prerequisites

• A C compiler

Steps

0. cargo new crc-in-c and cd crc-in-c

1. Copy crc.c and crc.h

2. Add the cc build dependency, by adding to Crate.toml the lines:

   [build-dependencies]
   cc = "1.0"

3. Create build.rs with contents

   extern crate cc;
   
   fn main() {
       cc::Build::new().file("crc32.c").compile("crc32.a");
   }

   This will find your c code, compile it, and link it into the executable rust produces

4. Define an extern (fill in the argument and return types)

   extern "C" {
       fn CRC32( ... ) -> ...; // hint: https://doc.rust-lang.org/std/os/raw
   }

5. Create a rust wrapper that calls the extern function

   fn crc32( ... ) -> ... { 
       ... // (hints: `unsafe`, `.as_ptr()`, `.len()`)
   }

6. Call our wrapper on some example input

   fn main() {
       println!("{}", crc32(b"12345678"));
   }