leaninit 0.0.3

Initialized data compression for embedded systems

lean-init

Compression of initialized data for embedded systems.

Features

• Use a fast decompressor (lz4)
• Produce a fully debuggable elf file

Installation

Python package

pipenv shell
pip install leaninit

Native dependencies

The python package relies on lz4 to perform the compression and binutils to parse/edit elf files. Binutils package need to match the target CPU.

How to integrate

LD file

• User add a new section .leaninit and specify in it which sections shall be compressed.
  • Use ASCIZ statement to specify each section name.
  • Add BYTE(0) to mark the end of the list.
• Remove AT statement for sections to compress.

Start up file

• Replace uncompressed initialization loop by a call to the compressed initialization function.

C code

• Include leaninit.h in main.c.

Build system

• Invoke leansys.cli at the end of the build to generate the final elf file.

How to test

Native dependencies

The test use Renode.

Launching a test

The testit_env scripts build the python package in an isolated environment and then test the basic example for a particular build preset.

cd examples/basic
./testit_env minSizeRel

Examples overview

basic example

It is a bare metal application which outputs the full text of Saint Exupery's novel "Le petit prince" on a UART.

In this example, we compress the .data section. It contains all initialized variables including the array petitprince.

whole_fw example

It is a bare metal application which outputs the full text of Saint Exupery's novel "Le petit prince" on a UART.

In this example, we compress the whole firmware. Everything is compressed except the startup file and the decompressor. At startup the firmware is decompressed into RAM and executed from there.