This package provides a header-only version of the HIIR library by Laurent De Soras, updated to version 1.40. HIIR is a C++ library for changing the sampling rate of a signal by a factor two, in both directions (upsampling and downsampling), obtaining two signals with a π/2 phase difference (Hilbert transform). It is made of a two-path polyphase IIR filter, implemented with FPU, 3DNow!, SSE, SSE2, AVX, AVX-512 and NEON instruction sets.

This package contains the same as the original library, except with the contents of one source file moved into a header file (and set as inline) to make the library header-only, and with the test folder removed.