prelude

                                Prelude
                                -------

Introduction
============

Prelude is a high-level language for programming embedded control
systems. It is built upon Synchronous Languages (such as Lustre) and
inherits their formal properties. It adds real-time primitives to enable
the programming of multi-periodic systems. The objective of the language
is not to replace other synchronous languages but instead to provide a
higher layer of abstraction, on top of classic synchronous languages. It
can be considered as a real-time software architecture language that
enables to assemble locally mono-periodic synchronous systems into a
globally multi-periodic synchronous system. A complete definition of the
language is available in [forgetPHD] (see Section 4 mainly). A shorter
presentation is available in [forgetSAC'10].

The preludec compiler generates synchronized multi-task C code that is
independent of the target OS. Communication is achieved by a tailor-made
buffering communication protocol. The compilation was defined formally
and produces deterministic code, which respects the real-time semantics
of the original program (period, deadlines, release dates and
precedences) as well as its functional semantics (respect of variables
consumption). Prelude compiler produces code for either monocore or
multicore architectures.

Distribution Directory Overview
===============================

- INSTALL: Installation instructions.

- README: This file.

- lib/prelude: C header files included by C code generated by Prelude
- share: C source files and makefiles to compile and link C programs generated by Prelude

- examples: Prelude program examples

- examples/sampling_loop: a complete example with everything required to
  execute it. For new users, the README there is a good starting point.

Using preludec
==============
Use preludec -help for a complete list of options.

For a standard compilation with default options, use:
preludec -node <main_node> <program.plu>

The compiler generates two C files:
<program>_c/<main_node>.c and <program>_c/<main_node>.h

The main variants for the code generation are:

-aer: produce code that follows the Acquisition-Execution-Restitution
 multi-phase task model, which splits execution into communication
 phases (A/R) and computation phases (E);
-with_encoding: communication synchronizations are ensured by precedence
 encoding mechanisms
(default): mono-phase task model+synchronizations are ensured by semaphores

In all variants, the code is completely independent from the target RTOS.

Compiling and executing code generated by preludec
==================================================

The code generated by preludec is not the complete final program. An
"integration code" is required, to build threads/tasks from the task set
defined in the generated code. This part is OS-dependent. From there,
you have several choices:

A- Using Linux+ptask
1) Install ptask from https://github.com/glipari/ptask
2) Start by following the instructions in Examples/sampling_loop/README
3) Follow the instructions in that README to adapt your own program.

B- Using SchedMCore.
Prelude integration is directly supported by the SchedMCore framework:
1) Install SchedMCore from http://sites.onera.fr/schedmcore/
2) Start by following the instructions in Examples/sampling_loop/README
3) Follow the instructions in that README to adapt your own program.

C- Using your favorite RTOS:
1) You need to implement the "integration code" that builds threads from
the code generated by Prelude. See share/ptask_wrapper.c for an example;
2) If you want to rely on the scheduling policy based on precedence
encoding, you need to implement the EDF policy modified to support
deadline words, i.e. the equivalent of the "sched/sched_pluedf.c"
included in SchedMCore source distribution.


References
==========
[forgetPHD]
J. Forget
A Synchronous Language for Critical Embedded Systems with Multiple Real-Time Constraints.
PhD thesis, ISAE, Toulouse, France, November 2009.

[forgetSAC'10]
J. Forget, F. Boniol, D. Lesens, C. Pagetti
A Real-Time Architecture Design Language for Multi-Rate Embedded Control Systems.
In 25th ACM Symposium on Applied Computing (SAC'10), Sierre, Switzerland, March 22-26 2010.

[PreludeSchedMCore-RTNS2011]
M. Cordovilla, F. Boniol, J. Forget, E. Noulard, C. Pagetti
Developing critical embedded systems on multicore architectures: the Prelude-SchedMCore toolset.
In 19th International Conference on Real-Time and Network Systems, RTNS2011, Sep. 3 2013.

[AER-RTNS2018]
Pagetti, Claire, Julien Forget, Heiko Falk, Dominic Oehlert, and Arno Luppold.
Automated generation of time-predictable executables on multicore.
In 26th International Conference on Real-Time Networks and Systems, Oct 10-12 2018.

--------------------------------------------------------------------------
  Contact Address:                          Home site:
  julien.forget@univ-lille.fr    http://www.cristal.univ-lille.fr/~forget/
                                  https://svn.onera.fr/Prelude
                                  https://forge.onera.fr/projects/prelude
--------------------------------------------------------------------------