extend installation instructions, fix perm

README.md

@@ -5,7 +5,7 @@
 [![docs.rs](https://img.shields.io/docsrs/servicepoint_binding_c)](https://docs.rs/servicepoint/latest/servicepoint/)
 [![GPLv3 licensed](https://img.shields.io/crates/l/servicepoint_binding_c)](../LICENSE)
 
-In [CCCB](https://berlin.ccc.de/), there is a big pixel matrix hanging on the wall. 
+In [CCCB](https://berlin.ccc.de/), there is a big pixel matrix hanging on the wall.
 It is called  "Service Point Display" or "Airport Display".
 
 This crate contains C bindings for the `servicepoint` library, enabling users to parse, encode and send packets to this display via UDP.
@@ -43,21 +43,46 @@ Please specify the full version including patch in your Cargo.toml until 1.0 is
 
 ## Installation
 
-Copy the header to your project and compile against.
+1. Add this repo as a submodule:
+    ```bash
+    git submodule add https://git.berlin.ccc.de/servicepoint/servicepoint-binding-c.git
+    git commit -m "add servicepoint-binding-c submodule"
+    ```
+2. Add a build step for the servicepoint library. If you use make, this could look something like this:
+    ```
+    dependencies: FORCE
+    	cargo build --manifest-path=servicepoint-binding-c/Cargo.toml --release
+    FORCE: ; 
+    ```
+3. Link against the library. If you are on linux and linking statically:
+    ```
+    ${CC} main.c \
+    	-I servicepoint-binding-c/include \
+    	-L servicepoint-binding-c/target/release \
+    	-Wl,-Bstatic -lservicepoint_binding_c \
+    	-Wl,-Bdynamic -llzma \
+    	-o out/example
+    ```
 
 You have the choice of linking statically (recommended) or dynamically.
+
 - The C example shows how to link statically against the `staticlib` variant.
-- When linked dynamically, you have to provide the `cdylib` at runtime in the _same_ version, as there are no API/ABI guarantees yet.
+- When linked dynamically, you have to provide the `cdylib` at runtime in the _same_ version, as there are no API/ABI
+  guarantees yet.
 
 ## Notes on differences to rust library
 
 - function names are: `sp_` \<struct_name\> \<rust name\>.
-- Instances get consumed in the same way they do when writing rust code. Do not use an instance after an (implicit!) free.
+- Instances get consumed in the same way they do when writing rust code. Do not use an instance after an (implicit!)
+  free.
 - Option<T> or Result<T, E> turn into nullable return values - check for NULL!
-- There are no specifics for C++ here yet. You might get a nicer header when generating directly for C++, but it should be usable.
+- There are no specifics for C++ here yet. You might get a nicer header when generating directly for C++, but it should
+  be usable.
 - Reading and writing to instances concurrently is not safe. Only reading concurrently is safe.
-- documentation is included in the header and available [online](https://docs.rs/servicepoint_binding_c/latest/servicepoint_binding_c/)
+- documentation is included in the header and
+  available [online](https://docs.rs/servicepoint_binding_c/latest/servicepoint_binding_c/)
 
 ## Everything else
 
-Look at the main project [README](https://git.berlin.ccc.de/servicepoint/servicepoint/src/branch/main/README.md) for further information.
+Look at the main project [README](https://git.berlin.ccc.de/servicepoint/servicepoint/src/branch/main/README.md) for
+further information.