libtock-d: D userland for TockOS

This repository contains libraries and examples of applications written in D for the userspace of the Tock Operating System.

Prerequisites

1. Get familiar with TockOS by reading the TockOS getting started guide and installing the tools you need for developing TockOS applications.

2. Clone this repository

   ~$ git clone https://github.com/DLang-IoT/libtock-d
   ~$ cd libtock-d
   

3. In order to develop and run TockOS applications, you need two specific cross compilers for embedded targets. The D userspace requires both ldc2 for compiling D source files and an arm-none-eabi toolchain used for linking the object files with the libraries. Both support Cortex-M targets.

   For ldc2 please visit the Official LDC repository on Github and install the toolchain either from the command line or from source. Make sure the runtime library's source files can be found at the following path: /usr/import/.

   For the arm-none-eabi, install the toolchain from the command line.

   MacOS:

   ~$ brew tap ARMmbed/homebrew-formulae && brew update && brew install arm-none-eabi-gcc
   

   Ubuntu (18.04LTS or later):

   ~$ sudo apt install gcc-arm-none-eabi
   

   Arch:

   ~$ sudo pacman -Syu arm-none-eabi-gcc
   

   Unfortunately, the RISC-V targets are not yet supported by the D languange.

4. Other toolchains you need are elf2tab and Rust's cargo. To correctly install the toolchains, please follow the TockOS getting started guide.

5. After installing all the required toolchains, the userspace library can be compiled by following the next steps:

   ~/libtock-d$ cd libtock
   ~/libtock-d/libtock$ make
   

Compiling and Running Applications

The D userland provides a few examples with simple applications that can be easily compiled and run using TockOS in the examples directory.

Every example comes with a Makefile that compiles the source files and creates the .tab application that will further be merged with the kernel's application.

~$ cd examples/d_hello
~/examples/d_hello$ make 

The D userland works if it is linked with the runtime library of the C userspace. This library is architecture specific, and the supported targets so far are cortex-m0, cortex-m3 and cortex-m4. Each pre-built library can be found in the corresponding directory, in libtock-c/build. The C userspace is a submodule of this repository and it is found at libtock-c/libtock-c. In order to get access to its source files and to re-build the C userspace library, follow the next steps:

~$ git submodule init 
~$ git submodule update
~$ cd libtock-c
~/libtock-c$ make

The standard runtime libraries of C and C++ for the Cortex-M targets can be also used by the D applications.

The D userspace applications are being compiled using the betterC option, so there are no available concepts like classes or Garbage Collection.

According to the board you are using, the final application can be flashed either using tockloader or openocd.

• tockloader loads the .tab application generated by the Makefile in the example directory.

  • install an application:

    ~/libtock-d/examples$ tockloader install --board <board_name> --jlink <application_name>/build/<application_name>.tab
    

  • remove an application:

    ~/libtock-d/examples$ tockloader uninstall --board <board_name> --jlink <application_name>
    

  • remove all installed applicaions:

    ~/libtock-d/examples$ tockloader uninstall --board <board_name> --jlink
    

• openocd loads an application from the kernel directory. The Tock kernel provides for each supported board a Makefile that can be modified in order to link the correct userspace application to the kernel's executable and flashed on the board with this toolchain.

Adding a new userspace library

New userspace libraries are easy to develop and compile. The libtock directory contains the source files of all userspace libraries and a Makefile that compiles them. After writing the source file, just re-compile everything like this:

~/libtock-d/libtock$ make

License

Licensed under Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)