Writing a C preprocessor for bgfx shader compiler

Introduction For 14+ years, every shader that bgfx compiled, starting from the initial commit, went through a preprocessor written for the Amiga with origins in 1984:
fcpp - Frexx CPP (C Preprocessor)
This is a C preprocessor. It is a project based on public domain code, then forked by Daniel in 1993 and future work has been done under a BSD license.
That public domain code is the DECUS cpp, written by Martin Minow in 1984–85.