_t and added generics for the register-width type.