libcstruct-ocaml-dev 6.0.0-1build1 (arm64 binary) in ubuntu hirsute

 Cstruct is a library and syntax extension to make it easier to access
 C-like structures directly from OCaml. It supports both reading and
 writing to these structures, and they are accessed via the Bigarray
 module.
 .
 This package contains the development stuff needed to use the
 cstruct library in your programs.